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lecture 11- genetics Flashcards

1
Q

what do the law of segregation and the law of independent assortment have in common

A

both contribute to genetic diversity

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2
Q

what is incomplete dominance

A

neither allele is dominant
mix/blend of both homozygous alleles
pink flower = mix of homozygous red and white

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3
Q

what is the notation for incomplete dominance alleles (red pink and white)

A

R^1R^1
R^1R^2
R^2R^2

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4
Q

in incomplete dominance what terms do you use for the middle allele

A

heterozygous

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5
Q

in incomplete dominance what is the genotype ratio compared to the phenotype ratio

A

they are equal
all allele combination will display their phenotype

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6
Q

what is codominance

A

both alleles’ phenotype being expressed
not a mix, are independent

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7
Q

what is the notation for codominance

A

same as incomplete dominance (R^1R^2)

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8
Q

is a gene limited to having only two alleles

A

no (blood type antigens)

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9
Q

how many alleles can an individual have for a specific gene

A

two because theres only two homologous chromosomes for that gene

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10
Q

what are the blood cell antigens

A

I^A - type A
I^B - type B
i - type O

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11
Q

what are all the blood types you can have and their notations

A

type A - I^A I^A or I^A i
type B - I^B I^B or I^B i
type AB (codominant) - I^A I^B
type O - ii

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12
Q

what is epistasis

A

presence of a certain allele in one locus that can mask the expression of alleles in a different locus

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13
Q

is the epistasis gene dominant or recessive

A

recessive ee

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14
Q

how does epistasis work

A

if the epistasic gene is homozygous recessive then it blocks another gene from being expressed

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15
Q

what is pleiotropy

A

a single gene that can affect multiple phenotype

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16
Q

how does pleiotropy work

A

when a gene product is used in different cell types or a signaling functions on various targets it affects multiple organs

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17
Q

what are examples of pleiotropy

A

cystic fibrosis (defective protein found in the plasma membrane): affects lungs, intestines, pancreas, liver, sweat glands
sickle cell anemia (defective protein in red blood cells): symptoms such as heart failure, jaundice and pain

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18
Q

what is polygenic inheritance

A

many genes interacting to affect the expression of one trait (opposite of pleiotropy)

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19
Q

example of polygenic inheritance

A

skin color is controlled by at least three genes

20
Q

what is sex-linked inheritance

A

characteristics inherited on sex chromosomes other than sex related ones (mostly X)

21
Q

what types of genes do sex chromosomes contain

A

sex assigned
control of development of secondary sex characteristics (breasts, voice, etc)
other genes: hemophilia and color blindness

22
Q

are sex chromosomes homologous

A

no but they act as homologous (pair up during meiosis)
have a homologous region (bottom, small)

23
Q

where are sex linked genes

A

on one of the sex chromosomes but not on the other

24
Q

what is a hemizygous allele

A

allele that determines the condition in males because they only have that gene on one sex chromosome

25
Q

what is dosage compensation

A

mechanism that makes the 2 doses in females (XX) and the one dose in males (XY) equivalent

26
Q

how does dosage compensation work in mammals

A

inactivation of an X chromosome or part of it
creation of a barr body (inactive chromosome)

27
Q

what is the point of dosage compensation

A

avoiding over expression of X genes in females

28
Q

due to X inactivation what changes in the genetic material

A

nothing, they all keep the same genetic material

29
Q

what is polyploidy

A

presence of multiple sets of chromosomes (normal)

30
Q

what is aneuploidy

A

abnormalities caused by the presence or absence of a single chromosome (only affects one chromosome type)

31
Q

what is a nondisjunction

A

chromosomes failing to separate during meiotic division

32
Q

what is the result of nondisjunction

A

aneuploidies

33
Q

what is disomy

A

a normal pair of chromosomes

34
Q

what is trisomy

A

having an extra chromosome in a pair (3)

35
Q

what is monosomy

A

missing a chromosome in a pair (1)

36
Q

where can aneuploidies happen

A

autosomes and sex chromosomes

37
Q

what is the reason for down syndrome

A

trisomy 21 (extra chromosome #21)
so 47 chromosomes instead of 46

38
Q

what are the four chromosome structure mutation

A

deletion
duplication
inversion
reciprocal translocation (different chromosomes exchanging genes)

39
Q

is a phenotype solely based on genes and why

A

no its also based on the environment (height = how much you eat, sleep, etc)

40
Q

what are the different types of abnormal sex chromosome numbers

A

XXX
XXY
XYY
X0
Y0

41
Q

how will a XXX person develop

A

female
mild disorders
only one X active
taller than average
normal sexual development

42
Q

how will a XXY person develop

A

male
have some female characteristics

43
Q

how will a XYY person develop

A

male
normal sexual development
taller than average

44
Q

how will a X0 person develop

A

female
underdeveloped ovaries
male characteristics (lack breasts)

45
Q

how will a Y0 person develop

A

death
humans cannot live without at least one X chromosome

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