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IB 141 human genetics > chapter 6 - matters of sex > Flashcards

chapter 6 - matters of sex Flashcards

(78 cards)

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1
Q

biological maleness or femaleness is determined at _____

A

conception

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2
Q

SRY gene

A

in mice, sex-determining region of Y chromosome

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3
Q

TDF gene

A

testis determining factor in humans, essential for male development

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4
Q

Wnt4 gene

A

essential for development / maturation as a biological female

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5
Q

mutations in Wnt4 cause

A
  • XX females develop high levels of male sex hormones
  • lack of development of vaginal canal and uterus
  • ovaries do not develop properly
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6
Q

beta-catenin

A

induces ovary producing genes and blocks SRY (TDF)

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7
Q

heterogametic sex

A

males; have different sex chromosomes (XY)

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8
Q

homogametic sex

A

females; have the same sex chromosomes (XX)

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9
Q

how many genes in X chromosome

A

more than 1500 genes

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10
Q

the X chromosome is _______ than the Y chromosome

A

larger

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11
Q

X chromosome acts as a _____ to Y in males

A

homolog

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12
Q

how many genes are in the Y chromosome

A

more than 230 genes

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13
Q

Y chromosome does not _____ _____ along all of its length

A

cross over

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14
Q

the Y chromosome has many DNA segments that are _______ and may destabilize ___ ________

A

palindromes; DNA replication

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15
Q

Y chromosome anatomy

A

1 short arm, 1 long arm

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16
Q

pseudoautosomal regions of Y chromosome

A

PAR1 & PAR2

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17
Q

5% of the Y chromosome….

A

contains 63 genes shared with X chromosome that contribute to bone growth, cell division, etc

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18
Q

MSY

A

male specific region, most of the chromosome

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19
Q

MSY 3 classes of DNA sequences

A

1 - sequence almost identical to X chromosome. 2 - somewhat identical to X chromosome. 3 - palindromes

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20
Q

how many genes are in the MSY

A

22 genes

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21
Q

AZF gene

A

encodes a protein essential for producing sperm

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22
Q

AZF gene mutations cause

A

infertility

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23
Q

hermaphroditism

A

older/more general term for individual with male and female sexual structures

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24
Q

intersex

A

individuals whose internal structures are inconsistent with external structures or whose genitalia are ambiguous

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25
pseudohermaphroditism
refers to the presence of both female/male structures but at different life stages
26
pseudohermaphroditism includes
- androgen insensitivity syndrome, 5-alpha reductase deficiency, congenital adrenal hyperplasia
27
androgen insensitivity syndrome
mutation on the X - chromosome blocks formation of androgen receptors
28
5-alpha reductase deficiency
unable to convert testosterone to DHT, child has inside male anatomy but looks like a girl on the exterior
29
congenital adrenal hyperplasia
enzyme block causes androgens to accumulate, and can cause precocious puberty in males or male secondary sex characteristics to develop in females
30
in normal male prenatal development, activation of a set of genes beginning with SRY sends signals that destroy _____ _____, while activating the biochemical pathway that produces ______ and ________ ,which promotes the development of male structures
female rudiments; testosterone; dihydrotestosterone
31
congenital adrenal hyperplasia results in excess ____ and ____
testosterone and dihydrotestosterone
32
androgen insensitivity syndrome and 5-alpha reductase deficiency lower levels of _____ _____
male hormones
33
same-sex attraction
person's phenotype and genotype are consistent, but physical attraction is towards members of the same sex
34
sex ratio
calculated by number of males / number of females, multipled by 1000
35
primary sex ratio
at conception is 1000; equal
36
secondary sex ratio
at birth is 1050; Y bearing sperm weight lighter than X bearing sperm, so it could enter the oocyte faster
37
tertiary sex ratio
at maturity, doesn't say what it is though
38
Y-linked traits
-genes on Y chromosome -very rare -transmitted from male to male
39
X-linked traits in females
passed like autosomal traits
40
X-linked traits in males
a single copy of an X-linked allele causes expression of the trait or illness
41
human male is considered _______ for X-linked traits
hemizygous
42
X-linked recessive trait is always expressed in _____
male
43
X-linked recessive trait is expressed in female _____ and very rarely in a female ______
homozygote; heterozygote
44
X-linked recessive traits - affected female inherits from...
affected father and affected or heterozygote mother
45
X-linked dominant trait is expressed in _____ in one copy
females
46
X-linked dominant traits have more severe effects in _____
males
47
X-linked dominant traits cause high rates of ______ due to early lethality in males
miscarriage
48
X-linked dominant traits are passed from male to all ______ but not to ___
daughters; sons
49
X-linked recessive trait is expressed in females if the allele is _____ _____ ___ ____
present in 2 copies
50
examples of X-linked recessive traits
ichthyosis, colorblindness, hemophilia
51
ichthyosis
enzyme deficiency blocks removal of cholesterol from skin cells
52
colorblindness
about 8% of males of european ancestry have the condition
53
hemophilia
disorder of blood-clotting
54
hemophilia B is an X-linked _____ disease that usually passes from a _____ woman to ______ daughters or ______ sons.
recessive; heterozygous; heterozygous; hemizygous
55
why are males that inherits x-linked dominant traits usually more severely affected?
he has no other allele to mask its effect
56
most cases of x-linked dominant traits are a result of ____ _______, rather than ____ ____ __ _____
new mutations; transmission from a parent
57
examples of x-linked dominant traits
rett syndrome, incontinentia pigment
58
sex-limited traits
traits that affect a structure or function that is present in only 1 sex - could be autosomal or x-linked
59
sex-limited traits examples
- beard growth - milk production - preeclampsia in pregnancy
60
sex-influenced traits
allele is dominant in 1 sex but recessive in the other - could be autosomal or x-linked - difference in expression can be caused by hormonal differences between sexes
61
sex-influenced traits examples
pattern baldness in humans - heterozygous male is bald heterozygous female is not, response to treatment for glioblastoma - female patients live longer than male patients after surgery, radiation and use of a drug, temozolomide
62
X inactivation
balances the inequality of expression of genes on the X chromosome
63
XIST gene
encodes an RNA that binds to and inactivates the X chromosome
64
X inactivation occurs early in _____ _______
prenatal development
65
X inactivation alters the _____ and not the ____.
phenotype; genotype
66
barr body
inactive X chromosome
67
manifesting heterozygote
female that expresses the phenotype corresponding to an X-linked gene
68
X inactivation can be used to identify carriers of some X-linked disorders, such as
hunter syndrome, lesch-nyhan syndrome, affects the severity of rett syndrome
69
unequal x inactivation pattern can occur if...
the 2 X chromosomes have different alleles for a gene that controls cell division, giving certain cells a survival advantage
70
mechanisms of parent-of-origin effects
genomic imprinting
71
genomic imprinting
parental effect on gene expression is seen as diseases inherited from a parent
72
function of genomic imprinting
not super well understood, but may be a way to regulate abundance of key proteins in the embryo
73
imprinted genes are in ____ along a chromosome, controlled by ______ _____
clusters; imprinting centers
74
male genome controls _____ development, female genome controls ______ development
placenta; embryo
75
humans have ____ imprinted genes. at least ____ of them affect health if they are abnormally expressed
150+; 60
76
chromosome 15 deletion syndromes
prader-willi syndrome - inherited from father; angelman syndrome - inherited from mother
77
abnormal imprinting is associated with:
diabetes mellitus, autism, alzheimers, schizophrenia, male-male attraction
78

IB 141 human genetics (6 decks)

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