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Anatomy and Physiology I > Exam 3: Inheritance > Flashcards

Exam 3: Inheritance Flashcards

1
Q

humans have approx. ____ genes located on _____ chromosomes

A

23,000

46

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2
Q

chromosomes occur as _____ homologous pairs in ____ form

A

23

diploid

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3
Q

22 pairs are referred to as

A

autosomal

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4
Q

the 23rd pair is what pair??

A

sex-determining pair (XX, XY)

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5
Q

meiosis results in gametes that are ____

A

haploid

- containing one chromosome from each pair

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6
Q

what restores the diploid number

A

fertilization

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7
Q

genotype vs phenotype

A

genotype: genetic makeup
phenotype: physical expression

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8
Q

allele

A

variation of gene

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9
Q

locus

A

location of a gene on a chromosome

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10
Q

in simple inheritance, what is controlled by the interaction of one pair of alleles?

A

phenotype

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11
Q

homozygous

A

alleles in a pair that can be identical in expression

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12
Q

dominant

A

alleles that are expressed in phenotype

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13
Q

recessive

A

alleles that are masked by another allele’s expression

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14
Q

when can a recessive phenotype be expressed?

A

only in the homozygous state

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15
Q

when you have 2 diff alleles what interactions exist? (3)

A

complete dominance
codominance
incomplete dominance

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16
Q

complete dominance

A

one allele expressed as phenotype, the other is masked

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17
Q

codominance

A

both alleles fully expressed in phenotype

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18
Q

incomplete dominance

A

the phenotype is an intermediate expression of the 2 alleles

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19
Q

free earlobes, freckles, astigmatism, myopia or hyperopia, Rh+ factor, A or B blood type, Huntington’s Disease

A

dominant traits complete dominance

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20
Q

normal vision, short eyelashes, having 5 fingers, Rh-, O blood type, Tay-Sachs, Phenylketonuria

A

recessive traits complete dominance

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21
Q

2 complete dominance disorders

A

Huntington’s disease and Tay Sachs

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22
Q

Huntington’s Disease

A

neurodegenerative disorder, symptoms occur midlife

  • motor impairments
  • wild jerky movements (chorea)
  • insoluble aggregates
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23
Q

Tay Sachs

A

autosomal recessive

  • loss of group of enzymes that help break down lipids in CNS
  • lysosome storage problem
  • lazy baby syndrome
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24
Q

Application: Complete Dominance Disorder

A

Familial Hypercholesterolemia

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25
Q

Familial hypercholesterolemia

A

dominant disorder that impairs LDL removal

- high cholesterol levels due to genetics - dieting will not change this

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26
Q

HDL

A

good cholesterol

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27
Q

LDL

A

bad cholesterol

- gets distributed to cell, if high it is bad - excess deposits in blood vessels causing plaque formation

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28
Q

what 3 genes involved in familial hypercholesterolemia

A
  • mutation in gene encoding for LDL receptor
  • mutations in ApoB encoding gene impair ability of LDL to bind to receptor
  • mutations in regulating protein can diminish recycling of receptor causing abnormally low levels
    (cannot put receptors back on membrane)
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29
Q

Discuss how even a healthy diet these mutations in familial hypercholesterolemia would still result in high serum cholesterol levels?

A
  • mutations prevent LDLs from going into cell - stays in bloodstream, delay in receptors getting out to surface
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30
Q

Risks with high cholesterol levels

A
  • plaque build up in blood vessels - affects blood flow to heart, brain - heart attack, stroke
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31
Q

Would you expect the risks to be different in an individual who is homozygous vs heterozygous for one of the familial hypercholesterolemia mutatios?

A

no

- bc complete dominance only need one gene for this

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32
Q

Example of codominance

A

AB blood type

- both alleles for gene equally expressed

33
Q

Example of Incomplete dominance

A

Thallassemia

34
Q

Thallassemia

A 
can occur in alpha or beta globin gene 
- major form = homozygous
- minor form = heterozygous
can cause anemia
lower O2 carrying capacity - fatigue 
- incomplete bc carrier has symptoms
35
Q

Penetrance

A

not all people who have a specific genotype express the phenotype
- neurofibromatosis

36
Q

neurofibromatosis

A
  • autosomal dominant
  • if simple inheritance expect to see people with swellings
  • only see symptoms in 50-80%
  • if not 100% then it is penetrance
37
Q

expressivity

A

the degree to which the phenotype is expressed

  • severity , could be 100% penetrance
  • Marfan’s syndrome
38
Q

Marfan’s syndrome

A

connective tissue disorder

  • effects elastin fiber making ligaments less flexible
  • people have longer limbs, taller, lower % subcutaneous fat, connects retina to back of eye, heart problems
  • can just be tall and thin but others may have life threatening conditions
39
Q

X - linked Sex linked traits

A

red - green color vision
clotting factor VIII
hypohidrotic ectodermal dysplasia (sweat glands)
Duchenne’s muscular dystrophy

40
Q

Y-linked Sex linked traits

A

TDF
SRY
Spermatogenesis genes

41
Q

Men vs women with X linked traits

A

women would follow simple inheritance (may have one of these and one normal allele)
men (only get one X, so whatever is on it will show )- higher percent in men
- if give to son they would have it but if give to daughter it would depend on husband

42
Q

Sex Influenced Traits: Baldness

A

baldness controlled by an autosomal gene on chromosome 20
- it is dominant in men but recessive in women
difference due to effect of androgens
expressed differently depending on if male or female
need one gene for baldness (women need to be homozygous)

43
Q

Application: Pleiotropy - examples

A

one gene results in more than one phenotype

  • Marfan’s
  • albinism
  • sickle cell anemia
44
Q

example of polygenic inheritance

A

eye color

45
Q

EYCL 1 (gey) gene

A

locus on 19; green/blue

46
Q

EYCL 2 (gey) gene

A

locus on 15; central brown/blue

47
Q

EYCL 3 (gey) gene

A

locus on 15; brown/blue

48
Q

How do you get blue eyes?

A

have to be recessive for all colors

49
Q

How do you get brown eyes?

A

dominant for 2 and 3

50
Q

What staining do karyotypes involve?

A

Giemsa staining forming G bands

51
Q

which karyotype regions stain darker vs lighter?

A

A-T darker

C-G lighter

52
Q

euploid

A

refers to any exact multiple of a chromosome set (n)

- monoploid or diploid

53
Q

aneuploid

A

wen euploid does not apply -extra or missing chromosome

54
Q

trisomy vs monosomy

A

trisomy - has extra chromosome

monosomy - missing a chromosome

55
Q

nondisjunction in meiosis II

A

centromere did not separate, did not chromosome for pair and one cell got both from the pair

  • the one with chromosomes would be the trisomy (extra) the one with nothing would be monosomy (missing)
  • only half abnormal in meiosis II
56
Q

Nondisjunction in meiosis I

A

both would be in one cell, you would get 2 gametes missing chromosomes and 2 gametes with 2 chromosomes each

  • higher percentage of having fertilized embryo with problems
  • all abnormal
57
Q

2 types of structural abnormalities and what are they?

A

deletions: portion of chromosome lost due to breakage or unbalanced crossing-over (translocation)
additions: due to translocation

58
Q

translocation

A

unequal sharing - one loses info while the other gets too much

59
Q

Genetics of Down’s syndrome

A 
most common - trisomy 21
47, XY +21
less common - translocation
46, XY t(21:21) or 46, XY t(14:21)
- can have all or part of 21 on 14
60
Q

Clinical effects of Down’s Syndrome

A
  • growth retardation
  • learning disabilities
  • craniofacial abnormalities (eyes)
  • cardiac defects: heart formation problems)
  • poor muscle tone
  • high risk of Alzheimer’s
61
Q

Genetics of Turner’s Syndrome

A

only monosomy condition known to be survivable
45, X
presence of one X = female
ONLY in females!!!

62
Q

Clinical aspects of Turner’s Syndrome

A
  • short stature on average
  • lymphedema of extremities
  • low placed ears
  • webbed neck
  • infertile - only have one X will not get through checkpoint in metaphase
63
Q

Genetics of Cri du chat Syndrome

A 
unbalanced translocation
loss of short arm in chromosome 5
partial monosomy
46 XY (5p-)
    - means minus the short arm (p)
64
Q

short arm vs long arm in cri du chat

A

short arm = p

long arm = q

65
Q

Clinical aspects of Cri du chat Syndrome

A

high pitched catlike cry in infants
microcephaly
intellectual disabilities
congenital heart disease

66
Q

Genomic imprinting

A
  • expression dependent on parent or origin

- some genes always shut down in egg or always shut down in the sperm

67
Q

2 types of Genomic imprinting

A

Angelman syndrome and Prader-Willi Syndrome

68
Q

Angelman Syndrome

A 
maternal origin
 deletion from mother 
- learning disabilities
- speech disorders
- poor motor development
- prone to seizures
- happy, frequent laughter
46, XX (15q11-15q13)
69
Q

Prader-Willi Syndrome

A 
paternal origin 
- deletion from father
learning disabilities
poor muscle tone
compulsive eating
obesity
hypogonadism
hormone issues
70
Q

Barr bodies

A

only one X chromosome needed to survive

  • in development of females one X is inactivated in somatic cells. Both X remain active in germ cell line
  • inactivation mainly random
  • all cells descendant from the initial inactivated X cell will express same X chromosome
71
Q

Effects of Barr Bodies (2)

A

mosaics

fragile X syndrome

72
Q

mosaics

A
  • occurs in women who are heterozygous for X-linked traits
  • result of random inactivation
  • example: sweat gland distribution in patches of skin
    calico cats
    shut down early = big patches
    shuts down late = tiny patches - tortoise shells
73
Q

fragile X syndrome

A
  • inherited from mother
  • increased DNA repeats in inactivated X chromosome
  • 46, XY (Xq-27) it will break
  • learning disabilities
  • large ears, jaw, testes
  • some women carriers show cognitive effects
    second most common form of learning disabilities
74
Q

application: fragile X syndrome

A
  • occurs due to a break in chromosomes, causing a low folate
  • over 200 shuts down the gene and results in developmental issues
  • sperm cannot carry mutated X but can pass on premutations
75
Q

application: chromosomal abnormalities

A

turner’s and klinefelter’s

76
Q

In klinefelter’s would the disorder occur in men, women, or both?`

A

men

77
Q

How could the condition of klinefelter’s occur?

A

nondisjunction

- in meiosis I or II

78
Q

application: pseudoautosomal genes

A

PAR
on ends of sex chromosomes
when make barr body they are regions that do not shut down - so these regions are active even in barr bodies
- survives with one X but problems with deficiency

Anatomy and Physiology I (17 decks)

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