* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Multicellular Organisms Part 3
Hybrid (biology) wikipedia , lookup
Heritability of IQ wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Public health genomics wikipedia , lookup
Medical genetics wikipedia , lookup
Gene therapy of the human retina wikipedia , lookup
Saethre–Chotzen syndrome wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Genome evolution wikipedia , lookup
History of genetic engineering wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Genetic engineering wikipedia , lookup
Skewed X-inactivation wikipedia , lookup
Human genetic variation wikipedia , lookup
Genetic drift wikipedia , lookup
Genomic imprinting wikipedia , lookup
Point mutation wikipedia , lookup
Neocentromere wikipedia , lookup
Y chromosome wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Population genetics wikipedia , lookup
Gene expression programming wikipedia , lookup
Designer baby wikipedia , lookup
X-inactivation wikipedia , lookup
Genome (book) wikipedia , lookup
Multicellular Organisms Part 3 Genetic information 1 Genetic Information Success Criteria LI To understand the definition of the term species LI To understand the definition of the term variation and give examples of continuous and discontinuous variation LI To understand that characteristics are inherited from our parents LI To understand that chromosomes are inherited from our parents and are arranged in matching pairs LI To understand that we inherit two forms of every gene and these are called Alleles LI To understand the definition of the term genotype and phenotype LI To carry out a simple genetic cross and predict the characteristics of off-spring LI To apply my knowledge of genetics and create a “Reebop Baby” LI To understand how sex is determined by carrying out a simple genetic cross LI To identify some of the causes of mutation and give examples of genetic mutation in plants and animals 2 Genetic Information The Terms You will learn the definitions of several important terms as you complete this topic. 1. To help you remember these create a glossary by copying the following table in your jotter: Term Definition Species Variation Continuous Variation Discontinuous Variation Gamete Chromosome Gene Allele Genotype Phenotype Homozygous Heterozygous True breeding Mutation Add information to this table as you complete the topic and learn what these words mean. 3 What is Variation? LI To understand the definition of the term variation and give examples of continuous and discontinuous variation Variation is all the differences that exist between members of the same species. There are two kinds of variation: continuous and discontinuous. What to do 1. Draw the table below into your jotter. Then look around the room at your classmates, note some of the similarities and differences you notice in the table. Table – Similarities and differences between the people in my class Similarities Differences 1. 1. 2. 2. 3. 3. 4. 4. Variation Activity (Teacher Led) What to do Listen carefully to your teacher. They will explain to you where in the room you are allowed to move to. When they tell you, move to the area of the room that you think best describes you for the following characteristics: Eye Colour – green, blue, brown, grey Height Tongue roller/non-roller Hair colour – blonde, brunette, black, red Ear lobes – attached/not Left/Right handed Hand span Discuss with your neighbour: Think back to when you grouped yourselves according to eye colour, how did this differ to how you grouped yourselves according to height? 4 Continuous variation - type of variation where there is a range of values (E.g. height or mass) Discontinuous variation – type of variation where there are clear cut differences and distinct groups to belong to (e.g. eye colour). 2. Now go back and add the definition for variation, continuous variation and discontinuous variation into your glossary What to do 3. Draw this table into your jotter: Continuous Variation Discontinuous Variation 1. 1. 2. 2. 3. 3. 4. 4. 5. 5. 4. Add the following examples to your table under the correct heading: Pulse Rate Blood groups Tongue roller/non-roller Leaf length in grass Ear lobes attached/not Hand span Tail length in dogs Gender Flower colour in roses Stem length in plants Different types of variation are recorded in different ways: Continuous is recorded using a line graph or histogram Discontinuous is represented using a bar chart 5 5. Find “Continuous variation” diagram in your diagram pack. Using the What to do information below, create a histogram by: (i) Adding a scale to the vertical axis (ii) Adding a label to the horizontal axis (iii) Completing the bars (iv) Drawing a continuous line through the tops of the bars from start to end Height of Pupils (cm) 150-154 155-159 160-164 165-169 170-174 175-179 Number of Pupils in Height Category 3 5 7 6 4 3 6. Describe what happens to the number of pupils in each height category as the height of the pupil’s increases. 7. Find the “Discontinuous variation” diagram in your diagram pack. Using What to do the information below, create a bar chart by: (i) Adding labels to the horizontal and vertical axis (ii) Drawing the bars accurately Eye Colour Blue Green Grey Brown Percentage number of pupils with eye colour (%) 35 25 10 30 6 What is Inheritance? LI To understand that characteristics are inherited from our parents What to do 1. Collect the “inheritance” card sort from your teacher. Working with your neighbour, match up the celebrity with their children. 2. Discuss with your neighbour: Why do the children resemble their parents? Revision Activity 1. Copy and complete the sentence using the word bank below: ……………………………. carry genetic information and are contained in the ……………… of a cell. They are made of …………….. and are split into sections called ………………. Word Bank DNA genes chromosomes nucleus 7 What to do Read the following passage and answer the questions that follow: Every cell in the human body contains 46 chromosomes. Chromosomes carry genetic information that control what we will look like. Children often resemble their parents. This is because they share similar DNA with their parents. When a sperm (carrying the father’s genetics) fuses with an egg (carrying the mother’s genetics), the fertilised egg will contain genetic information from both parents. The sperm and egg are sex cells, also known as gametes. They are different from normal body cells because they contain half the number of chromosomes. A human sperm cell contains 23 chromosomes and a human egg cell contains 23 chromosomes, when they fuse the fertilised egg contains 46 chromosomes (or 23 pairs of chromosomes). Answer the following questions in full sentences: 1. How many chromosomes does a normal human body cell contain? 2. Explain why children resemble their parents. 3. Complete the following note using the information in the passage: Gamete is another name for a …………… cell. In mammals the male gamete is called a ………………. and the female gamete is called an ………... Gametes contain half the number of chromosomes of a normal body cell. In humans this means an egg and sperm only contain …………. chromosomes. When the sperm and egg fuse the fertilised egg contains a full complement of ……………. chromosomes (………. pairs). 8 4. Copy the following diagram into your jotter and complete it by adding the correct number of chromosomes into the nucleus of each cell (23 or 46): Sperm Cell + Fertilised Egg Cell Egg Cell = 5. Now go back and add a definition for gamete and chromosome into your glossary. 9 Species LI To understand the definition of the term species Dogs are members of the same species but there is still a lot of variation between different breeds of dog. 1. Draw this table and it’s heading into you jotter: Table – Similarities and differences between different breeds of dog Similarities Differences 1. 1. 2. 2. 3. 3. 4. 4. What to do 2. Study these 4 pictures of different dog breeds and note the similarities and differences that all these dogs share. 10 3. Draw the following table and it’s heading into your jotter: Table – Similarities and differences between a horse and a donkey Similarities What to do Differences 1. 1. 2. 2. 3. 3. 4. 4. 4. Study the two pictures below of a horse and donkey. Note in your table the similarities and differences that they share. Horse Donkey The picture below shows a mule. A mule is the result of breeding a horse and donkey. Mules are sterile. This is how we can tell whether or not two organisms are members of the same species. Mule 11 Interbreeding dogs produces fertile off-spring, even if great variation exists between two breeds. This shows dogs are members of the same species. If two organisms interbreed and produce sterile off-spring (e.g. when a horse and donkey interbreed to produce a mule), this shows that those two organisms are members of different species, despite their similarities. 5. What is the result of breeding a horse and donkey? 6. Does this tell us if a horse and donkey are members of the same species or not? 7. Are you surprised by this result? Explain your answer by discussing the similarities and differences you noted. A species is a group of organisms that are able to interbreed and produce fertile off-spring. 8. Go back to your glossary page and add the definition for species to your table 12 Chromosome Mapping LI To understand that chromosomes are inherited from our parents and are arranged in matching pairs Chromosomes are arranged in matching pairs – there are 23 pairs of chromosomes in a human body cell (23 x 2 = 46). We can see the arrangement of chromosomes in their pairs using a chromosome map called a karyotype. In each pair, one chromosome is from the mother and one chromosome is from the father. mother’s chromosome father’s chromosome Child’s karyotype Karyotype What to do 1. Find your diagram of a “Human karyotype” in your diagram pack and stick it in your jotter 13 2. Create a key at the side of the diagram like the one below: blue pink Father’s Chromosome Mother’s Chromosome 3. Colour one chromosome in each pair blue and one chromosome in each pair pink according to your key. 14 Genes and Alleles LI To understand that we inherit two forms of every gene and these are called alleles Chromosomes are split into sections called genes. Genes carry genetic information that will determine our physical characteristics. 1. Copy the diagram below into your jotter: Gene for hair colour Gene for eye colour Chromosome Gene for blood group Gene for hair type Gene for freckles 2. Go back to your glossary and add the definition for gene. 15 As you know, chromosomes are arranged in matching pairs. In each chromosome pair, one is from the father and one is from the mother. This means that we inherit two copies of each gene – one copy from each parent. Genes can have different forms, for example in eye colour there can be a brown form of the eye colour gene and a blue form of the eye colour gene. It is possible to inherit two different forms of the same gene: Father’s Chromosome Mother’s Chromosome Gene for brown eyes Gene for blue eyes Chromosome Pair There can be more than one form of the same gene. Different forms of the same gene are called alleles. Discuss with your neighbour: What colour of eyes would a child have if they inherited two different forms of the eye colour gene? (example: the blue colour gene from the mother and the brown eye colour gene from the father) 16 When two different forms of a gene (alleles) are inherited, the resulting characteristic will depend on gene dominance. Genes can have dominant or recessive forms. A dominant allele hides the recessive allele (as though it was never there!!) So, if brown eyes were dominant and blue eyes were recessive, the child would have brown eyes because the blue eyed allele is hidden by the brown eyed allele. We represent alleles using letters, and show dominant and recessive alleles using capital letters for dominant alleles and small letters for recessive alleles. In the example of eye colour: Brown eyes – B (a capital letter because brown is dominant) Blue eyes – b (a small letter because blue eyes are recessive) 3. Copy and complete (using words below) the passage below using the information from the passage above to help you: We inherit t……… copies of the same g…………… – o…….. from each parent. There can be more than one form of the s……..…… gene. These are called a……..……….. For example – there is an eye colour gene. But this might have a blue a…………….. and a brown a………….…… (two different forms of the same gene). Some alleles hide other alleles – these are d……………..……. alleles, and the ones that are hidden are r…………………………. If the brown eyed a……..………. was dominant and the blue eyed a……………… was recessive, then the child born would have b……………. eyes because the b……………. eyed a……………… was hidden by the b…………….. eyed allele. Genes are represented using l…………..…. Dominant alleles are given c……………… letters, whilst recessive alleles are given s…………..……. letters. Example: B……………. eyes – B (a capital letter because it is ……………………..) B…………… eyes – b (a small letter because it is ……..……………………) WORDS- recessive one gene same alleles allele brown blue dominant 4. Go back and add the definition of “allele” to your table. 17 Genotype and Phenotype LI To understand the definition of the term genotype and phenotype We have already found out that genes are shown using letters. The genes that you inherit are called your genotype. What you physically look like is called your phenotype. Hint: remember - genes you inherit = genotype - physical characteristic = phenotype Example: A person inherits one dominant allele of a gene for curly hair (T) from her father and one recessive allele of a gene for straight hair (t) from her mother. Therefore her genotype = Tt (the genes she inherited). But, her physical characteristic (phenotype) is curly hair (what she actually looks like). Genotype – the alleles of a gene that are inherited by an organism for a particular characteristic Phenotype - the physical appearance of an organism (what you actually look like) 1. Go back and add the definition of “genotype” and “phenotype” to your glossary. 18 2. Complete the questions below in your jotter. Q1 Below is a list of genotypes and phenotypes. Write the list in your jotter and beside each note if it is a genotype or phenotype. The first has been done for you. a. b. c. d. e. f. Blue eyes – phenotype Gg Blonde Hair Freckles TT Blood group O Q2. Joe has brown hair. Joe has had his chromosomes mapped and knows he has one allele for brown hair and one allele for black hair. Which allele was dominant - Brown or black haired gene? Q3. Liz has blue eyes. Blue eyes is a recessive trait, could Liz also have inherited an allele for brown eyes (a dominant characteristic)? Explain your answer What to do Q4. Read the passage below and answer the questions that follow: Brian has freckles. He has blonde hair like his dad and green eyes like his mum. Brian is 6 foot tall and is training to be a rugby player like his dad who is just as tall. Brian sometimes gets teased by his friends for having attached ear lobes. a. List all the phenotypes that appeared in the passage. b. Brian knows he inherited one allele for blonde hair (from his dad) and one for red hair (from his mum): i. Which form of the hair colour gene was dominant? ii. What name is given to more than one form of the same gene? c. Choose one phrase from the passage that supports the statement that characteristics are inherited. 19 3. Find your “mini-me” diagram in your diagram pack. Complete the “mini-me” by: What to do a. adding your “phenotype” (physical characteristics) b. Noting which of your characteristics you think you have inherited from your mother and which you have inherited from your father AND/OR The characteristics you share with your siblings 20 Genetic Cross LI To carry out a simple genetic cross and predict the characteristics of off-spring Your teacher will show you a video: GCSE Genetics You now know that your physical characteristics (phenotype) depend on the alleles you inherit. If you inherit a dominant allele you will have a dominant characteristic – even if you inherited a recessive allele!! You only inherit a recessive characteristic if you inherit two recessive alleles. We describe the genotype of a person, based on the genes they inherit: If they inherit two alleles that are the same, their genotype is called homozygous (example – BB for brown eyes, or bb for blue eyes). If they inherit two alleles that are different, their genotype is called heterozygous (example – Bb for brown eyes). 1. Draw this diagram into your jotter: Homozygous Homozygous Heterozygous 3. Add a definition for homozygous and heterozygous into your glossary. Discuss with your neighbour: What characteristics would be present in the offspring if the father was homozygous for brown eyes (BB) and the mother was homozygous for blue eyes (bb)? 21 We can work out the off-springs genotype and phenotype using a Punnett square: B B b b 1. Listen as you teacher explains how to use a Punnett square 2. Draw the Punnett square above into your jotter and complete it 3. Your teacher will give you several examples to work through 22 Extension work; What to do Read the following passage and complete the questions that follow: In genetics we use the letter “P” to symbolise the parent generation. The first generation of off-spring is called the first filial generation, represented by the symbol “F1”. If two members of the F1 generation are bred (crossed) then the resulting off-spring are known as the Second filial generation and they are represented by the symbol “F2”. True-breeding is the term used to describe a situation when two homozygous parents are crossed. These parents are both true-breeding for one characteristic. For example, one parent will be true-breeding for brown eyes (BB) and one will be true-breeding for blue eyes (bb). All the members of the F1 generation are heterozygous and display the dominant characteristic (e.g. Bb brown eyes). If two heterozygous members from the F1 generation are bred (crossed) then the hidden recessive characteristic carried by both F1 individuals may appear in the F2 generation. 1. Copy and complete the statement below: In genetic crosses symbols are used to show each generation: Parent generation = …………… First Filial generation = ……………… Second Filial generation = ……………… 2. Which generation are bred to produce the first filial generation? 3. When both parents are homozygous for a particular characteristic, what will the genotype of all members of the first filial generation be? 4. What name is given to a cross between two parents who are both homozygous for a particular characteristic? 23 5. Which generation are bred to produce the second filial generation? 6. Which characteristic is hidden in the first filial generation but may appear in the second filial generation? 7. Complete the “genetic cross” diagram in your diagram pack. Use your knowledge of punnett squares and the information above to help you. 8. Circle in red all the individuals who could be described as true-breeding on your genetic cross diagram. Make this key in your jotter. 9. Add a definition for true-breeding into your glossary. 10. Add the following Black Box statement into the box below your “genetic cross” diagram: This is a true breeding cross for 3 reasons: 1. Both parents are homozygous for one characteristic 2. All members of the F1 generation will display the dominant characteristic (black fur) only 3. The F2 generation will show both dominant and recessive characteristics in a 3:1 ratio Predicted vs Actual ratios Listen as your teacher explains why in a true-breeding cross, sometimes the predicted ratio is different from the actual ratio. It is predicted that in a true breeding cross, the F2 generation will display the dominant and recessive traits of the original parents in a 3 dominant:1 recessive ratio. However, often the actual ratio is different from the predicted ratio. There are several reasons for this: 1. Fertilisation is a random process, involving an element of chance. 2. Number of off-spring produced is often too small. 24 Reebops LI To apply my knowledge of genetics and create a “Reebop Baby” What to do Collect the following equipment: One pack of Blue chromosomes (dad) One pack of Pink chromosomes (mum) 1. Lay the chromosomes face down on the desk in their pairs (separated into the mum’s and the dad’s chromosomes) 2. Randomly choose one blue chromosome from the dad’s chromosomes and one pink chromosome from the mum’s chromosomes from each pair. 3. Match the chosen pink and blue chromosomes with their corresponding pair (hint: they should be the same length) 4. Draw the following table in your jotter: Genotype (letters) Phenotype (physical characteristic) 5. Complete the table using the Key below: AA – 2 antenna Aa – 2 antennae aa – 1 antenna QQ – red nose Qq – red nose qq – yellow nose EE – 2 eyes Ee – 2 eyes ee – 3 eyes DD – 3 body segments Dd – 3 body segments dd – 2 body segments MM – 2 hump Mm – 2 humps mm – 1 humps TT – curly tail Tt – curly tail tt – straight tail LL – blue legs Ll – blue legs ll – red legs 25 Draw a diagram in your jotter of what you think your Reebop Baby will look like based on the characteristics it has inherited. What to do 6. Now collect the correct equipment from the list below to create your Reebop using the genetic instructions you have created in your table: Body segments Humps Antenna Tail Eyes Nose Legs 26 Sex Determination LI To understand how sex is determined by carrying out a simple genetic cross Discuss with your neighbour – what chromosomes must an individual inherit to be: - male? - female? 1. After class discussion – note this in your jotter Revision Bite: Answer the following questions in full sentences in your jotter: 2. What name is given to sex cells? 3. What is special about a sex cells chromosomes? 4. Copy the black box statement below and the diagram into your jotter: Sex cells are produced by Gamete mother cells. Gamete mother cells are present in the testes of the male and the ovaries of the female. = Female Gamete Mother Cell X Male Gamete Mother Cell X X Y Female Gametes X Male Gametes X Every female gamete gets an X chromosome X Y Half the male gametes receive an X and half receive a Y 27 We can use this information to determine the chance of parents having a girl or a boy. 1. Complete the punnett square below: X Y X X 2. Colour in the squares in the punnett square that show a boy in blue 3. Colour in the squares in the punnett square that show a girl in pink [Hint remember: male = XY female = XX] 4. Express as a percentage the number of off-spring who will be male, and the number that will be female. 28 Mutation LI To identify some of the causes of mutation and give examples of genetic mutation in plants and animals A mutation occurs when an organism’s genes or chromosomes become altered in some way. 1. Go back to your glossary and add the definition of Down’s syndrome Some mutations are detrimental to development of an organism. For example, in humans Down’s syndrome occurs when a gamete carrying an extra chromosome is fertilised, forming a zygote with 47 chromosomes rather than 46. The presence of just one extra chromosome in Down’s syndrome leads to mental deficiency and a characteristic appearance. ultrasound Amniotic Fluid Foetus Amniocentesis: During pregnancy the amniotic fluid surrounding an embryo contains skin cells. Amniocentesis is a technique used to sample the skin cells, and these can be tested for abnormalities before birth. Down syndrome is one of the abnormalities tested for. Amniocentesis only gives an indication that the child might have an abnormality, but some parent’s will choose to terminate a pregnancy if they suspect the child may have inherited an abnormality. Amniocentesis can also lead to a miscarriage even if the child is healthy. 29 2. Describe the genetic mutation that occurs in the chromosomes of a person suffering from Down’s syndrome. 3. What are the symptoms of Downs Syndrome? 4. Describe what happens during the Amniocentesis procedure 5. Below are some of the cases for and against amniocentesis. Can you arrange them in the table below under the correct heading? Amniocentesis allows parents to prepare if their child does have a genetic disability Amniocentesis can lead to miscarriage of a foetus Amniocentesis cannot say for certain that a foetus has an abnormality and therefore parents might choose to terminate a child, even though it may be healthy. Amniocentesis allows parents to decide whether or not to maintain a pregnancy if their child has a genetic abnormality Amniocentesis Arguments For Against Debate 6. Choose an argument above and prepare a short speech that you will give to the class as to why Amniocentesis should or should not be allowed. 30 Useful mutations (take this sub-heading in your jotter) Although most mutations are detrimental to the organism, some mutations can be useful. For example, some plant species possess an extra complete set of chromosomes due to a chromosome mutation. These plants are known as polyploids. Polyploid strawberries are much larger than normal strawberries, polyploid tomatoes contain extra vitamin C, polyploid wheat produce more flour. 6. What is the chromosome mutation that occurs in polyploids? 7. Give 2 examples of polyploid fruits and their useful mutation. Mutagenic Agents Naturally occurring mutations are rare and therefore mutation is slow. There are some mutagenic agents that speed up the rate of mutation: nuclear radiation (atomic), ultra-violet light (sunlight – leads to mutation in skin cells and may lead to skin cancer) and x-rays (pregnant woman are not recommended for x-rays past a certain point in their pregnancy). In Down’s syndrome, the rate of mutation increases as the mother’s age increases, so the older the mother, the greater the chance of a child with Down’s syndrome. 8. Take the sub-heading “Mutagenic Agents”. Then copy and complete the sentence below using information in the above passage: The rate of mutation can be increased by ……………………….. ………………….., such as: 1. ………………………. radiation 2. ……………………. ………………………… (UV) light 3. X-rays 4. The ………………… of the mother 31 There have been many fictional representations of mutations in Humans, such as the X-Men comics. Some scientists believe that as the human species continues to evolve there will be more mutations that occur in the human race that benefit the species. Watch the “X-men first class movie trailer” What to do 9. Find the “Create your own Mutant” diagram in your diagram pack. Complete the diagram by: Describing which part of the mutants genetics have been altered (a particular gene or chromosome?) Describing the physical appearance of your mutant and any additional powers they may possess Drawing a labelled diagram of your mutant 32