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Genes Brain and Behaviour > Genetics Lectures (2-3) > Flashcards

Genetics Lectures (2-3) Flashcards

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1
Q

What are the four principles of evolutionary theory proposed by Wallace and Darwin?

A
  1. ‘Principle of Variation’: Individuals within a species show variation in their physical and behavioural traits.
    • 2. ‘Principle of Inheritance’: Some of this variation is heritable.
    • 3. ‘Principle of Adaptation’: Individuals are in competition with one another for scarce resources and some inherited variations will have survival advantages. (neurons can ‘compete’ in the brain)
    • 4. ‘Principle of Evolution’: as a consequence of being better adapted to an environment, some individuals will produce more offspring, who will inherit the same advantages. This is called ‘fitness’.
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2
Q

What is adaptive behaviour?

A

A fine tuning mechanism that produces phenotypic variability. It evolves as natural selection fine-tunes an animal to its environment.

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3
Q

What is proximate causation?

A

Proximate Causation
–the immediate psychological, physiological, biochemical, and environmental reasons for the existance of a trait
• Sensory systems - need to be able to perceive danger
• Mechanisms that drive muscles that elicit behaviour
• Need to be able to contract muscles to run
• Cellular activities regulate development, nerve function

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4
Q

What is ultime causation?

A

The reason why a trait increased fitness in the evolutionary past:
• How does the internal machinery work?
• Why does machinery work that way?
• Is that behaviour an adaptation?
• How does that behaviour allow the individual to survive, find food, find mates, escape predators, communicate?

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5
Q

What are spandrels?

A

Design constraints in evolution that are supportive for adaptions, but not adaptions themselves.

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6
Q

Define evolutionary psychology

A

The study of the physiological, evolutionary and devleopmental mechanisms of behaviour and experience (ie. the application of Darwinian principles to the understanding of human nature)

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7
Q

What are four categories for biological explanations of behaviour (evolutionary psychology)?

A
  • Physiological (activity of brain/other organs)
  • Ontogenetic (Development of structure/behaviour)
  • Evolutionary (history of behaviour)
  • Functional (why a structure/behaviour evolved)

Understanding a particular behaviour requires explanations from each perspective!

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8
Q

Where was the biggest increase in brain size observed in homo sapiens?

A

The prefrontal cortex

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9
Q

Criticism of evolutionary psychology led to the development of what two perspectives?

A
  • Evolutionary psychology as just one theory of many
  • Bidirectional view: the environment and biological conditions influence EACH OTHER. Individuals create behaviour in the context of culture
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10
Q

How does the length of juvenile period correlate with brain size?

A

Longer juvenile period (altricial species) have bigger brains and a larger window of plasticity (programming period)

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11
Q

What percent of DNA codes for mRNA?

A

3%

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12
Q

True or false? DNA is the SAME in all somatic cells of an organism?

A

True!

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13
Q

True or false? Humans have more proteins than they have genes?

A

True

Genes collaborate with each other and with non-genetic factors inside and outside the body (bidirectional modality)

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14
Q

How many chromosomes are there in humans?

A

46 (23 pairs)

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15
Q

Do stem cells divide via mitosis or meiosis?

A

Mitosis

Meiosis only for sex gametes. Meiosis has processes of recombination which gives rise to increased variation

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16
Q

When do chromosomal abnormalities occur? List a few

A

When there is an error in cell division following meiosis or mitosis. It can be caused by a missing, extra or irregular portion of chromosomal DNA

  • Down syndrome (trisomy 21)
  • Kinefelter syndrome
  • Fragile X syndrome
  • Turner syndrome (X0)
  • XYY syndrome
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17
Q

What is the observable and measurable component of a person’s phenotype in regards to behavioural genetics?

A

Human behavioural and personality ‘characteristics.’ These are detectable expressions of a person’s genotype interacting with his or her environment

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18
Q

What is a genetic marker in linkage studies?

A

These are segments of DNA that vary among individuals. Patterns of inheritance of genetic markers in large families can be observed.

Using genetic markers is how genes for many diseases were found in classic gene linkage studies.

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19
Q

What is heritability?

A

The statistical estimate of the proportion of the total variance in some strait that is attributable to genetic differences among individuals within a group.

Expressed as a proportion (eg. .6 or 6/10) so that maximum value is 1.

20
Q

What are three limitations of heritability estimates?

A
  1. An estimate of heritability applies only to a particular group living in a particular environment.
  2. Heritability estimates do not apply to individuals, only to variations within a group.
  3. Even highly heritable traits can be modified by the environment.
21
Q

What are the three ways in which heritability of a behaviour is estimated?

A
  1. Examining whether children more closely resemble their adoptive or biological parents
  2. Comparing monozygotic (identical) and diozygotic (fraternal) twins
  3. Examining identical twins raised in different households
22
Q

True or false? The relative contributions of heredity and environment are not additive.

Why or why not?

A

True

This is because all traits (regardless of heredity) are not rigidly fixed and can be modified by experience.

  • Complex behaviours have some genetic loading, that provide an individual with a risk for a particular developmental outcome.
  • Our environment is complex and the interaction of heredity and environment is extensive
23
Q

List the four major experiments that revealed that DNA is the molecular basis of heredity (rather than protein or RNA).

A
  • Griffith’s heat transformation experiment (nucleic acid not protein)
  • Avery’s nuclease transformation experiment (DNA not RNA)
  • Hershey-Chase bacteriophage experiment (DNA not protein is genetic material)
  • Tobacco mosaic virus experiment (RNA is genetic material of some viruses)
24
Q

List the purines and the pyrimidines

A

Purines

  • Adenine
  • Guanine

Pyrimidine

  • Cytosine
  • Thymine
  • Uracil
25
Q

Which pentose carbon is the phosphate group of the backbone attached to?

A

The 5’ carbon

26
Q

What is a phosphodiester bond?

A

A covalent bond between the phosphate group of one nucleotide and the 3’ carbon of the sugar of another.

Very strong bond (DNA can be boiled and even autoclaved without degrading)

27
Q

What are the two sources of information for the double helix model of DNA?

A
  1. Base composition studies by Erwin Chargaff (50% purines and 50% pyrimidines). Chargaff’s rule is amount of A=T and amount of G=C
  2. Rosaline Franklin and Maurice Wilkins’ x-ray diffraction studies
28
Q

DNA is to PENTOSE as RNA is to ____

A

RIBOSE

29
Q

What is the organization of DNA in prokaryotes called?

A

The genophore (a chromosome without chromatin)

30
Q

What provides the ‘indexing’ for the densely backed DNA in the nucleus?

A

Chromatin

31
Q

How many times is DNA wrapped around the histone core complex?

A

Twice (about 200 bp)

32
Q

What is heterochromatin?

A

– Compacted
– Untranscribed
– Two types:

Constitutive heterochromatin:
– Chromatin that is ‘always’ heterochromatic. Telomeres,
(peri)Centromeres.

Facultative heterochromatin:
– Chromatin that does not always need to be heterochromatic, but can convert to euchromatin when needed. e.g., X- chromosome in female mammals (dosage compensation).

33
Q

Regulatory proteins bind to DNA to either block or stimulate transcription, depending on how they interact with RNA polymerase. They gain access to the bases of DNA at ____?

A

The major groove

Regulatory proteins possess DNA-binding motifs for sequences within major grooves

34
Q

List the four DNA binding motifs that a protein might have to facilitate binding with the major groove of DNA?

A
  • Helix-turn-helix motif
  • Homeodomain motif
  • Zinc finger motif
  • Leucine zipper motif
35
Q

What are coactivators and mediators? (gene expression)

A

These can bind to transcription factors that bind to DNA activate genes to transcribe RNA

They can also bind to other parts of the transcription apparatus. They are required for function of transcription factors!

36
Q

List the 6 steps towards transcription

A
  1. Promoter site recognition
  2. Promoter binding
  3. Promoter melting
  4. Transcript initiation (+1 = start site)
  5. Promoter escape clearance
  6. Transcription
37
Q

What are specific and general transcription factors?

A

– general transcription factors are required for transcription initiation and are required for proper binding of RNA polymerase to the DNA

– specific transcription factors increase transcription in certain cells or in response to signals


38
Q

Why is chromatin remodelling necessary for transcription?

What is the most important way that chromatin is remodelled to make DNA accessible for transcription?

A

The nucleosome blocks RNA polymerase II from gaining access to promoters

Addition of acetyl groups to histone tails remodels the solenoid so that DNA is accessible for transcription.

39
Q

What is the Swi/Snf complex?

A

a nucleosome remodeling complex found in both eukaryotes and prokaryotes. In simpler terms, it is a group of proteins that associate to remodel the way DNA is packaged.

It possesses a DNA-stimulated ATPase activity and can destabilise histone-DNA interactions in reconstituted nucleosomes in an ATP-dependent manner, though the exact nature of this structural change is unknown.

40
Q

What are transposons?

A

Jumping genes. These have special ends that can insert into different regions in the genome (insertion can cause a frame shift mutation).

41
Q

List the 4 proteins of the octameric core of histones

A
  • H2A
  • H2B
  • H3 (forms tails which can be modified)
  • H4

H1 is like a guide for linker DNA, outside of the core octamer.

42
Q

Why are histones considered one of the most universal proteins in nature?

A

They are among the most highly conserved genes in evolution (both among plants and animals).

43
Q

What characteristic of histones facilitates binding with DNA?

A

High proportion of positively charged (basic) amino acids:

arginine and lysine

44
Q

How are histones assembled?

A

There is replication machinery. They fold through histone ‘handshakes.’

45
Q

Is chromatin found in prokaryotes?

A

No. They have a genophore (a chromosome without chromatin)

46
Q

What are the four primary functions of chromatin?

A
  • To package DNA into a smaller volume
  • To strengthen the DNA to allow mitosis
  • To prevent DNA damage
  • To control gene expression and DNA replication

Genes Brain and Behaviour (9 decks)

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