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Molecular Genetics exam 1 > Molecular genetics exam 3 > Flashcards

Molecular genetics exam 3 Flashcards

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Biology 101 flashcards
1
Q

Mendel chose the garden pea as his model system because

A

obvious phenotypes, easy to control pollination, short generation time, and a lot of progeny

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2
Q

Name 5 characteristics that are important for a good model organism

A

easy to breed, easy to maintain, a lot of progeny, observable characteristics, and true breeding strains

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3
Q

name the 7 characteristics that Mendel observed

A

seed color, seed shape, seed coat color, pod color, pod shape, flower position, and stem length

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4
Q

Gene

A

an inherited factor(region of DNA) that helps determine a characteristic

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5
Q

Allele

A

One of two or more alternative forms of a gene

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6
Q

Locus

A

Specific place on a chromosome occupied by an allele

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7
Q

Genotype

A

Set of alleles possessed by an individual organism

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8
Q

Heterozygote

A

an individual organism possessing 2 different alleles at a locus

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9
Q

Homozygote

A

an individual organism possessing 2 of the same alleles at a locus

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10
Q

Phenotype of a trait

A

appearance or manifestation of a characteristic

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11
Q

characteristic or character

A

an attribute or feature possessed by an organism

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12
Q

Genotype is the listing

A

of alleles an individual carries for a specific gene

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13
Q

WW is

A

Homozygous dominant

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14
Q

Ww is

A

heterozygous

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15
Q

ww is

A

homozygous recessive

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16
Q

The molecular difference between alleles can be detected as a restriction length polymorphism (RFLP) using

A

the enzyme EcoRl and a probe that hybridizes at the site shown

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17
Q

P generation (P1 or P0) is

A

the initial cross

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18
Q

True breeding

A

have the same alleles for the gene

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19
Q

With true breeding strains, every time you self breed them you get

A

100% of the population as with the same phenotype as parent

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20
Q

If you breed 2 pure lines then the F1 is

A

heterozygous and displays the dominant phenotype

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21
Q

a cross of F1 plants forms the

A

f2 generation

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22
Q

2 heterozygotes crossed leads to what ratio of genotypes

A

1:2:1

1 YY, 1 Yy and 1 yy

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23
Q

2 heterozygotes crossed leads to what ratio of phenotypes

A

3:1

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24
Q

Results can be expressed as

A

homozygous or heterozygous

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25
Q

monohybrid crosses involve __ gene(s)

A

1

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26
Q

Monohybrid crosses reveal how

A

one trait is transmitted for generation to generation

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27
Q

Name of mendels 3 postulates

A

unit factors in pairs, dominance/recessiveness, and segregation

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28
Q

Describe the unit factors in pairs postulate

A

genetic characters are controlled by unit factors (genes) existing in pairs in individual organisms

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29
Q

Describe dominance/recessiveness postulate

A

In the pair of unit factors for a single characteristic in an individual, one unit factor is dominant and the other is recessive

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30
Q

Describe segregation postulate

A

the paired unit factors segregate (separate) independently during gamete formation

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31
Q

A way to determine whether an individual displaying the dominant phenotype is homozygous or heterozygous for the trait is to

A

test cross with a ww homozygous recessive because if it it is homozygous dominant, all of the progeny will be dominant because the dominant allele will hide it

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32
Q

what does not true breeding mean??

A

heterozygous for the trait

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33
Q

dihybrid cross involves

A

2 independent traits

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34
Q

what is mendels fourth postulate

A

independent assortment-traits assort independently during gamete formation and all possible combinations of gametes will form with equal frequency

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35
Q

the principle of segregation says that the alleles____ and the principle of independent assortment says that alleles ____

A

separate, separate independently of alleles at different loci

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36
Q

Trihybrid cross

A

involves 3 independent traits

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37
Q

chromatin fibers coil and condense to form __ during mitosis and meiosis

A

chromosomes

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38
Q

Chromosomes exist in __ in diploid organisms

A

homologous pairs

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39
Q

Somatic cells are aka

A

body cells

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40
Q

Humans have 46 chromosomes or 23__

A

pairs

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41
Q

how many autosome pairs are there?

A

22

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42
Q

how many pairs of sex chromosomes are there

A

1

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43
Q

Homologous chromosomes carry genes for

A

the same inherited characteristics but are not identical

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44
Q

what are alleles

A

different versions of the same genes

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45
Q

Genetic locus

A

the location of a particular gene on a chromosome

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46
Q

at each genetic locus, an individual has __ alleles, or one on each chromosome

A

2

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47
Q

are sex determining chromosomes homologous?

A

usually not homologous yet behave as homologous in meiosis

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48
Q

what does the letter before n mean ex. 2n

A

number of sets (2 sets)

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49
Q

n means

A

the number of unique chromosomes

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50
Q

chromatid is an

A

unreplicated chromosome

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51
Q

after replication there are 2 chromatids connected by a

A

centromere

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52
Q

what are the 2 chromatids connected by a centromere that are exactly the same?

A

sister chromatids

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53
Q

what are non sister chromatids?

A

a chromatid from each chromosome from a pair of homologous chromosomes

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54
Q

homologous chromosomes carry the same genes but can carry different __ of those genes

A

alleles

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55
Q

In males, how may of the 4 products of meiosis develop into functional sperm?

A

4

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56
Q

In females, how many of the 4 products of meiosis develop into an egg?

A

1

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57
Q

the egg producing spore in higher plants is the

A

megaspore

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58
Q

the sperm producing spore in higher plants is the

A

microspore

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59
Q

in higher plants, the diploid spore producing generation (___) is conspicuois

A

sporophyte

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60
Q

in higher p-lants, the gamete producing (___) generation is microscopic

A

gametophyte

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61
Q

meiosis creates __ and mitosis creates the __

A

gametes, organism

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62
Q

what is meiosis

A

specialize form of cell division that makes sexual reproduction possible and produces gametes or sex cells

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63
Q

why does meiosis reduce the genetic info passed down to the daughter by half?

A

sperm and egg come together to make 2n a diploid organism

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64
Q

why do males create 4 sperm to a females 1 egg?

A

the egg provides every component of the cell and thus there is an unequal division of the cytoplasmic material and sperm only contributes DNA

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65
Q

in mitosis the daughter cells are _n

A

2

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66
Q

in meiosis the daughter cells are _n

A

1

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67
Q

when does crossing over occur?

A

In prophase 1

68
Q

when do homologous pairs of chromosomes allign on the metaphase plate?

A

metaphase 1

69
Q

when do pairs of chromosomes separate?

A

anaphase 1

70
Q

when do individual chromosomes allign on the metaphase plate?

A

metaphase 2

71
Q

when do chromatids separate?

A

anaphase 2

72
Q

meiosis 1

A

reduces the number of chromosomes by separating homologous pairs

73
Q

meiosis 2

A

separates sister chromatids into 2 different daughter cells

74
Q

which part of meiosis looks exactly like mitosis?

A

meiosis 2

75
Q

what happens in prophase 1?

A

homologous chromosomes pair and crossing over between non sister chromatids

76
Q

why is chromosome pairing important?

A

so that the number of chromosomes can be reduced

77
Q

what is crossing over?

A

an equal exchange of genetic material such that nothing is lost. It is a rearrangement such that alleles will be inherited will alleles of different genes

78
Q

what happens in metaphase?

A

paired homologas chromosomes line up together on the metaphase plate and independent assortment

79
Q

what is independent assortment

A

orientation of pairs to poles is random. this leaves some paternal and some maternal on the left and right

80
Q

what happens in anaphase 1

A

homologous chromosomes separate and move toward poles

81
Q

what happens in telophase 1?

A

each pole now has a haploid set of chromosomes

82
Q

the 2 cells at the end of meiosis 1 now have a compliment of

A

n

83
Q

meiosis 2 starts as __ and ends as __

A

haploid, haploid

84
Q

meiosis 1 starts as __ and ends as __

A

diploid, haploid

85
Q

what is the product law?

A

when 2 independent events occur simultaneously, the probability of the two outcomes occurring incolmbineation is equal to the product of their individual probabilities

86
Q

what does a pedigree analysis do?

A

demonstrates a family tree with respect to a given trait and reveals a pattern of inheritance

87
Q

the sex of the progeny after fertilization is determined by the

A

sex chromosome contained in the sperm

88
Q

the result of meiosis is _ type(s) of egg and __ type(s) of sperm

A

1, 2

89
Q

heteromorphic chromosomes (___) characterize ___

A

(dissimilar) one sex or the other

90
Q

what is another word for heteromorphic chromosomes

A

sex chromosomes

91
Q

what serves as the underlying basis of sex determination?

A

genes, not chromosomes

92
Q

life cycles depend on

A

sexual differentiation

93
Q

in multicellular organisms it is important to distinguish between __ and __

A

primary sexual differentiation and secondary sexual differentiation

94
Q

what is primary sexual differentiation?

A

involves only the gonads where gametes are produced

95
Q

what is secondary sexual differentiation ?

A

involves the overall appearance of the organism

96
Q

what is unisexual?

A

individuals that contain only male or female reproductive organs

97
Q

what are 2 other names for unisexual?

A

dioecious or gonochoric

98
Q

what is bisexual?

A

individuals that contain both male and female reproductive organs and can produce both male and female gametes

99
Q

2 other names for bisexual

A

monoecious and hermaphroditic

100
Q

for c elegans XX is

A

hemaphrodite

101
Q

for c elegans X or X0 is

A

male

102
Q

for c elegans, when males are crossed with a hermaphrodite, the progeny will be

A

50% hermaphrodite and 50% male

103
Q

Female gametes have _ chromosome(s)

A

x

104
Q

Male gametes have _ chromsome(s)

A

either an x or y

105
Q

in chromosomal sex determination, each son gets his X chromosome from his _ and y from his _

A

mother, father

106
Q

two X chromosomes (_) result in _ offspring

A

homogametous, female

107
Q

one x and one Y chromosome (_) result in _ offspring

A

heterogametous. male

108
Q

pseudoautosomal regions present where?

A

on Both ends of the y chromosome

109
Q

pseudoautosomal regions share homology with regions on the _ chromosome

A

x

110
Q

Y chromosomes have at least _ genes

A

75

111
Q

which chromosome has pseudoautosomal regions?

A

y chromosomes

112
Q

SRY is the

A

sex determining region on a y chromosome

113
Q

when do SRY genes become active in XY embryos

A

6-8 weeks of development

114
Q

what is the testis determining factor (TDF)?

A

a protein encoded by a gene in the SRY that triggers testes formation

115
Q

what is nondisjunction?

A

when the chromosomes do not properly segregate during meiosis

116
Q

what happens if nondisjunction occurs?

A

if this happens to the X chromosome, the result is 1 egg with 2xs and one with none. When it joins the sperm it can result in a number of disorders. it can also happen in sperm

117
Q

homozygous traits, if parents are unaffected Both parents must be

A

heterozygous

118
Q

sex determination in drosphilia

A

Y does not determine sex. Sex is determined by the ration of X chromosomes to autosomes

119
Q

what controls sex determination in reptiles?

A

temperature

120
Q

For all crocodiles, most turtles, and some lizards, sex determination is achieved according to the

A

incubation temperature of eggs during a critical period of embryonic development

121
Q

what is the genie sex determining system?

A

No sex chromosomes, only sex determining genes. Found in some plants fungi, protozoans and fish

122
Q

sex linked characteristics

A

gene located on the sex chromosome

123
Q

dosage compensation of x linked genes

A

prevents excessive expression of x linked genes in humans other than mammals and balances the dose of X chromosome gene expression in females and males

124
Q

a calico cat is female and the coloring pattern is due to

A

dosage compensation

125
Q

describe dosage compensation in cats

A

fur color is on the X chromosome so when some cells deactivate the x for black and some cells deactivate the x for orange, both will be expressed.

126
Q

what is dominant and recessive inheritance?

A

when it deals with recessive and dominant inheritance

127
Q

what is incomplete dominance?

A

The resulting offspring have a phenotype that is a blending of the parental traits.

128
Q

in incomplete dominance and codominance how do the phenotypic and genotypic ratio compare? Why?

A

they are the same. because heterozygotes have their own phenotype

129
Q

what is codominance?

A

two alleles at a locus produce different and detectable gene products in heterozygote. A condition in which both alleles for a gene are fully expressed

130
Q

what occurs due to codominance?

A

No dominance or recessiveness, no blended phenotype

131
Q

multiple alleles

A

three or more alleles of a gene that code for a single trait

132
Q

Blood type a or Ia allele is responsible for

A

an enzyme that can add the terminal sugar n-acetylflactosamine to the H substance

133
Q

Blood type B or Ib is responsible for

A

a modified enzyme that can add a terminal galactose

134
Q

Blood type or or the o phenotype results

A

from an absence of either terminal sugar

135
Q

Ia and Ib alleles

A

are dominant over I

136
Q

Ia and Ib alleles are

A

codominant

137
Q

Type 0 blood type has what kind of antigens? antibodies?

A

none, anti a and anti b

138
Q

type a has what kind of antigens?antibodies?

A

a, anti b

139
Q

type b has what kind of antigens? antibodies?

A

b, anti a

140
Q

type ab has what kind of antigens? antibodies?

A

a and b, none

141
Q

what is an example of multiple alleles?

A

colors of rabbits

142
Q

what is pleiotropy?

A

when the expression of a single gene has multiple phenotypic effects

143
Q

give an example of pleiotropy

A

marfan syndrome-the autosomal dominant mutation in the gene encoding the connective tissue protein fibrillar

144
Q

what all does Marfan syndrome cause?

A

Many tissues including eye lens dislocation, increased risk or aortic aneurysm and lengthened bones in limbs

145
Q

Gene interaction

A

the cellular function of numerous gene oviducts contributes to the development of a common phenotype

146
Q

what is epigenesis?

A

development concept whereby each step of development increases the complexity of the sensory organ and is under the control and influence of one or more genes

147
Q

sex limited

A

Autosomal genes whose expression is limited to one sex

148
Q

example of sex limited traits

A

feather plumage in chickens

149
Q

Sex influenced

A

Genes on an autosome that are more readily expressed in one sexF

150
Q

example of sex influenced traits

A

pattern baldnesss in humans. Allele B for baldness acts as dominant in males and recessive in females and appears to be related to the levels of the male sex hormones

151
Q

what are temperature sensitive mutations?

A

expression is affected by the temperature

152
Q

what is organelle heredity?

A

DNA contained in the mitochondria or chloroplasts determine certain phenotypic characteristics of offspring

153
Q

what is the maternal effect?

A

nuclear gene products are stored in the egg and transmitted through the ooplasm to the offspring effecting the genotype

154
Q

two forms of extranuclear inheritance

A

organelle heredity and maternal effect

155
Q

what makes the analysis fo inheritance patterns resulting from mutant alleles in chloroplast and mitochondria difficult?

A

function fo these organelles is dependent on the gene products from the nucleus and the organelle DNA making the origin of mutations affecting the organelle function difficult

156
Q

what are the 4 characteristics of cytoplasmic inherited traits?

A

1-present in male and females,
2-usually inherited from 1 parent, typically the maternal parent.
3-reciprocal crosses give different results
4-exhibit extensive phenotypic variations, even within a single family

157
Q

describe how genes are related to chloroplast

A

genes carried on the DNA encode products involved in photosynthesis and translation and mutation in these genes may inactivate photosynthesis

158
Q

products of the maternal genes are

A

synthesized in the developing egg
stored in the oocyte prior to fertilization
following fertilization, they specify molecular gradients that determine spatial organization within the zygote

159
Q

genetic maternal effects

A

nuclear genotype of the maternal parent

160
Q

cytoplasmic inheritance

A

cytoplasmic genes, which are usually inherited entirely from one parent

161
Q

genomic imprinting

A

genes whose expression is affected by the sex of the transmitting parent

162
Q

Dominant

A

an allele that is always expressed

163
Q

recessive

A

an allele that is masked when the dominant allele is present

164
Q

epistasis

A

A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited.

165
Q

complementary gene interaction

A

Must have at least one dominant allele at each locus (A-B-) to have the phenotype

Molecular Genetics exam 1 (6 decks)

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