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Genetics- Fall 2022 > Chap 20 > Flashcards

Chap 20 Flashcards

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Biology 101 flashcards
1
Q

Height in humans, milk and meat production in cattle, field in various crops are controlled by many ___

A

Genes

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2
Q

This ___ is measured and described in quantitative terms and is known as ____

A

Continuous variation; quantitative inheritance

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3
Q

A continuous quantitative trait is often the results of ___ and is frequently influenced by the ___ or ___

A

Polygenic inheritance; environment; multifactorial

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4
Q

___ is determined by a single gene

A

Simple trait

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5
Q

___ trait determined by two or more genes

A

Polygenic trait

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6
Q

___ trait determined by 2 or more genes +/-environmental contribution

A

Multifactorial trait

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7
Q

___ phenotypes fall into distinct categories (red vs. white)

A

Discontinuous variation

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8
Q

___ phenotypes varies over range, with most falling ~ midway between the extremes

A

Continuous variation

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9
Q

Bateson and Yule proposed the ___ or the ___ in which many genes, each individually behaving in a Mendelian fashion, contribute to the phenotype in a cumulative or quantitative way

A

Multiple-factor; multiple-gene hypothesis

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10
Q

This ___ hypothesis is demonstrated by grain color in wheat to test the concept that the cumulative effects of alleles at multiple loci produce the range of ___ seen in ___ traits.

A

Multiple-gene; phenotypes; quantitative

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11
Q

Each gene has an ___ allele and a ____ allele

A

Additive; nonadditive

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12
Q

The greater the number of ___ alleles in the ___, the more intense the red color expressed in the phenotype

A

Additive; genotype

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13
Q

Each ___ allele contributes equally to pigment in the grain, and the _____ allele failed to contribute to any pigment

A

Additive; nonadditive

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14
Q

What are the multiple-gene hypothesis consists of the following major points?

A
  1. Phenotypic traits show continuous variation that can be quantified by measuring, weighing, etc.
  2. Two or more loci show an additive effect on expression of the phenotype and is called polygenic inheritance
  3. An additive allele contributes an equal amount to the phenotype, whereas a nonadditive contributes nothing
  4. Each additive alleles contribute to a single quantitative trait to produce substantial phenotypic variation
  5. The additive alleles contribute to a single quantitative trait to produce substantial phenotypic variation
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15
Q

The number of __ contributing to a ___ trait can be estimated based on the ratio of F2 individuals resembling either of the two extreme P1 phenotypes

A

Polygenes; quantitative

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16
Q

For low numbers of ___, the number of ___ loci n can be estimated from the total number of possible ___

A

Polygenes; additive; phenotypes

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17
Q

The estimates of low numbers of Polygenes estimates assume that all of the __ alleles contribute equally and ___. There are no significant environmental effects on ___ expression.

A

Additive; additively; phenotypic

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18
Q

__ traits are usually measured in a sample of individuals that is __ and __ of the population from which it is drawn

A

Polygenic; large; representative

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19
Q

The data often form a ___ distribution that is a characteristic bell-shaped curve when plotted as a frequency histogram

A

Normal

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20
Q

Measurements clustering around a central point called a ____ and the central point is the mean

A

Central tendency

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21
Q

___ is the average of a set of measurements

A

Mean

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22
Q

___ provides information about the spread of data around the mean

A

Variance

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23
Q

If multiple individuals have same measurement, data for each measurement class can be ___

A

Grouped

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24
Q

___ deviation is the square root of the variance

A

Standard

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25
Q

Two phenotypic traits may ___ variation in one trait may be ___ on/associated with variation in a second trait

A

Correlate; dependent

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26
Q

___ is a measurement of how much variation is common to both quantitative traits

A

Covariance

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27
Q

The ___ coefficient indicates to what extent variation in one trait is associated with variation in a second trait

A

Correlation

28
Q

When r is ___, the two traits both increase or decrease together or one increases as the other decreases when r is ___

A

Positive; negative

29
Q

___ indicate that an increase in the measure of one traits tends to correlate with an increase in the measure of the second trait

A

Positive values

30
Q

___ indicate that an increase in one trait tends to be associated with a decrease in the measure of the second trait

A

Negative values

31
Q

___ described the proportion of total phenotypic variation in a population due to genetic factors

A

Heritability

32
Q

For a ___ trait, high heritability means most variation is due to ___ factors and less ____ impact

A

Multifactorial; genetic; environmental

33
Q

With low heritability, environmental factors are likely to have a ___ impact on ___

A

Greater; phenotype

34
Q

A heritability estimate tells the proportion of ___ variation that can be attributed to ___ variation within a certain population in a particular environment

A

Phenotypic; genetic

35
Q

Total ___ variance can be divided into ___ variance or ___ variance

A

Phenotypic; genotypes; environmental

36
Q

When obtaining ___ estimates for multi-factorial traits, researchers often assume that the genotype by environment interaction is small enough to ignore or combine with ___ variance

A

Heritability; environmental

37
Q

In order to minimize genetic differences between individuals, researchers of tern compare highly inbred ___ and ___ species when estimating heritabilities

A

Plant; animal

38
Q

Expose different members of the same inbred strain to ___ environments to estimate VE

A

Different

39
Q

Expose different inbred strains to the ___ environment to estimate VG

A

Same

40
Q

Broad sense heritability (H2) measure the contribution of the ___ variance to the total ___ variance

A

Genotypic; phenotypic

41
Q

A value approaching 1.0 indicates that the environment has ___ impact on the ___ variance

A

Little; phenotypic

42
Q

Low values close to 0.0 indicate that ___ factors, and not the ___ are responsible for ___ variation within a population

A

Environmental; genotype; phenotypic

43
Q

Estimates of ___ heritability are expressed as percentage values for traits among different ____

A

Narrow-sense; organisms

44
Q

Narrow-sense heritability more valuable predictor of response to ___

A

Selection

45
Q

Narrow-sense heritability is the proportion of phenotypic variance due to additive ___ alone

A

Genotypic variance

46
Q

Narrow-sense heritability estimate are valuable to plant and animal breeders because they estimate the proportion of total ____ variance for that trait that is due to ____ variance

A

Phenotype; additive genetic

47
Q

It is best to select individuals with superior ___ for the desired ___ trait from a ___ population and to breed offspring from those individuals

A

Phenotypes; quantitative; heterogeneous

48
Q

Artificial selection:
- Choosing specific individuals with ___ from initially ___ population for future breeding

- Purpose is to develop population containing high frequency of individuals with \_\_\_ traits
A

Preferred phenotypes; heterogenous; desired

49
Q

Artificial trait selection:
- Can be __ and multifactorial
- Traits of ___ importance:
- crops and livestock
- grain yield in plants
- weight gain or milk yield in cattle
- speed or stamina in horses

A

Polygenic; economic

50
Q

Realized heritability:
- ___ breeding estimate potential success for artificial selection

A

Selective

51
Q

Heritability values:
- Provide no information on genes involved in ___
- Measure in populations- limited application to ___

A

Traits; individuals

52
Q

Future changes in ___ factors can affect ___

A

Environmental; heritability

53
Q

Humans twins are useful for examining ___ versus ___ variance for a multifactorial trait

A

Genotypic; environmental

54
Q

For monozygotic (MZ) or identical twins, ___ variance is due to VE environmental variance, as there is no VG Genotypic variance

A

Phenotypic

55
Q

For dizygotic (DZ) or fraternal twins, ___ difference represent both environmental variance and approximately half the Genotypic variance

A

Phenotypic

56
Q

Comparison of phenotypic variances for the same trait in identical and fraternal twin sets provides an estimate of ____ heritability of the Genotypic variance to the total ___ for that trait

A

Broad-sense; phenotypic

57
Q

The difference in ___ for a given trait in identical versus fraternal twins suggests whether a strong genetic component is involved in ___ of the trait

A

Concordance; determination

58
Q

Twins are ___ for a trait if both or neither ___ it

A

Concordant; express

59
Q

If one expresses it and the other does not, the pair is said to be ___ for that trait

A

Discordant

60
Q

MZ twins are treat more ___ than DZ twins, which may ___ environmental variance among DZ twins

A

Equally; inflate

61
Q

Interactions between ___ and ___ may produce variability in phenotype, which can ___ total phenotypic variance of DZ twins compared to MZ twins raised in the ___ environment

A

Genotype; environment; increase; same

62
Q

The assumption that MZ twins share the same ___ has been valuable for estimating heritability for many ___ diseases such as cardiovascular disease, diabetes, mental illness

A

Genome; multifactorial

63
Q

Results from ___ research has challenged whether MZ twins are truly ___

A

Genomic; identical

64
Q

Most recent genomic discoveries about identical twins include the following:
By the time MZ twins are born, they do no necessarily have identical ___
- they develop from a single egg but become two independent ___
- genotypes can diverge slightly with differences in copy number variation (CNV)- variation in number of copes of numerous large DNA sequences resulting in ___ mosaicism
-CNV difference between MZ twins has been associated with ___ lymphoma in one twin but not the other

A

Genomes; embryos; somatic; chronic

65
Q

Gene-expression patterns in MZ twins change with age, leading to ___ differences
- This involves ___- the chemical modification of their DNA and associated histone
- MZ. Twins are epigenetically ___ at birth, but adult MZ twins show significant ___ in methylation patterns of both DNA and his tones, which in turn affect gene expression
-Progressive age-related genomic ___ may be due to expire to ___ environments or to failure of epigenetic marking following DNA replication

A

Phenotypic; epigenetics; identical; differences; modifications; different

Genetics- Fall 2022 (8 decks)

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