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BIOL2316.088TR > Ch. 7 - Complex Traits > Flashcards

Ch. 7 - Complex Traits Flashcards

1
Q

A trait that is influenced by two or more genes is a _____ trait.

A

Polygenic

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2
Q

A trait that is influenced by both genes and the environment is a _____ trait.

A

Complex

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3
Q

A trait that is influenced by only one gene is a _____ trait.

A

Mendelian

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4
Q

DNA sequences that contribute to polygenic traits are called _____.

A

Quantitative trait loci

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5
Q

Polygenic traits have all-or-none phenotypes.

A

False

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6
Q

The individual genes that contribute to a polygenic trait are dominant or recessive to each other.

A

False

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7
Q

All genes that influence a polygenic trait contribute equally to the phenotype.

A

False

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8
Q

The graph of the frequency of phenotypes in a polygenic trait has the shape of a bell curve.

A

True

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9
Q

When a trait is polygenic, individuals cannot be categorized into classes with respect to their phenotypes.

A

False

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10
Q

Polygenic traits may be influenced by the environment.

A

True

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11
Q

DNA sequences that contribute to polygenic traits are called quantitative trait loci.

A

True

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12
Q

Some inherited disorders (such as Down syndrome) are associated with unusual fingerprint ridge patterns.

A

Genes

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13
Q

Fingerprint patterns are altered when a fetus touches fingers and toes to the walls of the amniotic sac.

A

Environment

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14
Q

Height is affected by diet.

A

Environment

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15
Q

Certain patterns of SNPs are common in individuals who experience a period of rapid height increase.

A

Genes

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16
Q

A certain allele of the E4 gene, which encodes apolipoprotein E, increases the risk of a heart attack in people who smoke but not in people who do not smoke.

A

Genes and environment

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17
Q

Exercise decreases the risk of heart disease.

A

Environment

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18
Q

Exposure to the sun increases melanin synthesis.

A

Environment

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19
Q

Calculations of empiric risk are based on Mendel’s laws.

A

False

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20
Q

Prevalence is the number of new cases of a disorder that are diagnosed per year in a population of a given size.

A

False

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21
Q

Empiric risk increases with the severity of the disorder.

A

True

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22
Q

Empiric risk increases with the number of family members who are affected with the disorder.

A

True

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23
Q

To use empiric risk to predict the likelihood that an individual will have a disorder, it is necessary to understand the transmission pattern of the disorder.

A

False

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24
Q

The chance that a polygenic complex trait will occur in an individual is the _____.

A

Empiric risk

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25
Q

The _____ of a genetic disorder is the proportion of individuals in a population who have the disorder at a specific time.

A

Prevalence

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26
Q

The number of new cases of a genetic disorder diagnosed per year in a population of a given size is the _____ of the disorder.

A

Incidence

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27
Q

The proportion of phenotypic variance for a trait that is due to genetic differences in a population is the trait’s _____.

A

Heritability

28
Q

The proportion of genes that two people with a certain relationship share is the _____.

A

Coefficient of relatedness

29
Q

Among pairs of twins in whom at least one has a trait, the percentage of pairs in which both twins express the trait is the _____ of the trait.

A

Concordance

30
Q

If a trait is determined entirely by genes, not by the environment, then the heritability of the trait is 0.

A

False

31
Q

Heritability is defined as the proportion of the phenotypic variance for a trait that is due to genetic differences in a population at a certain time.

A

True

32
Q

The heritability of a single-gene trait is always 1.0

A

False

33
Q

The heritability of a trait changes when the environment changes.

A

True

34
Q

If the heritability of a trait is very high, then all siblings will have the same phenotype.

A

False

35
Q

Genetic variance for a polygenic trait is due mainly to the additive effects of dominant alleles of different genes.

A

False

36
Q

Identical twins are also called _____ twins.

A

Monozygotic

37
Q

Among pairs of twins in whom at least one has a particular trait, the _____ of the trait is equal to the percentage of pairs in which both twins express the trait.

A

Concordance

38
Q

Twins who differ in a trait are _____ for the trait.

A

Discordant

39
Q

Diseases caused by single genes that approach 100 percent penetrance approach _____ concordance in monozygotic twins.

A

100%

40
Q

Among dizygotic twins, concordance is usually around _____ for a dominant trait.

A

50

41
Q

Among dizygotic twins, concordance is usually around _____ for a recessive trait.

A

25

42
Q

For a polygenic trait with little or no environmental influence, the concordance value for monozygotic twins will be _____ the concordance value for dizygotic twins.

A

Greater than

43
Q

To assess the genetic component of a complex trait, it would be most appropriate to study _____.

A

Monozygotic twins separated at birth

44
Q

In _____, families that are consanguineous are studied.

A

Homozygosity mapping

45
Q

A(n) _____ seeks correlations between SNP patterns and phenotypes in large groups of individuals.

A

Genome-wide association study

46
Q

If there is a(n) _____ between two characteristics, then if one measurement increases, the other characteristic changes in a predictable direction.

A

Correlation

47
Q

In a(n) _____, researchers follow a large group of individuals over time.

A

Cohort study

48
Q

In a(n) _____, each individual in one group is matched to an individual in another group who shares as many characteristics as possible.

A

Case-control study

49
Q

If there is a(n) _____ between two events, then one occurs when the other occurs.

A

Association

50
Q

Scientific studies of body weight use a measurement called _____, which is weight in proportion to height.

A

Body mass index

51
Q

The protein hormone _____ stimulates the hypothalamus to decrease appetite.

A

Leptin

52
Q

Treatment with leptin results in weight loss for some people but not for others. Leptin resistance, or unresponsiveness to leptin when it is given as a drug, is due to mutations in the gene that encodes _____.

A

The leptin receptor

53
Q

The hormone that is produced by the stomach in response to hunger is _____.

A

Ghrelin

54
Q

In a study of celiac disease in twin pairs in which at least one twin had celiac disease, both twins had celiac disease in 17/23 monozygotic twin pairs. In the same study, both twins had celiac disease in 5/50 dizygotic twins pairs. What is the concordance for monozygotic and dizygotic twin, respectively?

A

74%; 10%

55
Q

The “Blue Fugates”, an inbred family who lived in the hills of Kentucky in the 1800s, had children with blue skin. It was discovered that they suffered from the recessive genetic disease methemoglobinemia. If genome wide association studies had been available at that time, what would have been the best type of study to use to identify the cause of their blue skin?

A

Homozygosity mapping

56
Q

You are a doctor. A patient comes into your office who is 5’10’’ and 220 pounds. Based on his BMI what advice should you give him?

A

The man is obese and likely needs to make major changes to his diet and exercise routines.

57
Q

The difference between cystic fibrosis and migraine is that the _____.

A

Former can be traced to a single gene

58
Q

Rasheed suffers from terrible migraine headaches. They are likely caused by _____.

A

At least three genes and perhaps environmental triggers, such as foods

59
Q

In a polygenic trait _____.

A

Genes contribute to varying degrees, and alleles have differing degrees of impact

60
Q

DNA sequences that contribute to polygenic traits are called _____.

A

Quantitative trait loci

61
Q

Skin color is not a good way to distinguish “races” of people because _____.

A

It is but one of many traits that vary within and between human populations

62
Q

“Total ridge count” is _____.

A

A complex trait that considers the number of ridges in whorls, loops, or arches of the finger pad skin

63
Q

Concordance refers to _____.

A

Percentage of twin pairs in which both express a trait among pairs in which at least one twin has the trait

64
Q

Heritability of a trait can change because _____.

A

The environment can change

65
Q

A brother and sister share _____ percent of their genes.

A

50

66
Q

Studies that implicate the environment in influencing body weight consider _____.

A

Populations that split, with some people remaining in the homeland and others moving to areas where their diet changes dramatically, resulting in weight gain

BIOL2316.088TR (16 decks)

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