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Quiz 2 > Q2-FUN18+19/Mendelian Genetics I and II > Flashcards

Q2-FUN18+19/Mendelian Genetics I and II Flashcards

1
Q

most cells are ________ ploid

A

diploid

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2
Q

what does it mean that diploid cells are homologous?

A

we have 2 homologous copies of each chromosome

2 copies of each gene, 1 per chromosome copy (maternal + paternal)

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3
Q

each gene copy is called an ______

A

allele

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4
Q

alleles can _________ in their DNA base seq. so an individual can have diff alleles of a gene ( A and a)

A

vary slightly

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5
Q

what are the mendelian inheritance patterns?

A

autosomal dominant/recessive

Y-linked

X-linked dominant/recessive

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6
Q

What does this mean in a pedigree?

A

male, female, sex unknown

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7
Q

What do these mean in a pedigree?

A
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8
Q

What do these mean in a pedigree?

A
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9
Q

how many autosomal dominant traits have been found so far?

A

over 1000

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10
Q

auto. dom. traits are expressed at ________zygous

A

heterozygous (Aa)

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11
Q

most cases of auto. dom. disease will be ______

A

heterozygous

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12
Q

what is the range of auto. dom. disorders?

A

they can die before maturity or have late onset diseases (wide range)

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13
Q

dom. homozygotes are at a ________ relative to heterozygotes and frequently die before reproductive maturity

A

selective disadvantage

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14
Q

auto. dom. allel frequencies are usually high/low

A

low

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15
Q

What are some types of auto. dom. disease? (4)

A

familial hypercholesterolaemia, polycystic kidney disease, familial adenomatous polyposis (FAP), neurofibromatosis

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16
Q

what is familial hypercholesterolaemia?

A

genetic disorder, caused by defect in chromosome 19, that makes the body unable to remove LDL cholesterol from the blood which results in people who are 30-40 years old be at high risk of myocardial infarction

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17
Q

1/______ people have a het mutation for familial hypercholesterolaemia and their plama LDL levels are ___x as much as a normal.

A

500, 2

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18
Q

1/______ people have a homo mutation for familial hypercholesterolaemia and their plama LDL levels are ___x as much as a normal.

A

1M, 10

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19
Q

what happens to people that have homozygous familial hypercholesterolaemia?

A

fatal myocardial infarctions in childhood/adolescence.

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20
Q

what is polycystic kidney disease?

A

many cysts grow in kidney, and these cysts fill w/ fluid. if there are too many or they get too big, kidneys become damaged.

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21
Q

What is familial adenomatous polyposis (FAP)?

A

cancer develops in colon and rectum

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22
Q

What is neurofibromatosis?

A

tumors form on nerve tissues

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23
Q

What is the characteristic pattern of auto dom inheritance?

A

vertical, disease is passed from one generation to the next and each affected person has an affected parent

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24
Q

which has a larger probably of being affected by auto. dom.?

A

male and female are equal

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25
Q

if affected, males/females/both will transmit the mutation if it is auto dom

A

both

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26
Q

approx ___% of the offspring of an auto dom affected parent will be affected

A

50

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27
Q

What may cause exceptions to the auto dom pattern?

A

mutations, variable expressivity, and reduced penetrance

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28
Q

how is a mutation an exception to the auto dom inheritance pattern?

A

random cases may arise within families by de novo mutation which causes auto dom traits to not be expressed

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29
Q

how is variable expressivity an exception to the auto dom inheritance pattern?

A

everyone with the genotype shows it, it just varies from person to person how severely the phenotype is expressed

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30
Q

how is reduced penetrance an exception to the auto dom inheritance pattern?

A

some people have the genotype but dont express the phenotype

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31
Q

What is haploinsufficiency?

A

This occurs when one copy of a gene is inactivated/deleted and the other copy of the gene isn’t strong enough to produce the needed product to keep normal function.

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32
Q

What is dominant negative effect?

A

Dominant-negative effects occur when cells express mutant proteins that impair the activity of the cells’ usually-made functional counterpart.

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33
Q

how can a gain-of-function mutation at a single gene cause a disease phenotype?

A

the function of a mutant protein is enhanced

ex. achrondroplasia, huntingtons disease

34
Q

how does a loss of heterozygosity cause a disease phenotype?

A

inhertied copy of mutant gene and random loss of normal allele, even in only a few cells, renders those cells cancerous

35
Q

symptoms of auto rec diseases are only seen in _________

A

recessive homozygotes (2 mutant alleles and no normal allele)

36
Q

heterozygotes are said to be _______ of a mutation if auto rec

A

carriers

37
Q

auto rec is more/less common than auto dom

A

more

38
Q

most common auto dom mating type?

A
39
Q

most common auto rec mating type?

A
40
Q

what are some ways to identify auto rec diseases?

A

newborn screening programs, multiple affected siblings within large sib-ships, parental consanguinity, demonstration of partial defect in obligate heterozygotes

41
Q

identifying auto rec diseases can be complicated by _____ and _____

A

de novo mutation and genetic heterogeneity

42
Q

What is genetic heterogeneity?

A

Genetic heterogeneity can be defined as mutations at 2+ genetic loci that produce the same or similar phenotypes

43
Q

What are the 2 types of genetic heterogeneity?

A

allelic geterogeneity and locus heterogeneity

44
Q

what is the diff b/w allelic and locus heterogeneity?

A
45
Q

explain mutation nomenclature.

A
46
Q

What is allelic heterogeneity?

A
47
Q

What is locus heterogeneity?

A
48
Q

Males are ________ for the X chromosome

A

hemizygous

49
Q

What is lyonization?

A

X chromosome inactivation

50
Q

in female cells, one of the two ____ chromosomes is inactivated

A

X chromosomes

51
Q

inactivation occurs when?

A

early in embryonic life

52
Q

inactivation is _________

A

random, either the paternal/maternal X may be inactivated

53
Q

inactivation is permanent and ______ propagated

A

clonally

54
Q

inactivation is virtually ________

A

complete

55
Q

the inactive X appears as a dark-staining mass known as a _________

A

Barr-body

56
Q

What is a Barr body?

A

condensed heterochromatic chromosome

57
Q
A
58
Q

x linked diseases may be ______ or ________

A

rec or dom

59
Q

X linked mutant genes are ____ expressed in males

A

fully

60
Q

X linked traits are _______ expressed in females

A

variably

61
Q

What does intermediate effect mean regarding X linked diseases?

A

clinically unaffected but biochemically abnormal

62
Q

What is skewed X inactivation?

A

normal phenotype

more than random X chromosomes containing the MUTANT gene are inactivated

occurs when the X-inactivation of one X chromosome is favored over the other, leading to an uneven number of cells with each chromosome inactivated

63
Q

what is manifesting heterozygote?

A

clinically affected

more than random X chromosomes containing the Normal gene are inactivated

A female heterozygous for a sex-linked recessive mutant gene who expresses the same phenotype as a male hemizygous for the mutation. This rare phenomenon results from the situation where, by chance, most somatic cells critical to the expression of the mutant phenotype contain an inactivated X chromosome carrying the normal allele of the gene.

64
Q

An X-linked disease may or may not be expressed clinically in a _______________

A

heterozygous female

65
Q

diseases which are rarely expressed clinically in females are said to be ___________

A

X-linked recessive (most known X-linked diseases are X-linked rec)

66
Q

diseases which are expressed clinically in many females are said to be _____________

A
67
Q

diseases are characterized as XLR vs XLD depending on _________________

A

the relative proportions of females who are affected

68
Q

Describe and X linked recessive pedigree.

A
69
Q

What are 2 types of XLR diseases?

A

hemophilia A and Duchenne muscular dystrophy

70
Q

What is hemophilia A?

A

incidence is 1/5000-10000

deficiency in factor VIII

soft tissue bleeding in joints

71
Q

What is Duchenne Muscular dystrophy?

A

incidence is 1/3300

form of muscular dystrophy

onset at approx 5 years old

progressive muscle weakness

death due to resp/card complications in 20’s

72
Q

what is Hypophosphatemic rickets?

A

condition where the bones become painfully soft and bend easily

73
Q

typically, expression of XLD symptoms is more severe and constant in _____ than in ______

A

males, females

74
Q

What is extranuclear inheritance?

A

transmission of genes that occur outside of the nucleus (mitochondria)

75
Q

What is mtDNA?

A

the mitochondria has a small circular DNA genome (abt 16kbp long)

76
Q

mtDNA is maternally transmitted via the ______

A

ovum

77
Q

certain human diseases characterized by abnormal mitochondria often involve ________ and _____ muscle impairment and neurological problems

A

skeletal, cardiac

78
Q

What is the difference between homoplasmy and heteroplasmy?

A

Homoplasmy refers to the state of having uniformly normal or abnormal mitochondria in a tissue, while heteroplasmy refers to the state of having a mixture of normal and abnormal mitochondria in a tissue.

79
Q

What is the difference between normal, premutation, and mutation triplet repeat disorders?

A
80
Q

triplet repeat disorders may be classified as _____, _______, or ________ inheritance

A

dominant, recessive, X-linked

81
Q

What does unstable expansion mean?

A

variation

Quiz 2 (18 decks)

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