Genetics

Question 1

Mendel (1872-1884)

Answer 1

Dichotomous traits. One form or another never in combination.

Question 2

What is phenotype?

Answer 2

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Question 3

What is genotype?

Answer 3

the genetic constitution of an individual organism.

Question 4

What is allele?

Answer 4

each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Question 5

What is heterozygous and homozygous?

Answer 5

When an individual has two of the same allele, whether dominant or recessive, they are homozygous. Heterozygous means having one each of two different alleles.

Question 6

What do you call the grid of genes?

Answer 6

Punnet square

Question 7

What is autosomal chromosome?

Answer 7

Any chromosome that is not sex chromosome.

Question 8

How many autosomal and sex chromosomes do we have?

Answer 8

22 pairs of autosomal chromosome and 1 pair of sex chromosomes.

Question 9

If a recessive gens is on an autosomal…

Answer 9

its effects will be found equally in males and females.

Question 10

If recessive gene is an x chromosome…

Answer 10

It’s effects will be formed more often in males

Question 11

What are chromosomes made of?

Answer 11

DNA

Question 12

What are the base pairs?

Answer 12

Adenine Thymine

Cytosine Guanine

Question 13

What is the structure of DNA?

Answer 13

Alpha helix- good shape allows DNA unwinds so it can replicate- Good because makes new cells or babies
Spare bases bind to complementary bases in unwound strands

Question 14

What is mitosis?

Answer 14

Cell replicate complementary strands of DNA form new chromosomes get twice as many as you started with. Cell splits new cell as DNA you started with. Needed to make new cells or babies.

Question 15

What is meiosis?

Answer 15

In sperm/egg cells end up with cells with one of each chromosome pair DNA still replicates left with sperm or cells when they fuse one pair of chromosome from mum and one from dad - random which pair you have.

Question 16

What happens when crossing over occurs?

Answer 16

Sometimes in meiotic cell crossing over can occur, when chromosome line up a bit of chromosome gets swapped with another bit called chiasma official name recombinant chromatids.

Question 17

What does DNA make?

Answer 17

Proteins

Question 18

What do genes hold the instructions of? How?

Answer 18

To make proteins- Unwinding of the alpha double helix makes complementary strand of single stranded mRNA .
RNA- Ribonucleic acid CGAU into DNA.

Question 19

Describe the process of translation…

Answer 19

RNA gets translated into a protein. DNA unwinds mRNA copies DNA in to AGCU single strands mRNA out of the nucleus into the cytoplasm and mRNA gets translated tRNA brings amino acid complementary base pairs on heads specific amino acids. Ribosome reads letters of three calls tRNA and ribosome then builds chain of amino acids - becomes peptide - may become more complex to secondary tertiary structure and become a protein.

Question 20

What chromosome causes down syndrome? What does it cause? What percentage of genes, mRNA and protein (amyloid) does it have?

Answer 20

Trisomy chromosome 21 - three copies of it cause downs syndrome. Cognitive deficit. 150% of each.

Question 21

RNA is a complimentary copy of one strand…

Answer 21

of a DNA molecule.

Question 22

Briefly state the process of down syndrome in terms of genes..

Answer 22

Gene overexpression -> Neuropathology -> Cognitive deficit

Question 23

What gene is involved in Alzheimer’s disease?

Answer 23

21 on Amyloid Precursor Protein (APP) there are amyloid plaques that lead to neurofibilary tangles.

Question 24

What is phenylketonuria (PKU)?

Answer 24

Autosomal recessive gene
Single mutation
Inability to metabolise phenylalanine (an amino acid)
Results in brain damage
Caused by mutation in the gene for the hepatic enzyme phenylalanine hydroxylase (PAH) rendering it non-functional.
When PAH activity is reduced, phenylalanine accumulate and in converted into phenyl pyruvate.

Question 25

Define heritability and how it's measured

Answer 25

Estimate of how much variance in some characteristic within some population is due to differences in heredity. Varies between 0 and 1 (0.5 is intermediate.)

Question 26

What did Thomas Bouchard do?

Answer 26

Studies on heritability in twin studies on personality traits and psychological interests.

Question 27

How is heritability calculated?

Answer 27

Comparing the correlation co-efficient of identical and non-identical twins for particular traits.

Question 28

Heritability is 'specific' to the...

Answer 28

population in which it's calculated. It looks at variance between individuals.

Question 29

High heritability does not imply that...

Answer 29

the environment doesn't alter that trait.

Question 30

What did Robert Paloma do?

Answer 30

Looked at twins across the UK and calculated hereditability of twins across the UK on a website called TED. High heritability does not imply that the environment does not play a role.

Question 31

If a group of individuals share a highly similar environment, what effect does this have on the heritability estimate of a characteristic?

Answer 31

Heritability estimate will be high.

Question 32

Thee heritability of general cognitive ability increases...

Answer 32

linearly from childhood to young adulthood.

Question 33

Overtime tendency to seek out environments that...

Answer 33

increase cognitive ability.

Question 34

What is the multiplier effect (Flynn, 2001)?

Answer 34

If genetic or prenatal influences produce even a small increase in some activity, the early tendency will change the environment in a way that magnifies that tendency - explanation for heritability changing over time.

Question 35

Briefly show the Weinberger approach

Answer 35

Gene -> Neurophysiology -> cognition

Question 36

Briefly show the process for the gene Tryptophan Hydroxylase

Answer 36

Tryptophan -> Tryptophan hydroxylase -> 5 - hydroxyl tryptophan -> aromatic l- amino acid and decarboxylase -> Serotonin 5HT

Question 37

Sometimes mutant form of Tryptophan Hydroxylase gene ---

Answer 37

rare mutation not applied to all depressed people. In vitro cells with this gene make less serotonin than cells with normal genes.

Question 38

Zheng et al (2005) did what?

Answer 38

Studied how many depressed had mutant form of gene 9/87 in depressed group had mutant form of gene 3/219 in control group had mutant form of gene. More prevalent in depressed than control. Subjects with mutant form had anxiety, alcoholism and family history of mental health problems. It's the case that many people who are depressed don't necessarily have the mutant form of the gene for tryptophan hydroxylase so other genes and environment may be involved.

Question 39

The serotonin transporter has two forms which are...

Answer 39

long and short. Brain overrespond to negative emotions - environment.

Question 40

What does amygdala deal with?

Answer 40

Emotions and memory

Question 41

fMRI is different for short gene and

Answer 41

normal gene in relation to serotonin transporter gene.

Question 42

What did Caspi et al, 2003 do?

Answer 42

Divided into groups based on serotonin transporter gene measured depressive symptoms. Results no difference in number of stressful events between genetic groups. Genotype - non-significant. Interaction - highly significant.

Question 43

What can longitudinal studies do with genes?

Answer 43

Reveal how these genes interact with the environment and produce depressive symptoms.