Genetics 2

Question 1

What is heritability?

Answer 1

Variance in a trait explained by heritable factors

Question 2

Heritability estimates vary from

Answer 2

0-1

Question 3

Key study for working out heritability estimates?

Answer 3

Minnesota twin study

Question 4

MZ twins share what % of the same genes?

Answer 4

100%

Question 5

DZ twins share what % of the same genes?

Answer 5

50%

Question 6

If a trait was 100% hereditary, the heritability estimate would be

Answer 6

1

Question 7

Heritability estimates are specific to the

Answer 7

Population from which it was calculated

Question 8

High heritability DOES not imply

Answer 8

The environment doesn’t have an effect on the trait

Question 9

How might environment influence heritability estimates?

Answer 9

Can exert an effect on the trait over time

Question 10

If a group of individuals share a similar environment, what effect might this have on heritability estimates?

Answer 10

Heritability estimate will be high

Question 11

Example of a trait where the heritability estimate increases from childhood to adulthood?

Answer 11

Intelligence

Question 12

What is the ‘Multiplier Effect’?

Answer 12

Phenomenon where a small genetic effect is amplified by the environment - attributed more to genetics than it should be

Question 13

Depression concordance rate for MZ and DZ twins?

Answer 13

60%

15%

Question 14

Two gene theories for depression?

Answer 14

1. Tryptophan hydoxylase gene

2. Serotonin transporter gene

Question 15

Serotonin is synthesised from

Answer 15

Amino acid - Tryptophan

Question 16

First step of serotonin synthesis involves

Answer 16

Tryptophan hydroxolase (enzyme)

Question 17

Mutant form of the Tryptophan hydroxolase means

Answer 17

80% less serotonin produced

Question 18

Zhang et al., 2005

How many of the depressed participants had the faulty tryptophan gene?

Answer 18

9

Question 19

What is a problem with the Tryptophan hydroxolase theory of depression?

Answer 19

Many are depressed and don’t have this gene

Some have this gene and are not depressed

Question 20

Gene for serotonin transport has two forms

Answer 20

Short and long

Question 21

Gene for serotonin transport

What are the non-normal genes?

Answer 21

Short

Question 22

Gene for serotonin transport

The group with the short gene….

Answer 22

Had a larger emotional response to stimuli (in amygdala)

Question 23

Gene for serotonin transport

The group with the short gene had a larger emotional response to stimuli. However, this particular study is limited in its application to depressed people…

Answer 23

Pps were not depressed

Question 24

Caspi et al., 2003

Two groups

Answer 24

L or S serotonin transporter gene

Question 25

Caspi et al., 2003

What was the study design?

Answer 25

Longitudinal

Question 26

Caspi et al., 2003

What was the finding?

Answer 26

HIGHLY significant interaction between gene + stress event

Question 27

Caspi et al., 2003

What was measured?

Answer 27

Depressive symptoms

Question 28

Caspi et al., 2003

What model do the results support?

Answer 28

Diathesis stress model