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Genetics > Test 2 > Flashcards

Test 2 Flashcards

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Biology 101 flashcards
1
Q

T/F Most alleles act in a dominant recessive manner

A

F

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2
Q

Mutation

A

the ultimate source of alleles

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3
Q

how do new phenotypes arise

A

from changes in the functional activity of the gene product

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4
Q

ways that functional activity of gene product is changed

A

eliminating enzyme function
changing relative enzyme efficiency
changing overall enzyme function
the enzyme could be more or less active

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5
Q

what are the mutation types

A

loss of function mutations, gain-of-function muta tions, neutral mutations

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6
Q

what is a loss of function mutation

A 
"inactivating mutations" 
mutation causes loss of wild type function 
lose function of that allele 
gene is partially or fully inactive 
usually recessive
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7
Q

what is a gain of function mutation

A

“activating mutation”
mutation enhances the function of wild type
quantity of gene product increases
enzyme or gene mutates so that it has extra activity than the original allele, need gene quantity to increase
causes enhanced activation of the gene or its products
dominant

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8
Q

what is a neutral mutation

A

no change in phenotype
no change in evolutionary fitness of the organism
no selective benefit or negative selective effect
cant be seen

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9
Q

what is the fitness of an organism

A

depends on how many offspring you have

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10
Q

what is it called if the loss of a gene is complete

A

null allele

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11
Q

dominant-negative mutation

A

called anti morphic mutations
mutant allele acts antagonistically to the wild type allele
overrides and actively shuts down activity of another allele

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12
Q

example of a neutral mutation

A

silent mutation

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13
Q

example of dominant-negative mutation

A

marphans

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14
Q

incomplete or partial dominance

A

intermediate phenotype
neither allele is dominant
heterozygotes are an in between

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15
Q

how to designate a gene without a dominant or recessive trait

A

Superscript

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16
Q

Incomplete dominance

Cross true-breeding red flowers with true-breeding white flowers

A

get 100% heterozygote pink flowers

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17
Q

Incomplete dominance

cross 2 heterozygotes

A

1:2:1 genotype and phenotypic ration

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18
Q

example of incomplete dominance in humans

A

Tay-Sachs

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19
Q

how does tay sachs work

A

heterozygotes will onyl have 1/2 the enzyme activty
homozygous dominant will have all enzyme activity
homozygous recessive will have no enzyme activity

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20
Q

codominance

A

two alleles of a single gene produce 2 gene products
joint expression of both alleles in heterozygote
no dominance or recessiveness
see both alleles
Distinct expression of gene products of both alleles:

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21
Q

example of codominance in humans

A

MN Blood Groups

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22
Q

how is MN blood groups characterized

A

by antigen glycoprotein: found on surface of red blood cells

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23
Q

what are the glycoproteins that exist on blood

A

M and N

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24
Q

What glycoproteins can we exhibit on blood

A

either M or N or both

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25
Q

multiple alleles

A

3 or more alleles of the same gene

resulting mode of inheritance is unique

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26
Q

human example of multiple alleles

A

ABO blood groups

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27
Q

what antigens are present on the surface of red blood cells

A

A and B

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28
Q

which antigens are dominant to eachother for blood

A

iA codominant to iB

i recessesive to A and B

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29
Q

what are essential genes

A

absolutely required for survival
mutations can be tolerated if heterozygous
a gene is considered essential when loss of its function compromises the viability or fitness of the organism

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30
Q

what happens to homozygous recessive individuals of an essential gene

A

will not tolerate it, therefore will not survive

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31
Q

what are apart of essential genes

A

lethal alleles

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32
Q

recessive lethal allele

A

results in homozygous recessive individuals and do not survive

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33
Q

dominant lethal allele

A

presence of one copy of the allele results in death

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34
Q

example of a dominant lethal allele

A

Huntingtons

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35
Q

what is huntingtons

A

carry the allele, late-onset, characterized by progressive degeneration of nervous system, dementia, and early death

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36
Q

what is a homozygous lethal allele

A

must have 2 copies of the allele and could result in a mutant phenotype, 2 copies and the organism will die so you won’t see a new phenotype, carrier of the allele may cause mutant phenotype

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37
Q

T/F phenotypes are influenced by only one gene

A

False

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38
Q

what can contribute to the development of common phenotypes

A

cellular functions

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39
Q

what is epistasis

A

the interaction of genes that are not alleles, in particular, the suppression of the effect of one such gene by another, an allele of one gene hides or masks the visible output, or phenotype of another gene,

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40
Q

what is the Bombay phenotype

A

incomplete formed H substance which is a rare recessive mutation at locus results in the inadequate substrate for the enzyme, rare mutation in gene FUT1

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41
Q

FUT1 gene

A

FUT1 gene encodes the enzyme fucosyltransferase

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42
Q

how does an AB and A blood parent get an O child?

A

the parents must be heterozygous for FUT1 at the fucosyltransferase locus which prevents the parent from producing H substance so she is behaving as a type O

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43
Q

dominant epistasis

A

the dominant allele at one loci masks an allele at second loci, phenotype happens regardless of the second loci allele

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44
Q

recessive epistasis

A

2 recessive alleles will be one color no matter the other alleles

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45
Q

complementation analyses

A

occurs when 2 strains of an organism with different homozygous recessive mutations that produce the same mutant offspring with the wild type phenotype when mated or crossed

46
Q

what are the possibilities of complementation analyses

A

mutations occur in the same gene
one mutation affects the expression of another
one mutation may result in an inhibitory product

47
Q

pleiotropy

A

expression of single gene has mutliple phenotypic events

48
Q

example of pleiotropy

A

marfans

49
Q

what is marfans syndrome

A

autosomal dominant mutation in gene encoding connective tissue protein fibrillin, results on multiple pleitropic events, affects eyes, aorta, bones and other tissues

50
Q

what are pleiotropic expressions of a trait influenced by

A

environment and genotype

51
Q

penetrance

A

Percentage of expression of mutant genotype in population

52
Q

expressivity

A

Range of expression of mutant phenotype

Result of genetic background differences and/or environmental effects.

53
Q

eyeless mutation in drosophilia

A

Homozygous recessive mutant gene.

Phenotype ranges from presence of normal eyes to absence of one or both eyes.

54
Q

what can physical location on a gene do

A

influence gene expression

55
Q

what events modify expression in terms of physical location

A

translocation and inversion

56
Q

conditional mutations

A

temperature effects phenotypes

modifies exprected ratios

57
Q

examples of conditional mutations

A

siamese cats and himalayan rabbits

58
Q

what is special about siamese cats and himalayan rabbits

A

darker fur on extremities which are cooler because they are farther away from the core, enzymes responsible for functions loose catalytic function at different temperatures

59
Q

extranuclear inheritance

A

inheritance patterns which vary from traditional biparental inheritance of nuclear genes, inherit things based on mitochondrial DNA, genes in mitochondrial are not inherited normally becuase they generally only come form mom

60
Q

organelle heredity

A

organisms phenotype affected by genes in mitochondria and chloroplasts

61
Q

maternal affect

A

Organism’s phenotype determined by genetic information expressed in maternal gamete.
Following fertilization, developing zygote’s phenotype is determined not by individual’s genotype but by gene products directed by mother’s genotype

62
Q

heteroplasmy

A

Cell may or may not have mutant genes in organelles—phenotype may not be revealed.
More than one type of organellar genome

63
Q

what are the identified mitochondrial gene products

A

13 proteins required or aerobic cellular respiration.
22 transfer RNA’s —required for translation.
2 ribosomal RNA’s —required for translation.

64
Q

what does MERF stand for

A

Myoclonic epilepsy and ragged-red fiber disease

65
Q

what is merf

A

Specifically the gene encoding tRNALys
Interferes with translation—leads to disorders.
Affected cells exhibit heteroplasmy.
Contain mixture of normal and abnormal mitochondria.

66
Q

what are the types of chromosomal modifications

A

deletion, translocation, inversion, duplication,

67
Q

what type of ploidy is a monosomy

A

aneuploidy

68
Q

monosomy

A

loss of single chromosome from diploid genome

69
Q

what is a euploidy

A

complete haploid set of chromosomes are present

70
Q

what is polyploidy

A

more than 2 sets of chromosomes are present

71
Q

what is an aneuploidy

A

where you are missing one or more chromosomes or you have an extra one

72
Q

autopolyploidy

A

Addition of one or more sets of chromosomes identical to the haploid complement of the same species, each identical set of chromosomes is identical to the parent species

73
Q

how does autoploidy occur

A

a diploid gamete is produced

two sperm fertilize one ovum

74
Q

how to get a diploid gamete

A

failure of chromosomes to segregate during meiotic division

75
Q

allopolyploidy

A

results from hybridizing 2 closely related species, the hybrid plant may be sterile, chromosomes are not homologous, Combination of chromosome sets from different species as a consequence of hybridization

76
Q

nondisjunction

A

chromosomes fail to separate in meiosis or mitosis

77
Q

disjunction

A

separation of homologous chromatids

78
Q

what is occurring when nondisjunction happens in meiosis 1

A

tetrads fail to separate

79
Q

what is occurring when nondisjunction happens in meiosis 2

A

sister chromatids fail to separate

80
Q

what causes nondisjunction

A

mutations in the spindles if they aren’t attached to all the centromeres

81
Q

haploinsufficiency

A

a single copy of a gene is insufficient to provide life-sustaining function for organism

82
Q

extra chromosome in a trisomy

A

produced more viable organism than loss of chromosome

83
Q

deletion

A

remove part of chromosome

84
Q

duplication

A

add genes we didn’t see before

85
Q

inversions

A

invert/flip the chromosomes

86
Q

translocation

A

piece of a chromosome moves to another piece

87
Q

nonreciprocal translocation

A

genes are not swapped just taken from one, lost from another

88
Q

reciprocal translocation

A

share, swap pieces on nonhomologous chromosomes, different pieces of genes

89
Q

terminal deletion

A

the deletion that occurs near the end

90
Q

intercalary deletion

A

deletion from the interior of the chromosome

91
Q

can synapsis occur with intercalary deletions

A

yes

92
Q

what is a chromosomal duplication?

A

a repeated segment of a chromosome that arises through replication error before meiosis, unequal crossing over between synapsed chromosomes

93
Q

what does unequal crossing over cause

A

duplication in one and deletion in the other

94
Q

what are the results of duplications

A

gene redundancy
phenotypic variation
source of genetic variability during evolution

95
Q

when is gene redundancy seen

A

in ribosomal RNAs there are multiple copies of a genes that code of rRNA, need lots of this gene product in the cell to support protein synthesis

96
Q

example of an organism that uses gene redundancy

A

frogs

97
Q

where are the many copies of rDNA found in the chromosome

A

in the nucleolar organizer region

98
Q

ways new genes arise

A

non functionalization
neo functionalization
sub functionalization

99
Q

what is non-functionalization

A

the duplicated copy mutates on itself and is eroded away by the mutations

100
Q

what is neo-functionalization

A

mutation takes up new sequence and forms a new function

101
Q

what is sub-functionalization

A

both copies split up the chore of the original gene, split apart between copies

102
Q

what is an inversion

A

rearrangment of linear gene sequences
no loss of genetic information
segment of a chromosome is turned 180 degrees

103
Q

what must happen for an inversion to occur

A

there must be 2 breaks in the chromosome, chromosomal loop forms creating sticky ends that will join together

104
Q

what are the types of inversion

A

pericentric and paracentric

105
Q

what is paracentric

A

does not include the centromere

106
Q

what is pericentric

A

includes the centromere

107
Q

what are the consequences of inversion during gamete formation

A

linear synapse is not possible if only one member of the homologous pair has an inverted segment, inversion heterozygotes can form

108
Q

what is an inversion heterozygote

A

an organism with one inverted chromosome and one noninverted homolog

109
Q

how do inversion heterozygotes pair

A

requires an inversion loop

110
Q

what happens with crossing over in paracentric inversion

A

can get dicentric and acentric recombinants

111
Q

what is a dicentric chromatid

A

2 centromeres

112
Q

what is a acentric chromatid

A

lacks a centromere

Genetics (4 decks)

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