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IB 141 human genetics > chapter 7 - complex traits > Flashcards

chapter 7 - complex traits Flashcards

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Biology 101 flashcards
1
Q

mendelian traits

A

caused by a single gene

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2
Q

polygenic traits

A

caused by multiple genes

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3
Q

polygenic trait examples

A

height, skin color, body weight, illnesses, etc

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4
Q

single gene traits often produce an _______ effect

A

all or none

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5
Q

polygenic traits produce a continuously _____ phenotype

A

varying

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6
Q

polygenic traits can also be called ______ traits

A

quantitative

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7
Q

Quantitative Trait Loci

A

QTL’s; name for DNA sequences

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8
Q

frequency of distribution of phenotypes forms a __________ curve

A

bell-shaped

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9
Q

empiric risk

A

used to predict the chance that a polygenic complex trait will occur in an individual based on familial relationship; uses the incidence of the characteristic in a specific population

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10
Q

incidence

A

rate at which a certain event occurs

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11
Q

prevalence

A

proportion/number of individuals who have a particular trait at a specific time

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12
Q

empiric risk is not a calculation, but a ….

A

population statistic based on observation

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13
Q

empiric risk increases with 3 things:

A

1) severity of disease
2) number of affected family members
3) how closely related a person is to affected persons

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14
Q

heritability

A

estimates the proportion of variation in a complex trait due to genetics in a particular population at a certain time; refers to the degree of variation in a trait due to genetics, and not to the proportion of the trait itself attributed to genes

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15
Q

heritability equals ____ for a trait whose variability is completely the result of gene action

A

1.0

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16
Q

broad-sense heritability

A

H^2

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17
Q

sibling to sibling % shared genes (coefficient of relatedness)

A

50%

18
Q

parent to child % shared genes (coefficient of relatedness)

A

50%

19
Q

uncle/aunt to niece/nephew % shared genes (coefficient of relatedness)

A

25%

20
Q

half-siblings % shared genes (coefficient of relatedness)

A

25%

21
Q

grandparent to grandchild % shared genes (coefficient of relatedness)

A

25%

22
Q

first cousin to first cousin % shared genes (coefficient of relatedness)

A

12.5%

23
Q

concordance

A

measures the frequency of expression of a trait in both members of monozygotic or dizygotic twins

24
Q

discordant

A

twins who differ in a trait

25
Q

dizygotic twins

A

shared environment % 50% of genes

26
Q

monozygotic twins

A

identical genotype and shared environmnet

27
Q

genome-wide association study (GWAS)

A

compares many genetic markers across the genome between 2 large groups of people, usually 1 with a particular trait/disease and 1 without it

28
Q

GWAS uses genetic markers, including SNP’s and CNV’s

A

single nucleotide polymorphisms, copy number variants

29
Q

single nucleotide polymorphism (SNP)

A

a site in the genome that has a different DNA base in >1% of a population

30
Q

copy number variation (CNV)

A

tandomly repeated DNA sequence

31
Q

to achieve statistical significance, a GWAS must include at least _____ markers

A

100,000

32
Q

study designs in GWAS

A
  • cohort study
  • case-control study
  • affected sibling pair strategy
  • homozygosity mapping
33
Q

cohort study

A

researchers follow a large group of individuals over time and measure many aspects of their health

34
Q

case-control study

A

pairs of individuals are matched so that they share as many characteristics as possible

35
Q

affected sibling pair strategy

A

tests identify SNP’s that siblings with the same condition share but that siblings who do not both have the condition do not share

36
Q

homozygosity mapping

A

disease-causing mutations are identified in homozygous genome regions that children inherit from parents who are related to each other

37
Q

limitations of GWAS

A
  • so much data - prone to error
  • reveal associations between information, not causes
  • bias can be a part of it
  • accuracy is affected by complicating factors like phenocopy and epistasis
  • could miss rare SNP’s
38
Q

body mass index BMI

A

weight (kg) / height2^2(m^2)

39
Q

leptin

A

protein hormone produced by fat cells
- signals the hypothalamus to decrease appetite
- acts in the long term to maintain weight

40
Q

ghrelin

A

peptide hormone produced in the stomach
- responds to hunger by increasing appetite
- functions in the short term to regulate weight

IB 141 human genetics (6 decks)

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