Chapter 5 - Non-Mendelian Inheritance Flashcards

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1
Q

What are four patterns of inheritance that deviate from the Mendelian pattern?

A
  1. Maternal effect; 2. Epigenetic inheritance; 3. Extranuclear inheritance; 4. Linkage
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2
Q

In this deviation from Mendelian genetics, the genotype of offspring does not directly govern the phenotype

A

Maternal effect

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3
Q

In this deviation from Mendelian genetics, genes are modified during gametogenesis or early embryonic development

A

Epigenetic inheritance

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4
Q

This deviation from Mendelian inheritance involves genes in organelles other than the nucleus (i.e. in mitochondria or chloroplasts)

A

Extranuclear inheritance

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5
Q

In this deviation from Mendelian inheritance, two or more genes are close to each other on the same chromosome

A

Linkage

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6
Q

The maternal effect on genes is due to the accumulation of these that the mother provides to her developing eggs

A

Gene products

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7
Q

This scientist first discovered the maternal effect in the 1920s

A

A. E. Boycott

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8
Q

What organism was A. E. Boycott studying when he discovered the maternal effect?

A

Water snail (Limnaea peregra)

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9
Q

What physical feature of water snails was A. E. Boycott studying when he discovered the maternal effect on genes?

A

Shell and internal organ coiling orientation

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10
Q

The maternal effect can be explained by this process

A

Oogenesis

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11
Q

In the maternal effect, maturing animal oocytes are surrounded by these that provide them with nutrients

A

Maternal cells (nurse cells)

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12
Q

Are maternal/nurse cells diploid or haploid?

A

Diploid

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13
Q

This type of inheritance refers to a pattern in which a modification occurs to a nuclear gene or chromosome that alters gene expression

A

Epigenetic inheritance

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14
Q

Is epigenetic inheritance expression changed over the course of many generations?

A

No

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15
Q

Is epigenetic inheritance reversible?

A

Yes

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16
Q

Does epigenetic inheritance change the DNA sequence?

A

No

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17
Q

The purpose of this is to offset differences in the number of active sex chromosomes

A

Dosage compensation

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18
Q

In 1949, these two scientists identified the Barr body, a highly condensed structure in the interphase nuclei of somatic cells in female cats but not in male cats

A

Murray Barr and Ewart Bertram

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19
Q

In 1960, this scientist correctly proposed that the Barr body is a highly condensed chromosome

A

Susumu Ohno

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20
Q

In 1961, this scientist proposed that dosage compensation in mammals occurs by the inactivation of a single X chromosome in females

A

Mary Lyon

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21
Q

This is another term for dosage compensation in mammals

A

Lyon hypothesis

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22
Q

This is the mechanism for dosage compensation in mammals

A

X-chromosome inactivation

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23
Q

Is X-chromosome inactivation passed along to all future somatic cells?

A

Yes

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24
Q

When inactivated X-chromosomes are replicated during cell division, do both copies remain compacted and inactive?

A

Yes

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25
Q

In 1963, these three scientists tested the Lyon hypothesis at the cellular level

A

Ronald Davidson, Harold Nitowsky and Barton Childs

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26
Q

How many X-chromosomes do mammalian cells allow to remain active?

A

1

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27
Q

Additional X-chromosomes are converted to these in mammalian cells

A

Barr bodies

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28
Q

How many Barr bodies does a cell with XXX have?

A

2

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29
Q

How many Barr bodies does a cell with X0 have?

A

0

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30
Q

What is the sex chromosome composition of a female with Turner syndrome?

A

X0

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31
Q

What is the sex chromosome composition of a female with Triple X syndrome?

A

XXX

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32
Q

What is the sex chromosome composition of a male with Klinefelter syndrome?

A

XXY

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33
Q

How many Barr bodies does a cell with XXY have?

A

1

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34
Q

Is the genetic control of X-chromosome inactivation entirely understood at the molecular interval?

A

No

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35
Q

This short region on the X chromosome plays a critical role in X-chromosome inactivation

A

X-inactivation center (Xic)

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36
Q

What are three functions of the Xic region during X-chromosome inactivation?

A

Nucleation, spreading, and maintenance of X-chromosome inactivation

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37
Q

This is the term for genes on the inactivated X-chromosome that are expressed in somatic cells of adult female mammals

A

Pseudoautosomal genes

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38
Q

How many X-linked genes in humans may escape full inactivation?

A

Up to 1/4

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39
Q

This is a phenomenon in which a segment of DNA is marked and the effect is maintained throughout the life of the organism inheriting the marked DNA

A

Genomic imprinting

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40
Q

This is the term for the genetic expression of offspring to express either the maternally-inherited or paternally-inherited allele in genomic imprinting

A

Monoallelic expression

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41
Q

Can offspring express both the maternal and paternal marked genes from genomic imprinting?

A

No

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42
Q

What are the three stages of genomic imprinting at the cellular level?

A
  1. Establishment of imprint during gametogensis; 2. Maintenance of imprint during embryogenesis and in adult somatic cells; 3. Erasure and reestablishment of imprint in germ cells
43
Q

At the molecular level, the imprinting of several genes is known to involve this region, located near the imprinted gene

A

Imprinting control region (ICR)

44
Q

Can the imprinting control region (ICR) be methylated in both the oocyte and the sperm?

A

No

45
Q

The imprinting control region (ICR) contains these for one or more transcription factors that regulate the imprinted gene

A

Binding sites

46
Q

For most genes, this causes inhibition of transcription

A

Methylation

47
Q

This genomic imprinting syndrome is characterized by reduced motor function, obesity and small hands and feet

A

Prader-Willi syndrome (PWS)

48
Q

Both Prader-Willi syndrome and Angelman syndrome involve a deletion in this chromosome

A

Chromosome 15

49
Q

If a chromosome 15 deletion is inherited from the father, does it lead to Prader-Willi syndrome or to Angelman syndrome?

A

Prader-Willi syndrome

50
Q

If a chromosome 15 deletion is inherited from the mother, does it lead to Prader-Willi or Angelman syndrome?

A

Angelman syndrome

51
Q

Angelman syndrome results from the lack of expression this gene

A

UBE3A

52
Q

Does Prader-Willi syndrome result from the lack of expression of only one gene?

A

No

53
Q

This refers to inheritance patterns involving genetic material outside the nucleus

A

Extranuclear inheritance

54
Q

What is another term for extranuclear inheritance?

A

Cytoplasmic inheritance

55
Q

These two organelles are sources of genetic material in extranuclear inheritance

A

Mitochondria and chloroplasts

56
Q

The genetic material of mitochondria and chloroplasts is located in this region

A

Nucleoid

57
Q

How many chromosomes do mitochondria/chloroplasts have?

A

1

58
Q

Can a mitochondrion/chloroplast contain several copies of its chromosome?

A

Yes

59
Q

Can a mitochondrion/chloroplast contain only one nucleoid?

A

No

60
Q

Which organelle tends to have more nucleoids, mitochondria or chloroplasts?

A

Chloroplasts

61
Q

Do organelle genomes vary greatly among different species?

A

Yes

62
Q

Mitochondrial genomes are fairly small in this group of organisms

A

Animals

63
Q

Mitochondrial genomes are intermediate size in these two groups of organisms

A

Fungi and protists

64
Q

Mitochondrial genomes are fairly large in this group of organisms

A

Plants

65
Q

What is the main function of mitochondria?

A

Oxidative phosphorylation

66
Q

Oxidative phosphorylation is a process used to generate this molecule

A

Adenosine triphosphate (ATP)

67
Q

This molecule is the energy source that drives cellular reactions

A

ATP

68
Q

This element is consumed during ATP synthesis

A

Oxygen

69
Q

The human mitochondrial DNA consists of how many base pairs?

A

17,000

70
Q

Are most mitochondrial proteins encoded by genes in the nucleus or in the mitochondria?

A

Nucleus

71
Q

What is the main function of chloroplasts?

A

Photosynthesis

72
Q

How many base pairs are in the chloroplast DNA of the tobacco plant?

A

156,000

73
Q

This scientist discovered that pigmentation in Mirabilis jalapa (the four o’clock plant) shows a non-Mendelian pattern of inheritance

A

Carl Correns

74
Q

Carl Correns discovered that four o’clock plants show this pattern of inheritance

A

Maternal inheritance

75
Q

Is maternal inheritance the same as maternal effect?

A

No

76
Q

In the four o’clock plant, maternal inheritance occurs because chloroplasts are only transmitted through this

A

Egg cytoplasm

77
Q

A four o’clock plant that has inherited both white and green chloroplasts will display this phenotype

A

Variegated phenotype

78
Q

This type of species produces two kinds of gametes (a large female gamete and a small male gamete)

A

Heterogamous

79
Q

In heterogamous species, organelles are typically inherited from which parent?

A

Mother

80
Q

In heterogamous species with maternal inheritance, is it impossible for paternal mitochondria to be passed through sperm?

A

No

81
Q

What are two ways for human mitochondrial diseases to occur?

A
  1. Transfer from mother to offspring via egg cytoplasm; 2. Mitochondrial mutations in somatic cells
82
Q

Human mitochondrial diseases strictly follow this type of inheritance

A

Maternal inheritance

83
Q

Mitochondrial mutations may occur in these cells

A

Somatic cells

84
Q

Do mitochondrial mutations reduce with age?

A

No

85
Q

Are mitochondria very susceptible to DNA damage?

A

Yes

86
Q

High oxygen consumption leads to these

A

Free radicals

87
Q

Does mitochondrial DNA have extensive repair abilities?

A

No

88
Q

How many mitochondrial diseases have been identified?

A

Over 200

89
Q

Mitochondrial diseases are typically chronically degenerative and affect these two types of cells

A

Nerve and muscle cells

90
Q

This mitochondrial disease results from a mutation in one of several mitochondrial genes that encode respiratory chain proteins, and tends to affect males more than females

A

Leber hereditary optic neuropathy

91
Q

This mitochondrial disease results from a mutation in the ATPase6 gene that encodes a subunit of the mitochondrial ATP-synthetase, which is required for ATP synthesis

A

Neurogenic muscle weakness

92
Q

These two mitochondrial diseases result from a mutation in a gene that encodes a tRNA for leucine

A

Mitochondrial myopathy and maternal myopathy/cardiomyopathy

93
Q

This is an important factor in mitochondrial disease

A

Heteroplasmy

94
Q

This is when cells contain a mixed population of mitochondria - some carrying disease-causing mutations while others do not

A

Heteroplasmy

95
Q

When cells divide, do all cells receive the same ratio of mutant to normal mitochondria?

A

No

96
Q

Due to heteroplasmy, disease may occur when this reaches a threshold value

A

Ratio of mutant to normal mitochondria

97
Q

This theory describes the evolutionary origin of mitochondria and chloroplasts

A

Endosymbiosis theory

98
Q

What is the endosymbiosis theory?

A

Organelles (mitochondria and chloroplasts) originated when bacteria took up residence within a primordial eukaryotic cell

99
Q

According to endosymbiosis theory, what did chloroplasts originate as?

A

Cyanobacteria

100
Q

According to endosymbiosis theory, what did mitochondria originate as?

A

Gram-negative nonsulfur purple bacteria

101
Q

What are two observations that support the endosymbiotic theory?

A
  1. Organelles have circular chromosomes; 2. Organelle genes are more similar to bacterial genes than to nuclear genes
102
Q

What advantage did endosymbiotic chloroplasts give to eukaryotic cells?

A

Ability to photosynthesize

103
Q

What advantage did endosymbiotic mitochondria give to eukaryotic cells?

A

More ATP synthesis

104
Q

How did cyanobacteria/purple bacteria benefit from becoming endosymbiotes?

A

Eukaryotic cell provided stable environment/nutrient supply