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Gene Scene A pack of 5 topics exploring the world of Genetics, aimed at S1-S3 pupils Gene Scene Contents Contents Overview of Information Pack ................................................................................................. 3 Topic 1: Inheritance ................................................................................................................ 4 Activity 1: Nature or Nurture? .............................................................................................. 4 Activity 2: Traits ................................................................................................................... 6 Topic 2: What are genes made of? ......................................................................................... 9 Activity 1: DNA Codes ......................................................................................................... 9 DNA Code Grids ................................................................................................................ 11 DNA Information Sheet ...................................................................................................... 12 Activity 2: DNA Model ........................................................................................................ 13 Activity 3: DNA Isolation from Fruit and Vegetables .......................................................... 14 Topic 3: Breaking the Code : Teacher’s Notes ..................................................................... 16 Activity 1: RNA Transcription Jigsaw ................................................................................. 16 Activity 2: Breaking the Code Translating the Code ......................................................... 23 Topic 4: Proteins : Teacher’s Notes ...................................................................................... 25 Activity 1: Protein Match .................................................................................................... 25 Topic 4: Proteins – Protein Match : Pupil Worksheet ......................................................... 26 Activity 2: What’s in a Name? ............................................................................................ 27 Topic 5: Genetic Predictions……………………………………………………………………… 29 www.yecscotland.co.uk @scdiYESC 2 Gene Scene Overview Overview of Information Pack This information pack contains an overview of each of the 5 topics along with teacher’s notes, background information, details of how to set up the activities and Pupil worksheets where appropriate. Genetics is the study of the genome, which is a complete set of an organism’s genes. This is important as human genetics give information about people’s traits. The information pack introduces the topic of inherited traits before looking at some of the science behind this. Genes themselves are small pieces of DNA. Therefore, the resource also has activities looking at DNA and how it can code for mRNA, which in turn codes for functional proteins. It is proposed that this information pack contains enough material for at least 6 weeks work. It is aimed at S1-S3 pupils. For some of the topics, there are a number of activities that, depending on the duration of the club, may all be able to be carried out in the same week, but could be split over different sessions. www.yecscotland.co.uk @scdiYESC 3 Gene Scene Topic 1: Inheritance Teacher’s Notes Topic 1: Inheritance Overview: This topic is used to introduce the pupils to inherited traits. Every attempt has been made to generalise the information in as far as possible, to avoid any issues due to family circumstances, but this topic requires some sensitivity to pupils’ circumstances. There are two activities in this topic: 1. Nature or nurture? 2. Traits Activity 1: Nature or Nurture? Aims: To introduce different traits Materials: Tape measures may be helpful Enough clear space for the pupils to get into groups or a line Paper and pens for recording results Sort each person in the class into groups or a line by the following characteristics: 1. Male/female 2. Eye colour 3. Dimples 4. Hair colour 5. Height 6. Shoe size www.yecscotland.co.uk @scdiYESC 4 Gene Scene Topic 1: Inheritance Teacher’s Notes Suggested questions to ask the pupils [and expected results]: What characteristics were easy to determine your grouping? [Those with clear cut categories and those that were easily observable.] What groups were you in? Which characteristics have definite options? [Male/female, eye colour, hair colour, dimples – These are called discrete variables as there are definite categories.] What characteristics have a ranked line order? [Height, shoe size – These are continuous categories that have a large range.] Where did you come in the line? What characteristics can be affected by environmental conditions? [Height and shoe size – quality and quantity of food affect growth too. Eye colour – could have coloured lenses. Hair colour – could be dyed.] These observable characteristics are called traits. Some traits are passed down from parent to child or affected by the environmental conditions. www.yecscotland.co.uk @scdiYESC 5 Gene Scene Topic 1: Inheritance Teacher’s Notes Activity 2: Traits Traits are the observable characteristics that people exhibit. They can be inherited, learnt or affected by the environment. Aims: To investigate how common different traits are within a population group. Safety: In the past, the PTC taste test has also been used to test for genetic traits. However, there is concern about the safety and so it is advised that the PTC test should not be carried out. Materials: Pen Small sticky notes – two colours Large sheets of paper with one of the following headings: tongue rolling and ear lobe attachment. Below each heading, draw a line halving the paper and put yes in one half and no in the other. Mirrors (optional) Large piece of paper with the diagram shown in Figure 1 Part 1: 1. Give each boy one colour of post-it notes and the girls the other colour. Each pupil will need two post-it notes. 2. Ask the pupils if they can roll their tongue lengthways. They may wish to have access to a mirror to check. The pupils should put one post-it note in the yes or no column depending on their answer. 3. Ask the pupils if the bottom of their ear lobes attached right to the very bottom of the ear lobe, or are they detached at the bottom. Again the pupils should put one post-it note in the yes or no column depending on their answer. www.yecscotland.co.uk @scdiYESC 6 Gene Scene Topic 1: Inheritance Teacher’s Notes Suggested questions to ask the pupils [and expected results]: How many are in the class? How many people can roll their tongue? What percentage is this? How many people cannot roll their tongue? What percentage is this? What percentage of the people who can roll their tongue are male? What percentage of the people who can roll their tongue are female? How many people have attached earlobes? What percentage of males have attached earlobes? What percentage of females have detached earlobes?? There are lots of different traits. In a population, some traits are more common than others. Part 2: 1. Give each boy one colour of post-it notes and the girls the other colour. Each pupil will need four post-it notes. 2. Everyone should put one post it note next to class. 3. They should then add a post it note to each trait that applies to them, following the lines. (e.g. going along the top, the first is class, then males, then males who have their earlobe attached, then males who have their earlobe attached and who can roll their tongue). Suggested questions to ask the pupils [and expected results]: Can you see how there are common traits in the group? Do you notice anything about the groups as you move from left to right? [Less people as the groups get more specific.] Which group has the most people and therefore is the most common grouping of traits? Which group has the least people and therefore is the least common grouping of traits? Every person will have a slightly different combination of all the possible traits. www.yecscotland.co.uk @scdiYESC 7 Gene Scene Topic 1: Inheritance Teacher’s Notes Can roll tongue Ear lobe attached Cannot roll tongue Male Can roll tongue Ear lobe detached Cannot roll tongue Class Can roll tongue Ear lobe attached Cannot roll tongue Female Can roll tongue Ear lobe detached Cannot roll tongue Figure 1: Diagram for Traits Activity (part 2) www.yecscotland.co.uk @scdiYESC 8 Gene Scene Topic 2: What are genes made of? Teacher’s Notes Topic 2: What are genes made of? Overview: Genetics is the science of how traits are passed from one generation to another via genes. Genes are parts of DNA molecules. The DNA is contained in chromosomes in the nucleus of cells. Each person has 46 chromosomes – 23 from your mother and 23 from your father. There are lots of different combinations. Every person has a different genetic makeup. This topic uses two activities to illustrate the DNA structure: 1. DNA codes – this introduces the building blocks of DNA and how they join together 2. DNA model – this uses sweets and cocktail stick to model the DNA helix structure. There is then a third activity to isolate plant DNA. Extension: Make a DNA origami model from http://www.yourgenome.org/teachers/origami.shtml Activity 1: DNA Codes Aims: To introduce the students to the DNA code Materials: DNA Information Sheets (see page 13) DNA Code Sheets (see below and page 11) Pens _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Figure 2: DNA Code Grid www.yecscotland.co.uk @scdiYESC 9 Gene Scene Topic 2: What are genes made of? Teacher’s Notes 1. On the top line of the grid in the code sheet, write a random list in the blank boxes of the following four letters: A, C, G and T. These letters, A, C, G and T represent the DNA building blocks, called bases. The bases are bonded to each other. This is represented by the – between the boxes. 2. DNA is made up of two chains. Fill in the bottom line according to the DNA ‘rules’: o If there is an A in the top row, put a T in the bottom square. o If there is a C in the top row, put a Gin the bottom square. o If there is a G in the top row, put a C in the bottom square. o If there is a T in the top row, put an A in the bottom square. 3. As well as being bonded to each other in the chain, the bases are also bonded to the other chain. Join the each of the letters in the top row with the bottom row by bond lines. Keep the code you have written as it will be used in later activities. The order of this code gives the genetic detail. The chains are then twisted into a shape called a double helix. This will be demonstrated in the next activity. Suggested questions to ask the pupils [and expected results]: Does anyone have a matching code? [Unlikely as there are so many combinations possible.] www.yecscotland.co.uk @scdiYESC 10 Gene Scene Topic 2: What are genes made of? DNA Code Grids DNA Code Grids _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ www.yecscotland.co.uk @scdiYESC 11 Gene Scene Topic 2: What are genes made of? Teacher’s Notes DNA Information Sheet DNA stands for deoxyribonucleic acid. DNA is contained in chromosomes in the nucleus of cells. It is a long molecule made up of combinations of 4 different subunits called bases. These are known by the letters A, C, G and T and are shown in Figure 3: A, Adenine T, Thymine G, Guanine C, Cytosine Figure 3: Structures of the DNA bases These bases are joined together in long chains via deoxyribose and phosphate. Two chains are joined together via base pairing, where A bonds with T and G bonds with C. These chains are twisted as shown in Figure 4. This shape is called a double helix. Figure 4: DNA double helix structure. www.yecscotland.co.uk @scdiYESC 12 Gene Scene Topic 2: What are genes made of? Teacher’s Notes Activity 2: DNA Model Aims: To model the 3D shape of DNA Safety: DO NOT eat the sweets Check for allergies Take care when using the cocktail sticks Materials: DNA information sheet Cocktail sticks Jelly sweets in 4 different colours The code from the previous activity 1. Read the DNA information sheet 2. As a class decide on a colour code for the bases. 3. Using the jelly sweets and the colour code, going along the top row of your code, join the jelly sweets together using the cocktail sticks. 4. Repeat with the bottom row of the code. 5. Join the rows together so each complementary base pair is “bonded” using the cocktail sticks. 6. Once you have completed this, it will look like a ladder. To make this into a double helix, lift the model at both ends and twist. This twisted model (as shown in Figure 5) illustrates the double helix structure of DNA. Figure 5: DNA model www.yecscotland.co.uk @scdiYESC 13 Gene Scene Topic 2: What are genes made of? Teacher’s Notes Activity 3: DNA Isolation from Fruit and Vegetables Aims: To isolate a DNA sample from fruit and vegetables Safety: Do not eat the fruit and vegetables Take care the water temperature is not too hot Care should be taken when using the blender – it is best that the teacher blends the fruit and then portions this. A risk assessment and COSHH form should be completed for using ethanol and all necessary precautions taken. Materials: Cold water Ice Salt Washing up detergent Warm water Plastic bowl 100 ml and 250 ml beakers Ethanol Salt Balance or teaspoon Measuring cylinder Blender Fruit, e.g. banana, strawberries, onions Sieve Filter paper Stirring rod Boiling tube www.yecscotland.co.uk @scdiYESC 14 Gene Scene Topic 2: What are genes made of? Teacher’s Notes Method: 1. Place ice and some cold water in the plastic bowl. 2. Pour approximately 50 ml of ethanol into a beaker and place the beaker in the ice bath to cool the ethanol. 3. Dissolve approximately 5 g (or add a small teaspoonful) of salt and 10 ml (or two teaspoonfuls) of detergent in 150 ml warm water. 4. Blend the fruit (approximately 50 g per experiment) 5. Add the warm water, salt and detergent mix to the blended fruit, then mix. 6. Put the filter paper in the sieve and sieve the mixture into the beaker. The pupils will need to mix with care, taking care not to rip the filter paper. 7. Transfer about 5 ml of filtrate to the boiling tube. 8. Carefully add 5-10 ml of the cold ethanol down the side of the boiling tube on top of the filtrate. 9. Let the solution sit for about 2 minutes without disturbing the layers. 10. Look at where the ethanol meets the water mixture and you will see some white strands. This is the DNA from the fruit. Point out that it doesn’t look like the twisted structure from the earlier activity as it is very small and you cannot see one individual strand. www.yecscotland.co.uk @scdiYESC 15 Gene Scene Topic 3: Breaking the Code Teacher’s Notes Topic 3: Breaking the Code : Teacher’s Notes Overview: The DNA letters are the DNA code. The order of the DNA bases A, C, G and T gives the DNA code. It is used for making proteins, but it doesn’t do this directly. The DNA code can determine the structure of proteins. To do this, there is a two-step process. First the DNA code is transcribed to a RNA code. This RNA code is then translated into a sequence of amino acids which are joined together to form the protein. This topic uses two activities to illustrate how DNA codes for proteins via mRNA: 1. RNA Transcription Jigsaw 2. Translating the Code Activity 1: RNA Transcription Jigsaw Aims: To transcribe the DNA code to an RNA code. Materials: Jigsaw pieces - each sheet of jigsaw pieces should be copied on different colours of paper so each base has a different colour – see p20-24. Scissors – ask the pupils to cut out the jigsaw pieces The code from the previous activities 1. After cutting out the jigsaw pieces, put them in a pile to mix them up. The pupils should use the A, C, G and T jigsaw pieces to make the DNA code written earlier. You should have two linked chains. The DNA code is then transcribed into another code called a RNA code. RNA stands for ribonucleic acid. The RNA is only a single strand and is made up of A, C, G and U (Uracil). This time A bonds with U. www.yecscotland.co.uk @scdiYESC 16 Gene Scene Topic 3: Breaking the Code Teacher’s Notes 2. Separate the two DNA chains from each other and then use the RNA jigsaw pieces to form the RNA code. 3. Write down the RNA sequence and keep a copy of this for the next activity The RNA code is then translated into a protein. www.yecscotland.co.uk @scdiYESC 17 Gene Scene Topic 3: Breaking the Code Teacher’s Notes A A A A A A A A A A A A A A A A A A A A A A A A www.yecscotland.co.uk @scdiYESC 18 Gene Scene Topic 3: Breaking the Code Teacher’s Notes T T T T T T T T T T T T T T T T T T T T T T T T www.yecscotland.co.uk @scdiYESC 19 Gene Scene Topic 3: Breaking the Code Teacher’s Notes C C C C C C C C C C C C C C C C C C C C C C C C www.yecscotland.co.uk @scdiYESC 20 Gene Scene Topic 3: Breaking the Code Teacher’s Notes G G G G G G G G G G G G G G G G G G G G G G G G www.yecscotland.co.uk @scdiYESC 21 Gene Scene Topic 3: Breaking the Code Teacher’s Notes U U U U U U U U U U U U U U U U U U U U U U U U www.yecscotland.co.uk @scdiYESC 22 Gene Scene Topic 3: Breaking the Code Teacher’s Notes Activity 2: Breaking the Code Translating the Code Aims: To translate the RNA code into a protein Materials: The RNA code from the previous activity The amino acid code sheet – see p26 From your DNA code, you transcribed a RNA code. To get a protein, you need to translate the RNA code. In this activity you will translate your RNA code into amino acids. The amino acids join together to form a protein. 1. When translating the RNA code into a protein, starting from the end, group the RNA code into three letter groups. 2. Using the amino acid code sheet, find the amino acid that corresponds to each of the three letter codes. e.g. AGU is Ser or S 3. Continue until you have a list of five amino acids. The amino acids are bonded together to form a protein. The sequence determines the type of protein and its function. Suggested questions to ask the pupils [and expected results]: Has anyone got the same protein sequence? [This is very unlikely as although there are only 4 different options for the bases, these bases can create lots of different sequences.] www.yecscotland.co.uk @scdiYESC 23 Gene Scene Topic 3: Breaking the Code Teacher’s Notes Amino Acid Code Sheet Second Letter A C G U AAA Lys (K) ACA AGA Arg (R) AUA AAC Asn (N) ACC AGC Ser (S) AUC AAG Lys (K) ACG AGG Arg (R) AUG Met (M) AAU Asn (N) ACU AGU Ser (S) AUU Ile (I) CAA Gln (Q) CCA CGA CAC His (H) CCC CAG Gln (Q) CCG First CAU His (H) CCU CGU CUU Third Letter GAA Glu (E) GCA GGA GUA Letter GAC Asp (D) GCC GAG Glu (E) GCG GAU Asp (D) GCU GGU UAA STOP UCA UGA STOP UUA Leu (L) UAC Tyr (Y) UCC UGC Cys (C) UUC Phe (F) UAG STOP UCG UGG Trp (W) UUG Leu (L) UAU Tyr (Y) UCU UGU Cys (C) UUU Phe (F) A C G U Thr (T) Pro (P) Arg (R) Ser (S) CGC CGG GGC GGG Ile (I) A CUA Arg (R) Gly (G) CUC CUG GUC GUG Leu (L) Val (V) C G GUU U www.yecscotland.co.uk @scdiYESC 24 Gene Scene Topic 4: Proteins Teacher’s Notes Topic 4: Proteins : Overview: The previous two topics have looked at DNA and how it codes for proteins. Often pupils think of proteins as components of food. This topic introduces the wide range of proteins. This topic uses two activities to discuss proteins: 1. Protein Match 2. What’s in a Name? Activity 1: Protein Match Aims: To show some the wide variety of functions of proteins within the body Materials: Protein grid Pens Internet access will be needed for some of the examples Table 1 shows some functions for proteins within the body. Match the names to the descriptions – complete the table on p28. Table 1: Answers for the protein match activity Name Description Haemoglobin in blood Transports oxygen round the body Insulin Involved in regulating blood sugar uptake Myosin and actin in muscles Involved in movement Fibrin Involved in wound healing Antibodies Defend your body against infection Pepsin Example of digestive enzyme Collagen Structural protein that supports connective tissues, e.g. skin, ligaments and tendons. Tubulin Forms hollow tubes supporting cell structure Keratin In strands of hair and in nails www.yecscotland.co.uk @scdiYESC 25 Gene Scene Proteins Match Pupils Worksheet Topic 4: Proteins – Protein Match : Pupil Worksheet In the previous activities, you have shown how the DNA code can be translated to a protein (via RNA). In this activity, you will try to identify some of the proteins that are found in your body. The following table shows some functions for proteins within the body. Match the names to the descriptions. You may need to do some research for this activity. Name Description Transports oxygen round the body Involved in regulating blood sugar uptake Involved in movement Involved in wound healing Defend your body against infection Example of digestive enzyme Structural protein that supports connective tissues, e.g. skin, ligaments and tendons. Forms hollow tubes supporting cell structure In strands of hair and in nails Antibodies; Collagen; Fibrin; Haemoglobin in blood; Insulin; Keratin; Myosin and actin in muscles; Pepsin; Tubulin www.yecscotland.co.uk @scdiYESC 26 Gene Scene Topic 4: Proteins Teacher’s Notes Activity 2: What’s in a Name? Aims: To use the concept of coding to find a DNA sequence and a protein, using the pupils’ name as the amino acid code Materials: Access to internet Paper and pens Amino acid code table In the previous activities you have used the DNA code to find the RNA code and then find the protein amino acid code. The sequence of the letters can be in any order so there are lots of possible combinations. In this activity, you will use your name as an amino acid code and see if you can find the DNA code and then identify your name as a protein! Part 1: 1. Write your name down. 2. Use the amino acid code table to convert your name into an RNA sequence. E.g. if the first letter is L, then this would correspond to the amino acid leucine (Leu). From the table, the RNA code for Leu is either UUA or UUG, choose one and write this down. If your name has a letter that is not an amino acid then the RNA triplet should be written as NNN. The N means that it could stand for any combination of bases. 3. Convert the RNA sequence to a DNA sequence (A becomes T, U becomes A, C becomes G and G becomes C). If you have used NNN in the RNA sequence then keep this as NNN for the DNA sequence. This is the DNA code for your name. www.yecscotland.co.uk @scdiYESC 27 Gene Scene Topic 4: Proteins Teacher’s Notes Part 2: 1. Find the website page http://www.ebi.ac.uk/cgi-bin/decode/decode.cgi 2. Type your name in the box and press decode. This will give you a similar DNA code and also search the database to see if this DNA code corresponds to any known proteins that are found in any genomes that have been sequenced to date. Which genome contains YOUR protein? www.yecscotland.co.uk @scdiYESC 28 Gene Scene Topic 5: Genetic Predictions Teacher’s Notes Topic 5: Genetic Predictions Overview: Since people’s traits can be inherited, knowing the full genotypes of the parents allows you to make predictions for the probability of the offspring exhibiting certain traits and characteristics. This topic uses three different examples to illustrate how this can be achieved using the Punnett Square method: 1. Boy or Girl? 2. Dominant vs Recessive 3. Eye Colour 4. Blood Types Aims: To predict the probability of a number of characteristics using a tool called a Punnett Square. Materials: Pen Copies of the Punnett square sheets (pupils’ worksheet) Example 1: Boy or Girl? In their genetic material, females have XX chromosomes, while males have XY chromosomes. If each parent were to give one of these chromosomes to their offspring, what percentage chance would there be of them having a boy and what percentage chance would there be of them having a girl? To find this out, we use something called a Punnett square. www.yecscotland.co.uk @scdiYESC 29 Gene Scene Topic 5: Genetic Predictions Teacher’s Notes In the grid shown in Table 2, you will see four empty boxes which you will fill in with the children’s inherited chromosomes. Table 2: Male or female Punnett square grid Father: XY Mother: XX X Y X X The father’s XY chromosomes are at the top. The offspring can inherit either an X or a Y. To show this on the grid, they should write an X in each of the boxes in the column below the X. Then do the same for the Y column. Next, the mother’s chromosomes are XX and are on the side of the grid. The offspring can either inherit one X or the other. To show this on the grid, they should then write an X in each of the boxes in the row next to the top X, before doing the same for the other row. They should now have written two letters in each of the blank boxes and be able to identify the % chance of having a boy or girl. www.yecscotland.co.uk @scdiYESC 30 Gene Scene Topic 5: Genetic Predictions Teacher’s Notes The same technique can be used for other characteristics inherited from through genes. Suggested questions to ask the pupils [and expected results]: How many XX have they written? [2] How many XY have they written? [2] What does this mean? [Remember back to the start, where we said females were XX and males were XY.] How many of the 4 offspring would be girls? [2] How many of the 4 offspring would be boys? [2] What % chance would the parents have of having a girl? [2 of the 4, therefore 50% chance] What % chance would the parents have of having a boy? [2 of the 4, therefore 50% chance] Example 2: Dominant vs recessive A similar process can be used for other genetic characteristics. Next, the pupils should repeat the previous process with the Punnett square in Table 3,. In this example, both parents have the same genetic information for this characteristic, Ee. This is going to represent earlobe attachment with both parents having unattached earlobes. It is written in this way because the capital E is dominant over the small e, which is the recessive characteristic of attached earlobes. This means that if the capital E is present then the earlobe will be unattached. The earlobe would only be attached if the person has the genotype ee. Table 3: Dominant or recessive Punnett square grid Father: Aa Mother: Aa E e E e www.yecscotland.co.uk @scdiYESC 31 Gene Scene Topic 5: Genetic Predictions Punnet Square Grids Suggested questions to ask the pupils [and expected results]: How many different combinations are there? [3, EE, Ee, ee] How many of each type? [I EE, 2 Ee and 1 ee] What % chance would the child have of having unattached earlobes? [75%, 3 out of the 4 have E present at least once] What % chance would the child have of having attached earlobes? [25%, only the ee genotype doesn’t have E present at all] Example 3: Eye Colour The previous example used one gene type. There are other characteristics that have two or more genes and this makes the Punnett square bigger and the predictions more difficult to predict. Eye colour can be simplified to two genes with them being represented by the letter A and B. The rules: 1. 2. 3. 4. A is for brown eyes a is for blue eyes A is dominant and a is recessive B is for green eyes 5. b is for lighter eyes 6. B is dominant and b is recessive 7. A is more dominant than B. Using a similar strategy to the previous examples, complete Table 4 Table 4: Eye colour Punnett square grid Father: AaBb AB Ab aB ab Mother: AaBb AB Ab aB ab www.yecscotland.co.uk @scdiYESC 32 Gene Scene Topic 5: Genetic Predictions Punnet Square Grids Male or female Punnett square grid Dominant or recessive Punnett square grid Father: Aa Father: XY E Y X Mother: Aa Mother: XX X X e E e Eye colour Punnett square grid Father: AaBb AB Ab aB ab Mother: AaBb AB Ab aB ab www.yecscotland.co.uk @scdiYESC 33 Gene Scene Topic 5: Genetic Predictions Teacher’s Notes Suggested questions to ask the pupils [and expected results]: Table 5: Answers Type How many of each? What colour would these give? AABB 1 Brown AABb 2 Brown AAbb 1 Brown AaBB 2 Brown AaBb 4 Brown Aabb 2 Brown aaBB 1 Green aaBb 2 Green aabb 1 Blue How many different types are there? How many of each? What colours would each type give? Do you think all the brown eyes would be the same colour? Why? [No, some will be darker than others due to the effect of the b gene.] Which brown genotype do you think would be darkest? [AABB would be darkest because of the presence of only dominant brown on one gene and no presence of the lighter b on the other gene.] www.yecscotland.co.uk @scdiYESC 34 Gene Scene Topic 5: Genetic Predictions Teacher’s Notes In practice, while this is a very good approximation for eye colour genetics, the genetics can be more complex than this. Example 4: Blood Types: Everyone has one of four blood types, A, B, AB or O. The genetic information for the blood types is shown in Table 6. Both A and B are dominant over O which is recessive. Table 6: Blood type genotypes Blood Type Genotype A AA or AO B BB or BO AB AB O OO Complete the family tree information (Figure 6) with blood type and genotype. HINT: Look for the blood types with only one genotype and fill these in first as this should help for the others. Answers are shown in Figure 7 www.yecscotland.co.uk @scdiYESC 35 Gene Scene Topic 5: Genetic Predictions Pupil Worksheet Blood Group A Blood Group B Genotype AO Genotype ___ Blood Group A Blood Group A Blood Group B Blood Group AB Blood Group O Blood Group __ Genotype AO Genotype ___ Genotype ___ Genotype ___ Genotype ___ Genotype ___ Blood Group A Blood Group A Blood Group A Blood Group B Genotype ___ Genotype ___ Genotype ___ Genotype ___ Figure 6: Blood type family tree www.yecscotland.co.uk @scdiYESC 36 Gene Scene Topic 5: Genetic Predictions Teacher’s Notes Blood Group A Blood Group B Genotype AO Genotype BO Blood Group A Blood Group A Blood Group B Blood Group AB Blood Group O Blood Group AB Genotype AO Genotype AO Genotype BO Genotype AB Genotype OO Genotype AB Blood Group A Blood Group A Blood Group A Blood Group B Genotype AO Genotype AO Genotype AO Genotype BO or AA or AA Figure 7: Blood type family tree answers www.yecscotland.co.uk @scdiYESC 37