Our Living World 4 - Genetics

1. Variation and Biological KeysBiological keys are used as a tool to identify organisms based on variation (differences) in their characteristics.

There are 2 types of keys commonly used in biology:(i) Branched keys(ii) Paired-statement keys

Notes: Copy the information above into your jotter.

Branched keys:The branched key below can be used to identify the sweets snickers, starburst, mars bars, milky way, twix and smarties.

Notes: Draw a branched key to identify the pupils in the table, using the information provided. Name Eye colour Hair colour Ear lobes

Harry Green Brown Fixed

Sally Blue Blonde Free

Jimmy Brown Black Fixed

Jenny Green Blonde Fixed

Barry Blue Brown Free

Paired Statement Keys: In a paired-statement key each characteristic is covered in a pair of statements which are usually the direct opposite of each other.

The paired statement key below could be used to identify between Coke, Irn Bru, Ribena and Capri Sun

1. Is fizzy ………………………….………………Go to 2 Is not fizzy ……………………………………Go to 3

2. Is Orange in colour ………………… …Irn BruIs not orange in colour ………………Coke

3. Comes in foil pouch …………………….Capri SunDoes not come in foil pouch ………Ribena

Lesson 2: Variation

Variation is the scientific word used to describe the differences between organisms. For example there are a range of different heights and eye colours within the class.

Variation can be continuous or discontinuous.

Features that show continuous variation fit into a range of possible measurements; examples include height, weight, hand span and arm length.

Characteristics that show discontinuous variation can be classed into 2 or more distinct groups; examples include eye colour, hair colour, left or right handedness and blood groups.

Copy:

Variation can be classed as continuous (fit into a range of measurements) or discontinuous (fit into distinct groups).

Notes:Copy and complete the table below to put each of the characteristics given under the correct type of variation.

Characteristics:

Leg length

Continuous Variation Discontinuous Variation

Activity - Measuring hand span and recording eye colour

Spread your fingers out as far as you possibly can. Lay them down flat on the table and measure the linear distance between the outside of the thumb to the outside of the little finger using a ruler.

Once you have measured your own hand span add them to the class results table. At the same time add your eye colour to the class table.

Draw a histogram of the class results for hand span (continuous variation).

Height Eye colour Ability to roll tongueShoe sizeBlood

group

WeightLeft or right handedness

Number of pupils

Draw a bar chart of the results for class eye colour.

Notes:

Copy and complete the following:

The most common hand span range in the class is ___________mm and the most common eye colour in the class is ______________.

Continuous variation is recorded using a line graph or_____________. Discontinuous variation is recorded using a _______ graph.

Range of hand spans (mm)

Number of pupils

Eye colour

Lesson 3: What is DNA?

Why do you look the way that you do? What determined your gender?In all living things characteristics are passed on by the genes that offspring inherit from their parents.

Living things contain lots of cells; chromosomes are structures found inside the cell nucleus. These are made of long strands of DNA. Sections of this DNA are called genes.

In the nucleus of human body cells there are 46 chromosomes altogether (23 pairs). One of each pair of chromosomes has come from the mother and one of each pair has come from the father. When you pair the chromosomes together you get a karyotype.

Notes:

Copy and complete the following:

Chromosomes are found in the _________ of cells. Each chromosome is made of long strands of DNA. Sections of these strands are called ________.Human cells have _____ pairs of chromosomes. One of each pair comes from the _______and one from the ________.Stick in the diagram of the human male and female karyotype.

What is different about them?

Sex Cells

Humans contain special cells called sex cells (gametes). Females have eggs and males have sperm. Gametes are special because they only contain 23 chromosomes. When they fuse during fertilisation a cell with 46 chromosomes (called a zygote) is made. This single cell will eventually develop into a fully formed human!

Notes:

Complete the fertilisation diagram and stick into your jotter.

Activity – Cartoon Fun!

DNA molecules look like twisted ladders called double helices.

The double helix ‘ladder’ is held together by ‘rungs’ – pairs of chemicals called bases. There are 4 types of base which can be identified by their initial (A, G, C and T)Base pairs hold the 2 strands of the double helix together. A always pairs with T and C always pairs with G. (A-T and C-G)

It is the sequence of the bases that forms the genetic code!

You are going to use genetic code to make your very own cartoon person!

Lesson 4 – DNA ExtractionCOLLECT: Ripe kiwi fruit (1/4) or 1 strawberry

Two plastic bags2 boiling tubesMethylated spirits (5 ml.)Beaker ½ full of ice25 cm3 extraction solution (made from salt, washing up liquid and water)Filter funnelFilter paperBeakerPlastic loop

EXPERIMENT:

1. Place the methylated spirits in a boiling tube and place the tube in the beaker of ice to keep cool.

2. Put one plastic bag inside the other one (double thickness).

3. Place a strawberry or the flesh from a half kiwi fruit in the plastic bags.

4. Seal the bags.5. Squash the fruit inside the plastic bags.6. Add 50 cm3 of extraction solution to the bag,

seal and mix.7. Place the bag in a water bath at 60C for 15

minutes.8. Place a filter paper in a filter funnel and

place the filter funnel in a boiling tube.9. Pour the fruit mixture from the bag through

the filter until the boiling tube is one quarter full.

10. Place in ice until cool.

11. Using a pipette, gently run cold methylated spirits down the inside of the boiling tube so that it forms a purple layer on top of the green layer until the tube is half full.

12. Strands of DNA will appear rising from the green layer into the purple layer. You can pull out the strands using the plastic loop.

NOTES: Write a report of the experiment you have just carried out using the headings Aim Method (include a labeled diagram) Results – were you successful?

Lesson 5 – Inherited characteristics

Hair colour and tongue rolling ability are 2 examples of characteristics that are determined by genetic information which is passed from one generation (parents) to the next (children).Each child receives two pieces of genetic information for each characteristic, one from each parent. This information can be shown using a biological family tree.

Create a fictional family tree for a characteristic of your choice for 3 generations (grandparents, parents and children).

Example characteristics: Red hair and non-red hair Cook and non-cook Crisp eater and non-crisp eater

Copy:

Phenotype and Genotype

The phenotype of an organism is the physical appearance which results from the genetic information inherited from parents (e.g. tongue roller or non-tongue roller).

The genotype of an organism is the genes that an offspring has inherited (e.g. 1 copy of the tongue roller and 1 copy of the non-roller gene)

A dominant gene is one that is expressed (shown) if there are 1 or 2 copies of the gene.

A recessive gene is one that is only expressed if there are 2 copies of the gene (the dominant gene is not present).

Activity - Punnet Squares:

Punnet squares are used to determine the genotype and phenotype of offspring. Example 1:A mother has brown hair (dominant) and has the genotype BBA father has red hair (recessive) and has the genotype bb

Q: What would the phenotype and genotype of the offspring be?

A: All the offspring would have the phenotype brown hair and all the genotypes would be Bb.

Example 2:Q: A mother and father with brown hair and the genotype Bb have children. WWhat would the phenotypes and genotypes of the offspring be?

A: Three of the offspring will have brown hair (1x BB, 2 x Bb) and 1 of the offspring will have red hair (bb).

Activity:Use punnet squares to work out phenotypes and genotypes of children from the parents’ genetic information.

a) Mother with freckles (FF) and father without freckles (ff)b) Mother without dimples (DD) and father with dimples (dd)c) Mother with wavy hair (Ww) and father with wavy hair

(Ww)d) Mother who likes apples (Aa) and father who likes apples

(Aa)e) Mother who can sing (Ss) and father who cannot sing (ss)

Lesson 6 – Beaker babies!In the previous lesson you learned about how parents pass down characteristics to their children depending on their own genotypes.Remember – phenotypes are the physical appearance and genotypes are the genes that the parents possess.

Today you are going to create your very own “beaker baby” to demonstrate how genes are passed down from parents to offspring (children).

Activity:

Collect a set of beaker baby pack and follow the instructions to create your “offspring”

7. Genetic DisordersA genetic disorder can occur when a change in one or more genes causes vital proteins in the body to be missing or faulty.Most disorders are recessive (both copies of the gene need to be faulty). There are some which are dominant (only 1 copy needs to be faulty).Some genetic disorders can be sex linked – meaning the disorder is carried on the X sex chromosome.Examples of genetic disorders include cystic fibrosis, sickle cell anaemia and Duchenne Muscular Dystrophy (DMD).

Activity:

Your teacher will show you a video about Connor, who has Duchenne Muscular Dystrophy (DMD).

Notes:

Copy and complete the table below by ticking the box to show whether each person is affected, not affected or a carrier of DMD.

DONNA MICHAEL CONNOR LUKE ADAMAffected by DMDUnaffected by DMDCarrier of DMD

Answer the questions below in sentences:1. How does DMD affect Connor’s body?2. How old was Connor when he was diagnosed by DMD3. How do you think having DMD has affected the daily lives

of:a) Connorb) Connor’s family

4. How do you think Connor’s mother feels about two of her sons having DMD?

5. How does Connor want people to think of him?

To Screen or not to Screen!

Activity:

Collect a copy of the discussion cards (there are 3). In groups of 4 decide to what extent you agree or disagree with each scenario. In your jotter write down why you think as you do. Remember that people in the group may have a different opinion…that is OK!!

Mutations

DMD occurs when someone does not have a working copy of the gene for a protein called dystrophin, a protein that

connects the muscle cell to its surroundings. This is called a mutation.You can think of a mutation being like a spelling mistake in the DNA. One type of spelling mistake stops the gene being read in full. This usually stops the protein being made at all and this can have serious implications. If a new spelling mistake generates a ‘stop code’ in the middle of a gene, it can cause medical conditions, such as Duchenne MuscularDystrophy.

DNA stop codes include TAG, TAA and TGA

Activity:

The following DNA sequences are from eight different people (some have DMD and others do not). Can you find any ‘stop codes’ in the DNA below?

Answer the questions below:

1. Which of the 8 people carry a stop code?2. Explain in your own words why these people may have

DMD3. How do you think computers may be used to process DNA

sequences?

23

Lesson 8: Genetic DisordersIn the previous lesson you learnt about mutations and a genetic disorder called DMD.

Your teacher will show you some short videos about other genetic disorders.

Activity:Using your knowledge, laptops and/or the information cards provided create a resource to teach someone in your class about a genetic disorder.You could use a poster, leaflet or storyboard.

9. Genetics and Blood TypingWe need to know our blood type for several reasons –

a) So we are given the correct blood transfusionb) To help confirm who is the father of a childc) Forensic testing at crime scenes

At a crime scene, a suspicious stain must first be tested to make sure it is blood!In today’s lesson, you will carry out the same tests that you see in programmes such as CSI.

ACTIVITY: Is it blood?

COLLECT: Petri dish IndicatorHydrogen peroxide Cotton bud

1. Dip a clean cotton bud in water and rub it firmly over the ‘blood’ stain.

2. Place the cotton bud on the Petri dish and add one drop of hydrogen peroxide to the stain on the cotton bud.

3. Add one drop of indicator. If the cotton bud turns pink, then the stain was blood.

Blood typing can be used as a test to exclude a suspect from the investigation. For example, if a suspect has Type O blood but the stain contains Type A blood, then he or she could not have left the bloodstain.

Blood testing kits use anti-A and anti-B serum.

Type A blood

Type B blood

Type AB blood

Type O blood

Anti-A Coagulates

No reaction

Coagulates No reaction

Anti-B No reaction

Coagulates

Coagulates No reaction

Reactions between the Anti-A and Anti-B serum and different types of blood are shown in the table.ACTIVITY: Who might have committed the crime?

COLLECT: Anti-A and Anti-B serumsDimple tileSample of blood from a crime sceneSamples of blood from two suspects (X and Y)

1. Add a drop of blood from the crime scene to two dimples on the white tile.

2. Add Anti-A serum to one and Anti-B serum to the other drop of blood. Mix the serum and blood using a small stick. (Make sure you use a different stick for each serum)

3. If you see grains or lumps in the mixture, then coagulation has occurred. What is the blood type?

Anti A

Anti B

Crime scene

4. Repeat steps 1 to 3 for blood taken from each of the two suspects.

5. Record your results in a table.

NOTES:Write a report about your experiment.Include what you did, a table for your results and who you think might have committed the crime.What other proof would you need to be sure that you have the right culprit?

10. Selective BreedingSelective breeding has been used by humans for thousands of years in animal and food crops to choose the best characteristics which result in the most productive offspring.

Selective breeding works as follows:1. Choose the animals or plants that have the best

characteristics2. Breed them with each other3. Choose the best offspring and breed them with each other4. Do this over and over again to improve the characteristics.

Copy:

Selective breeding is used to improve characteristics in certain species.Selective breeding can be used to

(i) Increase yield (how much is produced)(ii) Increase growth (size)(iii) Increase resistance to disease

11. CloningCloning is a process by which scientists can make organisms that are genetically identical – every bit of their DNA is exactly the same!Cloning occurs in nature all the time – plants can reproduce to create clones, bacteria can clone themselves and identical twins are clones!In 1996 scientists at the Rosalind Institute in Edinburgh made world news headlines when they cloned the first mammal. They created Dolly the Sheep!

“Dolly Recipe”

Step 1: Take a skin cell from the sheep you wish to clone (Dolly)Step 2: Remove the nucleus of the cell (this contains the DNA)Step 3: Remove an egg cell from a different sheep Step 4: Remove the nucleus from the eggStep 5: Place the skin cell nucleus into the egg cellStep 6: Implant the egg into the donor sheep Step 7: The donor sheep goes through a normal pregnancy and then gives birth to a lamb genetically identical to Dolly

Your teacher will show you a PowerPoint that goes over these steps with you.

Activity: Use the information from the PowerPoint and the booklet to create your own cloning storyboard. Your storyboard should have 6 sections and include some diagrams/pictures and appropriate explanations. You should try to include the terms nucleus, DNA, egg and clone.

Notes:Read the following passage and answer the questions in sentences.

Dolly was the first ever cloned animal. She was born on the 5th July 1996. She looked the same as any other sheep but she was made in a unique way. Most animals are conceived when sperm and egg fuse together at fertilisation. Dolly however was made from an ordinary body cell. The body cell’s DNA was taken out and put into an egg cell, which in turn, had its DNA removed. It was zapped with electricity to start its development. This new cell was then put into the uterus of a surrogate mother sheep and, 4 months later, out popped Dolly. Dolly developed arthritis earlier than would be normal. This could have been a result of cloning. Dolly sparked a revolution with scientific reports of successfully cloned mice, cattle, goats and pigs but equally there have been some unsuccessful attempts with cloning rabbits, rats, monkeys, cats and dogs. Success rates are very low (about 1%) with many cloned offspring developing placental abnormalities in the uterus and dying soon after birth. In North America a private cult organisation known as the Clonaid have vowed to clone the first human. It is only a matter of time before someone somewhere is successful.

1. Describe the difference between how normal animals are conceived and how Dolly was conceived.2. What was done to the cloned cells before they start to divide?3. What medical condition did Dolly develop and was it a result of cloning?4. Why is it unlikely you will be able to clone some family pets?5. Do you think cloning humans will ever be possible? Say why you think this is.

Extension:

Do you think we should try to clone a human? Write down all the arguments that you can think of for or against human cloning.

12. Cloning MimiToday you are going to make your very own clone!

Activity:

You are going to clone a mouse named Mimi. To do this, visit the following website:

http://learn.genetics.utah.edu/content/tech/cloning/clickandclone/

Follow the instructions on the programme to make your very own clone!

Task:

Using the internet or resources provided by your teacher write a newspaper article which reviews one of the scientific techniques that are used to produce new organisms or affect the characteristics that new organisms possess.

Your report should be on one side of A4 paper and include an appropriate title and a picture. Your report should include the scientific background, the advantages and disadvantages and your opinion.

There are 4 choices for you on the next page.

1. Cloning

2. Selective breeding of plants

3. Selective breeding of animals

4. “Designer” babies

13. Discover Stem CellsStem cells are a special kind of cell that have the ability to turn into any cell type in the body.

Activity: Stem cell decision maker

Collect the following equipment:

A decision maker 2 blood stem cells each and a pile of spares A pot for red blood cells and a pot for white blood cells

Activity Instructions:

1. Start with two blood stem cells and one decision maker each.

2. You need to make some red blood cells and white blood cells, but you can only keep playing as long as you have a blood stem cell.

3. Put your fingers in your decision maker and hold it closed.4. Take it in turns to roll the dice.5. When it’s your turn, roll the dice then open and close the

decision maker the number of times shown on the dice.6. Ask the person next to you to choose a number from 1 to

4. Open the flap with that number on it.7. If you find a stem cell picture, take another blood stem

cell. If you find a different kind of cell, put your token in the cup with that type of cell on it.

8. Play until everyone has run out of blood stem cells.9. Now discuss the questions below.

Discuss:

What TWO different things can the stem cell do? What happens when you run out of stem cell counters? What

do you think would happen if your body ran out of blood stem cells?

Copy:Stem cells are able to self-renew (copy themselves) and differentiate (specialise into different types of cell). This ensures that stem cells do not run out and that dead or damaged cells get replaced.

Activity: Cell familiesCollect a set of the cell families game and follow the instructions below• Shuffle and deal the cards face down.• The player to the left of the dealer starts.• On your turn, choose a card you don’t want and give it to

the person on your left. • When you are given a new card: If you’ve got a family of

4, put it down on the table for everyone to see. Then choose a card to give to the person on your left.

• Keep going until the cards are used up.

Copy:There are different kinds of stem cell:

1. Tissue stem cells which are in our bodies all our lives. These only make particular cell types.

2. Embryonic stem cells which are found in the early embryo. These can make all of the cells in the body.

14. CSI – Cell Science Investigators

In the last lesson you learnt that stem cells can differentiate and self-renew. You also found that stem cells can be classed as tissue stem cells and embryonic stem cells.During this lesson you will learn about a disease called Multiple Sclerosis and the potential use of stem cells in medicine.

What is multiple sclerosis (MS)?

MS is a disease which affects over 10,000 people in Scotland. It usually starts when people are about 20-30 years old and it affects the function of the nerves (these normally pass messages in the body). There is no cure for the disease, only medicines to treat the symptoms. Symptoms of MS include – pins and needles, hearing problems, dizziness, problems walking, blurred vision, tiredness, forgetfulness and mood swings.Scientists are currently researching the potential use of stem cells for the treatment of MS

Activity: Collect the pictures of nerve cells and discuss the questions below

Can you see a problem with the nerve cells taken from a person with MS?How could we use stem cells to treat this?Where would we get these stem cells from?

Notes:

Stick the how stem cells can help with MS diagram into your jotter

Activity: Using cells to look for new medicines

You are going to plan a drug screening experiment to test 5 potential drugs (A-E) and a control (water) to choose which drug should be put forward for further testing.

You should design an experiment which tests all of the substances for their effect on nerves tissue. If the cell sample turns red, the drug is helping the nerves. If the cell sample turns green, the drug is damaging the nerve.

Think about how you are going to make your test fair!Write out your planned method in your jotter before you collect any equipment. Check your plan with your teacher.

Collect:Dimple tilePipette1 beakerSolutions A-E and waterCell samples (discs)Safety glasses

Record your results in a table. Like the one below:

Test Substance Colour of cells after adding test substance

ABCDEWater

Conclusion:

Substance ________ should be put forward for more testing because ___________________

There are lots of different research projects being carried out across the world involving stem cells. Stem cells are also being used already in the treatment of blood diseases (bone marrow transplants), burns (skins grafts) and eyes (growing new corneas).