Next session: studying heritability Reading Preparation Qs

1. Next session: studying heritability • Reading • Preparation Qs

2. Evolution Cars kill many more people than spiders. So why are phobias of spiders much more common than phobias of cars?

3. Evolution of phobia

4. Evolution of phobia X

5. Evolution of phobia X

6. Evolution of phobia X

7. Evolution of phobia X

8. Evolution of phobia X

9. Evolution of phobia X X X X

10. Today you will… Learn about Learn how to Describe biological structures Distinguish between biological and psychological concepts • The role and influence of genes in humans

11. How many can you define? • Gene • Genetics • Heredity • Genotype • Phenotype • Dominant gene • Recessive gene

12. What are genes? • Genes are bits of DNA which make proteins • These proteins cause physiological responses in the body • An organism’s genes convey information about how to construct that organism from one generation to the next

13. Genetics and heredity • Genetics is the study of how genes influence physical and behavioural characteristics • Heredity refers to the traits, tendencies and characteristics inherited from our parents/ancestors

14. What’s the difference between genotype and phenotype?

15. Genotype vs Phenotype • Genotype: the whole set of genetic information carried by the organism • Phenotype: the physical manifestation of the genotype. Only some genes carried in the genotype will be expressed in the phenotype.

16. Why might a characteristic encoded in the genotype not be expressed in the phenotype?

17. How does this example illustrate the concepts of phenotype and genotype? • John and Alan are identical twins who were separated at birth. Alan was raised in a very impoverished environment. John is substantially taller than Alan.

18. Remember... • Just because it’s in the genotype that doesn’t necessarily mean it’ll be expressed in the phenotype: • The environment influences gene expression • Some genes are recessive and some are dominant

19. What’s the difference between a dominant and a recessive gene?

20. Genes are organised in chromosomes, these come in pairs – you inherit one half of each pair from each parent • Dominant genes are always expressed • Recessive genes are expressed only in the absence of a dominant gene

21. Which genes are expressed? • Consider eye colour: B = brown eyes (dominant) b = blue eyes (recessive) • So what colour eyes would a person have with the following gene pairs? • BB • Bb • bb

22. Dominant vs Recessive

23. Explain why… • Doug and Amber both have blonde hair. They have two children, Alex and Sam. Alex has red hair while Sam’s hair is dark brown.

24. Heritability The extent to which the variability found in a characteristic or trait is hereditary is known as the heritability coefficient (score from 0 to 1) O 1 100 % down to environment 100 % down to genes For example, eye colour is solely determined by genes so has a heritability coefficient of 1. Height is slightly influenced by environment and has a heritability coefficient of 0.9

25. What about psychology? • Where would you place these traits? • Memory, extraversion, academic achievement, verbal reasoning, intelligence, spatial reasoning O 1 100 % down to environment 100 % down to genes