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Genetics & Evolution for Psychology > Problem 2 > Flashcards

Problem 2 Flashcards

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1
Q

Single gene

A

When a certain gene is known to cause a disease, we refer to it as a single gene disorder or a Mendelian disorder

–> they follow his laws of heredity

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2
Q

Polygenic gene

A

Refers to a trait whose phenotype is influenced by more than one gene

–> offspring phenotype is predicted from parental phenotype using quantitative genetic models

ex.: height, skin color

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3
Q

Homozygous

(Reinerbig)

A

A diploid organism that has two copies of the same allele

ex.: AA or aa

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4
Q

Heterozygot (Mischerbig)

A

A diploid organism that has one copy of two different alleles

–> only the dominant allele will be visible in the phenotype

ex.: Aa

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5
Q

Mendels theory of heredity

A

Inheritance involves the passing of discrete units of inheritance, or genes, from parents to offspring

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6
Q

Mendels Principles of heredity

A
  1. Law of segregation
  2. Law of dominance
  3. Law of independent assortment
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7
Q

Law of dominance

A

The dominant allele determines the appearance/phenotype of the organism

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8
Q

Law of segregation

A

Each individual carries 2 alleles, one of each parent

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9
Q

Law of independent assortment

A

Phenotypic traits controlled by different genes can be separated from each other through generations

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10
Q

What does the law of independent assortment suggest ?

A
  1. Novel phenotypic combinations can arise through sexual reproduction
  2. Natural selection can change the frequencies of one phenotypic characteristic, without changing the frequency of another
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11
Q

Why does independent segregation occur ?

A

Because at meiosis, the selection between which of the 2 copies goes forward to the gamete is done INDEPENDENTLY for each chromosome

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12
Q

Mendelian diseases

A

Follow his principles of heredity + apply to all single gene characteristics

ex.: Huntingtons disease, phenotypic effects develop after the individual has reproduced

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13
Q

Hardy-Weinberg equilibrium

A

Model that predicts what will happen in a sexually reproducing population where there is no natural selection

  1. Alleles will become neither more common nor more rare over time
  2. The relative proportions of homo- and heterozygotes will be constant

FORMULA: P^2 + 2pg + g^2

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14
Q

Genetic drift

A

Refers to a variation in the relative frequency of different genotypes in a small population, leading to a disappearance of particular genes as individuals die or do not reproduce, all due to CHANCE

–> there will be a certain amount of change even in the absence of natural selection

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15
Q

Fixation

A

Results from fluctuation, (Genetic drift) and ends with everybody in the population having the same allele

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16
Q

Neutral theory of molecular evolution

(Kimura)

A

States that most evolutionary changes at the molecular level, and most of the variation within and between species, are due to random Genetic drift/Fluctuation of mutant alleles that are selectively neutral

  1. small population: high probability of fixation
  2. big population: high probability of mutation

=> both cancel each other out

17
Q

Heritability

A

Refers to the proportion of the observed phenotypic variation that can be accounted for by genetic variation within a particular population at a particular time

–> mainly estimated using twin + adoption studies

18
Q

Coefficient of relatedness

A

Refers to the probability that any particular allele in one individual is identical (=derived from the same immediate source) as the allele in individual B

–> the higher the level of inbreeding the closer the coefficient of relationship between the parents approaches a value of 1

ex.: the probability that my brother has the same allele as me is 50%, me and my grandma 25%

19
Q

Dizygotic twins vs Monozygotic Twins

A

DZ: result from the implantation of 2 fertilized eggs in the same cycle

–> genetically different

MZ: result from the implantation of 1 fertilized egg

–> genetically the same

20
Q

In which way do shared + non-shared environments influence twins ?

A

Shared environments will influence both twins, regardless if MZ or DZ

ex.: parental social class, parental behavior, schools

Non-shared environments won’t influence them both, but affect them individually

ex.: diseases, accidents

21
Q

ACE model (Twin studies)

A

Refers to a statistical model used to analyze the results of twin studies

–> aims to decompose sources of phenotypic variation into three categories

  1. Additive genetic variance (Heritability)
  2. Common environmental factors (Shared environment)
  3. Specific Environmental factors (Non shared environment)
22
Q

Dominant allele

A

Refers to an allele that is expressed even though only one copy is present

23
Q

Recessive allele

A

Refers to an allele for which both copies are required for phenotypic expression

24
Q

Population

A

Refers to a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

25
Q

Gene pool

A

Refers to the genetic makeup consisting of all copies of every type of allele at every locus in all members of the population

26
Q

True breeding

A

Refers to an organism that always passes down certain phenotypic traits to its offspring of many generations

ex.: purple flower will only produce purple flowers in the F generations

–> homozygous

27
Q

Hybridization

A

Refers to the crossing of 2 true-breeding varieties

–> heterozygous

28
Q

Co-Dominance

A

With co-dominance, a cross between organisms with two different phenotypes produces an offspring with a third phenotype in which both of the parental traits appear together

ex.: white cow + red cow = white + red cow

29
Q

Incomplete Dominance

A

Refers to a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele

–> results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles

ex.: white + red rose –> pink rose

30
Q

Do only dominant and recessive alleles determine an organisms appearance ?

A

No,

there is incomplete + codominance which contradicts the law of dominance

31
Q

Quantitative genetics

A

Deals with phenotypes that vary continuously as opposed to discretely identifiable phenotypes and gene products

–> assumes that characteristics are affected by multiple genes + traits (polygenic traits)

32
Q

Falconers estimate of heritability

A

Estimates the relative contribution of genetics vs. environment to variation in a particular trait based on the difference between twin correlations

33
Q

Epistasis

A

Phenotypic expression at one locus will alter the phenotypic expression of a gene at another locus, due to interaction between those alleles

–> the effect of one gene is suppressed by another

34
Q

Dominance effects

A

Refers to the interaction between the pair of alleles at the same locus

35
Q

Epistatic effects

A

Refers to the interaction between alleles at different loci

36
Q

Adaptation

A

Refers to the characteristics/traists that raise the relative fitness of an individual

37
Q

Which types of adaptation are there ?

A
  1. Being adapted as an individual

–> functioning properly in the environment

  1. Becoming adaptated as a population

–> increasing the frequency of adapted individuals

Genetics & Evolution for Psychology (5 decks)

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