Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics BSC-315 > Exam 1 > Flashcards

Exam 1 Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Genes are the basic units of

A

heredity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is heredity?

A

how genes transmit traits from parents to offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the study of biological information?

A

how organisms store, replicate, transmit, and utilize information that allows survival and reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

DNA –>

A

RNA –> Protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

__ was the first applied genetic technique

A

artificial selection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is artificial selection?

A

the purposeful control of mating by choice of parents for the next generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the crucial questions about selective breeding?

A
  • What is inherited?
  • How is it inherited?
  • What is the role of chance in heredity?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Who discovered the basic principles of genetics?

A

Gregor Mendel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the four general themes of Mendelian Genetics?

A
  1. variation is widespread in nature and provides for continuously evolving diversity
  2. observable variation is essential for following genes from one generation to another
  3. variation is inherited by genetic laws, which can explain why like begets like and unlike
  4. Mendel’s laws apply to all sexually reproducing organisms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What were the keys to the success of Mendel’s experiments?

A
  • pure-breeding lines of peas
  • inheritance of alternative (or antagonistic) forms of traits
  • experimental technique (controlled breeding)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Mendel performed __ crosses to control whether trait was passed on by sperm or egg

A

reciprocal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a phenotype?

A

an observable form of a given trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a monohybrid cross?

A

mating of pure-breeding parental plants antagonistic for a single trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In a monohybrid cross, both parental traits reappear in F2 progeny in a __ ratio

A

3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Mendel proposed that each plant carries

A

two copies of a unit of inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Trait that appears in F1 progeny is the

A

dominant form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Trait that is hidden in the F1 progeny is the

A

recessive form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are units of inheritance?

A

genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are alternative forms of a single gene?

A

alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Individuals with two different alleles for a single trait are

A

heterozygotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Pure breeding individuals are

A

homozygotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does Mendel’s law of segregation state?

A
  • the two alleles for each trait separate during gamete formation
  • two gametes, one from each parent, unite at random at fertilization
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a gamete?

A

specialized cells that carry genes between generations (egg/sperm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is segregation?

A

separation of alleles so that each gamete receives only one copy of each gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In a F2 progeny

A
  • 1/4 will breed true for the dominant trait
  • 1/2 will be hybrids
  • 1/4 will breed true for the recessive trait
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is probability?

A

a measure of how likely some event is to occur

-expresses a belief in future events, or outcomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are independent events?

A

the probability of event 1 does not affect the probability of event 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the product rule?

A

probability of two independent events occurring together is the product of their individual probabilities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the sum rule?

A

probability of either of two mutually exclusive events occurring is the sum of their individual probabilities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is an example of an ordered event?

A

What is the probability of flipping a heads, then a heads, then a tails?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is an example of an unordered event?

A

What is the probability that in 3 tosses you will get two heads and a tail?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is genotype?

A

a pair of alleles in an individual (e.g. YY or Yy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Genotypes in F2 progeny are in a ___ ratio

A

1:2:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Phenotypes in F2 progeny are in __ ratio

A

3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What can a test cross reveal?

A

an unknown genotype in an individual with a dominant phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Mendel’s dihybrid crosses revealed the law of

A

independent assortment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

The different types of germinal cells of a hybrid are produced on average in

A

equal numbers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The possible number of gamete genotypes from a hybrid =

A

2^n

n: number of heterozygous traits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What did Mendel’s work do?

A
  • Explained reappearance of hidden traits
  • disproved blended inheritance
  • showed that parents contributed equally to next generation
  • developed a testable model for making predictions about inheritance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

A specific gene determines a __ , whose activity may affect phenotype

A

specific enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

A dominant allele usually determines

A

a normally functioning protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

A recessive allele usually does not

A

encode a functional protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Why is it challenging to determine inheritance patterns in humans?

A
  • long generation time (lives a long time)
  • small numbers of progeny (so Mendel’s ratios rarely observed)
  • no controlled matings
  • no pure-breeding lines
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What are the categories of inheritance?

A
  • autosomal recessive
  • autosomal dominant
  • x-linked recessive
  • x-linked dominant
  • y’linked
  • organelle (mitochondria or chloroplast)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are pedigrees?

A

diagrams of a family’s genetic features that extends over multiple generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How are male and female represented in a pedigree?

A

female: circle
male: square

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

How is an affected individual represented in a pedigree?

A

box is colored in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What is characteristic of a horizontal pattern of inheritance?

A

parents of affected individuals are unaffected but are heterozygous (carriers) for the recessive allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is characteristic of a vertical pattern of inheritance?

A

every affected person has at least one affected parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What are the three key aspects of pedigrees with dominant traits?

A
  1. affected children always have at least one affected parent
  2. As a result, dominant traits show a vertical pattern of inheritance
  3. two affected parents can produce unaffected children, if both parents are heterozygotes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What are the four key aspects of pedigrees with recessive traits?

A
  1. affected individuals can be the children of two unaffected carriers, particularly as a result of consanguineous matings
  2. all the children of two affected parents should be affected
  3. rare recessive traits show a horizontal pattern of inheritance
  4. extremely common recessive traits might show a vertical pattern of inheritance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What are some of the most common single-gene traits caused by recessive alleles in humans?

A
  • Thallassemia
  • Sickle-cell anemia
  • Cystic fibrosis
  • Tay-Sachs disease
  • Phenylketonuria (PKU)
  • Hypercholesterolemia
  • Huntington disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Most traits in humans are due to the interaction of __ and do not show a simple Mendelian pattern of inheritance

A

multiple genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Most single-gene Mendelian traits will be

A

recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What is pleiotropy?

A

one gene may contribute to several characteristics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

The phenotype of the __ defines the dominance relationship of two alleles

A

heterozygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What is complete dominance?

A

when the hybrid resembles one of the two parents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What is incomplete dominance?

A

when the hybrid resembles neither parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Incomplete dominance is a blending of __ only, not the __

A

phenotype; genotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Pink flowers in snapdragons are the result of

A

incomplete dominance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

In codominance, the F1 hybrids display traits of

A

both parents

-neither phenotype dominant or recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

When two alleles at a gene both produce functional protein products, they will often be

A

codominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Dominance relations between alleles do not affect

A

transmission of alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Type of dominance (complete, incomplete, codominance) depends on the type of proteins encoded and their biochemical functions but have no effect on

A

allele segregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Dominance and recessiveness are not inherent properties of different mutant alleles, but are

A

effects observed relative to other alleles at the same locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What is allele frequency?

A

percentage of the total number of gene copies for one allele in a population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What is a wild type (+)?

A

most common allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What is a mutant allele?

A

rare allele (new alleles that are generated by mutation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What is a monomorphic gene?

A

has only one common allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What is a polymorphic gene?

A

has more than one common allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

With some pleiotropic genes, an allele can be dominant for a trait when heterozygous, but when homozygous it can be

A

inviable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Novel phenotypes can arise from incomplete dominance and codominance in the F1 generation and will be

A

the most common phenotype in F2’s (1:2:1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

If you see crosses of various phenotypes at one trait and each cross gives you a 3:1 ratio, you have

A

1 gene with many alleles (allele series)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Lethal mutations are usually __ and can’t be homozygous

A

recessive alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Single traits arising from interaction of multiple genes are

A

multifactorial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Phenotype can be modified by interaction of genes with

A

environmental conditions (temp, diet, etc)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What is multifactorial inheritance?

A

most common traits arise from the action of 1 or more genes or interaction of genes with the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Two genes can determine

A

one trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Novel phenotypes can result from

A

gene interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What is epistasis?

A

an allele at one locus masks the effects of an allele at another locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

In epistasis, the gene that does the masking is __ to the other gene

A

epistatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

In epistasis, the gene that is masked is __ to the other gene

A

hypostatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

Epistasis can be

A

recessive or dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

For epistasis to be recessive, the epistatic gene must be

A

homozygous recessive

e.g. ee

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

For epistasis to be dominant, the epistatic gene must

A

have at lease one dominant allele present

e.g. E-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What is an example of recessive epistasis?

A

dog coat color

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What is an example of dominant epistasis?

A

squash fruit color and chicken feather color

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

Dominant epistasis 1 produces a __ ratio in F2 progeny

A

12:3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

Dominant epistasis 2 produces a __ ratio in F2 progeny

A

13:3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What is recessive epistasis?

A

homozygous recessive of one gene masks both alleles of another gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What is dominant epistasis 1?

A

dominant allele of one gene hides effects of BOTH alleles of another gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

What is dominant epistasis 2?

A

dominant allele of one gene hides effects of DOMINANT ALLELE of another gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

What is complementary gene interaction?

A

one dominant allele of each of TWO genes is necessary to produce phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

What is the F2 phenotypic ratio of complementary gene interactions?

A

9:7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

What is the F2 phenotypic ratio of recessive epistasis?

A

9:3:4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

What is the F2 phenotypic ratio when there is no gene interaction?

A

9:3:3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

Heterogeneous traits have the same recessive phenotype but are caused by

A

mutations in different genes

98
Q

What is a genetic cross called?

A

a complementation test

99
Q

Complementation testing is used to determine if

A

a particular RECESSIVE phenotype arises from mutations in the same or separate genes

100
Q

T or F? Complementation testing can be used with dominant phenotypes

A

F

101
Q

__ __ help us determine the inheritance of the trait

A

breeding studies

102
Q

Phenotypic variation for some traits can occur because of

A
  • differences in penetrance and/or expressivity
  • effects of modifier genes
  • effects of environment
  • pure chance
103
Q

What is penetrance?

A

the percentage of a population with a particular genotype that shows the expected phenotype
-can be complete (100%) or incomplete (<100%)

104
Q

What is expressivity?

A

degree or intensity with which a particular genotype is expressed in a phenotype
-can be variable or unvarying

105
Q

What do modifier genes do?

A

alter the phenotypes produced by alleles of other genes

-have a subtle secondary effect on phenotype controlled by major genes

106
Q

__ can often have phenotypic effects

A

temp

107
Q

__ __ mutations are lethal only under some conditions

A

conditional lethal

108
Q

In permissive conditions, mutant allele has __ function

A

wild-type

109
Q

In restrictive conditions, mutant allele has __ functions

A

defective

110
Q

What is a phenocopy?

A

a phenotype arising from an environmental agent that mimics the effect of a mutant gene

111
Q

What is characteristic of phenocopy?

A
  • genetically “normal” individuals show abnormal phenotype due to environmental influence
  • not heritable
  • can be deleterious or beneficial
112
Q

What are discontinuous traits?

A

“either-or” phenotypic differences between alternative alleles

113
Q

What are continuous traits determined by?

A

segregating alleles of many genes that interact together and with with the environment

114
Q

What is characteristic of continuous traits?

A
  • appear to “blend” and “unblend”
  • also called quantitative traits because the traits vary over a range that can be measured
  • usually polygenic- controlled by multiple genes
115
Q

The more genes or alleles, the more

A

phenotypic classes and the greater the similarity to continuous variation

116
Q

Metaphase chromosomes can be classified by

A

centromere position

117
Q

Why are chromosomes studied in metaphase?

A

chromosomes are most visible at this point just before nucleus divides

118
Q

Following duplication, chromosomes have 2 identical halves (__ __) attached at centromere

A

sister chromatids

119
Q

What is characteristic of a metacentric chromosome?

A

centromere is in the middle

120
Q

What is characteristic of an afrocentric chromosome?

A

centromer is near one end

121
Q

Homologs contain the same set of genes, but have different __ for each gene

A

alleles

122
Q

Non homologs carry

A

completely unrelated sets of genes

123
Q

What is characteristic of human chromosomes at metaphase?

A

2n = 46, n = 23

124
Q

In a karyotype, each homologous pair is arranged in order of

A

decreasing size

125
Q

What is mitosis?

A

the mechanism that parcels out chromosomes into daughter cells, and maintains genetic integrity during cell division

126
Q

Mitosis __ chromosome number in cells between divisions

A

preserves

127
Q

The cell cycle is a repeating pattern of

A

cell growth and division

128
Q

Nuclear division during mitosis apportions chromosomes

A

equally to two genetically identical daughter cells

129
Q

What are the three parts of interphase?

A

gap 1 (G1) phase, synthesis (S) phase, and gap 2 (G2) phase

130
Q

What is interphase?

A

a period of cell growth and chromosome duplication between divisions

131
Q

What is formed during interphase?

A

microtubules in cytoplasm

132
Q

Are chromosomes duplicating or dividing in the G1 phase of interphase?

A

no

133
Q

What happens during the S phase of interphase?

A

duplication of chromosome into sister chromatids

  • remain joined at centromere
  • considered 1 chromosome as long as they remain joined at centromere
134
Q

What happens during the G2 phase of interphase?

A

synthesis of proteins required for mitosis

135
Q

What happens during prophase of mitosis?

A
  • chromosomes (consisting of 2 sister chromatids) condense and become visible
  • centrosomes move apart toward opposite poles
  • nucleoli begin to dissolve
  • nuclear envelope remains intact
136
Q

What happens during pro metaphase of mitosis?

A
  • nuclear envelope breaks down
  • microtubules invade the nucleus and connect to kinetochores in centromere of each chromatid
  • sister chromatids attach randomly to microtubules from opposite poles
137
Q

What are kinetochores?

A

specialized structure at centromere of each chromatid that function in conveyance of chromatids along microtubules

138
Q

What occurs during metaphase of mitosis?

A
  • chromosomes align on the metaphase plate with sister chromatids facing opposite poles
  • forces pushing and pulling chromosomes to or from each pole are in balanced equilibrium
139
Q

What occurs during anaphase of mitosis?

A
  • centromeres of all chromosomes divide simultaneously (chromosomes doubled during this stage)
  • kinetochore microtubules shorten and pull separated sister chromatids to opposite poles (characteristic V shape) (identical gene info heads to each pole)
140
Q

What happens during telophase of mitosis?

A
  • nuclear envelope forms around each group of chromatids
  • nucleoli re-form
  • spindle fibers disperse
  • chromosomes decondense
141
Q

What is the final stage of cell division?

A

cytokinesis

142
Q

Cytokinesis begins during __ but is not completed until after __

A

anaphase; telophase

143
Q

What happens during cytokinesis?

A

parent cells split into two daughter cells with identical nuclei

144
Q

What is fertilization?

A

the union of haploid gametes to produce diploid zygotes

145
Q

Fertilized eggs carry matching sets of chromosomes, one set from __ and one set from __

A

maternal gamete; paternal gamete

146
Q

Gametes are haploid (n), which means

A

they carry only a single set of chromosomes

147
Q

Zygotes are diploid (2n), which means

A

they carry two matching sets of chromosomes: 1 from each parent

148
Q

What does mitosis ensure?

A

that all cells of developing individuals have identical 2n chromosome sets

149
Q

What does meiosis ensure?

A

that each zygote only receives one copy of each homologous chromosome from each parent

150
Q

__ make up vast majority of cells in the organism

A

somatic cells

151
Q

__ are precursors to gametes

A

germ cells

152
Q

__ are set aside from somatic cells during embryogenesis

A

germ cells

153
Q

__ becomes incorporated into reproductive organs

A

germ cells

154
Q

In germ cells, only cells that undergo meiosis produce

A

haploid gametes

155
Q

How many rounds of meiosis are there?

A

2

156
Q

In meiosis, when do chromosomes duplicate?

A

once at start of meiosis 1

157
Q

In meiosis, nuclei divide

A

twice

158
Q

In meiosis, nuclei divide twice, in both __ and __

A

meiosis 1 and meiosis 2

159
Q

Why do gametes contain 1/2 the amount of chromosomes found in somatic cells?

A

because in meiosis the nuclei divide twice

160
Q

The end product of meiosis is

A

4 haploid cells

161
Q

Give an overview of meiosis 1

A
  1. homologs pair, exchange parts, and then segregate
  2. sister chromatids remain intact at centromere throughout meiosis 1
  3. recombination occurs between maternal and paternal homologs (non-sister chromatids)
  4. after recombination, homologous chromosomes (not chromatids) segregate to different daughter cells (chromatids still attached at centromere)
162
Q

What are the first three substages of prophase 1?

A

leptotene, zygotene, and pachytene

163
Q

What occurs during leptotene?

A
  1. chromosomes thicken and become visible, but the chromatids remain invisible
  2. centrosomes begin to move toward opposite poles
164
Q

What occurs during zygotene?

A
  1. homologous chromosomes enter synapsis

2. the synaptonemal complex forms

165
Q

What occurs during pachytene?

A
  1. synapsis is complete

2. crossing-over, genetic exchange between non sister chromatids of a homologous pair, occurs

166
Q

What are the last two substages of prophase 1?

A

diplotene and diakinesis

167
Q

What occurs during diplotene?

A
  1. synaptonemal complex dissolves
  2. a tetrad of four chromatids is visible
  3. crossover points appear as chiasmata, holding non sister chromatids together
  4. meiotic arrest occurs at this time in many species
168
Q

What occurs during diakinesis?

A
  1. chromatids thicken and shorten

2. at the end of prophase 1, the nuclear membrane (not shown earlier) breaks down, and the spindle begins to form

169
Q

In metaphase 1 and anaphase 1 (of meiosis 1), homologs move to

A

opposite poles

170
Q

What occurs during metaphase 1 of meiosis 1?

A
  1. tetrads line up along the metaphase plate
  2. each chromosome of a homologous pair attaches to fibers from opposite poles
  3. sister chromatids attach to fibers from the same pole
171
Q

What occurs during anaphase 1 (of meiosis 1)?

A
  1. the centromere does not divide
  2. the chiasmata migrate off chromatid ends
  3. homologous chromosomes move to opposite poles
172
Q

Meiosis 1 is a

A

reductional division

173
Q

What occurs during telophase 1 (of meiosis 1)?

A
  1. the nuclear envelope re-forms

2. resultant cells have half the number of chromosomes, each consisting of two sister chromatids

174
Q

What occurs during interkinesis (of meiosis 1)?

A
  1. this is similar to interphase with one important exception: NO CHROMOSOMAL DUPLICATION TAKES PLACE
  2. in some species, the chromosomes decondense; in others, they do not
  3. each daughter cell has 1/2 chromosomes of parent; no replication
175
Q

During meiosis 2, sister chromatids

A

separate and move to opposite poles

176
Q

How is metaphase 2 (of meiosis 2) distinct from mitosis metaphase?

A
  • number of chromosomes is 1/2

- chromatids not identical because of recombination

177
Q

What occurs in anaphase 2 (of meiosis 2)?

A

the sister chromatids separate

178
Q

What occurs in prophase 2 (of meiosis 2)?

A
  1. chromosomes condense
  2. centrioles move toward the poles
  3. the nuclear envelope breaks down at the end of prophase 2
179
Q

What occurs in metaphase 2 (of meiosis 2)?

A
  1. chromosomes align at the metaphase plate

2. sister chromatids attach to spindle fibers from opposite poles

180
Q

Meiosis 2 is an

A

equational division

181
Q

What occurs in telophase 2 (of meiosis 2)?

A
  1. chromosomes begin to uncoil

2. nuclear envelopes and nucleoli re-form

182
Q

What occurs in cytokinesis (of meiosis 2)?

A
  1. the cytoplasm divides, forming four new haploid cells
183
Q

Behavior of chromosomes __ the behavior of genes

A

parallels

184
Q

Separation of homologs during meiosis 1 ensures that gametes obtain either __ or __ for each gene on each chromosome in a __ ratio

A

1 maternal allele, 1 paternal allele; 1:1

185
Q

How does meiosis contribute to genetic diversity?

A
  1. independent assortment of non homologs at metaphase 1 creates different combinations of alleles
  2. crossing over between homologs creates different combos of alleles within each chromosome and ensures each gamete is unique
186
Q

Mitosis is a __, while meiosis involves __

A

conservative mechanism that preserves genetic identity; combinations associated with independent assortment and recombination alter variation

187
Q

The chromosome theory is confirmed and validated by the fact that:

A
  1. inheritance of genes and chromosomes correspond
  2. transmission of particular chromosome coincides with transmission of traits other than for sex determination
    - the inheritance of particular traits linked to inheritance of particular chromosome
188
Q

T.H. Morgan made major advancements to confirm chromosome theory with his work with

A

drosiphila

189
Q

Gene symbol is identifies by

A

abnormal phenotype

190
Q

Wild-type allele denoted with

A

superscript (+)

191
Q

Recessive mutant allele denoted with __; dominant mutant allele denoted with __

A

lower case; upper case

192
Q

Give a summary of chromosome theory

A
  1. assigns locations of Mendel’s genes within cells
  2. meiosis ensures that matching parts of homologous chromosomes segregate to different gametes (accounts for law of segregation)
  3. each homolog pair aligns independently at metaphase 1 (accounts for law of independent assortment)
  4. mutations on chromosomes (new alleles) can get transmitted if they occur in germ cells
  5. through mitotic division, each cell receives the same set of chromosomes
193
Q

A black mouse is crossed to a brown mouse. All of the F1 progeny (there are many of them) are black. One of
the F1 mice is crossed to a brown mouse. What proportion of the F2 mice will be brown?
A. none of them
B. all
C. 1/4
D. 1/2
E. 3/4

A

D

194
Q

In cats, unlinked autosomal genes control the presence of striped/solid coat and hair length. Striped coat is
dominant to solid coat, and short hair is dominant to long hair. A striped, short hair female cat that is
heterozygous for both traits mates with a solid, long hair male. What fraction of the progeny will have striped
coat and short hair?
A. none of them
B. 1/8
C. 1/4
D. 1/2
E. 9/16

A

C

195
Q

In tomatoes red fruit (R) is dominant to yellow fruit (r), and cut leaf (C) is dominant to potato leaf (c). The
genes that control these traits are on different chromosomes. The progeny of one mating were:
305 red, cut leaf; 312 red, potato leaf;
101 yellow, cut leaf; 97 yellow, potato leaf.
What were the genotypes of the parents that produced these progeny?
A. Rr Cc x Rr cc
B. RR Cc x rr Cc
C. Rr cc x Rr cc
D. Rr CC x RR cc
E. RR CC x rr Cc

A

A

196
Q 
In the following cross, what fraction of the progeny will have the same phenotype as the first parent?
AA Bb cc x aa Bb cc
A. All of them
B. 3/4
C. 1/2
D. 3/8
E. 1/4
A

B

197
Q

Allele D is completely dominant to d, and allele E is completely dominant to e. In the cross Dd Ee x Dd Ee,
what fraction of the progeny show both dominant traits?
A. none of them
B. 1/8
C. 1/4
D. 1/2
E. 9/16

A

E

198
Q

Two genes are responsible for purple flower color in sweet peas; recessive alleles at either or both genes
result in white flowers. A cross between two true-breeding white-flowered plants produces only purple F1s.
These F1s are self-crossed. What fraction of the F2s will have white flowers?
A. 1/4
B. 1/2
C. 7/16
D. 9/16
E. none of them

A

C

199
Q

Two genes control comb shape in chickens, producing four different phenotypes. A cross between two
dihybrids (each with a walnut comb) produces the following results: 9/16 walnut, 3/16 pea, 3/16 rose, 1/16
single. In a cross between a true-breeding rose and a true-breeding pea chicken, what will be the phenotypes
of the progeny?
A. 9:3:3:1 walnut:pea:rose:single
B. 1:1:1:1 walnut:pea:rose:single
C. all walnut
D. 1/2 pea, 1/2 rose

A

C

200
Q

Feather color in chickens in controlled by a gene C: C- individuals have colored feathers while cc individuals are
white. The dominant allele of a second gene A (unlinked to C) inhibits color production and is epistatic to C (Aindividuals
are always white, but aa individuals have colored or white feathers depending on the C genotype).
A cross between a colored chicken and a white chicken produces 3/4 white and 1/4 colored progeny. What
were the genotypes of the underlined chickens?
A. cc Aa x cc Aa
B. Cc aa x Cc aa
C. Cc aa x cc Aa
D. Cc aa x cc aa

A

C

201
Q

Tay-Sachs is a rare autosomal recessive disease that causes deterioration of the central nervous system early
in life. John and Mary visit you, a genetic counselor, and ask you to determine the probability that they will
have a child affected by the disease. John’s brother died of the disease. Mary’s sister has a child with the
disease. The disease-causing allele is rare, so assume individuals with unknown genotypes are homozygous for
the wildtype allele unless there is reason to believe otherwise. The probability that the couple’s first child will
have Tay-Sachs is:
A. 1/36
B. 1/12
C. 1/9
D. 1/8
E. 1/4

A

B

202
Q

A phenotypically normal couple has a son who has hemophilia, an X-linked recessive trait. What is the
probability that the couple’s daughter is a carrier of the trait?
A. absolutely certain
B. 2/3
C. 1/2
D. 1/4
E. not possible

A

C

203
Q 
Rabbit coat color is determined by a gene C with three alleles, C (agouti, the wildtype tan color), cCH (chinchilla,
a mottled grey) and cH
(Himalayan, mostly white with black paws and ears). These alleles form the following 
 4 
dominance series: C > c^CH > c^H
. In the following cross:
C c^CH x c^CH
c^H
what fraction of the offspring will have a chinchilla phenotype?
A. all of them
B. 3/4
C. 1/2
D. 1/4
E. none of them
A

C

204
Q

In snapdragons tall is dominant to short. Flower color shows incomplete dominance: homozygotes are either
red or white, but heterozygotes are pink. A red tall plant from a pure-breeding strain is mated to a pink short
plant. What fraction of the progeny will be pink tall?
A. 1/4
B. 3/8
C. 1/2
D. 3/4
E. 9/16

A

C

205
Q

The tortoiseshell / calico coat pattern in cats results from an X-linked gene with orange and black alleles, and
the effect of X-inactivation in female cats. A tortoiseshell female and a black male mate – what fraction of
their progeny will have a tortoiseshell coat?
A. All of them
B. 3/4
C. 1/2
D. 1/4
E. None of them

A

D

206
Q

Crimson argoweed plants isolated from the wild have two phenotypes, tall and short. A cross between two
short plants produces only short progeny. A cross between two tall plants produces 2/3 tall and 1/3 short. Not
believing the latter result you carry out the same cross several more times, between two tall plants taken from
the wild whose parentage and genotypes are not known. The same result is obtained every time: 2/3 tall and
1/3 short. Which is the likely explanation?
A. Short plants are homozygous for one allele and tall plants are homozygous for the other allele.
B. Tall plants are heterozygous and short plants are homozygous. One of the homozygous genotypes is
lethal.
C. The gene for plant height resides on a sex chromosome. More careful investigation will likely reveal
that tall and short phenotypes correlate with gender.
D. This result is indicative of three alleles forming a dominance series.

A

B

207
Q

Huntington disease is a rare neurodegenerative disease that is inherited as an autosomal dominant trait. Joe
has just learned that his father has HD. A genetic test on Joe’s mother reveals that she is not at risk for HD.
What is the probability that Joe will develop the disease?
A. zero
B. 1/8
C. 1/4
D. 1/2
E. 100% (absolutely certain)

A

D

208
Q

Which of the following is always true of a test cross?
A. One of the individuals is homozygous for the recessive allele for the gene(s) of interest.
B. One of the individuals is homozygous for the dominant allele for the genes(s) of interest.
C. Male and female gametes are obtained from the same individual, or from two individuals that are
genotypically identical to each other.
D. All of the above.

A

A

209
Q

In a classic series of experiments, geneticists analyzed the ability of several mutants of the fungus Neurospora
to grow on defined media that lacked the amino acid arginine or some of the precursors to arginine. The
conclusion from this series of experiments was that:
A. genes encode enzymes.
B. messenger RNAs are intermediates between gene and protein.
C. DNA is the genetic material.
D. introns must be removed from RNAs before protein synthesis can occur.
E. mutations are changes in DNA sequence

A

A

210
Q

Two mutations that do not complement each other:
A. produce F1 hybrid progeny with the mutant phenotype.
B. produce F1 hybrid progeny with the wildtype phenotype.
C. produce F1 hybrid progeny with a novel phenotype not observed in either single mutation alone.
D. are alleles of different genes.

A

A

211
Q

A leucine auxotrophic mutant would …
A. grow on both minimal medium and on minimal medium supplemented with leucine.
B. grow on minimal medium, but die on minimal medium in which leucine is the only energy source
C. die on minimal medium, but grow on minimal medium supplemented with leucine
D. die on both minimal medium and minimal medium supplemented with leucine

A

C

212
Q

A particular cross produces a 1:2:1 genotypic ratio and a 1:2:1 phenotypic ratio. This indicates:
A. a cross between two heterozygotes for a trait with a normal dominant:recessive relationship
B. a cross involving more than two alleles with a dominance series
C. a cross between two heterozygotes for a trait with incomplete dominance
D. a cross in which one of the genotypes is lethal

A

C

213
Q 
A cross between two heterozygotes produces progeny genotypes in the ratio of:
A. 1:0
B. 1:1
C. 1:2:1
D. 3:1
E. 1:1:1:1
A

C

214
Q 
The human diploid chromosome number is:
A. 12
B. 23
 6 
C. 34
D. 46
E. 78
A

D

215
Q 
How many genetically-distinct gametes are produced by an individual of genotype Aa Bb CC DD Ee?
A. 2
B. 4
C. 8
D. 16
E. 32
A

C

216
Q 
How many genetically distinct gametes (sperm) are produced by a male fruit fly that is heterozygous for one
autosomal gene?
A. 2
B. 3
C. 4
D. 6
E. 8
A

C

217
Q 
In a plant in which the diploid chromosome number is 18, how many chromatids are present during prophase I
of meiosis?
A. 18
B. 24
C. 36
D. 54
E. 72
A

C

218
Q

Which of the following is true of homologous chromosomes?
A. They carry alleles for the same genes in the same relative positions.
B. They exchange segments at meiosis by crossing over.
C. They physically pair at meiosis.
D. All of the above.
E. None of the above.

A

D

219
Q 
The phenomenon of crossing over occurs…
A. during prophase of mitosis
B. during prophase I of meiosis
C. during anaphase II of meiosis
D. during metaphase I of meiosis
E. two or more of the above
A

B

220
Q 
Drosophila has a diploid chromosome number of 8. At the end of meiosis I, each daughter cell contains \_\_
chromosomes and \_\_ chromatids.
A. 8, 16
B. 4, 16
C. 4, 8
D. 8, 8
A

C

221
Q

A 2:1 phenotypic ratio is characteristic of

A

recessive lethality

222
Q

Which of the following best describes meiosis?

A

cell divisions where the chromosomes replicate once and the nucleus divides twice

223
Q

T or F? An individual that is pure breeding for two traits must either be homozygous for the dominant allele at both traits or homozygous for the recessive allele at both traits

A

F

224
Q

If a plant of genotype Aa Bb CC is test crossed, what proportion of the progeny would be aa Bb Cc?

A

1/4

225
Q

In a trihybrid cross AA BB CC x aa bb cc parents, what proportion of homozygotes across all genes is expected among the F2 offspring?

A

1/8

226
Q

How many different progeny genotypes can result from a cross of Aa Bb Cc dd Ee with Aa Bb cc DD Ee?

A

54

227
Q

Assuming complete dominance and no gene interactions, in the cross Aa Bb Cc dd Ee x Aa Bb cc DD Ee, how many distinct phenotypes are possible for the offspring?

A

16

228
Q

During which of the stages of meiosis would homologous chromosomes be paired?

A

both prophase of meiosis 1 and metaphase of meiosis 1

229
Q

A diploid organism with 10 chromosomes in each somatic cell undergoes mitosis. How many cells will result from this meiotic event, and how many chromosomes will be present in each?

A

4 cells with 5 chromosomes each

230
Q

In labs, the E gene is __ to the B gene

A

recessively epistatic

231
Q

A pure breeding brown Lab and a pure-breeding yellow Lab were crossed and produced both black and brown puppies. What is the genotype of the yellow parent?

A

Bbee

232
Q

In the question above involving the brown and yellow dogs, what proportion of the puppies are expected to be black?

A

1/2

233
Q

A couple is concerned that their child will have a very rare dominant autosomal disease that has a penetrance of 25%. The woman and her father were both affected by the disease, but there is no history of the disease allele on her mother’s side of the family. The husband has no history of the disease allele in his family. What is the probability that the child will be affected by the disease?

A

1/8

234
Q

Several genes code for different types of antigens on the surface of red blood cells. These include the ABO that gives rise to the A, B, AB, and O blood types, as well as MN and Rh. The Rh locus can contain either a positive or negative allele, with positive being dominant to negative. M and N are codominant alleles of the MN gene. Which individual could not father a child with the blood type A M Rh(neg) if the mother has the O M Rh(pos) phenotype?

A

O M Rh(pos)

235
Q

Coat color in a certain species of rabbit is governed by multiple alleles. The dominance series for these alleles is as follows: colored (c+), himalayan (ch), and albino (c). Give the phenotypes and ratios of the cross c + c x ch c

A

2 colored: 1 himalayan: 1 albino

236
Q

Which stage of cell division best explains Mendel’s law of segregation?

A

movement of homologous chromosomes to opposite poles at anaphase of meiosis 1

237
Q

Chromosomes in the same cell that carry the same sets of genes are known as

A

homologous

238
Q

A female fruit fly with deformed bristles was mated with a male from a true-breeding wild-type stock with long bristles. All of the F1 females had wild-type bristles and all of the F1 males had deformed bristles. If the F1 flies are intercrossed, the expected ratio of long to deformed bristles in the F2 flies is

A

1:1 in both sexes

239
Q

Pea plants possess a number of characteristics that aided Mendel in the discovery of the laws of segregation and independent assortment. Which is not correct?

a. peas possess numerous traits with discrete antagonistic forms that could be easily studied in Mendel’s crosses
b. pure breeding lines could be easily generated
c. pea plants contain a large number of continuous forms at the traits Mendel selected, which provided the needed variation for experiments
d. peas produce large numbers of offspring
e. peas are amiable to carefully controlled experimental crosses

A

C

240
Q

A and B are dominant alleles of two independently assorting genes. Each gene produces an enzyme that catalyzes the conversion of one pigment to another, and a and b are recessive alleles, both are nonfunctional. A fully homozygous yellow eyed frog of genotype AA bb is crossed with a white eyed frog of genotype aa BB. The F1 progeny are allowed to mate. What proportion would you expect in the F2 progeny?

A

9 red: 4 white: 3 yellow

Genetics BSC-315 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions