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Yr2 Brain & Behaviour > Behavioural Genetics > Flashcards

Behavioural Genetics Flashcards

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1
Q

What are the four types of nucleotides (bases) that make up a DNA polymer?

A

Thymine(T), Adenine(A), Guanine(G), and Cytosine(C)

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2
Q

Describe a DNA molecule

A

Two strands of nucleotides running in opposite directions, coiled into a double-helix.
Nucleotides from each strand are held together by hydrogen bonds

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3
Q

What are the specific pairs that nucleotides can form bonds in?

A

T - A or A - T

C - G or G - C

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4
Q

What is being referred to by ‘the sequence’

A

The order nucleotides are found along the strand

- very important for DNA coding

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5
Q

How many chromosomes do humans have?

A

23 pairs

46 in total

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6
Q

How do mutations in DNA occur?

A

A cell divides, the DNA helix is ‘unzipped’ so a complimentary strand can be made.
Sometimes errors are made when the new strand is made, so it isn’t identical.
If a repair enzyme does not fix this error, a mutation occurs

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7
Q

Name the three ways DNA mutations can occur

A
  1. Base-pair substitution
    - one nucleotide and its partner are replaced by a different pair
  2. Deletion
    - the loss of one or more base pairs
  3. Insertion
    - the addition of one or more extra base pairs
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8
Q

What is RNA?

A

Ribonucleic acid

- single strand chemical that can serve as a template for the synthesis of proteins

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9
Q

What is the name of the process that creates RNA from DNA?

A

Transcription

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10
Q

What are the nucleotides found in RNA?

A

Uracil (replaces thymine)
Adenine
Guanine
Cytosine

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11
Q

What is mRNA?

A

Messenger ribonucleic acid

  • is essentially a disposable copy of a gene
  • carries the protein building information (codons)
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12
Q

What does mRNA do?

A

Translation

  • carries protein-building message that is encoded by sets of genetic words which occur one after another along the length of DNA
  • decodes protein-building information
  • results in a polypeptide chain
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13
Q

What is a codon?

A

The protein building information carried by mRNA

  • they are 3 bases long (e.g. A-C-G)
  • there are 64 codons
  • each codon refers to a specific amino acid
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14
Q

How many base pairs (nucleotide pairs) are there in a human chromosome?

A

50,000,000 - 300,000,000

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15
Q

What is a gene?

A

A segment of a chromosome

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16
Q

What is a homozygous gene?

A

An identical pair of alleles on the two chromosome

a base pair that is made up of the same base twice e.g. TT

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17
Q

What is a heterozygous gene?

A

A pair of alleles on the two chromosomes that are different (a base pair made up of two different nucleotides e.g. TA)

18
Q

What is epigenetics the study of?

A

How your behaviour and environment can cause changes that affect the way your genes work

  • e.g. some genes are only active at a certain point in one’s life
  • changes are reversible and do not alter DNA sequence
19
Q

What is a dominant gene?

A

A variant of a gene that expresses itself more strongly than any other version of the gene which the person is carrying
Shows a strong effect in both the homozygous and heterozygous condition

20
Q

What is a recessive gene?

A

A gene who’s effects are hidden in the presence of a dominant gene
It will only show its effect in the homozygous condition (if there are two bases the same)

21
Q

What is PER?

A

A protein produced by period genes, that promotes inactivity and sleep

22
Q

What is TIM?

A

A protein produced by timeless genes, that promotes inactivity and sleep

23
Q

What happens to the concentrations of PER and TIM throughout the day?

A

They oscillate

  • synthesis of PER and TIM are very low at sunrise but increase throughout the day
  • levels of the proteins themselves then increases later in the day, so PER&TIM levels are high at night
24
Q

What is Familial advanced sleep disorder (ASPD)?

A

A Circadian Rhythm Sleep Disorder
A mutation in the Per2 gene, that causes persistent advanced onset of sleep and awakening
- sufferers typically experience sleepiness in the early evenings rather than later on (at night)

25
Q

What is a proband?

A

A person serving as the starting point for a genetic study of a family

26
Q

How was Familial advanced sleep disorder (ASPD) discovered?

A
  • Proband’s sleep phase was brought forward 4-8 hours
  • Proband participated in time-isolation experiment for 3 weeks (stayed in an environment with no time cues)
  • showed a 1 hour shortening in her circadian period
  • a mutation in the Per2 gene was identified
27
Q

What are Familial natural short sleepers (FNSS)?

A

Circadian Rhythm Sleep Disorder

  • People with mutation in the DEC2 gene
  • Carriers needed only 6 hours of sleep a day
  • mutation leads to difference in EEG architecture of sleep (higher delta power during slow-wave NREM & less REM sleep)
28
Q

What is Brain-Derived Neurotrophic Factor (BDNF)?

A

A neurotrophin, important in neurogenesis and plasticity

29
Q

What is Heritability?

A

Refers to how much characteristics depend on genetic differences

30
Q

What can change the impact of genetic influences (heritable genes)?

A

Strong environmental influences can cause genetic influences to have less of an impact

31
Q

How do genes affect our behaviour?

A
  • They do not directly produce behaviours
  • Genes produce proteins that increase the probability that a behaviour will develop under certain circumstances
  • Genes can also have an indirect effect - can alter your environment by producing behaviours or traits that alter how people in your environment react to you
32
Q

What is the most common twin-model used in twin research to explain the amount of variance between twin pairs?

A

The ACE model:

  • A (or h2) = Additive genetic effect. This is the proportion of variance of a phenotype explained by genetic influences
  • C = Common environmental influences (proportion of the variance of a phenotype explained by shared environment)
  • E = Non-shared environmental influences, unique to each twin (proportion of the variance of a phenotype explained by a non-shared environment)
33
Q

What are some examples of Non-Shared Environmental factors for children growing up in the same family?

A

Peers
Child-specific illnesses / events
Events occurring to an individual

34
Q

What are some examples of Shared Environmental factors for children growing up in the same family?

A

Socioeconomic status
Characteristics of the home e.g. number of books in home

Parenting less likely to be shared - can’t be treated in exactly same way

35
Q

What is the Univariate twin model?

A

Asks how much of the variance (between twins) in a trait is explained by A, C or E from the ACE model?

36
Q

What is the Bivariate twin model?

A

Asks to what extent is trait 1 caused by the same genetic and environmental influences as trait 2

37
Q

What is Genetic Correlation?

A

Is independent of the phenotypic relationship between two traits
Is independent of the heritability estimates of either trait

38
Q

What are the Pros of twin studies?

A
  • All Ps are same age
  • Can partition variance into A + C + E
  • Reasonably representative of general population
  • Don’t need a control group
39
Q

What are the Cons of twin studies?

A
  • Requires large samples (>1000 pairs) to have sufficient power
  • Design has many assumptions
  • Some twin-specific characteristics are not generalisable to singletons
40
Q

What are the assumptions of twin studies?

A
  • Findings from twins are generalisable to singletons
  • Assumes no gene-environment correlation or interaction
  • Equal environments assumption: assumes environmental influences are equivalent for MZ and DZ pairs

Yr2 Brain & Behaviour (9 decks)

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