Slide 1

What is mitochondria? Mitochondria are known as the powerhouse of the cell. The mitochondria is the part of the cell responsible for energy production. Mitochondria turn glucose and oxygen into energy respiration. Mitochondria take in nutrients, breaks them down, and creates energy for the cell. The process of creating cell energy is known as cellular respiration. Most of the chemical reactions involved in cellular respiration happen in the mitochondria. A mitochondrion is shaped perfectly to maximise its efforts. Slide 2 Mitochondria Structure Mitochondria have two membranes. The outer membrane covers the organelle and contains it. The inner membrane folds over many times. The folding increases the surface area inside the organelle. Many of the chemical reactions happen on the inner membrane of the mitochondria. The increased surface area allows the small organelle to do as much work as possible. Mitochondria numbers differ in cells as it depends on the job of that cell, e.g. muscle cells require a very large number of mitochondria whereas nerve cells require less. Slide 3 In order of size... Slide 4 What are the functions of DNA? 1.Make exact copies of itself 2.Provide instructions so that the cell can make the right proteins at the right time Slide 5 The Discovery of DNA In 1953 two scientists called Watson and Crick worked out the structure of DNA The structure is a double helix a bit like a twisted ladder Slide 6 DNA structure How many strands are there? 2 DNA is double stranded (made of phosphates and sugar (deoxyribose)) How many bases (letters) are there? What are they? 4 = T, A, C, G Which ones always pair up with one another? T and A Base G and C pairing What are the shapes like for the bases that pair up? They are complementary to one another (like a jigsaw) NOT THE SAME SHAPE!! Hydrogen bonds hold them together Slide 7 The structure of DNA DNA is made up of nucleotides. A nucleotide consists of: 1.A phosphate 2.A sugar (deoxyribose) 3.A nitrogenous base (1 of 4 - GTCA) Slide 8 A always pairs with T C always pairs with G Slide 9 Proteins Proteins are made of amino acids DNA contains the instructions to make amino acids triplet amino acid Slide 10 The amino acids join together to form a protein We need proteins to make and repair cells Proteins are made in the cytoplasm Slide 11 DNA Replication The basis for biological inheritance How living organisms copy their DNA Growth and Repair Growth of new organisms Every cell needs a copy if new cells are made, DNA needs to be copied Slide 12 DNA replication Base pairing means that it is possible to make exact copies of DNA strands 1.Weak bonds split. This opens up the DNA to form 2 strands 2.Immediately, new strands start to form from free bases in the cell 3.The 2 new chains are identical Slide 13 The Role of the Ribosome in Translation The DNA controls the functions of the cell by coding for proteins, for example DNA codes for the enzymes involved with respiration. Without these enzymes respiration would not take place. Slide 14 1. What do genes code for? 2. Which of the following is the odd one out and why? Animal Cell Proteins DNA Proteinsynthesis Explain how proteins are made in the cell Slide 15 Proteins They are important in the cell for many things including: Energy source Growth and repair (new/damaged tissues) Enzymes (for chemical reactions) Needed for cell membranes E.g.s include: Haemoglobin in the blood Collagen most abundant protein (connective tissue) Slide 16 How are they made? Step 1: Inside the nucleus The gene unzips, and mRNA bases pair with DNA bases This forms a matching strand of mRNA U matches up with A instead of T C and G match up like normal Slide 17 How are they made? Step 2: Moving out the nucleus into cytoplasm The mRNA strand moves out of the nucleus via nuclear pores to one of the many ribosomes in the cytoplasm The mRNA moves through the cytoplasm towards a ribosome Slide 18 How are they made? Step 3: In the cytoplasm The ribosome attaches to one end of the mRNA strand As the ribosome moves along the mRNA, the ribosome translates (reads) the genetic code Every 3 bases = 1 amino acid As it moves along, it makes a lot of amino acids (you will make 2) joined together a protein or poly-peptide When it is finished reading it the protein is released into the cytoplasm Slide 19 This process is called transcription. The original DNA strand unzips and mRNA is created from the DNA bases REMEMBER G matches with C but in mRNA, A matches up with U (uracil) Slide 20 This part of protein synthesis is called translation. The mRNA is translated to make a chain of amino acids (eventually a poly-peptide) http://www.teachertub e.com/video/protein- synthesis-animation- 60707# Slide 21 DNA double helix is separated. mRNA is made using DNA strand. = Translation mRNA leaves nucleus and enters cytoplasm. mRNA joins onto a ribosome. The mRNA acts as a code for tRNA. = Translation Amino acid on neighbouring tRNA join together. A chain of amino acids is a poly-peptide. The poly-peptide chain folds to form a protein which is used in the cell or exported to the body. Slide 22 Proteins and Amino Acids Proteins build up, maintain and replace the tissues in your body. Your muscles, organs and immune system are made up mostly of protein. Your body uses the protein you eat to make lots of specialised protein molecules that have specific jobs. Proteins are sometimes described as long necklaces with differently shaped heads. Each bead is a small amino acid. Amino acids are the building blocks of proteins. They make thousands of different proteins when they join together. Slide 23 Proteins and Amino Acids In your body you have 22 amino acids. Your body makes 13, the 9 other amino acids come from proteins in food. It is essential for the body to eat proteins. Protein is a major functional and structural component of all our cells. They provide the body with roughly 10-15% of all our dietary energy and is needed for growth and repair. Slide 24 Types of Proteins Contractile Proteins are responsible for movement cardiac muscle. Hormonal Proteins are messenger proteins which help to coordinate certain bodily activities. Structural Proteins are fibrous and stringy and provide support cardiac muscle. Transport Proteins are carrier proteins which move muscles from one place to another around the body, e.g. antibodies and haemoglobin. Enzymes are proteins that speed up chemical reactions. Slide 25 Structural Protein Collagen is a protein found in the walls of arteries. It makes the walls stronger. It is also found in bones, tendons and cartilage. Slide 26 Protein Hormone Insulin is a hormone used to control blood glucose levels. Insulin is made in the pancreas. Hormones help control many of your body functions. Slide 27 Haemoglobin Haemoglobin is a carrier molecule. It is used to carry oxygen around the body. Slide 28 Enzymes Enzymes are proteins which control many activities in your body, like digestion. Slide 29 Mutations Genes code for proteins. Sometimes a gene code can change. This is called a mutation. Mutations to genes can cause the shape of the protein to change so it can no longer do its job in the cell. Gene mutations can occur spontaneously or be caused by: -radiation -chemicals (such as tar in cigarettes). Slide 30 Multicellular and unicellular Amoeba is a unicellular organism. It has 1 cell which makes up its entire body. It is microscopic and reproduction is asexual one cell divides into 2 Organisms bigger than this have to be multicellular. These can be very large (humans) and have specialised cells which carryout certain functions. Cell division in multicellular organisms is much more complex Slide 31 Multicellular cell division 100% chromosomes in all body cells 50% of chromosomes are found in sex cells In humans, 46 chromosomes are paired (23 pairs) and each pair carries similar information (homologous pair) Chromosomes in pairs diploid cell (body cells) Singles chromosomes haploid cell (sex cells) Slide 32 What is mitosis? Each new cell has a full set of chromosomes and is identical to the original cell. Mitosis begins with a single cell. How many chromosomes does this cell contain? First the cell makes a copy of each chromosome original cell cell division 2 new cells then it divides. Slide 33 What is mitosis? Each new cell can keep on dividing by mitosis. Mitosis makes new cells for growth and repair in all living things. Thats how you get from one cell to 50 billion! Mitosis is also called copying division. What does this mean? Slide 34 Mitosis activity Slide 35 Mitosis animation Slide 36 Key Words Active Site the part of the molecule where the reaction occurs used particularly with reference to enzymes. Denature active site of the enzyme changes size, it can no longer act on the body. Enzyme special proteins found in living organisms that speed up the rate of a chemical reaction. Lock-and-Key Mechanism where the substrate fits into an active site. pH level of how acidic or alkaline a substance is. Specific relating to a particular type of species. Temperature how hot or cold something is. Slide 37 Enzymes Enzymes are catalysts. They speed up chemical reactions that occur in cells. Enzymes are made from proteins. Each enzyme is specific to the substance (substrate) it acts on. Examples of chemical processes where enzymes are important include: -Photosynthesis -Respiration -Protein Synthesis -Cheese Making -Detergents (breaks down stains). Slide 38 Amino Acids Enzymes are made from amino acids, and they are proteins. When an enzyme is formed, it is made by stringing together between 100 and 1000 amino acids in a very specific and unique order. The chain of amino acids then folds into a unique shape. That shape allows the enzyme to carry out specific chemical reactions an enzyme acts as a very efficient catalyst for a specific chemical reaction. The enzyme speeds that reaction up tremendously. Slide 39 What do enzymes do? Enzymes can put atoms and molecules together and break molecules apart. There is a specific enzyme for each chemical reaction needed to make the cell work properly. Slide 40 Why do living things respire? Plants and animals need energy to carry out processes such as: -Movement (by contracting muscles) -Maintain body temperatures -Make proteins for growth and repair. Slide 41 Aerobic Respiration Aerobic respiration uses oxygen to release energy that is trapped in glucose. Aerobic respiration releases lots of energy. Word Equation glucose + oxygen carbon dioxide + water (+ energy) Symbol Equation C 6 H 12 O 6 + 6 CO 2 6 H 2 O (+ energy) Slide 42 Burning Sugar If you burn sugar it releases a lot of energy. Your body can release energy in sugar, however it does it in a very controlled way. To release energy the cells need glucose and oxygen. Respiration is the releasing of energy in cells. Respiration is controlled by enzymes. Changes to the pH and temperature can affect enzymes. This is why respiration is dependent on pH and temperature. Slide 43 Respiratory Quotient Once the volumes of carbon dioxide and oxygen have been found, the respiratory quotient (RQ) can be calculated using the following formula: Carbon dioxide produced Oxygen used For aerobic respiration that uses glucose the RQ is always 1. Slide 44 Where does respiration occur? Respiration occurs in the mitochondria. Respiration releases energy which is stored in ATP (adenosine triphosphate) molecules. The ATP molecule is used as an energy source for many processes inside the cell. Slide 45 Mitochondrion Slide 46 The Circulatory System The circulatory system consists of the heart, arteries, veins capillaries and blood. Arteries transport blood away from the heart. Veins transport blood towards the heart. Capillaries join arteries to veins, materials such as oxygen are exchanges between capillaries and body tissue. Slide 47 Red Blood Cells These cells transport oxygen around the body. They contain haemoglobin which oxygen joins to become oxyhaemoglobin. Red blood cells have no nucleus, this means they can carry more oxygen. They are disc shaped, this means there is more surface area for oxygen to move in and out. They are small so they can get to all parts of the body. Slide 48 White Blood Cells These cells destroy microbes. They wrap around microbes and engulf them. They are small cells so that they can squeeze through capillary walls to reach microbes. Slide 49 Plasma Liquid in the blood to transport dissolved substances such as, water, hormones, antibodies and waste around the body. Slide 50 Blood Vessels There are three types of blood vessels: Arteries go away from the heart. Veins go towards the heart. Capillaries join the arteries to the veins. Substances (oxygen and glucose) are exchanged between capillaries and the body tissue. These are very small blood vessels. The beating of the heart squeezes the blood through blood vessels called arteries. Slide 51 Adaptations of Blood Vessels Arteries They have a thick muscular and elastic wall to help it withstand high blood pressure as blood leaves the heart. Veins They have a large lumen to help blood flow at low pressure. Valves stop blood flowing the wrong way. Capillaries They have thin, permeable walls to allow exchange of material with body tissue. Slide 52 The heart pumps blood around the body. It has two sides: Right side pumps blood to the lungs. Left side pumps blood to the rest of the body. There are four parts of the heart called chambers. Two atria receive blood from veins. Two ventricles pumps blood into arteries. Valves prevent the blood flowing backwards when the heart relaxes and so keeps the blood under pressure. The Structure of the Heart Slide 53 Double Circulatory System Humans have a double circulatory system. One circuit links to the heart to the lungs. One circuit links to the heart and the body. The heart is made up of two pumps. This is an advantage because blood going to the body can be at a much higher pressure than blood going to the lungs. Slide 54 Growth When plants and animals grow, cells need to divide and change into specialised cells. For example, nerve cells and bone cells. The specialised cells can carry out different jobs. When a cell changes to become specialised the process is called cell differentiation. Slide 55 Growth in Animals Only grow in the early stages of their lives. The whole animal grows. Tend to grow a certain size then stop. Growth is by cell division only. Cells lose the ability to differentiate. Slide 56 Growth in Plants Keep on growing all their life. Only specialised parts of the plant continue to grow. Cell division takes place in special areas called meristems. Meristems are found at the tips of the roots and shoots. Plants increase in height because their cells get larger rather than just cell division. Cells retain their ability to differentiate. Slide 57 Genetic Engineering Genetic engineering is also called genetic modification or GM. It is not the same as closing. Although cloning techniques are used in genetic engineering, the two things should not be confused. Humans, plants, animals and food can be genetically modified. Slide 58 How Genetic Engineering Works Modifying DNA by genetic engineering follows these basic steps: Select the characteristic Identify and isolate the gene Insert the gene into the chromosome of a different organism Replicate (copy) the gene in the organism and produce the protein. Slide 59 Examples of Genetic Engineering Insulin A bacterium called E-coli has been genetically engineered to make human insulin. This is needed to control blood sugar. Diabetics cannot produce enough insulin and rely on daily injections of insulin. Rice containing Vitamin A Rice is the main diet for people living in Asian countries. Scientists have taken the gene to make beta-cartone from carrots and put it into rice plants. Slide 60 Advantages and Disadvantages Advantages Allows organisms with new features to be produced rapidly. Saves peoples lives. Disadvantages The inserted genes may have unexpected harmful effects. Not natural. Slide 61 Ethical Considerations Benefits Producing disease- resistant crops and higher yields which could feed more of the worlds population. Creating crops that will grow in poor or dry soil to feed people in poor areas. Potentially replacing faulty genes to reduce certain diseases. Concerns GM plants may cross-breed with wild plants and release their new genes into the environment. GM foods may not be safe to eat in the long term. It could lead to the genetic make-up of children being modified or engineered (designer babies). Unborn babies with genetic faults could be aborted. Insurance companies could genetically screen applicants and refuse to insure people who have an increased risk of illness. Slide 62 Gene Therapy Changing a persons genes in an attempt to cure genetic disorders is called gene therapy. Gene therapy can involve body cells or gametes. Gene therapy involving gametes (sex cells sperm and egg) is very controversial. This is because the genetic changes that are made dont just affect the individual being treated but affect all future generations as those are the genes passed on to the offspring. The future generations dont have a say in the treatment and it may affect them especially if it leads to problems. Slide 63 Making Copies The process of cloning is used to make copies of animals and plants. The copies are called clones. Clones are genetically identical. They all have the same DNA as the original animal or plant. Cloning involves only one parent. This is called asexual reproduction. Slide 64 Natural Clones Clones are genetically identical organisms. Sometimes clones are produced naturally. Human twins can be genetically identical. They are called natural clones. Slide 65 Cloning Animals Animals can be cloned artificially. The most famous example is Dolly the sheep, who was the first mammal to be successfully cloned from an adult body cell. A cloning technique called embryo transplantation is now commonly used in cattle breeding. Slide 66 Nuclear Transfer Dolly was produced by the process of nuclear transfer. This involved scientists placing the nucleus of a body cell (an udder cell) from the sheep the wanted to clone into an empty egg cell, which had its nucleus removed. A short sharp electric current helped the cell start dividing. It was then implanted into another sheep to grow. Slide 67 Uses of Cloning Its possible to clone human embryos in the same way that animals are cloned. This technique could be used to provide stem cells for medical purposes. The mass production of animals with desirable characteristics. Producing animals that have been genetically engineered to provide human products. Slide 68 Ethical Issues The cloning process is very unreliable the majority of cloned embryos dont survive. Cloned animals seem to have a limited life span and die early. The effect of cloning on a humans mental and emotional development isnt known. Religious views say that cloning humans is wrong. Using human embryos and tampering with them is controversial. Slide 69 Cloning in Plants Many plants can reproduce asexually. Asexual reproduction produces identical copies. Plants can reproduce asexually, i.e. in the absence of sex cells and fertilisation. Spider plants, strawberry plants and potato plants all reproduce in this way. Slide 70 Strawberries Strawberries grow stems called runners. The runners spread over the ground and have buds that grow into tiny strawberry plants called plantlets. Slide 71 Potatoes If potatoes are left long enough they begin to sprout. It will begin to grow shoots and roots and eventually another potato plant will grow. Slide 72 Spider Plants Spider plants grow new plants on their stems. The new plants are called plantlets. If the plantlets are cut off the parent plant and are planted in the soil. They grow into adults. Slide 73 Commercial Cloning of Plants ADVANTAGES All the plants are genetically identical. Plants can take a long time to grow from seeds. Cloning is a lot quicker. Cloning enables growers to produce plants that are difficult to grow from seeds, such as bananas. Can be used to keep good characteristics in a plant. DISADVANTAGES If an environment changes or a new disease breaks out, all the plants will die out. Cloning plants over many years can result in little genetic variation because genes do not mix. Slide 74 Tissue Culture Small sections of plant tissue can be cloned using tissue culture. Plants with the desired characteristics are chosen. Tissue samples are taken from the plant. They are put in sterile test tubes and grown in sustainable conditions. Slide 75 Grafting Grafting is where you cut part of a tree off (i.e. a branch) and you fix it onto another tree. On an apple tree, which has been grafted, it will have different apples from different trees when they fruit. Slide 76 Differentiation Cloned plant cells can differentiate into many different cells. Root cells used in tissue culture have been found to change cell type required for a plant to grow. Most animal cells have lost the ability to differentiate.