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Biochem 4 > Sex-linked And Mitochondrial Inheritance > Flashcards

Sex-linked And Mitochondrial Inheritance Flashcards

1
Q

Gene dosage:

A

The number of copies that we have of a gene

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2
Q

Mechanism for dosage compensation in women

A

X-inactivation

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3
Q

X-inactivation was hypothesized by:

A

Mary Lyon

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4
Q

X-inactivation is a ______ and _______ process

A

Random and permanent

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5
Q

X-inactivation is random except for cells that

A

Become the placenta, they inactivate the paternal X chromosome

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6
Q

Mosaic definition

A

Two different populations of cells, with either the paternal or maternal X chromosome inactivated

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7
Q

Hemizygous definition

A

One X chromosome which is expressed in all cells

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8
Q

Hypohidrotic ectodermal displasia is a ______ disease

A

X-linked recessive

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9
Q

Symptoms of hypoidrotic ectodermal dysplasia

A

Abnormal delvelopment of nails, hair or sweat glands greatly reduce ability to sweat

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10
Q

Barr bodies are:

A

Dense masses of chromatin present in interphase of female somatic cells that are not observed in male somatic cells

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11
Q

How many Barr bodies does a male have

A

Zero

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12
Q

How many Barr bodies does a female have

A

1

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13
Q

Turner syndrome has how many Barr bodies

A

XO = zero Barr bodies (female, cells look male)

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14
Q

Klinefelter syndome has how many Barr bodies

A

XXY = 1 Barr body, is male

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15
Q

Quintuple X syndrome has how many Barr bodies

A

4 Barr bodies, female XXXXX

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16
Q

X inactivation starts at the:

A

XIC which contains the gene XIST

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17
Q

XIST RNA is only expressed on the _____ X chromosome

A

Inactive

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18
Q

How does XIST RNA inactivate?

A

It inactivates itself by coating the inactive X chromosome

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19
Q

What helps to ensure the long-term stability of the inactivation of an X chromosome?

A

High methylation of DNA and histone hypoacetylation

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20
Q

About ____% of the genes on the X chromosome escape inactivation

A

15

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21
Q

Genes that escape X-inactivation: Why?

A

PAR1 and PAR2 regions (pseudo autosomal regions) because they behave more like autosomal genes

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22
Q

If there is only one active X chromosome in a cell, why would having extra or missing inactive X chromosomes present any problem?

A

X-activation is incomplete, resulting in altered dosages

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23
Q

There is no father to son transmission in ______ inheritance

A

X-linked recessive

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24
Q

Lesch-Nyhan syndrome is a ____________ disease

A

X-linked recessive disease

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25
Q

Lesch-Nyhan disease effects which gene

A

HGPRT (hypoxantine-Guanine Phosphoribosyl Transferase)

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26
Q

HGPRT gene is involved in:

A

The salvage pathway of purines

27
Q

decreased HGPRT activity results in:

A

Increase in Uric acid (waste from not recycling purines)

28
Q

Symptoms of Lesch-Nyhan syndrome:

A

Premature gout Kidney stones Decreased dopamine Low IQ Spastic cerebral palsy, dystonia Self-mutilation and aggressive behavior

29
Q

gene mutation in Duchenne Muscular Dystrophy and Becker Muscular Dystrophy

A

dystrophin (present in muscle fibers)

30
Q

What is the largest known human gene? How large?

A

dystropin, 2.5 million base pairs

31
Q

Where is the dystrophin gene located

A

X chromosome

32
Q

Duchenne Muscular Dystrophy and Becker Muscular Dystrophy specific type of mutation

A

Duchenne: small deletions leading to frameshifts

Bercker: larger deletions without frameshifts

33
Q

What are grower’s signs

A

weakness of lower limbs, children have to leverage themselves standing up from the floor to compensate

34
Q

dystrophin function in the cell

A

necessary to matintain the structural integriy of the cell’s cytoskeleton

35
Q

What is a hallmark of an x-linked dominant inheritance

A

vertical transmission pattern, no father-to-son transmission

36
Q

Why are X-linked dominant diseases less prevelent than X-linked recessive diseases?

A

decreased survivability and less likely ro reproduce

37
Q

Rhett syndrome is a ______ disease

A

x-linked dominant

38
Q

Why is Rhett syndrome more common in females?

A

usually lethal in males

39
Q

Rhett syndrome specific mutations

A

various mutation of methyl-CpG binding protein 2 (MeCP2) which controls expression of genes in important brain functions

40
Q

symptoms of Rhett syndrome

A

autistic behaviors, hand wringing, iltellectural disability, seizures, gait ataxia, heart rhythm and breathing abnormalities

41
Q

variation in severety of Rhett syndrome is attributed to

A

skewed X-inactivation patterns

42
Q

How is Rhett syndome typically transmitted

A

not in families, but in mutations. Except when females in earlier generations have X-inactivation skewed in favor of the X chromosome with the normal allele

43
Q

Fragile X syndome effects which gene

A

FMR1 gene affects protein FMRP involved in cognitive development

44
Q

Fragile X syndome is a __________ disease

A

X-linked dominant

45
Q

symptoms of fragile X syndrome

A

itellectural disability, distinct facial appearance

46
Q

Fragile X syndrome specific mutation

A

CGC repeat expansion in the promotor region of he FMR1 gene

47
Q

trinucleotide repeat expansion leads to:

A

anticipation

48
Q

Anticipation tends to occur when _______ pass the trait

A

female carriers

49
Q

What is the “male determining factor”

A

SRY gene

50
Q

The short arm (p) of the y chromosome has genes involved in:

A

bone growth

51
Q

the long arm (q) of the y chromosome has genes involves with

A

azoospermia (sperm production)

52
Q

regions of the sex chromosome that behave like autosomal chromosomes are called

A

pseudoautosomal regions

53
Q

Langer mesolmelic dysplasia effects which gene

A

SHOX gene in the pseudoautosomal region

54
Q

Leri-Weill dyschondrosteosis effects which gene

A

SHOX gene in psuedoautosomal region

55
Q

Swyer syndome is a mutation of the ____ gene

A

SRY gene

56
Q

syndrome where a genotypic male develops as a female

A

Swyer syndrome

57
Q

46, XX testicular disorder of sex development results from:

A

translocation of the SRY gene onto an X chromosome. Develop as males with symptoms similar to klinefelter syndrome

58
Q

How many genes are in mitochondrial DNA

A

37

59
Q

mitochondrial DNA provides genes that are required for

A

oxidative phosphorylation

60
Q

replicative segregation refers to:

A

random distribution of mtDNA between daughter mitochondria and random distribution of mitochondria between daughter cells

61
Q

homoplasmy:

A

daughter cell received pure population of mitochondria all with normal or all with mutated DNA

62
Q

heteroplasmy:

A

daughter cell received a mixed population of mitochondra, some with and some without mutated DNA

63
Q

none of the offspring of an affected male will manifest the disease if the disease is:

A

a mitochondrial disease

64
Q

All of the offspring of an affected female will inherit the disease if the disease is

A

a mitochondrial disease

Biochem 4 (9 decks)

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