Next session studying heritability psychlotron org uk Reading

• Next session: studying heritability psychlotron. org. uk – Reading – Preparation Qs

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

psychlotron. org. uk Evolution of phobia

Evolution of phobia psychlotron. org. uk X

Evolution of phobia X X X psychlotron. org. uk X

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

• • Genetics Heredity Genotype Phenotype Dominant gene Recessive gene psychlotron. org. uk How many can you define?

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

Genetics and heredity psychlotron. org. uk • 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

psychlotron. org. uk • What’s the difference between genotype and phenotype?

Genotype vs Phenotype psychlotron. org. uk • 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.

psychlotron. org. uk • Why might a characteristic encoded in the genotype not be expressed in the phenotype?

• How does this example illustrate the concepts of phenotype and genotype? psychlotron. org. uk – 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.

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

psychlotron. org. uk • What’s the difference between a dominant and a recessive gene?

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

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

Brown eyes Blue eyes Dark hair Blond/red hair Curly hair Straight hair Colour vision Colour blindness Normal sight Night blindness Normal blood Haemophilia Hearing Congenital Deafness psychlotron. org. uk Dominant vs Recessive

Explain why… psychlotron. org. uk • 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.

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 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 psychlotron. org. uk 100 % down to environment 1

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

psychlotron. org. uk