Glossary of Terms33

(Duncanrig Secondary School S2 Biology Course Unit 3: Inheritance)

( Pupils Activity Booklet)

Inheritance1

What you should know by the end of this unit:

State that a species is a group of interbreeding organisms whose offspring are fertile.

Explain the terms continuous and discrete variation.

Explain that DNA is the building blocks of life and all of our characteristics are determined by our DNA.

State that DNA is unique to every individual organism and is inherited from each parent.

Explain that chromosomes are made up of genes and genes contain information relating to a particular characteristic.

State that phenotype is the physical appearance of an organism.

Explain the terms dominant and recessive.

State that genotype is the set of genes that has been inherited from each parent.

Explain that alleles are the alternative versions of a gene and be able to give examples.

Explain DNA Profiling

Use knowledge of DNA profiling to make informed decisions with regards to its uses and applications.

Skills that you should be able to carry out by the end of this unit are:

Write up experiments with an aim, method, results and conclusion.

Appreciate the importance of variables in an experiment and how to improve the reliability of results.

Demonstrate the ability to be able to extract DNA from a plant source and be able to explain each step.

Be able to perform genetic crosses and use them to predict offspring genotypes and phenotypes.

Work as part of a group and take responsibility to support the work of the group.

Be able to perform gel electrophoresis and use the results to identify an individual using their DNA profile.

What is a Species?

A species is a group of organisms which are so similar that they can interbreed to produce fertile offspring.

For example, there are many varieties of dog, but all of them can interbreed to produce fertile offspring.

How many dog breeds can you identify from the pictures below? List as many as you can in your jotter. Add any other ones you know to your list.

Continuous and Discrete Variation

Although all individuals of a species are similar and can be recognised as being from the same species, they are not identical. The diversity between members of a species is called variation.

Some variation is said to be discrete because it can be arranged into separate groups of two or more. If the same group of people are arranged according to whether they can roll their tongue or not, each person would either be in the rolling group or the non-rolling group.

Some variation is said to be continuous because it cannot be separated into groups. If a group of people are arranged according to height, there would be a gradual difference from the smallest to the tallest.

1.

Here are some more examples of discrete and continuous variation, pick one from each list and do a survey of all the members of your class.

Discrete Variation

Continuous Variation

Eye colour

Size of feet

Tongue rolling (roller non roller)

Height

Blood group (A/B/AB/O)

Hand span

Ear lobes (attached/detached)

2.

3.

Collect graph paper and draw a bar graph to show your discrete variation results and draw a line graph to show your continuous variation results.

Glue the graph paper into your jotter.

Topic 1: Variation3

Inheritance Fact or Fiction?

1.

Collect a pack of fact or fiction cards.

2.

In your group, arrange the cards on your desk.

3.

Read each card one by one and then discuss the statement.

4.

Decide whether each statement is fact or fiction and arrange them into two groups under the fact or fiction headings cards.

5.

You may be undecided about some of the statements, but try to agree where every card should be placed.

6.

Your teacher will now discuss your group decisions with the rest of the class.

Pass it on

All organisms are like their parents in some characteristics. These characteristics are inherited and are determined by genetic information received from both parents.

This genetic information is held in your DNA (deoxyribonucleic acid). DNA is the building blocks of all life and is arranged into chromosomes. Every human being has 46 chromosomes arranged into 23 pairs that are all made of DNA. Every chromosome contains about 10, 000 genes which are made from DNA and each gene is a specific instruction for a particular characteristic. No two humans have exactly the same DNA, apart from identical twins, who have a matching DNA code.

(Chromatid)

(Chromosome) (Nucleus) (Centromere)

(Cell)

(DNA Strand) (Chromatid)

Fruity DNA

1.

Collect the following equipment:

A small piece of kiwi fruit Beaker

Extraction BufferBoiling tube or test tube

Mortar and pestlefilter funnel

filter paperstopclock

2.

Remove the skin from the kiwi fruit

and then put it into you mortar and

mash it very thoroughly with the

pestle until you have a green liquid.

3.

Add 50ml of extraction buffer to a beaker and then pour your kiwi fruit macerate into the beaker.

4.

Incubate you beaker in a

60oC waterbath for 15 minutes.

5.

Line a filter funnel with filter paper. After 15 minutes, pour the contents of your beaker through a filter funnel into a clean test tube. You should be left with a green liquid but all of the kiwi fruit pieces should have been removed.

6.

VERY GENTLY pour 10ml of the ice

cold alcohol down the inside of your

test tube. You are trying to form a layer

of alcohol on top of the green kiwi fruit

extract. Two layers should appear.

7.

Where the two layers meet, you should see a cloudy white layer. This is the extracted DNA from billions of kiwi fruit plant cells. You can try to hook some strands of DNA on the end of a paper clip.

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Key Questions (answer in sentences in your jotter)

1.

Explain the purpose of each of the following steps:

a) mashing the kiwi fruit

b) pouring the mixture through a filter funnel

c) pouring the alcohol down the inside of the test tube.

2.

Which part of the cell contains the DNA?

3.

What is the importance of DNA?

Trace the chromosome diagram below into your jotter and use a textbook or classroom resource to label the diagram.

DNA A Closer Look

One of the most exciting breakthroughs in Biology was the

discovery of the structure of DNA. Three scientists James

Watson, Francis Crick and Maurice Wilkins won the Nobel Prize for describing the DNA Double Helix.

The double helix looks like a ladder that has been twisted into a spiral. Each rung in the ladder is made up of two bases which are joined together. There are four bases in total called A, T, G and C. These bases pair up with each other to make the rungs of the ladder in a special way. A and T always pair together and G and C always pair together. In this way, if you know one half of the base pair, you automatically know the other half:

A matches with T

T matches with A

C matches with G

G matches with C

All the possible sequences of A, T, G and C make an infinite number of combinations and the genetic code for all living things. The human DNA sequence, for example, contains 3 billion of these 4 bases!

Using the rules you have just read about, you are

going to build your own DNA model with its own

unique genetic code.

1.

Collect a copy of the DNA template, scissors and glue.

2.

Cut out the spines labelled A and B.

3.

Cut out the rungs.

4.

Fold the tab attached to each rung so that it is a right angles to each rung.

5.

Glue the tab of each rung onto spine A into the numbered boxes. The rungs can be glued on in any order.

6.

When dry, glue to tab at the other end of each rung onto spine B at the corresponding numbered boxes. This is the tricky bit!!

7.

Your DNA double helix is complete, why dont you hang it up in your classroom?

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Key Questions

Use the following words to complete each of the sentences:

ChromosomesHelix

GenesBases

DNA

1.

The chemical code for all living things is contained within a chemical called ___________.

2.

Humans have 46 ______________, 23 pairs which include all the __________ in a particular sequence.

3.

DNA is a spiral ladder. Watson and Crick described it as a double _________.

4.

DNA always has the same amounts of the bases A and T and C and G. These __________ contain the genetic code.

Topic 2: DNA and Inheritance5

Phenotype What We look Like

The way an organism looks, its physical appearance, results from the genetic information that has been received from both parents. The physical appearance of an organism resulting from this inherited information is called the phenotype. The word phenotype can be used to describe any physical characteristic. For example, look at the organisms below.

(The dogs phenotype for coat colour is spotted.)

(The peas phenotype for shape is wrinkled.) (The peas phenotype for shape is round.)

(The flys phenotype for wing shape is normal.) (The flys phenotype for wing shape is short.)

Look at the phenotypes of the rabbits below, parent 1 will pass on black coat colour and parent 2 will pass on white coat colour to their offspring.

(Parent 1Parent 2)

Now look at their offspring, all of them are black, although, it can be seen from the parental phenotypes that they inherited both black and white.

(offspring)

The phenotype that is found more frequently through each generation is called the dominant phenotype and the one that is less common is called the recessive phenotype. In the rabbits, black coat colour is dominant and white coat colour is recessive.

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Key Questions

1.

Where do living things inherit their genetic information from?

2.

Explain the meaning of the word phenotype?

3.

Copy the table shown below into your jotter and complete it by adding 3 more human characteristics and two possible phenotypes of each.

Characteristic

Possible Phenotypes

Phenotype 1

Phenotype 2

1.Tongue Rolling

Roller

Non roller

2.

3.

4.

4.

Copy and complete the following sentences:

When the rabbit with black coat colour was bred with the rabbit with white coat colour, all of their offspring were the _________ phenotype. The dominant phenotype is _________ and the recessive phenotype is ___________.

5.

Collect a copy of the Inheritance Problem Solving Booklet and complete problems 1 and 2 on pages 1 and 2 in your jotter.

Topic 3: Phenotype15

Genotype What genes do we inherit?

Most genes have at least two different versions; for example, coat colour in rabbits has a black and a white version. The alternative versions for each gene are known as alleles. The set of genes that have been inherited from each parent are known as your genotype. Each genotype is represented by two letters to show the alleles that have been inherited from each parent. This alien example should help explain these new terms:

Black and grey eyes are both examples of the phenotypes for eye colour in aliens.

(BB or Bb)Black eyes are dominant to grey eyes, so, black eyes are assigned a capital letter, B and grey eyes are assigned a small letter, b. The genotype, the combination of genes, for an alien with black eyes can be BB or Bb. Even though the Bb genotype has the allele for both black and grey, the grey allele is masked because of the dominance of the black allele.

The genotype for an alien with grey eyes can only be bb because it is the recessive allele.

bb

When an individuals genotype is known, it is possible to predict what their offspring might look like.

Alien Genetics What genes do we inherit? (Continued)

If the parents discussed on the previous page were to have offspring, it is possible to predict what genotypes and phenotypes their offspring will inherit.

Scenario 1:

Parent 1Parent 2

(X)

Phenotype:Black eyesGrey eyes

Genotype: BB bb

Phenotype:All black eyes

Genotype:Bb

Parent 1 can only pass on the dominant B (black eye) allele to the offspring and Parent 2 can only pass on the recessive b (grey eye) allele to the offspring. As a result, all the offspring will have the Bb genotype and will have black eyes.

Scenario 2:

Parent 1Parent 2

(X)

Phenotype: Black eyes Grey eyes

Genotype: Bb bb

Phenotype: Black eyesGrey eyes

Genotype: Bb bb

Parent 1 can pass on either the dominant B (black eye) allele to the offspring or the recessive b (grey eye) allele whereas and Parent 2 can only pass on the recessive b (grey eye) allele to the offspring. As a result, half of the offspring will have the Bb genotype and will have black eyes and the other half will have the bb genotype and will have grey eyes.

This diagram should help you understand how the alleles are inherited:

(These are the two possible alleles that can be passed on from Parent 1.)

B

b

b

Bb

bb

b

Bb

bb

(These are the two possible alleles that can be passed on from Parent 2.)

Collect a copy of the Inheritance Problem Solving Booklet and complete questions 1, 2 and 3 on pages 3, 4 and 5 in your jotter.

Topic 4: Genotype19

Read the Background Information about DNA profiling on pages 21 and 22. This will give you an overview of the uses of DNA Profiling. Your teacher will organise your class into groups of 4. You will be assigned a letter from A-D. This is your chance to become an expert!

1.

Collect the appropriate fact sheet that corresponds to your letter. You will be the expert on the information contained in your fact sheet.

2.

Read the information on the card.

3.

Make notes on the important points from the fact sheet. You should come up with at least 4 points.

4.

After everyone in your group has done the same thing, each person will report to the other members of the group on what they have learnt.

5.

Once each person has reported, discuss what you think are the most important points from each expert.

6.

Write these points in your jotter.

7.

Your teacher will now discuss your findings with the whole class.

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Key Questions (Answer these questions in sentences in your jotter)

1.

Often genetic testing shows that a person has a genetic condition that has no cure. How is the information given by a genetic test helpful to the person?

2.

Can information someone gets from a genetic test cause discrimination for or against them? Explain your answer.

3.

How are genetic tests performed?

Background Information - DNA Profiling

DNA Profiling is a technique that is used by scientists to identify individuals or information about individuals. DNA Profiling can be done using just a few skin cells, hairs roots or any body fluids such as saliva. It relies on the fact that the nucleus of each one of our cells contains all of the genetic information that is unique to every individual. This technique is very useful for solving crimes but can also be used to establish paternity, which means whether or not two people are related to one another.

Solving Crimes

Sometimes, there are only a few drops of blood or a few hairs left at a crime scene. This is enough to get a DNA profile and identify who the blood or hair belongs to. The samples taken from the crimes scene can then be compared to the victim or the suspects DNA to look for a match. If two DNA profiles match, there is only a one in a billion chance that they are from different people unless they are from identical twins!

Paternity Testing

Paternity testing is used in cases where there is uncertainty who a childs father is. To carry out paternity testing, scientists take a pinprick of blood or a swab from inside the mouth (which contains some skin cells) from the child. They will then take similar samples from the childs mother and then the possible father. Since half of the genetic information is inherited from each parent, it is possible to identify this in the DNA profile and if the childs DNA shows a match to both the mother and the possible father, then this confirms that the possible father is in fact the biological father.

Tracing Large Numbers of People

DNA Profiling is often used in disaster situations when a large number of bodies have to be identified. This has been used to identify victims from the World Trade Centre attacks on September 11th 2001 as well as the Tsunami that hit Japan in March 2011. In these cases, the DNA profiles of the victims are compared to samples provided by relatives of the victims.

Disease and Genetic Counselling

Some diseases are inherited through our genes from one or both parents. An example of this is Cystic Fibrosis which causes a thick mucus to affect the lungs and pancreas. Other examples of inherited diseases are Phenylketonuria (PKU) and Sickle Cell Anaemia. Some people carry genetic diseases without showing any symptoms at all, these individuals are known as carriers because they have inherited the disease gene from only one parent and a normal gene from the other parent. When two carriers have children, the disease gene can be passed on to their children and cause those children to suffer from the disease. Families in this situation are offered Genetic Counselling where the chances of their disease genes being passed on are calculated and discussed with Geneticists (gene experts).

Read the Background Information on pages 23 (below) and 24 on Analysing DNA Profiles.

Background Information-Analysing DNA Profiles

There are many different techniques for looking at DNA profiles, most of them depend on chopping up the DNA sequence into different sized fragments.DNA sequences can be cut up with special chemicals called restriction enzymes. The result is small pieces of DNA of different sizes.

(Restriction enzymes)

(DNA strand)

(bases)

Electrophoresis

Once the DNA strand has been chopped up, all the differently sized fragments can be separated from one another by running an electrical current over them. The DNA samples are loaded into wells cut into a special jelly plate and then the electrical current is applied to start the electrophoresis. Because the chopped up fragments are all different sizes, they will move through the jelly at different rates and leave bands in the jelly at different positions. These bands are unique to every individual person so, can be used for identification purposes. The bands produced look like the ones in the picture above. The bands from two sources can be compared to look for any similarities. The more similarities that appear in the banding patterns on the gel, the more likely the two DNA samples have come from the same person.

Look at the Gel Electrophoresis results:

When the control sample is compared to samples A to D, it can be seen that the banding pattern produced by Sample C is the same as the control. It can therefore be said that Sample C matches the control sample.

Who Dunnit?

As you have been learning, DNA Profiling can be used to identify individuals from the trace amounts of genetic evidence that they may leave at crime scene. This is used to help connect victims and suspects to each other and to a particular location. You are going to learn some the skills to solve the Case of the Missing Skeleton..........

(Please help to find me!!!)

Someone has kidnapped the much loved model

skeleton from the Biology Department. A number of items of evidence were collected from the scene. Genetic profiling has been performed on some suspicious hairs that were found close to where the skeleton is kept. Use the information to work out which suspect kidnapped the skeleton.

The Suspects:

(Suspect 1) (Suspect 2) (Suspect 3) (Suspect 4)

DNA Profile for each suspect and the hair sample:

(Suspect 4) (Suspect 3) (Suspect 2) (Suspect 1) (Hair sample)

1.

Examine each suspects sample and then compare this to the DNA profile taken from the suspicious hairs found at the crime scene.

2.

Decide which suspects sample matches the hair sample from the crime scene.

3.

Copy and complete the sentences in your jotter:

The hair sample taken from the crime scene was found to match the sample taken from suspect __. It is most likely that suspect __ kidnapped the skeleton.

Wizard Genes

Now that you have learned what gel electrophoresis is, you are going to get the chance to try it for yourself. There are four wizards Fangorblood, Warpleberry, Crawming and Payningal. Each wizard has a different set of magical genes and one of them contains the Evil gene. Your task is to identify which magic genes each of the wizards possesses and figure out which wizard has the evil gene.

The Wonderful Wizardry of Finding a Gene

1.

Collect the following equipment:

DNA samples: Fangorblood (F), Warpleberry (W), Crawming (C) and Payningal (P)Syringe pipettor

Carbon fibre electrodes4 micropipette tips

Red and black electrical wires36V mains transformer

Electrophoresis tank containing

an agarose gel and filled with water

2.

Label the side of your electrophoresis tank with the initial F, W, C and P using a chinagraph or non permanent OHP pen.

3.

Push a micropipette tip onto the end of the syringe pipettor.

4.

Draw up a pipette full of the Wizard Fs DNA into the tip.

5.

Very carefully, load the Wizard DNA into the first well of your agarose gel. You need to have the tip of the pipette below the surface of the water until it is inside the well but does not pierce the bottom of the gel.

6.

Repeat the same procedure for each of the other 3 samples using a different pipette tip for each sample to avoid cross contaminating the DNA samples.

7.

Place a carbon fibre electrode at each end of the electrophoresis tank:

8.

Connect the black wire (-ve) to carbon fibre at the end of the tank nearest the wells using the crocodile clip.

9.

Connect the red wire (+ve) to the carbon fibre at the other end of the tank furthest from the wells using the crocodile clip.

10.

Connect the other end of the black and red wires to each battery.

11.

Leave the DNA to run for 10-20 minutes.

12.

Disconnect the wires and gently pour the water out of the gel tank.

13.

Examine each band, you may be able to visualise the DNA better if you place a sheet of with paper under your gel electrophoresis tank.

Use this table to identify which genes each wizard possesses:

Colour

Magical Gene

Power

Yellow

Psychokinesis

Ability to move objects from one place to another by thought

Pink

Transfiguration

Ability to change an object from one thing into another by thought

Blue

Vanishing

Ability to disappear in a puff of smoke

Red

Evil

No ability to block out evil

Orange

Creation

Ability to create objects out of nothing

Key Questions (answer in sentences in your jotter)

1.

Why is in necessary to change the micropipette tip between each sample?

2.

Copy the following table into your jotter and complete it by adding the results of your DNA Profiling:

Wizard Sample

Genes Identified

Psychokinesis

Transfiguration

Vanishing

Evil

Creation

Fangorblood

Warpleberry

Crawming

Payningal

3.

Which Wizard(s) possess the Evil gene in their DNA profile?

4.

Explain how the genes are able to be separated from each other?

5.

Copy and complete the following sentences into your jotter:

DNA samples can be chopped up using restriction _________. The fragments that are created are all different _______ so they can be separated from each other by running an e__________ c___________ over them. This technique is called g__ e___________.

Genetic Testing Have Your Say

Your teacher will organise you into groups of 2.

1.

Collect a set of discussion cards and a set of fact cards.

2.

Lay all the discussion cards out in front of you on the desk

3.

Pick a card at random and read it carefully. If there are words or names mentioned on the discussion card that you are unfamiliar with, then find the fact card that matches it. The fact card will give you information about each disease that will help you understand it more.

4.

Discuss with your partner how strongly you agree or disagree with the statement on the discussion card.

5.

Pick a second card at random and repeat step 4, do this for as many of the discussion cards as you can.

6.

Your teacher will now pick one of the statements at a time and ask you to stand somewhere in the room to show how strongly you AGREE or DISAGREE with it. You will get the chance to share your opinions with other members of your class.

Topic 5: DNA Profiling20

Allele

Bases

Centromere

Characteristics

Chromatid

Chromosome

Continuous Variation

Cystic Fibrosis

Discrete Variation

DNA

DNA Profiling

Dominant

Gel Electrophoresis

Gene

Genetic Code

Genotype

Helix

Phenotype

Phenylketonuria (PKU)

Recessive

Sickle Cell Anaemia

Species

Alternative forms of a gene

Chemicals inside DNA that provide the genetic code for an individual

Hold two chromatids together in a chromosome

Inherited traits such as hair colour and eye colour

Carry the genes

Made up of two chromatids held together by a centromere

Type of variation that cannot be separated into groups, such as height

Inherited disease affecting the lungs and pancreas

Type of variation that can be separated into groups such as blood type

Holds the genetic information that is inherited from each parent

Using the DNA sequence to identify a person or information about that person

The allele of a gene that always appears in the phenotype

Technique used to separate DNA samples using an electrical current.

Area of DNA on a chromosome that controls a particular characteristic

The sequence of chemical bases in an individuals DNA

The set of genes inherited by an individual

A spiral

The physical appearance of an individual

Inherited disease affecting metabolism

The allele of a gene that is less common and usually masked by the presence of the dominant allele

Fatal inherited disease that affects red blood cells

A group of organisms that can breed to produce fertile offspring

Control

Sample

Sample

A

Sample

B

Sample

C

Sample

D