1. What is Inheritance? Standard Grade Biology

2. By the end of this lesson you should be able to:  Know how many chromosomes are in body cells  Understand the word phenotype  Give examples of phenotypes  Understand what true breeding means  Know what the letters P, F 1 and F 2 represent  Understand what dominant and recessive mean and be able to give examples

3. What is Inheritance? What makes us who we are? Your environment The genetic information and your experiences you got from your parents YOU

4. What is Inheritance? The characteristics that an organism has have mostly been inherited from the parents. They are determined by the genetic information from their mother and their father E.g. eye colour, blood type, flower colour

5. Genes & Chromosomes We inherit information in the form of genes. We inherit information in the form of genes. Each gene controls a different characteristic Each gene controls a different characteristic Genes can be found on CHROMOSOMES (thread like structures) Genes can be found on CHROMOSOMES (thread like structures)

6. Genes & Chromosomes

7. Chromosomes Chromosomes can be found in the NUCLEUS of a cell Chromosomes can be found in the NUCLEUS of a cell Every cell in an individual contains a full set of chromosomes in the nucleus (except sex cells) Every cell in an individual contains a full set of chromosomes in the nucleus (except sex cells) The number of chromosomes varies between species The number of chromosomes varies between species Some species can have as few as 2 chromosomes and others as many as 100! Some species can have as few as 2 chromosomes and others as many as 100! Humans have 46 chromosomes Humans have 46 chromosomes

8. Chromosomes Each chromosome can have thousands of genes on it Each chromosome can have thousands of genes on it Chromosomes are passed from parents to offspring during fertilisation. Chromosomes are passed from parents to offspring during fertilisation. This is how we acquire inherited information This is how we acquire inherited information

9. PHENOTYPE The PHENOTYPE is the organism’s appearance which has resulted from the genetic information inherited from the parents. There can be a number of different forms of the phenotype e.g. wing type of fruit flies can be normal or vestigial.

10. PHENOTYPE Fruit flies “normal” wings/Vestigial wings

11. PHENOTYPE Fruit flies can have grey bodies or ebony bodies

12. PHENOTYPE Copy the table 21.1 from P158 in Torrance

13. True Breeding Sometimes two organisms with the opposite phenotype can be crossed (mate) and produce offspring with the different phenotypes Sometimes two organisms with the opposite phenotype can be crossed (mate) and produce offspring with the different phenotypes X

14. True Breeding However if all the offspring show the same phenotype, the parents are said to be TRUE BREEDING However if all the offspring show the same phenotype, the parents are said to be TRUE BREEDING

15. True Breeding So if a true breeding black cat and a true breeding white cat are crossed all the offspring will be……. So if a true breeding black cat and a true breeding white cat are crossed all the offspring will be……. BLACK! BLACK!

16. Why????????? This is because the gene for a black coat is ‘stronger’ than the gene for white coat. This is because the gene for a black coat is ‘stronger’ than the gene for white coat. The gene for a black coat is DOMINANT The gene for a black coat is DOMINANT The gene for white coat is RECESSIVE The gene for white coat is RECESSIVE

17. Task Insert the “Guinea Pig Cross- diagram 1” into your jotter. Insert the “Guinea Pig Cross- diagram 1” into your jotter. Answer the following questions in sentences: Answer the following questions in sentences: 1. What letter is used to represent the parents? 2. What letter and number are used to represent the first generation?

18. Task…. Copy and complete the following paragraph: The parents in both crosses are described as true breeding. This means that, when bred together, black guinea pigs will always produce offspring. True breeding white guinea pigs, when bred together, will always produce offspring.

19. An example The gene for a long coat is dominant to the gene for short coat in dogs The gene for a long coat is dominant to the gene for short coat in dogs Imagine a cross between a true breeding short haired dog and another true breeding short haired dog. Imagine a cross between a true breeding short haired dog and another true breeding short haired dog. What will the hair of the puppies be like? What will the hair of the puppies be like?

20. Task Insert the “Guinea Pig Cross- diagram 2” into your jotter. Insert the “Guinea Pig Cross- diagram 2” into your jotter. Answer the following questions in sentences: Answer the following questions in sentences: 1. What colour coat do the parents have? 2. What colour coat are the F 1 generation? 3. What colour coat are the F 2 generation? 4. Which phenotype does not show in the F 1 generation?

21. Task 5. Which phenotype does show up? 6. In which generation are both phenotypes present? 7. In the F 2 generation, which phenotype is most common? 8. Which phenotype is dominant? 9. Which phenotype is recessive?

22. Task Copy and complete the following paragraph: If two individuals, of different phenotypes are crossed, all of the offspring will have the of one of the parents. This phenotype is, the other phenotype is dominantrecessivephenotypetrue-breeding dominant phenotype recessive

23. What do you know? Can you do the following?:  Say how many chromosomes are in body cells  Say what the word phenotype means  Give examples of phenotypes  Say what true breeding means  Say what the letters P, F 1 and F 2 represent  Say what dominant and recessive mean and be able to give examples