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PSYCHOBIOLOGY > 3 - GENES > Flashcards

3 - GENES Flashcards

1
Q

how are genes structural?

A

they are sections of dna

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2
Q

statement:
- genes are evolutionary as they are the hereditary
- carry information down generations

A

-

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3
Q

what is the passive stage of genes?

A

chromatin strands densely packed

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4
Q

what is the active stage of genes?

A
  • DNA is in loose chromatin strands

- wrapped around a histone protein

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5
Q

what is a chromosome?

A

tightly coiled band of chromatin

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6
Q

information:

cells + chemical soup

A
  • cells are chemical factories
  • thick chemical soup inside membrane
  • and outside membrane
  • exchange chemicals through cell membrane
  • involves proteins
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7
Q

what are proteins?

4 things

A

1 - complex molecules (very long, highly folded amino acid chains)

2- building blocks of cell structures

3 - active ingredient that ‘work’ on inert biological molecules (e.g. enzymes)

4 - produced in response to chemical environment

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8
Q

what does ‘activating’ a gene mean?

A
  • gene expression!
  • causing the production of the protein
  • because genes code for specific proteins
  • some genes may only indirectly contribute to protein synthesis - they may not code for a protein directly themselves
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9
Q

how can genetic rules produce a large variety of outcomes?

A

due to:

  • the exact environment
  • the exact starting point
  • environment changes the rules as changes which rules are active
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10
Q

what makes a genetic code a rule book, rather than a blueprint?

A

because it contains instructions on how to respond to the environment

  • some responses alter a cells form or function
  • some alter which genes (rules) are active - thereby changing a cells response to the environment
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11
Q

are genes and the environment linked?

A

yes!

only the two together can cause the outcome

genes are the means to respond to the environment

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12
Q

what are sequicygotic twins?

A

twins fertilised by two sperm cells

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13
Q

what type of enzymes aids the production (genesis) of steroids?

A

steroidogenic enzymes

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14
Q

characteristics of steroids

2 things

A

1 - fat-like substances

2 - easily pass through cell membranes

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15
Q

how many types of steroids?

A

2 (sex hormones and corticosteroids)

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16
Q

which sex hormones promote the development of female sex characteristics? (2)

A

estrogens and progesterone

17
Q

which sex hormone promote the development of male sex characteristics?

A

androgens

18
Q

what is the function of corticosteroids

A

control stress response

+ sugar metabolism

19
Q

what are the sources of steroids?

A

gonads + adrenal gland

20
Q

where is the adrenal gland located?

A

on top of the kidneys

21
Q 
function of steroids
(4 things)
A

1 - modify gene expression (activate genes)

2 - bind to specific receptor molecules inside of cell (receptor molecules floating around inside of cell - if encounter specific hormone = bind to it, and then bind to specific gene)

3 - receptor molecules bind to specific gene and activates it (must enter nucleus first)

4 - proteins will be produced

22
Q

how many chromosomes in a human?

A

46 chromosomes (23 pairs)

  • 22 pairs of autosomes (members of each pair very similar)
  • 1 pair of sex chromosomes (can be similar or dissimilar)
23
Q

how many chromosomes in a human gamete?

A

23 chromosomes - one from each pair

  • 22 autosomes
  • 1 chromosome (X or Y)
24
Q

what is fertilisation?

A

combination or the maternal and paternal half sets

25
Q

what is chromosomal sex in humans?

A 
XX = chromosomal female
XY = chromosomal male
26
Q

examples:

chromosomal sex in other animals
fish/reptiles/honey bees/birds+snakes

A

some species of fish:

  • change sex due to environment
  • aggression = female

reptiles:
- sex determined by temp at which egg is hatched

honey bees:

  • fertilised eggs develop into females
  • unfertilised = males
  • food and pheromones determine whether genetically female larvae develop ovaries (queen)

birds + many snakes
- W-Z system

27
Q

what causes XX males?

A

when a particular section (SRY) of the Y chromosome is trans located to another chromosome

  • chromosomes say female but body says male as the particular section is still present
28
Q

what causes XY females?

A

when a particular section (SRY) of the Y chromosome is missing

29
Q

which region of the Y chromosome determines male development?

A

SRY region

30
Q

what does the SRY region of the Y chromosome carry?

A

the TDF gene (testis determining factor)

31
Q

what happens if embryo doesn’t have an X chromosome?

A

it doesn’t develop

  • all embryos need an X chromosome
32
Q

what does the TDF gene code for?

A

TDF protein

33
Q

statement:

egg cells can never carry Y chromosomes

A

-

34
Q

why do boys typically suffer more from inherited diseases?

A
  • if it is caused by a faulty gene on the X chromosome - means boys inherit it from their mothers
  • males only have 1 X, so if it’s faulty then they can’t compensate that
  • females have a second intact (mainly) X chromosome which can compensate for the faulty one
35
Q

statement:

in order for a characteristic to be heritable (genetically passed down generations) it has nothing to do with reproductive success - eg baldness

A

-

36
Q

haemophilia

A
  • heritable
  • causes no blood clotting if have 2 chromosomes
  • on X chromosome
  • so women more likely to only be a carrier as have another X chromosome intact
  • how a gene that reduces reproductive success can be passed down generations
37
Q

sickle cell anaemia

A
  • if only 1 chromosome = protects against malaria
  • 2 chromosomes = causes sickle cell anaemia
  • but benefit of 1 outweighs likelihood of having both

PSYCHOBIOLOGY (29 decks)

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