Sex-linked And Mitochondrial Inheritance Flashcards Preview

Biochem 4 > Sex-linked And Mitochondrial Inheritance > Flashcards

Flashcards in Sex-linked And Mitochondrial Inheritance Deck (64):
1

Gene dosage:

The number of copies that we have of a gene

2

Mechanism for dosage compensation in women

X-inactivation

3

X-inactivation was hypothesized by:

Mary Lyon

4

X-inactivation is a ______ and _______ process

Random and permanent

5

X-inactivation is random except for cells that

Become the placenta, they inactivate the paternal X chromosome

6

Mosaic definition

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

7

Hemizygous definition

One X chromosome which is expressed in all cells

8

Hypohidrotic ectodermal displasia is a ______ disease

X-linked recessive

9

Symptoms of hypoidrotic ectodermal dysplasia

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

10

Barr bodies are:

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

11

How many Barr bodies does a male have

Zero

12

How many Barr bodies does a female have

1

13

Turner syndrome has how many Barr bodies

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

14

Klinefelter syndome has how many Barr bodies

XXY = 1 Barr body, is male

15

Quintuple X syndrome has how many Barr bodies

4 Barr bodies, female XXXXX

16

X inactivation starts at the:

XIC which contains the gene XIST

17

XIST RNA is only expressed on the _____ X chromosome

Inactive

18

How does XIST RNA inactivate?

It inactivates itself by coating the inactive X chromosome

19

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

High methylation of DNA and histone hypoacetylation

20

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

15

21

Genes that escape X-inactivation: Why?

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

22

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

X-activation is incomplete, resulting in altered dosages

23

There is no father to son transmission in ______ inheritance

X-linked recessive

24

Lesch-Nyhan syndrome is a ____________ disease

X-linked recessive disease

25

Lesch-Nyhan disease effects which gene

HGPRT (hypoxantine-Guanine Phosphoribosyl Transferase)

26

HGPRT gene is involved in:

The salvage pathway of purines

27

decreased HGPRT activity results in:

Increase in Uric acid (waste from not recycling purines)

28

Symptoms of Lesch-Nyhan syndrome:

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

29

gene mutation in Duchenne Muscular Dystrophy and Becker Muscular Dystrophy

dystrophin (present in muscle fibers)

30

What is the largest known human gene? How large?

dystropin, 2.5 million base pairs

31

Where is the dystrophin gene located

X chromosome

32

Duchenne Muscular Dystrophy and Becker Muscular Dystrophy specific type of mutation

Duchenne: small deletions leading to frameshifts

Bercker: larger deletions without frameshifts

33

What are grower's signs

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

34

dystrophin function in the cell

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

35

What is a hallmark of an x-linked dominant inheritance 

vertical transmission pattern, no father-to-son transmission

36

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

decreased survivability and less likely ro reproduce

37

Rhett syndrome is a ______ disease

x-linked dominant

38

Why is Rhett syndrome more common in females?

usually lethal in males

39

Rhett syndrome specific mutations

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

40

symptoms of Rhett syndrome

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

41

variation in severety of Rhett syndrome is attributed to

skewed X-inactivation patterns

42

How is Rhett syndome typically transmitted

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

Fragile X syndome effects which gene

FMR1 gene  affects protein FMRP involved in cognitive development

44

Fragile X syndome is a __________ disease

X-linked dominant

45

symptoms of fragile X syndrome 

itellectural disability, distinct facial appearance 

46

Fragile X syndrome specific mutation

CGC repeat expansion in the promotor region of he FMR1 gene

47

trinucleotide repeat expansion leads to:

anticipation

48

Anticipation tends to occur when _______ pass the trait

female carriers

49

What is the "male determining factor"

SRY gene

50

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

bone growth

51

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

azoospermia (sperm production)

52

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

pseudoautosomal regions

53

Langer mesolmelic dysplasia effects which gene

SHOX gene in the pseudoautosomal region

54

Leri-Weill dyschondrosteosis effects which gene

SHOX gene in psuedoautosomal region 

55

Swyer syndome is a mutation of the ____ gene

SRY gene

56

syndrome where a genotypic male develops as a female

Swyer syndrome

57

46, XX testicular disorder of sex development results from:

 

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

58

How many genes are in mitochondrial DNA

37

59

mitochondrial DNA provides genes that are required for

oxidative phosphorylation

60

replicative segregation refers to:

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

61

homoplasmy:

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

62

heteroplasmy:

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

63

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

a mitochondrial disease

64

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

a mitochondrial disease