unit one: cell biology. national 4/5 biology course unit 1 national 4/5 units: cell biology – now...

Unit One: Cell Biology

National 4/5 Biology Course Unit 1

National 4/5

Units:• Cell Biology – now till October• Multicellular Animals – October – Feb• Life on Earth – February - April


How is the course assessed?

• Course work:– 3 end of unit tests (one for each unit) –

can have resits if necessary– One Practical investigation– One mini research project (100 words)– One LARGE research project (Added

Value) (500-800 words)– NATIONAL 5 – Final exam!


Work

Classwork to be done in jotter. Remember it every day!

You will get set homework sometimes – but expected to learn the work done each day as you go along!!!


What is in Unit One?

• Cell Biology:– Cell Structure– Transport across membranes– Producing new cells– DNA and protein production– Genetic engineering– Proteins and enzymes– Aerobic respiration– Photosynthesis

1: Cell Structure


Level What you need to be able to do…

4/5 Label an animal cell – Cell membrane, cytoplasm and nucleus

4/5 Label a plant cell – Cell wall, cell membrane, cytoplasm, nucleus, chloroplast and vacuole

4/5 State the function of all the parts of animal and plant cells listed above

5 Identify the mitochondria and ribosomes in a cell diagram

5 Explain the function of a mitochondria and a ribosome

5 Label a bacterial cell and explain the differences between it and other types of cell.

5 Label a fungal cell and explain the differences between it and other types of cell.


Cell Structure

Cells are the building blocks of all life.

Cells video

http://www.youtube.com/watch?v=gFuEo2ccTPA


Cell StructureWe will be looking at 4 different cell types:-

• Animal cells• Plant cells• Bacterial cells, and • Fungal cells.

You have already looked at the basic structure of animal and plant cells in S1- S3. We will be looking at all of these cells in greater detail.


What can you remember from last year?

Task One: Complete the revision worksheet on cells.


Cell Structure

Task 2: Prepare slides for examination under a light microscope.

Using the help sheets provided prepare one type of slide – cheek cell, onion cell or Elodea pondweed. After you have examined your own slide share your slide with a group that has prepared a different slide . You should look at all 3 cell types.


Cheek Cells

These are cheek cells viewed at 100x magnification using a light microscope.

http://www.stancoe.org/patterson/cms/staff/humancheekcellwebpage.htm


Onion Skin Cells

These are onion skin cells viewed at 40x magnification using a light microscope.

http://www.baileybio.com/plogger/images/biology/lab_-_plant___animal_cells/onion_cells.jpg

http://www.baileybio.com/plogger/images/biology/lab_-_plant___animal_cells/onion_cells.jpg


Elodea Pondweed CellsThese are Elodea pondweed cells viewed at 100x magnification using a light microscope

http://seys-science.wikispaces.com/elodea+g


Cell StructureWe will now look in more

detail at the structure of animal and plant cells.

To see more detail or the ultra structure of cells we need to use and electron microscope.

Image from Wikipedia commons http://en.wikipedia.org/wiki/File:Electron_Microscope.jpg


Cell Structure - Organelles

Organelle is the name given to the structures found inside the cell e.g. Nucleus, vacuole, chloroplasts etc.

You need to know about 2 more organelles.

Mitochondria and Ribosomes


MitochondriaMitochondria are the power houses of

cells. They convert energy into forms that are usable by the cell. They are found in the cytoplasm and are the sites of cellular respiration which generates fuel for the cell's activities.

Mitochondria are found in the cytoplasm of the cell.


Electron microscope image of a mitochondrion

(credit: Tom Deerinck and Jeff Martell/MIT)

http://people.eku.edu/ritchisong/ritchiso/mitochondrion2.gif


RibosomesRibosomes can be found

floating free in the cytoplasm or attached to another type of organelle called Rough Endoplasmic Reticulum or R.E.R. for short. (you don’t have to know about R.E.R!)


http://bioweb.uwlax.edu/genweb/molecular/theory/translation/ribosome.jpg

http://www.cbv.ns.ca/bec/science/cell/page11a.gif

Electron Microscope image of ribosomes.

Ribosomes are responsible for

protein synthesis, i.e. this is where

amino acids are assembled into

proteins.


Cell Structure – Organelles

Task 3 – Collect the diagram sheets of the animal cell and the plant cell. Label any structures you recognise.

You will need to include:- Cell membrane, nucleus, cell wall, vacuole, chloroplast, cytoplasm, ribosome and mitochondria.


Animal Cell Diagram

Nucleus

MitochondrionRibosomes

Cell Membrane

Cytoplasm


Plant Cell Diagram

VacuoleChloroplastNucleus

Ribosomes Mitochondria

Cell Wall

Cell MembraneCytoplasm


Cell Structure - Organelles

Task 4 – Collect and complete the worksheet :–

Cell structures and functions.


Bacterial Cells

“For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria.”

Richard Dawkins


BacteriaTThey are the oldest living organisms on earth. They are everywhere. We find them on and in the human body, in the air we breathe, on the surfaces we touch, in the food we eat. Almost 99% of these bacteria are helpful, whereas the remaining are the notorious ones. Some are essential for proper growth of other living beings. They are either free-living or form a symbiotic relationship with animals or plants.

http://en.wikipedia.org/wiki/File:Gram_Stain_Anthrax.jpg


Bacteria

Task 1 : Using the information cards, list the helpful and harmful bacteria with a brief description of why they are useful or what disease they cause.Bacteria Helpful of harmful Why are they useful

or what disease do they cause?


Structure of BacteriaBacteria can occur in different shapes.

However their basic structure is the same.

Task 2: Collect the bacterial cell diagram handout and the information sheet.

Use the information to complete the labels on the diagram and to complete the table.


Capsule

Genetic material

Cell Wall

Plasmid

Cell Membrane

Cytoplasm


Structure Function and importance

Capsule

Cell Wall

Cell Membrane

Genetic Material

Plasmid

Cytoplasm

Provides additional protection from the environment

It strengthens and supports the cellControls the movement of substances into and out of the cell

Made of DNA and controls the activities of the cell

Circular genetic material. Can convey special abilities, e.g. a resistance to certain antibiotics. They can be manipulated by man to produce bacterial cells that produce useful products e.g. Insulin, hormones and enzymes.Most chemical processes take place here controlled by enzymes


Fungal CellsFungi are one of the most important

groups of organisms on the planet. They are important in an enormous variety of ways: -

Task 3: Listen and take brief notes to produce a spider diagram of the importance of fungi.


Recycling

Fungi, together with bacteria, are responsible for most of the recycling of nutrients returning dead material to the soil in a form in which it can be reused. Without fungi, these recycling activities would be seriously reduced.

http://commons.wikimedia.org/wiki/File:Chanterelle_Cantharellus_cibarius.jpg


Fungi are vitally important for the good growth of most plants, including crops. They do this through the development of mycorrhizal associations which help plants obtain more nutrients from the soil.

Mycorrhizae and plant growth

http://en.wikipedia.org/wiki/File:Mycorrhizal_root_tips_(amanita).jpg


FoodFungi are also important directly as food for

humans. Many mushrooms are edible and different species are cultivated for sale worldwide. Fungi are also widely used in the production of many foods and drinks. These include cheeses, beer and wine, bread, some cakes, and some soya bean products.

http://en.wikipedia.org/wiki/File:Asian_mushrooms.jpg


MedicinesPenicillin, perhaps the

most famous of all antibiotic drugs, is derived from a common fungus called Penicillium. Many other fungi also produce antibiotic substances, which are now widely used to control diseases in human and animal populations.

Photo by: Dr. David Midgley Cultures: Dr. David Midgley University of Sydney, Australia.


BiocontrolFungi such as the Chinese caterpillar

fungus, which parasitise insects, can be extremely useful for controlling insect pests of crops. The spores of the fungi are sprayed on the crop pests which then infect the insect resulting in its death. Fungi have also been used to control Colorado potato beetles, spittlebugs, leaf hoppers and citrus rust mites. This method is generally cheaper and less damaging to the environment than using chemical pesticides.

Author : L. Shyamal http://upload.wikimedia.org/wikipedia/commons/9/94/CordycepsSinensis.jpg


Crop Diseases

Fungal parasites may be useful in biocontrol, but they can also have enormous negative consequences for crop production. Some fungi are parasites of plants. Most of our common crop plants are susceptible to fungal attack of one kind or another. Spore production and dispersal is enormously efficient in fungi and plants of the same species crowded together in fields are ripe for attack. Fungal diseases can on occasion result in the loss of entire crops if they are not treated with antifungal agents.


Animal DiseaseFungi can also parasitise domestic animals causing

diseases, but this is not usually a major economic problem. A wide range of fungi also live on and in humans, but most coexist harmlessly. Athletes foot and Candida infections are examples of human fungal infections.

Author:James Heilman, MD http://en.wikipedia.org/wiki/File:FeetFungal.JPG


Food SpoilageIt has already been noted that fungi play a major

role in recycling organic material. The fungi which make our bread and jam go mouldy are only recycling organic matter, even though in this case, we would prefer that it didn't happen! Fungal damage can be responsible for large losses of stored food, particularly food which contains any moisture. Dry grains can usually be stored successfully, but the minute they become damp, moulds are likely to render them inedible. This is obviously a problem where large quantities of food are being produced seasonally and then require storage until they are needed.


Structure of a fungal cell

Task 4: Collect the diagram sheet and label any of the structures and organelles you recognise.


Structure of a fungal cell

Cell Wall

Cell Membrane Vacuole

CytoplasmNucleus


All the cell parts are now familiar. You should be able to compare all the cell types and identify which parts are similar and which are not. While all the cell parts have the same functions as before there is one difference.

The fungal cell wall.

Just as the bacterial cell wall has a different chemical structure from a plant cell wall, so does the fungal cell wall.

The fungal cell wall is made from a chemical called chitin.


It is important that you know

The cell walls in plant, bacterial and fungal cells is structurally and chemically different.


Homework

Collect the homework sheet :-

Cell Structure – Review Homework

2. Transport across cell membranes



4/5 Describe the structure of the cell membrane

4/5 Explain what happens during diffusion

4/5 Explain what happens during osmosis

5 Describe the effects of different water concentrations on animal and plant cells

5 Explain the difference between passive and active transport


Cell membrane

•The thin, flexible cell membrane enclosing the cell contents controls which substances may enter and leave the cell.


•The cell membrane (or plasma membrane) is made up of a bilayer of lipids with protein scattered throughout and is selectively permeable.

•Proteins can;– be attached to the surface– be embedded within the bilayer– span the whole bilayer– form channels in the lipid bilayer

The Cell Membrane


•Small molecules can pass through pores in the membrane made by channel forming proteins and enter or leave the cell. This is why the plasma membrane is selectively permeable.

• This transport of molecules is passive and requires no energy as it is with the concentration gradient.


•When molecules in gases or liquids are unevenly distributed we say that a concentration gradient exists.

•Because the molecules are constantly moving around they tend to distribute themselves evenly, i.e. they always move from an area of high concentration to an area of low concentration, down the concentration gradient.

Concentration Gradients


High

Low

Con

cent

ratio

n

Area 1 Area 2

Molecules move down the concentration gradient


•Teacher demonstration of diffusion


•Diffusion is the name given to this movement of the molecules of a substance from a region of high concentration of that substance to a region of low concentration of that substance until the concentration becomes equal.

Diffusion


• Cut a 20cm piece of visking tubing and tie a knot in one end.

• Soak the tubing in water and never let it dry out during the experiment.

• Fill the visking tubing with 5-10cm3 starch and glucose solution and seal with another knot.

• Place this in a boiling tube of water completely submerged and leave until the next lesson.

Diffusion Activity


Take a small sample of the water from around the test tube. Test for starch and sugar

Test for

starch

1. Put sample on tray

2. Add 4 drops of IODINE

3. If starch is present it goes from brown to black

Test for

sugarBOILING WATER

1. Put sample in test tube – IN a beaker of BOILING WATER

2. Add 4 drops of BENEDICTSSOLUTION

3. If sugar is present it goes from blue to orange


•Perform Benedict’s test and starch test on the water in the boiling tube from Diffusion in a Model Cell experiment you set up last lesson.

•Explain your results in terms of diffusion. (LO1 assessment).

Activity


Importance of diffusion to cells

In an animal cell, food (such as glucose), oxygen and carbon dioxide will diffuse like this:


GlucoseOxygen

Carbon dioxide


Substances which diffuse in or out of cells

Diffuse IN Diffuse OUT

Oxygen (raw material for respiration)

Carbon dioxide (waste from respiration)

Carbon dioxide (PLANTS ONLY, raw material for

photosynthesis)

Oxygen (PLANTS ONLY, made in photosynthesis)

Glucose (raw material for respiration)

Urea (a cell waste product)

Amino acids (raw materials to build the cell)


Osmosis: the diffusion of water


•The diffusion of water through a selectively-permeable membrane from an area of high concentration of water molecules to an area of low concentration of water molecules is called osmosis.

Osmosis


Osmosis words

Isotonic – same water concentration.

Hypotonic – High water concentration e.g.. Pure water

Hypertonic – Low water concentration e.g. water with sugar and salt dissolved in it.


Effects of Osmosis on Plant Cells

Cells in a dilute/ hypotonic solution become turgid

Cells in the same/ isotonic solution stay the same.

Cells in concentrated/ hypertonic solutions become flaccid.

Plasmolysed cell – cytoplasm is pulled away from the cell wall.


Turgid Cells•Osmosis makes plant cells

swell. Water moves into the plant cell vacuole and pushes against the cell wall. The cell wall stops the cell from bursting. We say that the plant is turgid. This is useful as it gives plant stems support.


Flaccid Cells• If a plant lacks water, it wilts

and the cells become flaccid as water has moved out of the cell. If alot of water leaves the cell, the cytoplasm starts to peel away from the cell wall. We say the cell has undergone plasmolysis.


Osmosis in Animal Cells

Cell placed in distilled water/hypotonic solution

Cell placed in concentrated/hypertonic solution


•Active transport is the movement of molecules across a cell membrane from a low to a high concentration i.e against a concentration gradient.

•Active transport works in the opposite direction to the passive transport of diffusion and always requires energy.

•This energy is released during respiration.

Active Transport


ENERGY


•Active transport carriers are often called pumps.

•In this example, the same carrier molecule actively pumps sodium ions out of the cell and potassium ions into the cell, each against a concentration gradient.

•Video clip

Sodium/potassium pumps

3. Producing New Cells



4/5 Describe what happens during mitosis

4/5 Explain what the chromosome complement is and why it important that it is maintained

4/5 Explain how mitosis (cell cycle) is controlled and how this can lead to cancer


Everyone in this room started life as a single cell, a fusion of

a sperm and egg cell.

What processes must have happened to develop you

from that single cell?


How many new cells do you think you will make in

a day?Cell Division throughout Life


330 000 000 in 20 minutes so…

23,760,000,000 new cells every day!


What do these pictures all have in common?


They are all examples of Cell Division in action for growth

or repair!


How do Cells Divide?

Mitosis – watch this clip on the process of mitosis and answer the following questions:1.How are new cells produced?2.What are chromosomes? Where are they found?3.What kind of cells undergo mitosis?4.What are the only kind of cells that do not undergo mitosis?


Put the following stages of mitosis in the correct order:

• New nuclear membranes form around the chromosomes, followed by new cell membranes, creating two new identical cells.

• Chromosomes replicate to form identical chromatids.

• Spindle fibres then pull the matching chromatids apart, to opposite poles of the cell.

• The membrane around the nucleus breaks down, and spindle fibres attach to the chromatids and line them up in the centre of the cell - equator.


Why do chromosomes need to be copied so carefully and put into

each new cell?• Chromosomes carry GENES, which are

stretches of DNA. • Each GENE codes for one protein e.g.

one gene codes for haemoglobin, the substance in red blood cells that carries oxygen. Other genes will code for other molecules that make up the body.


Chromosome Complement

• The number of chromosomes that a species of animal or plant possesses.

• Why so you think it is important that each new cell has the same chromosome complement as the parent cell?


• During growth and development of an organism will be able to provide the animal or plant with all the characteristics of its species.

• Losing any chromosome would mean a loss of genetic information – the information that forms the code allowing the cell to function correctly!


The Cell Cycle

Second Growth Phase

First Growth PhaseDNA

Synthesis


What happens in each phase?

• First Growth Phase - Cell grows and increases in mass by adding cytoplasm, cell membrane and cell wall (if it is a plant). The materials needed for DNA replication are made.

• DNA Synthesis phase – DNA is replicated. We’d see the chromosomes replicate and become chromatids.


• Second Growth Phase - It’s another period of growth. The cell builds up an energy reserve to last it through the rest of the process and proteins necessary for cell division are made.

• Mitosis Phase – Mitosis takes place and cell divides.


Need for Checkpoints

• We know that it is important that each new cell produces is identical to the parent cell and can perform the same function.

• The cell self checks at THREE stages to make sure that it is ready to proceed.

• If the cell is not ready then it should not proceed to the next stage and if there is something wrong then the cell should not divide at all but should be destroyed!


The Cell Cycle

Second Growth Phase

First Growth PhaseDNA

Synthesis

Checkpoint One

Checkpoint Two

Checkpoint Three


What are the checkpoints?• End of First Growth Phase. Checking the Cell

Size – is the cell big enough to continue? Yes – go to S phase!

• End of Second Growth Phase. Has the DNA been copied correctly? Is DNA replication complete? Has the cell enough energy/materials to continue. Yes – can enter mitosis!

• During mitosis, have the chromatids been pulled apart correctly? Then the cell can divide!


What would happen if the controls failed?


What goes wrong in Cancer?

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2

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2 3 33 33

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33

33

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Increased cell division = more cells

Decreased cell death = more cells

Loss of contact inhibition – the cells no longer stay in one place

Ability to invade surrounding tissues

Ability to move - metastasis

Loss of DNA Repair

Escape from immune surveillance = cells not destroyed


Cancer cells – Research Task1. Find out the meaning of the following terms…

• Benign• Malignant• Metastasis2. Research a type of cancer and find out the

following:• What part of the body does this cancer affect?• What are the clinical symptoms?• How common is this cancer (in the UK)?• What is the treatment given for this cancer?• What research is being done on this cancer? • Is there a charity fundraising to help support

people affected by this type of cancer?

4. DNA and Protein Production



4/5 Explain what is meant by DNA, genes and chromosomes

5 Describe structure of a nucleotide

5 State the letters which identify the 4 different bases and how they pair up

5 Explain how the genetic code works

4/5 Explain the structure of proteins


What is DNA?

Watch the following video that introduces DNA and its importance.

DNA video


DNA, genes and chromosomes

ChromosomesThe cell’s nucleus contains chromosomes made from long DNA molecules.

DNADNA molecules are large and complex. They carry the genetic code that determines the characteristics of a living thing.

GenesThink back to the last section!


DNA, genes and chromosomes

The diagram shows the relationship between the cell, its nucleus and the chromosomes in the nucleus that are made up of DNA, and genes.

DNA

Collect the handout sheet and stick it into your jotters.


From Genes to Proteins?

Watch the following video that gives a basic definition of a gene and what genes do.

What exactly is a gene?


DNA Structure

DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix.

A molecule of DNA is made up of millions of tiny subunits called Nucleotides.


Nucleotide Structure

Each nucleotide consists of:

PhosphateGroup

DeoxyriboseSugar

OrganicBase

Copy this diagram into your jotters.


DNA StructureThe phosphate and

sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”. Collect the handout and stick it into your jotters.


The Genetic CodeThe genetic code determines the order in

which amino acids are joined together to produce a specific protein.

The code itself is determined by the order of the organic bases in the DNA molecule.

There are 4 different bases.

Guanine Cytosine Adenine and Thymine


Each base can only join with one other type of base:-

Guanine always pairs with CytosineAdenine always pairs with Thymine

G-Cand A-T

These are called complementary base pairs.


Complementary Base Pairs


Build your own DNA Molecule

Task 1: Collect the handout sheets

DNA origami instructions and template

Follow the instructions to complete your own model DNA!


Protein StructureProteins are made up of amino acids.

The order of the amino acids determines the proteins molecular structure, its shape and its function.

The order of the amino acids is determined by the order of the bases in the DNA molecule – the genetic code.


So how does the genetic code get translated into a protein?


Watch AgainWatch the ‘What is DNA?’ video again. This time try to answer the following questions:- Video

• How is the genetic code from the DNA molecule copied?

• What happens to the copy of the genetic code? Where does it go?

• In which organelle is the copy of the genetic code translated to form proteins?

• How are the proteins formed?


Translating the genetic code

Task 1: Using the information in the video, the questions and discussion with your teacher write a short paragraph to describe how the genetic code from the DNA is translated into a protein.

You could use a diagram to help illustrate you description.


Translating the genetic codeThe genetic code in the DNA is copied or transcribed by another molecule called Messenger RNA (mRNA).

The mRNA carries the code out of the nucleus to the ribosomes in the cytoplasm.

The ribosomes then translate the code from the mRNA into the specific protein using amino acids found free in the cytoplasm.


mRNA

The DNA for the gene being turned into a protein is copied into a mRNA molecule.

It is different from DNA, it is:• Shorter• Single stranded• Have URACIL instead of THYMINE.


How does mRNA become a protein

Every 3 letters in the mRNA tell the ribosome which amino acid to add to the protein.

A U G C G A U G G A C G mRNA

Alanine Serine Glycine Proline


Translating the genetic code

Task 3: In groups produce an A4 poster to illustrate protein synthesis.

Your poster should contain the following information:-

• DNA carries the genetic code for producing proteins• mRNA copies the code• mRNA carries the copy of the code to the ribosomes• The ribosomes translate the copy of the code to produce proteins


Glossary of terms

Task 4: Homework – collect the handout

Glossary of Terms – DNA and the production of proteins.


Research Task – Who Discovered DNA?

Your task is to write an essay or newspaper/magazine article that discusses the scientists who played significant roles in the discovery of DNA, its structure and its importance.

You should include:

• James Watson, Francis Crick, Rosalind Franklin, Maurice Wilkins and Erwin Chargaff and any other scientist you think is important.• The importance of the roles they played in the discoveries about DNA, including dates.• Any special recognition they received (or did not receive) for their discoveries

Your work should be at least one side of A4 and should contain some illustrations. Your work should be in your own words and not copied and pasted directly from the web.

5. Genetic Engineering



4/5 Describe the process of genetic engineering

4/5 List examples of how genetic engineering has been used

5 Describe what is meant by a GM organism and why it might be controversial


What is genetic engineering?

What is it used for?


Watch the following clip on Genetic Engineering and in pairs answer the following questions:1.What 3 things are produced by genetically modifying microbes?2.Name the first organisms to be genetically modified and when this was done.3.What does insulin normally do? What condition arises from not making insulin?


GMO Defined…• An organism that is generated through

genetic engineering is considered to be a genetically modified organism (GMO).

• The first GMOs were bacteria in 1973; GM mice were generated in 1974. Insulin-producing bacteria were commercialized in 1982 and genetically modified food has been sold since 1994.


The process of Genetic Engineering

• The control of all the normal activities of a bacterium depends upon its single chromosome and small rings of genes called plasmids.

• In genetic engineering pieces of chromosome from a different organism can be inserted into a plasmid. This allows the bacteria to make a new substance.


Task 1 – Use the cut out sheet and put the stages of genetic engineering in the

correct order. Use the following diagram to

help you.


Uses of Genetic Engineering 1

Genetic engineering is used for the production of substances which used to be both expensive and difficult to produce. Examples include:•insulin for the control of diabetes•antibiotics such as penicillin•various vaccines for the control of disease•enzymes for laundry detergent


Uses of Genetic Engineering 2

Genetic engineering is a way of producing organisms which have genotypes best suited for a particular function. In the past man has used selective breeding to achieve this. This was done by choosing only his most suitable animals and plants for breeding.


Genetic engineering has several advantages over selective breeding. Some are:

• particular single characteristics can be selected

• the selection may be quicker• a desirable characteristic can be transferred

from one species to another


Genetic Engineering – now and the future?

• It is not just bacteria that can be genetically modified, plants and animals can be modified too.

• It is therefore possible to genetically engineer people!

• It holds the promise of curing genetic diseases like cystic fibrosis, and increasing the immunity of people to viruses.


• It is speculated that genetic engineering could be used to change physical appearance, metabolism, and even improve mental faculties like memory and intelligence, although for now these uses seem to be of lower priority to researchers and are therefore limited to science fiction.


Issues?

• There are dangers involved with genetic engineering since it involves creating completely new strains of bacteria. There is a possibility of creating some which are harmful to animal or plant life.

• What is your opinion on GM Food (plant and animal), GM organisms for research and GM People?


Task 2 – Genetically Engineering the Future

• Thinking about the possibilities and issues surrounding genetic engineering, I want you to imagine 50 years from now. Technology has moved on and GMO is commonplace in agriculture, medicine and all organisms.

• Write a letter to your present self, describing this new world. Be honest in this letter, what are the good and bad points about GMO in the future?


Therapeutic Uses of Cells - HeLa Cell Line


Henrietta Lacks

Listen as your teacher reads out the poem “The Life and Life of Henrietta Lacks” by Carol Satyamurti.


Task 1 – Find out more…using the Fox Thinking Tool

1. In pairs divide the information sheets about Henrietta Lacks and the HeLa Cell Line and spend time reading through them.2. Individually on a piece of paper/card or sticky note write a brief summary of what you have read3. Individually on a second piece of paper/card or sticky note write your opinions of what you have read4. Talk to your partner to exchange findings and ideas about the section you have read. 5. Compare your pairs ideas with the rest of your group/table by carrying out a quick “sweep” of the information that you write down.6. Stick the summaries and opinions on the poster paper to form a “doughnut” or ring shape7. In the middle of “doughnut” give the points (3-5) the group thinks are the most important8. Around the outside give the reasons (3-5) why the group thinks these are most important •You will then be asked to use your work to discuss a Key Question


The story of Henrietta Lacks and the HeLa Cell Line bring up a lot of issues including:

1. Scientific progress and the possibilities of human cloning

2. Scientific ethics (the rights and wrongs in how things are done)

3. The moral and legal aspects of cloning – for example, if you are cloned, will you be you, or something like your own child, or a completely new person?

4. Aspects of social history, relating to – Poverty– Gender– Race


The Key Question to debate:

Should scientists be free to use our cells in scientific

research such as in the case of the HeLa Cell Line?


• Further Reading: The Immortal Life of Henrietta Lacks by Rebecca Skloot.

6. Proteins and Enzymes



4/5 Explain what enzymes do and what the main features of an enzyme are

4/5 Give 3 named examples of chemical reactions carried out by enzymes and be able to draw the word equations

4/5 Explain how temperature effects enzyme activity

4/5 Explain how pH effects enzyme activity

4 Describe some uses of enzymes in industry e.g. Biological detergents and rennet in cheese making


Protein structure

• Proteins are made up of sub-units called amino acids.

• There are 21 amino acids.• The order of amino acids in a protein

is dictated by the genetic code.• Every protein has different amino

acids in different orders.


• The order of the amino acids affects the shape of the protein.

• Proteins can be fibrous or globular:• GLOBULAR – enzymes• FIBROUS – keratin (hair)


Catalysts

A catalyst speeds up a chemical reaction, but is unchanged in the process and can be used over and over again.

In living things, catalysts are known as enzymes.


If cells did not have enzymes in their cytoplasm, then the chemical reactions which happen in our cells would happen so slowly that life would be impossible!


An example of an enzyme: CATALASE

Hydrogen peroxide (H2O2) is a liquid similar to water (H2O), but with one extra oxygen.

Over a long period of time hydrogen peroxide naturally breaks down into water and oxygen.


The word equation for this reaction is:

Hydrogen peroxide water + oxygen

This process can be sped up using an enzyme.


Into each test tube – measure out 5 ml of Hydrogen peroxide AND 5 drops of

detergent.

CAUTION!!

Hydrogen peroxide is a dangerous chemical.

Safety goggles must

be worn!!

1. Add nothing 2. Potato 3. Carrot 4. Liver

Leave for 10 minutes. Measure the height of the foam bubbles.


Test tube contents Height of foam (mm)

Nothing – “CONTROL”

Potato

Carrot

Liver


Conclusion

Only the plant and animal tissues speed up the breakdown of hydrogen peroxide.

This is because the cells contain catalase. Catalase is an enzyme found in living cells.


CatalaseHydrogen peroxide water +

oxygen

The tissue which contained the most catalase was ______________.


Breakdown and Synthesis

Catalase is an enzyme involved in chemical breakdown.

“Breakdown” means chopping up larger molecules into smaller molecules.


Other enzymes do the opposite – the build large molecules from smaller molecules. This is called synthesis.


An example of a synthesis enzyme: Phosphorylase

Glucose-1-phosphate is a chemical made by plants during photosynthesis. It is stored in plant cells be converting it into a large molecule called starch.


Phosphorylase

PhosphorylaseGlucose-1-phosphate Starch


Substrates and products

The substrate is the substance the enzyme works on.

The product is the substance the enzyme makes.

EnzymeSubstrate Product


Enzyme Substrate Product

Catalase

Phosphorylase

Amylase

Pepsin

Lipase


How enzymes work

Enzymes are made of protein. This protein has a special shape which is unique to each enzyme.

Enzyme Active site


Enzyme

The active site is the correct shape to fit the substrate.

Substrate

Enzyme

Substrate

Turned into the products


Enzyme

Substrate

Other substrates are the wrong shape to fit in the active site of the enzyme.

Therefore the enzyme will only work with one substrate. This is described as being SPECIFIC.


“Specific”

When talking about enzymes, SPECIFIC means that the ENZYME WILL ONLY WORK WITH ONE SUBSTRATE.


One enzyme = one substrate

5 ml Starch 5 ml Starch 5 ml Starch 5 ml Starch

3 ml Water 3 ml Amylase 3 ml Pepsin 3 ml LipasePut in waterbath for 10 minutes. Test all 4 test-tubes with

Benedict’s Solution


Results

Sugar present?

Starch + water

Starch + amylase

Starch + Pepsin

Starch + Lipase


Conclusion

The test-tube containing Starch and Amylase had the most sugar.

This shows that only Amylase can convert starch to sugar.

Amylase is said to be SPECIFIC to starch.


Effect of temperature on enzymes


5 ml Starch 5 ml Starch 5 ml Starch

3 ml Cold Amylase 3 ml Amylase 3 ml 80oC Amylase

Iced water 37oC 80oC

Put in waterbath for 10 minutes. Test all 3 test-tubes with Benedict’s Solution


Temperature Was sugar present?

0 oC

37 oC

80 oC


All enzymes have a temperature at which the work fastest.

This is called the optimum temperature.

In humans the optimum temperature for all enzymes is 37oC.


Enzymes work slowly at cold temperatures.


At very high temperatures enzymes become changed and do not work.

This is called being denatured.

Once an enzyme is denatured it will never work again.


The effect of pH on enzymes

Into all 5 test tubes put 5ml Hydrogen Peroxide and 5 drops of soap

3ml pH1 buffer 3ml pH4 buffer 3ml pH7 buffer 3ml pH9 buffer 3ml pH 14 buffer

LAST: Add 1 cm cylinder of potato to each test tube. Measure height of foam after 10 minutes.


Results

pH Height of foam (mm)

1

4

7

9

14


Conclusion

The optimum pH for the catalase enzyme is pH _______.

All enzymes have a different optimum pH depending on where they are found in the body.

Uses of enzymes

Yoghurt and cheese making Biological detergents


Yoghurt and cheese

Yoghurt and cheese making depend on the activities of enzymes in bacteria.

Bacteria used lactose sugar in milk as a source of energy.


They make the waste product called lactic acid which makes the milk increasingly acidic and sour tasting.

Lactose energy + lactic acid


• This is another example of fermentation.


1. Yoghurt making• Milk is heated to kill microbes• Special yoghurt bacteria are added• The lactose in the milk is fermented

by the bacteria.• The milk becomes acidic and so it:

– Thickens– Tastes sour


2. Cheese making

The process is similar to yoghurt making, but after the fermentation, rennet is added which curdles the milk.

The solid curds are separated from the liquid whey.

The curds are then pressed into hard cheese.


Task 3 – Note Taking

• The following slides will tell you about biological detergents; how they are made, why they are useful and their environmental impact.

• Your task is to take notes from the slides – this could be mind mapping key words and concepts under the headings above or a table of information or bullet point. Decide quickly which method you find most useful when revising and try it this way.


How Biological Detergents are produced:

• Biological detergents contain enzymes such as protease, amylase and lipase to digest proteins, starch and fats respectively.

• Enzymes can be produced using bacteria that have been genetically engineered to make these enzymes. They are grown in industrial fermenters in vast quantities. This equipment ensures that the bacteria receive food and oxygen so that they grow well. The bacteria will produce the enzymes and pass them out into the culture liquid. The bacteria and the filtered off and the enzymes extracted from the liquid. The enzymes are purified and added to washing powder.


Value and Use of Product:

• Advantages of using biological detergents include reducing fuel costs as clothes can be washed at lower temperatures reducing the electricity consumption; Less damage to delicate fabrics such as acrylic and wool whilst still cleaning effectively and the ability to remove difficult stains such as grass and blood. These will be completely removed by biological washing powder but not by non-biological even at high temperatures.


Environmental Impact 1:

• Reduced Fuel Consumption - using Biological Detergents has a positive impact on our environment as it reduces CO2 and SO2 production from burning fossil fuels in Power Stations to generate electricity.


Environmental Impact 2:

• Detergents are rich in chemicals called phosphates. This chemical passes from waste water from people’s homes to sewage works. Unfortunately it is hard to remove during processing and can end up in local rivers where they cause algal bloom. This single celled plant can overwhelm the balance of the ecosystem and when it dies can cause bacterial numbers to increase. The bacteria use up oxygen in the water which leads to the death of other organisms.


Task 3 – Note Taking

• Your task was to take notes from the slides – it would be useful to check your notes with a peer. Have you covered similar key areas?

• If you are not sure, the check with your teacher!


Task 4 – Write a Newspaper Article

OPTION 1 – Write a newspaper article advocating the Use of Biological Detergents. This should look favourably on their usage, highlighting their value rather than any negative aspect.

OPTION 2 – Write a newspaper article examining the Environmental Impact of Biological Detergents. In this option you should be highlighting why people should not use these and the damage that they can cause.

BE AWARE: Be sure that you justify your argument with facts and do not make up “facts” to suit your argument!

This task has to be completed for homework.


Task• Create a Summary of

Enzymes. This can be done in any format you choose; bullet point notes, mind map, poster. Before you start think about how you learn and what you create should be suited to your learning style – do you need colour? Or pictures? Or real life examples?

• The summary should include information about the following:

• Enzymes are Biological Catalysts

• Enzymes are protein• Enzymes are specific (active

site)• Enzyme activity is affected

by pH and temperature• They have optimum

conditions and can be denatured

• Enzymes are used in a variety of industries including producing detergents and making cheese


Peer Review

• Check your table and summary with a peer to check that you have both covered all the key areas!

7. Respiration



4/5 Explain what cells need energy for

4/5 Write the word equation for aerobic respiration

5 Explain what ATP is and draw its structure

5 Explain how ATP is produced in the cell and how many ATP are produced for each molecule of glucose

5 Explain what happens during glycolysis

4/5 Describe what is meant by anaerobic respiration

5 Explain what the products of anaerobic respiration are in humans and yeast

4 Explain how anaerobic respiration can be used to benefit man (fermentation in yeast – breadmaking and brewing)

4 Explain how exercise and training can improve your recovery time


Why do cells need energy?


Respiration

Why do cells need energy?

Living cells need energy to carry out a variety of cell functions.

energy in

living cells

cell growth

muscular contraction

cell division

nerve impulses

building up large molecules

chemical reactions


energy from food


• The three main food groups are _____, ____________, and __________.

• _____ contains the most energy.


Aerobic Respiration

glucose+oxygen +water

carbon dioxide

energy released

Energy in a cell is produced by a chemical reaction called aerobic respiration.


ATP

The energy produced during aerobic respiration is stored in a molecule called ATP (Adenosine triphosphate).

Every molecule of glucose that is “burned” in the cell produces 38 ATP molecules.


ATP structure

ATP is made up of one Adenosine and three phosphates

3 PHOSPHATE GROUPS

ADENOSINE

High Energy Bond

P P P


ATP is made by joining ADP (Adenosine diphosphate) and phosphate.

ADP Pi ATP


• As a molecule to transfer energy in cells

Glucose+

Oxygen

Carbon Dioxide

+Water

Energy

Energy

ATP

ADP+Pi

e.g. Amino Acids

Protein molecul

e

Energy

Energy

RESPIRATION ENERGY TRANSFER

WORK


Respiration should be seen as a series of enzyme controlled reactions in which

• 6-carbon glucose is oxidised (broken down) to form carbon dioxide

• this is accompanied by the synthesis of ATP from adenosine diphosphate (ADP) and inorganic phosphate (Pi).

Glycolysis


2ADP + 2Pi

Pyruvic Acid

Glucose

2ATP

(6C)

(2x3C)


The first stage of respiration is called Glycolysis.

• This process takes place within the cytoplasm.

• does not require oxygen• involves the step by step breakdown of a

6-carbon sugar such as glucose to form two 3-carbon pyruvic acid units

Glycolysis results in a production of 2ATP.


What happens next?

If there is oxygen available ( the normal situation), then the pyruvic acid produced by glycolysis diffuses into an organelle called mitochondrion for further breakdown if oxygen becomes available.


Structure of a Mitochondrion

Outer Membrane

Cristae

Matrix Fluid

Inner Membrane


• Pyruvic acid from glycolysis diffuses into central matrix fluid

• Pyruvic acid is broken down further in the presence of oxygen by a cycle of reactions called the Kreb’s cycle releasing most of the 38 ATP produced during respiration


Anaerobic respiration

• If there is no Oxygen- Anaerobic Respiration occurs.

• Anaerobic respiration occurs in human after heavy exercise.


Pyruvic acid is converted to either(i) Lactic Acid (in animal and bacterial cells)(ii) Ethanol and carbon dioxide (in plant and

fungal cells)

• No further ATP is made – so only the net 2 ATPs are produced.

• In animal cells the Lactic Acid is converted back to Pyruvic Acid when oxygen becomes available.


Complete this summary table

Aerobic respiration

Anaerobic respiration Humans Yeast/Plant

Site in the cell

Number of ATP

Final products


Complete this summary table

Aerobic respiration

Anaerobic respiration Humans Yeast/Plant

Site in the cell

Cytoplasm &

Mitochondria

Cytoplasm Cytoplasm

Number of ATP

38 2 2

Final products

Carbon dioxide &

water

Lactic acid Ethanol & Carbon dioxide

8. Photosynthesis



4 Explain the importance of plants and give examples of the uses of named plants e.g. food, raw materials and medicines

4/5 Explain the importance of photosynthesis

4/5 Write the word equation for photosynthesis

4/5 Describe how to test a leaf for starch

5 Explain what happens in the first stage (light reaction) of photosynthesis

5 Explain what happens in the second stage (carbon fixation) of photosynthesis

4/5 Label the parts of a leaf

5 Explain the role of the xylem and phloem

4/5 Explain what a limiting factor is

4/5 List the limiting factors for photosynthesis

4 Describe how farmers and gardeners control the limiting factors to ensure healthy plant growth


Photosynthesis Why are plants important?

What is photosynthesis?

What do plants need for photosynthesis?


The importance of plants


Raw materials


Food


Medicines


Photosynthesis

Importance of plants

FOOD RAW MATERIALS MEDICINES

Wheat – for bread Wood – for building

Poppy – pain killers

Grapes – for wine Cotton – for clothes

Foxglove – heart medicine

Sugar cane – for sugar

Flowers – for perfumes

Mint – menthol for cough sweets


Green plants make their own food using light energy

Green plants convert light energy to chemical energy (food) using a green pigment in the leaves called chlorophyll.

Photosynthesis


Carbon Dioxidetaken up from air

Water - from soil

Light energy- from sun

Oxygen givenoff as waste

Glucoseused for energyor stored as starch


This can be summarised by the following equation

Carbon dioxide

Water Light energyChlorophyll

Glucose Oxygen

Raw MaterialsEnergy source

and pigment whichtraps it

ProductsGlucose is used forenergy, stored as

starch or built up intocellulose

Oxygen is waste gas


• Glucose which are used for energy (respiration)

• Storage carbohydrates such as starch - these can be broken down to simple sugars if needed

• Structural carbohydrates such as cellulose - these are used to build the cell wall

What happens to the glucose?


Chloroplast structure


Stages of Photosynthesis biochemistry

• There are two stages of photosynthesis. The equation you have just learned is actually more complex and occurs at two

separate stages.


Stage 1• The first stage is called PHOTOLYSIS.

• This stage involves using energy from the sunlight to split water molecules into

hydrogen and oxygen.


WATER

ENERGY

(ATP)

Oxygen Hydrogen


Light energy

Chlorophyll

Chemicalenergy

ADP + Pi

ATP

Water

Hydrogen + Oxygen

Passed on to second stage

Passed on to second stage

Released to the air as oxygen gas


Stage 2•The second stage is known as the

Carbon Fixation stage•Here the energy and hydrogen from

stage one are used along with the carbon dioxide.

•It is at this stage where glucose molecules are produced.


Hydrogen

Carbon dioxide

ATP ADP + Pi

Glucose

From the first stage

From the first stage

From the air

Enzyme controlled reactions


•This stage is energy consuming so that is where the ATP comes in.

•This stage is also controlled by enzymes.

•Carbon dioxide and hydrogen join to give us glucose


Leaf cut through

Cut end magnified

Section highlymagnified


Cuticle

Upper Epidermis

Palisade Mesophyll

Spongy Mesophyll

Lower Epidermis

StomataGuard Cells Stoma Pore

Xylem / Phloem

National 4/5 Biology Course Unit 1CO2

H2O

Glucose O2

Light


Stomata are made up of special cells which control the size of a smallpore

A) Guard cells – these change shape and control the size of :

B) Pore

Stomata also control theexchange of gases by the leaf

Stomata are found on the bottom surface


The guard cells take in water by osmosis.

They swell more outwards than inwards due to the size of cell wall.

This pushes back epidermal cells and opens the pore.

They close by losing water.

Guard Cells


Part of Leaf Function

Waxy Cuticle Waterproof layer prevents water evaporation

Epidermis These cells on top and bottom of leaf are for protection

Palisade Mesophyll These cells under the upper epidermis is where photosynthesis occurs

Spongy Mesophyll Photosynthesis occur in the cells and O2 and CO2 can diffuse through the air spaces

Stomata These cells are in the lower epidermis and let gases

and water in and out.


Three possible factors can limit the rate of photosynthesis in a plant when they are in short supply :-

• Light intensity – this limits the energy available.• Carbon dioxide concentration – this is an essential raw material

• Temperature – this limits the rate at which the enzymes controlling photosynthesis work.

Limiting factors


Effect of light on the rate of photosynthesis

We can use the rate of production of oxygen bubbles by pond weed to measure the rate of photosynthesis

Diagram “bubbler”


• A large water trough or sheet of glass stops the heat from the lamp from affecting the experiment.

• Lamp moved away -> less oxygen bubbles produced

• The amount of light therefore limits the rate of photosynthesis. It is called a limiting factor.


Incr

easi

ng r

ate

of

phot

osyn

thes

is

Increasing light intensity

Part AAs light intensity increases the rate of photosynthesis increases.

Part BFurther increases in light causes no further increase in the rate of photosynthesis since the rate is limited by a shortage of some other factor e.g. carbon dioxide or temperature

Point X Optimum


Incr

easi

ng r

ate

of

phot

osyn

thes

is

Carbon Dioxide Concentration

Part AAs CO2 conc. increases the rate of photosynthesis increases.

Part BFurther increases in CO2 conc. causes no further increase in the rate of photosynthesis since the rate is limited by a shortage of some other factor e.g. light or temperature

Point X Optimum


Incr

easi

ng r

ate

of

phot

osyn

thes

is

Increasing light intensity

0.2% CO2

0.3% CO2

0.4% CO2

light intensity is limiting factor

CO2 is limiting factor


Incr

easi

ng r

ate

of

phot

osyn

thes

is

Increasing temperature

Part AAs temperature increases the rate of photosynthesis increases.

Part BFurther increases in temperature results in a drop in the rate due to the denaturing of the enzymes that carry out photosynthesis

Point X Optimum


Photosynthesis and horticulture


Photosynthesis and horticulture

Horticulture is the cultivation of plants in gardens and greenhouses.

The use of a greenhouse helps remove limiting factors:


(a) Lighting and heat

By increasing the light, the rate of photosynthesis increases and leads to an increase in the growth rate of the crop:

• crop is ready to be picked earlier.• increased crop yield.


(b) Carbon dioxide enrichment

Increased carbon dioxide in the atmosphere increases the yield (size) of crops. This happens because the rate of photosynthesis is increased.

unit one: cell biology. national 4/5 biology course unit 1 national 4/5 units: cell biology – now...

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