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Genetics > Chapter 4 - Extension of Mendelian Inheritance > Flashcards

Chapter 4 - Extension of Mendelian Inheritance Flashcards

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Biology 101 flashcards
1
Q

Mendelian inheritance describes inheritance patterns that obey these two laws

A

Law of segregation and law of independent assortment

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2
Q

Simple Mendelian inheritance involves these two assumptions

A

A single gene has two different alleles and the alleles display a simple dominant/recessive relationship

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3
Q

This term is commonly applied to the inheritance of alleles that obey Mendel’s laws and follow a strict dominant/recessive relationship

A

Simple Mendelian

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4
Q

In this type of inheritance pattern, 50% of a protein, produced by a single copy of the dominant allele in a heterozygote, is sufficient to produce a dominant trait

A

Simple Mendelian

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5
Q

This inheritance pattern occurs when a dominant phenotype is not expressed even though an individual carries a dominant allele

A

Incomplete penetrance

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6
Q

What are two reasons why a dominant allele may have incomplete penetrance?

A

Environmental influence or other genes that encode counteracting proteins

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7
Q

This inheritance pattern occurs when the heterozygote has a phenotype that is intermediate between either corresponding homozygote

A

Incomplete dominance

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8
Q

In this inheritance pattern, 50% of a protein produced by a single copy of the functional allele in a heterozygote is not sufficient to produce the same trait as in a homozygote making 100% of that protein

A

Incomplete dominance

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9
Q

This inheritance pattern occurs when the heterozygote has a trait that confers a greater level of reproductive success than either homozygote

A

Overdominance

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10
Q

What are three common ways that heterozygotes may gain benefits from overdominance?

A
  1. Their cells may have increased resistance to infection by microorganisms; 2. They may produce more forms of protein dimers with enhanced function; 3. They may produce proteins that function under a wider range of conditions
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11
Q

This inheritance pattern occurs when the heterozygote expresses both alleles simultaneously without forming an intermediate phenotype

A

Codominance

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12
Q

In this inheritance pattern, alleles encode proteins that function slightly differently from each other and the function of each protein in the heterozygote affects the phenotype uniquely

A

Codominance

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13
Q

This inheritance pattern involves genes that are located on the X chromosome

A

X-linked inheritance

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14
Q

This inheritance pattern refers to the effect of sex on the phenotype of the individual, where some alleles are recessive in one sex and dominant in the other

A

Sex-influenced inheritance

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15
Q

In this inheritance pattern, sex hormones may regulate the molecular expression of genes, influencing the phenotypic effects of alleles

A

Sex-influenced inheritance

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16
Q

This is an allele that has the potential of causing the death of an organism

A

Lethal allele

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17
Q

Lethal alleles are most commonly this type of allele that may be due to a mutation in a nonessential gene that changes a protein so that it functions with abnormal/detrimental consequences

A

Loss-of-function allele

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18
Q

These alleles are prevalent in a population

A

Wild-type alleles

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19
Q

This can produce more than one wild-type allele in large populations

A

Genetic polymorphism

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20
Q

These altered and often defective alleles tend to be rare in natural populations

A

Mutant alleles

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21
Q

Are mutant alleles often inherited in a dominant or recessive fashion?

A

Recessive

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22
Q

These are usually caused by mutant alleles preventing production of a fully functional protein

A

Genetic diseases

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23
Q

This recessive genetic disease is characterized by the inability to metabolize phenylalanine

A

Phenylketonuria

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24
Q

Phenylketonuria is caused by lack of production of this protein

A

Phenylalanine hydroxylase

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25
Q

Albinism is caused by lack of production of this protein

A

Tyrosinase

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26
Q

This genetic disease is a defect in lipid metabolism and leads to paralysis, blindness and death

A

Tay-Sachs disease

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27
Q

Tay-Sachs disease is caused by lack of production of this protein

A

Hexosaminidase A

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28
Q

This genetic disease is a defect in lipid metabolism that causes muscle weakness in infancy, early blindness and progressive mental and motor deterioration

A

Sandhoff disease

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29
Q

Sandhoff disease is caused by lack of production of this protein

A

Hexosaminidase B

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30
Q

This genetic disease is characterized by the inability to regulate ion balance across epithelial cells and leads to production of thick mucus, chronic lung infections, poor weight gain and organ malfunctions

A

Cystic fibrosis

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31
Q

Cystic fibrosis is caused by lack of production of this protein

A

Chloride transporter

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32
Q

This genetic disease is characterized by an inability to metabolize purines, leading to self-mutilation behavior, poor motor skills, mental impairment and kidney failure

A

Lesch-Nyhan syndrome

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33
Q

Lesch-Nyhan syndrome is caused by lack of production of this protein

A

Hypoxanthine-guanine phosphoribosyl transferase

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34
Q

This type of dominant mutation encodes a protein with a new or abnormal function

A

Gain-of-function

35
Q

This type of dominant mutation encodes a protein that acts antagonistically to the normal protein

A

Dominant-negative

36
Q

In this type of dominant mutation, the mutant is loss-of-function and the heterozygote does not make enough product to give the wild-type phenotype

A

Haploinsufficiency

37
Q

This is the degree to which a trait is expressed

A

Expressivity

38
Q
A

Environment

39
Q

This is another term for overdominance

A

Heterozygote advantage

40
Q

This autosomal recessive disorder in which affected individuals produce an abnormal form of hemoglobin is an example of overdominance/heterozygote advantage

A

Sickle-cell disease

41
Q

What are two effects of red blood cells forming a sickle shape under conditions of low oxygen tension?

A
  1. Red blood cell lifespan shortens, causing anemia; 2. Odd-shaped cells clump, forming capillary blockages
42
Q

What is the advantage of individuals that are heterozygous for sickle-cell disease?

A

Malaria resistance

43
Q

This protozoan causes malaria

A

Plasmodium

44
Q

This type of mosquito is host for one part of the Plasmodium life cycle

A

Anopheles mosquito

45
Q

The red blood cells of sickle-cell heterozygotes are likely to do this when infected by Plasmodium

A

Rupture, preventing propagation of the parasite

46
Q

At the molecular level, overdominance is due to two alleles that do this to produce a favorable phenotype in the heterozygote

A

Produce slightly different proteins

47
Q

What are three possible explanations for overdominance at the molecular/cellular level?

A
  1. Disease resistance; 2. Homodimer formation; 3. Variation in functional activity
48
Q

These are proteins composed of two subunits encoded by the same type of gene, but the alleles of that gene can be different

A

Homodimers

49
Q

Individuals with heterozygote advantage may produce two of these that function over a wider range of conditions

A

Enzymes

50
Q

These proteins may have better functional activity in individuals with heterozygote advantage

A

Homodimers

51
Q

This is determined by the antigen present on the surface of red blood cells

A

Blood type

52
Q

These are substances that are recognized by antibodies produced by the immune system

A

Antigens

53
Q

On the surface of red blood cells, this is composed of three sugars

A

Carbohydrate tree

54
Q

This enzyme can add a fourth sugar to the carbohydrate tree on red blood cells

A

Glycosyl transferase

55
Q

These are genes found on one of the two types of sex chromosomes, but not both

A

Sex-linked genes

56
Q

Males are more likely to be affected by these sex-linked genes

A

X-linked genes

57
Q

This is another name for Y-linked genes

A

Holandric genes

58
Q

Are Y-linked genes common in humans?

A

No

59
Q

This type of inheritance refers to the very few genes found on both X and Y chromosomes

A

Pseudoautosomal inheritance

60
Q

Does sex-influenced mean the same thing as sex-linked?

A

No

61
Q

In this type of inheritance, traits occur in only one of the two sexes

A

Sex-limited inheritance

62
Q

Are sex-influenced traits autosomal?

A

Yes

63
Q

It is estimated that this portion of all genes is essential for survival

A

1/3

64
Q

Can a lethal allele produce ratios that seemingly deviate from Mendelian ratios?

A

Yes

65
Q

Does the effect of a lethal allele always exert at the same time during organism development?

A

No

66
Q

This disease caused by a lethal allele is characterized by progressive degeneration of the nervous system, dementia and early death

A

Huntington disease

67
Q

What is the usual age of onset of Huntington disease?

A

30-50

68
Q

This type of lethal allele may kill an organism only when certain environmental conditions prevail

A

Conditional lethal allele

69
Q

These conditional lethal alleles are typically caused by mutations that alter structure of the protein at the nonpermissive temperature

A

Temperature-sensitive lethal alleles

70
Q

This type of allele kills some individuals in a population, but not all of them

A

Semilethal alleles

71
Q

This is when genes have multiple effects on the phenotype of an organism

A

Pleiotropy

72
Q

What are three types of pleiotropy?

A
  1. Gene product affects cell function in multiple ways; 2. Gene may be expressed in different cell types; 3. Gene may be expressed at different stages of developement
73
Q

Do most genes have pleiotropy?

A

Yes

74
Q

This genetic disease affecting ionic balance is an example of a mutation causing multiple effects due to pleiotropy

A

Cystic fibrosis

75
Q

These occur when two or more different genes influence the outcome of a single trait

A

Gene interactions

76
Q

This is an inheritance pattern in which the alleles of one gene mask the phenotypic effects of the alleles of a different gene

A

Epistasis

77
Q

This is a phenomenon in which two parents that express the same or similar recessive phenotypes produce offspring with a wild-type phenotype

A

Complementation

78
Q

This is a phenomenon in which an allele of one gene modifies the phenotypic outcome of the alleles of a different gene

A

Gene modifier effect

79
Q

This is a pattern in which the loss of function in a single gene has no phenotypic effect, but the loss of function of two genes has an effect

A

Gene redundancy

80
Q

These often arise because two (or more) different proteins participate in a common cellular function

A

Epistatic interactions

81
Q

This is a technique to directly generate loss-of-function alleles to understand the effects of a gene on structure or function of the organism

A

Gene knockout

82
Q

These are gene copies that are similar but not identical due to the accumulation of random changes during evolution

A

Paralogs

83
Q

If one gene is missing, may a paralog carry out the missing function?

A

Yes

84
Q

This scientist investigated gene redundancy in Shepherd’s purse seed capsule shape

A

George Shull

Genetics (11 decks)

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