Sex-linked And Mitochondrial Inheritance

Question 1

Gene dosage:

Answer 1

The number of copies that we have of a gene

Question 2

Mechanism for dosage compensation in women

Answer 2

X-inactivation

Question 3

X-inactivation was hypothesized by:

Answer 3

Mary Lyon

Question 4

X-inactivation is a ______ and _______ process

Answer 4

Random and permanent

Question 5

X-inactivation is random except for cells that

Answer 5

Become the placenta, they inactivate the paternal X chromosome

Question 6

Mosaic definition

Answer 6

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

Question 7

Hemizygous definition

Answer 7

One X chromosome which is expressed in all cells

Question 8

Hypohidrotic ectodermal displasia is a ______ disease

Answer 8

X-linked recessive

Question 9

Symptoms of hypoidrotic ectodermal dysplasia

Answer 9

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

Question 10

Barr bodies are:

Answer 10

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

Question 11

How many Barr bodies does a male have

Answer 11

Zero

Question 12

How many Barr bodies does a female have

Answer 12

1

Question 13

Turner syndrome has how many Barr bodies

Answer 13

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

Question 14

Klinefelter syndome has how many Barr bodies

Answer 14

XXY = 1 Barr body, is male

Question 15

Quintuple X syndrome has how many Barr bodies

Answer 15

4 Barr bodies, female XXXXX

Question 16

X inactivation starts at the:

Answer 16

XIC which contains the gene XIST

Question 17

XIST RNA is only expressed on the _____ X chromosome

Answer 17

Inactive

Question 18

How does XIST RNA inactivate?

Answer 18

It inactivates itself by coating the inactive X chromosome

Question 19

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

Answer 19

High methylation of DNA and histone hypoacetylation

Question 20

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

Answer 20

15

Question 21

Genes that escape X-inactivation: Why?

Answer 21

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

Question 22

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

Answer 22

X-activation is incomplete, resulting in altered dosages

Question 23

There is no father to son transmission in ______ inheritance

Answer 23

X-linked recessive

Question 24

Lesch-Nyhan syndrome is a ____________ disease

Answer 24

X-linked recessive disease

Question 25

Lesch-Nyhan disease effects which gene

Answer 25

HGPRT (hypoxantine-Guanine Phosphoribosyl Transferase)

Question 26

HGPRT gene is involved in:

Answer 26

The salvage pathway of purines

Question 27

decreased HGPRT activity results in:

Answer 27

Increase in Uric acid (waste from not recycling purines)

Question 28

Symptoms of Lesch-Nyhan syndrome:

Answer 28

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

Question 29

gene mutation in Duchenne Muscular Dystrophy and Becker Muscular Dystrophy

Answer 29

dystrophin (present in muscle fibers)

Question 30

What is the largest known human gene? How large?

Answer 30

dystropin, 2.5 million base pairs

Question 31

Where is the dystrophin gene located

Answer 31

X chromosome

Question 32

Duchenne Muscular Dystrophy and Becker Muscular Dystrophy specific type of mutation

Answer 32

Duchenne: small deletions leading to frameshifts Bercker: larger deletions without frameshifts

Question 33

What are grower's signs

Answer 33

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

Question 34

dystrophin function in the cell

Answer 34

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

Question 35

What is a hallmark of an x-linked dominant inheritance

Answer 35

vertical transmission pattern, no father-to-son transmission

Question 36

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

Answer 36

decreased survivability and less likely ro reproduce

Question 37

Rhett syndrome is a ______ disease

Answer 37

x-linked dominant

Question 38

Why is Rhett syndrome more common in females?

Answer 38

usually lethal in males

Question 39

Rhett syndrome specific mutations

Answer 39

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

Question 40

symptoms of Rhett syndrome

Answer 40

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

Question 41

variation in severety of Rhett syndrome is attributed to

Answer 41

skewed X-inactivation patterns

Question 42

How is Rhett syndome typically transmitted

Answer 42

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

Question 43

Fragile X syndome effects which gene

Answer 43

FMR1 gene affects protein FMRP involved in cognitive development

Question 44

Fragile X syndome is a __________ disease

Answer 44

X-linked dominant

Question 45

symptoms of fragile X syndrome

Answer 45

itellectural disability, distinct facial appearance

Question 46

Fragile X syndrome specific mutation

Answer 46

CGC repeat expansion in the promotor region of he FMR1 gene

Question 47

trinucleotide repeat expansion leads to:

Answer 47

anticipation

Question 48

Anticipation tends to occur when _______ pass the trait

Answer 48

female carriers

Question 49

What is the "male determining factor"

Answer 49

SRY gene

Question 50

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

Answer 50

bone growth

Question 51

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

Answer 51

azoospermia (sperm production)

Question 52

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

Answer 52

pseudoautosomal regions

Question 53

Langer mesolmelic dysplasia effects which gene

Answer 53

SHOX gene in the pseudoautosomal region

Question 54

Leri-Weill dyschondrosteosis effects which gene

Answer 54

SHOX gene in psuedoautosomal region

Question 55

Swyer syndome is a mutation of the ____ gene

Answer 55

SRY gene

Question 56

syndrome where a genotypic male develops as a female

Answer 56

Swyer syndrome

Question 57

46, XX testicular disorder of sex development results from:

Answer 57

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

Question 58

How many genes are in mitochondrial DNA

Answer 58

37

Question 59

mitochondrial DNA provides genes that are required for

Answer 59

oxidative phosphorylation

Question 60

replicative segregation refers to:

Answer 60

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

Question 61

homoplasmy:

Answer 61

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

Question 62

heteroplasmy:

Answer 62

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

Question 63

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

Answer 63

a mitochondrial disease

Question 64

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

Answer 64

a mitochondrial disease