epigenetics

Question 1

darwin

Answer 1

Darwin first conceived the theory of evolution by natural selection, and that adaptive heritable characteristics were passed on from parent to offspring. This led to the publication of “origin of the species”

Question 2

punnett squares

Answer 2

show the chance of a dominate and recessive gene, specifically an allele being passed from parent to offspring

Question 3

chromosomea

Answer 3

Out of the 23 pairs of chromosomes we have in ur DNA, 1-22 are called autosomes, and the 23rd is the sex chromosome (XX for females, as here, or XY for males). We inherit one chromosome from each of our parents

Question 4

alleles

Answer 4

Alleles are alternate forms of a gene inherited one from the father and one from the mother (and so found on corresponding sites on homologous chromosomes). There can be dominant and recessive versions of the gene.
In any combination with the dominant version, it is the one that is expressed. The recessive only expresses in the absence of the dominant.

Question 5

what do genes show

Answer 5

Genes are responsible for the type of the body they express (e.g., the eye colour). Alleles dictate what the characteristic of that body part is expressed (e.g., blue, brown, green, grey, etc)

Question 6

autosomal dominant diseases

Answer 6

for example Huntingdon’s. means it is always carried on the dominant gene. Therefore, when one parent has it, it expresses 50% of the time. If both parents have it, there is a 75% chance of the child inheriting.

Question 7

ketys research

Answer 7

schizphrenia

We can look at concordance for a variety of phenomena by exploring the degree to which individuals are biological related and/or have shared environments.

Individuals who do not have a shared environment BUT have a biological parent who has schizophrenia have a 9x higher chance of developing schizophrenia than is observed in the general population.

Question 8

fischers twin study

Answer 8

schizophrenia

The concordance rate, the probability that a second twin will develop a disorder if the proband (first examined) twin has the disorder, is commonly used. The concordance rates of schizophrenia for monozygotic twins have been found to be about 40 to 50%, and heritability estimates are around 80%.

Question 9

4 laws of behavioural genetics

Answer 9

Turkenheimer (2000), Chabris et al., (2015)

1. All human behavioural trait are heritable
2. The effect of the genes is larger than the effect of the shared environment
3. A lot of variance is not attributable to either genes or shared environment

. Most complex traits are shaped by many genes of small effect

Question 10

DNA

Answer 10

Chromosomes are a packaging system for DNA, and form the essential unit in cell division. It is wound around spool-like histone proteins such that the total of about 2 metres of DNA in our cells can be packing into about 0.1 mm of chromatin

(Adenine-Thymine and Guanine-Cytosine)

Question 11

DNA replication

Answer 11

To replicate, the strands unwind; each nucleotide attracts its complementary base (floating about in the cell nucleus), making two DNA molecules identical to the original
Replication errors affecting particular genes are called mutations

Question 12

gene expression

Answer 12

just having a gene doesn’t do a whole lot. It’s only when the gene expresses itself (by triggering protein synthesis) that it has an effect. Gene expression depends heavily on the organisms internal and external environment

Question 13

Polygenicity

Answer 13

involvement of multiple genes in 1 trait e.g. ADHD – 33 genes

Question 14

Pleiotropy

Answer 14

involvement of one gene in multiple traits e.g. phenylketonuria

Question 15

epigentetic mechanism

Answer 15

RNA methylation
DNA methylation
Histone acetylation

Question 16

passive gene-environment interactions

Answer 16

• Parents create environment to suit their genetic predispositions
• This can enhance children’s inherited characteristics

Question 17

evocative gene-environment interactions

Answer 17

• People have inherited tendencies to evoke certain responses
• These evoked responses reinforce inherited characteristics

Question 18

active gene-environment interactions

Answer 18

• People select/create environments compatible with their inherited characteristics
• The resulting experiences enhance the effects of inheritance

Question 19

dutch hunger winter

Answer 19

long term effects on dutch population

starvation had long lasting effects on the body, even after food was normal

Barker proposed that a situation where there is an adverse fetal environment (e.g, shortage of food), followed by a plentiful food environment may be a recipe for adult chronic disease.

Question 20

The Dutch Famine Birth Cohort Study

Answer 20

revealed that the children of women who had starved during the Hunger Winter had health problems: including higher rates of diabetes, obesity, and cardiovascular disease.

Question 21

late gestation period

Answer 21

• Glucose intolerance - Glucose intolerance is an umbrella term for metabolic conditions which result in higher than normal blood glucose levels - hyperglycemia. Associated with T2 diabetes

Question 22

mid gestation period

Answer 22

• Glucose intolerance
• Microalbuminuria - Microalbuminuria means that there’s more of a protein called albumin leaking from your kidneys into your urine than normal. Associated with high blood pressure and diabetes
• Obstructive airway disease

Question 23

early gestation period

Answer 23

• Glucose intolerance
• Hyperlipidaemia – hyperlipidaemia means your blood has too many lipids (or fats), such as cholesterol and triglycerides. One type of hyperlipidaemia , hypercholesterolemia, means there’s too much LDL (bad) cholesterol in your blood.

Question 24

birth weights

Answer 24

Intrauterine exposures that have long-lasting consequences for adult health do not necessarily result in altered birth weight. Women exposed to the famine during mid- to late gestation had babies with significantly reduced birth weights. Babies whose mothers were exposed only during early gestation had normal birth weights; however, they grew up to have higher rates of obesity than those born before and after the war and higher rates than those exposed during mid- to late gestation

Question 25

animal models

Answer 25

One mice is methylated, one is not. So, these mice are also genetically identical – they have exactly the same DNA. The reason they look different is due to epigenetic modifications, in this example DNA methylation. So when a certain gene is methylated, expression is reduced, then mice appear normal.
However, when expression of this gene is not methylated, it is over expressed leading to the obese, pale mouse with reduce lifespan and increased susceptibility to cancer.

Question 26

diet in animal models

Answer 26

differences in maternal diet can alter gene expression in offspring. So, healthy behaviour including diet, and physical activity has links with adaptive epigenetic modifications.
What is also important to note, is the pale mice tend to have pale offspring, and the brown mice tend to have brown, skinny offspring. This is another example of transgenerational inheritance.