Chapter 10 Flashcards
1
Q
Genetics
A
scientific study of heredity and inherited variation
1
Q
Heredity
A
transmission of traits from one generation to the next
2
Q
Asexual Reproduction
A
-offspring is a clone, or genetically identical to the parent
-genetic recombination doesnt occur
3
Q
Sexual Reproduction
A
offspring has unique combinations of genes from two parents
-both gamete production and fertilization increase variation
4
Q
Gene
A
section of DNA molecule that codes for one polypeptide
5
Q
Locus
A
place on a chromosome where a gene is located
6
Q
Genome
A
collection of all genes that belong to a single individual
7
Q
True or False: each somatic cell of a multicellular organism contains this organism’s entire genome
A
true
8
Q
Karyotype
A
display of all chromosomes from a somatic cell arranged as homologous pairs
9
Q
Homologous pairs
A
two chromosomes with the same size, shape, and staining pattern
10
Q
X and Y chromosome means
A
male
11
Q
X and X chromosome means
A
female
12
Q
cells with 46 chromosomes
23 pairs of homologous chromosomes
22 pairs of autosomes
1 pair of sex chromosomes
A
Somatic Cells
13
Q
Are somatic cells haploid or diploid?
A
Diploid
14
Q
of sets of somatic cells?
A
2
15
Q
Shorthand configuration for somatic cells
A
2n=46
16
Q
egg and sperm cells with 23 chromosomes
produced by diploid germ cells in reproductive tissue that undergo meiosis
A
Gametes
17
Q
Are gametes haploid or diploid
A
haploid
18
Q
of sets of Gametes
A
1
19
Q
Shorthand configuration for Gametes
A
n=23
20
Q
True or False: a normal male sperm has 22 pairs of autosomes, a X and Y chromosome
A
false
21
Q
True or False: All autosomes in normal cells exist in homologous pairs
A
true
22
Q
sexual life cycle typical of animals
all adults are diploid
gametes are produced via meiosis
a zygote is produced via fertilization
A
Diplontic Cycle
23
Q
All adults are _________
A
diploid
24
sexual life cycle of plants and algae
alternating generations of adults are either haploid or diploid
meiosis produces haploid cells known as germ cells
gametophyte produces haploid gametes via mitosis
Alternation of Generations
25
Alternation of Generations is the sexual life cycle of
plants and algae
26
Alternating generations of plant and algae adults are
either haploid or diploid
27
Meiosis produces haploid cells known as
germ cells
28
Gametophyte produces haploid gametes via
mitosis
29
True or False: plants have both diploid and haploid stages that are multicellular
true
30
sexual life cycle of fungi and some protists
haploid adult produces haploid gametes via diploid
Haplontic Cycle
31
The haplontic cycle is the sexual life cycle of
fungi and some protists
32
True or False: the only diploid stage is a zygote
true
33
True or False: a human somatic cell has 23 sets of chromosomes
true
34
True or False: each homologous pair is composed of one chromosome from the maternal set and one chromosomes from the paternal set
true
35
Prophase 1 of Meiosis
chromosome condense
nuclear envelope fragments, spindle forms
homologous chromosomes pair in synapsis
36
During prophase 1, homologous chromosomes pair up in
synapsis
37
At the chiasma, homologous chromosomes overlap and exchange segments between _________ chromatids in a process called ____________
non-sister
crossing over
38
True or False: during prophase 1, genetic variation results from crossing-over between sister chromatids
false
39
What stage does crossing over take place in?
Prophase 1
40
Metaphase 1 of Meiosis
still in synapsis, each pair of duplicated homologous chromosomes or tetrad, lines up at the metaphase plate
-kinetochore microtubules attach to homologs at the centromere
41
True or False: each pair of homologous chromosomes line up independently of other pairs
true
42
Anaphase 1 of Meiosis
duplicated homologous chromosomes are separated to opposite poles of the cell
43
True or False: during anaphase 1, homologous chromosomes separate while sister chromatids remain attached
true
44
Telophase 1 and Cytokinesis of Meiosis
the result of two haploid cells with duplicated chromosomes
45
True or False: if a germ cell has 6 picograms of DNA at the end of interphase, each of the two cells following Telophase 1 and cytokinesis would also have 6 picograms of DNA
False
46
True or False: DNA replication happens before Meiosis 1, but not immediately before Meiosis 2
true
47
Description of Prophase 2
spindle formation
48
Description of Metaphase 2
chromosomes line up at metaphase plate
49
Description of Anaphase 2
spindle fibers pull sister chromatids to the opposite poles
50
Description of Telophase 2
the result is four haploid cells with non-duplicated chromosomes
51
True or False: Meiosis 2 is similar to mitosis in that both separate sister chromatids
true
52
True or False: the number of chromosomes and the amount of DNA per chromosome does not change during Meiosis 2
false
53
First Contribution to Genetic Variation
Crossing Over
54
Crossing Over Produces
recombinant chromosomes, individual chromosomes that carry genes from two different parents
55
Second Contribution to Genetic Variation
independent assortment
56
When does Independent Assortment Take Place?
Metaphase 1 to Anaphase 1
57
Independent Assortment Description
random orientation of pairs of homologs along the metaphase plate
58
The formula for calculating the number of possible combinations is ______, where n is the haploid number, or number of pairs
2n
59
Random Fertilization
any sperm can fuse with any ovum, or unfertilized egg
60
True or False: in species that reproduce sexually, the behavior of chromosomes during meiosis and fertilization is responsible for most of the variation that arises in each generation
true
61
Mitosis: Parental Cells Divide to Become
somatic cells
62
Meiosis: parental cells divide to become
gametes
63
Mitosis can occur in which type of cells?
haploid and diploid cells
64
Mitosis: DNA replication occurs during interphase
yes
65
Meiosis: DNA replication occurs during interphase
yes
66
Mitosis: Number of Divisions
1
67
Meiosis: Number of Divisions
2
68
Mitosis: does synapsis and crossing over occur?
no
69
Meiosis: does synapsis and crossing over occur?
yes
70
Mitosis: number of daughter cells
2
71
Meiosis: number of daughter cells
4
72
Mitosis: ploidy of daughter cells
diploid
73
Meiosis: ploidy of daughter cells
haploid
74
Mitosis: genetic composition to the parent cell is unique or identical
identical
75
Meiosis: genetic composition to the parent cell is unique or identical
genetically unique
76
Number of chromosomes before interphase
46
77
Number of chromosomes after interphase
46
78
Number of chromosomes after Meiosis 1
23
79
Number of chromosomes after Meiosis 2
23
80
Number of DNA molecules before interphase
46
81
Number of DNA molecules after interphase
92
82
Number of DNA molecules after Meiosis 1
46
83
Number of DNA molecules after Meiosis 2
23
84
In both males and females, gametogenesis generates _______ gametes via meiosis
haploid
85
Production of sperm is termed
spermatogenesis
86
In mature testes, stem cells undergo _________ to produce _________ spermatogonia
mitosis
diploid
87
________ of spermatogonia produces the _______ primary spermatocytes
mitosis
diploid
88
Meiosis 1 produces the ________ secondary spermatocytes
haploid
89
Meiosis 2 produces four ________ early spermatids
haploid
90
Cell differentiation results in 4 ________ sperm cells
haploid
91
True or False: production of sperm is continuous in adult males
true
92
Oogenesis
production of oocytes
93
In the female embryo, the primordial germ cell divides by mitosis to produce _______ oogonium
diploid
94
The oogonium divides by _______ to produce the primary oocyte. The primary oocyte is stopped in _________ of meiosis
mitosis
prophase 1
95
Starting at puberty, ____ follicle fully matures each month. Unequal cytokinesis at the completion of meiosis 1 produces _____ polar body and ____ secondary oocyte
1
1
1
96
The secondary oocyte is paused in ____________ of meiosis. The secondary oocyte is released during ______________
metaphase 2
ovulation
97
After a sperm penetrates the egg, _________ is completed. Unequal cytokinesis produces ____ polar body and _____ mature egg containing a sperm head
meiosis 2
1
1
98
________________ occurs when the haploid nuclei form the sperm and egg fuse
fertilization
99
True or False: both spermatogenesis and oogenesis produce four mature gametes
false
100
True or False: at birth, the ovaries contain 1-2 million primary oocytes, but only about 500 fully mature between puberty and menopause
true
101
process that contributes to genetic diversity
Meiosis
102
Interphase
happens before meiosis even starts
-growth
-replication of DNA
-cell functions
103
Prophase 1
-comes before all of the other phases start
-chromosomes are condensing and thickening
-lining up with the homologous pairs
104
Homologous
chromosomes are about the same size and they contain the same type of genes in the same locations; they are going to match up
105
Metaphase 1
-the chromosomes are going to be in the middle of the cell
-NOT a single file line like in mitosis because the chromosomes are gonna be in pairs
106
Anaphase 1
-the chromosomes are pulled away by the spindle fibers
107
Telophase 1
-two newly formed nuclei is formed
-cytokinesis follows with splitting the cytoplasm
108
Prophase 2
there are no homologous pairs and crossing over does not happen
109
Metaphase 2
-chromosomes line up in the middle
-chromosomes are in a single file line
110
Anaphase 2
-the chromatids are being pulled away by spindle fibers
-pulled to opposite sides of the cell
111
Telophase 2
-nuclei form and the 2 cells divide again and 4 cells are formed
-cytokinesis happens and the cytoplasm is split
112
when a cell can receieve too many or too few chromosomes in its separation
Nondisjunction
113
A karyotype is a
photograph of all of an individual's chromosomes
114
What contributes to genetic variation in sexually reproducing species?
independent assortment, crossing over, random fertilization
115
How many genes are present in the human genome?
ten of thousands
116
How many different combinations of maternal and parental chromosomes can be packages i gametes made by an organism with a diploid number of 8 (2n=8)
16
117
Homologous chromosomes move toward opposite poles of a dividing cell during
meiosis 1
118
What is a locus?
the precise location of a gene on a chromosome
119
What's an example of a human cell that contains 46 chromosomes
liver cells
120
In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _______ chromosomes
5
121
The egg ( ovum) of rabbit contains 22 chromosomes. How many chromosomes are in the somatic ( body) cells of a rabbit?
44
122
Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment
Statement that best describes the advantage that sexual reproduction likely provides over asexual reproduction
123
Crossing over occurs during
prophase 1
124
What event occurs during prophase 1 of the first meiotic division?
synapsis of homologous chromosomes occurs
125
Synapsis occurs during
prophase 1
126
Spores and gametes differ in that
gametes must fuse to form a zygote and continue development, but each spore can develop into a different independent multicellular organisms on its own
127
In a male mammal, every germ cell that undergoes meiosis in the production of gametes gives rise to ______ sperm
four
128
What occurs during anaphase 2
sister chromatids separate and migrate toward opposite poles
129
How many pairs of autosomes do humans have?
22
130
Sister chromatids
are identical copies of each other formed during DNA synthesis
131
Fertilization produces a
diploid zygote
132
A human cell containing 22 autosomes and Y chromosome is a
sperm
133
In sexually reproducing species, the chromosome number remains stable over time because _________ and __________ always alternate
meiosis
fertilization
134
In a diploid set of chromosomes, one member of each pair of homologous chromosomes is derived from the father (paternal) and the other comes from the mother (maternal). If 2n = 6, what is the probability of obtaining a gamete in which all the chromosomes are paternal ones?
1/8
135
Human somatic cells contain _____ set(s) of chromosomes and are therefore termed _________
two
diploid
136
The synaptonemal complex
physically connects homologous chromosomes during prophase 1
137
True or False: humans form gametes by a process called gametogenesis
true
138
What role do germ cells play in gametogenesis
they produce cells that divide by mitosis and then undergo meiosis to form gametes
139
What products are formed when a diploid cell undergoes meiosis
four haploid cells
140
Beginning at puberty, a primary oocyte completes its first meiotic division to form a secondary oocyte and a polar body approximately every month.
true statement about oogenesis in humans
141
Which diploid cells are produced by an embryonic germ cell
spermatogonia
142
True or False: The production of sperm begins at puberty when spermatogonia undergo meiosis I to form primary spermatocytes, which then undergo meiosis II to form secondary spermatocytes. These secondary spermatocytes go on to form spermatids, which mature into sperm cells.
false
143
How does spermatogenesis differ from oogenesis
diploid cells give rise to four functional gametes in spermatogenesis
144
correct model for metaphase 1 for a 2n=4 cell
145
What is true about the human life cycle?
gametes are produced by meiosis
146
Name 2 true statements about human gametes
-gametes contain 23 pairs of chromosomes
-both eggs and sperm contribute 23 chromosomes to the zygote
147
Name the processes that contribute to heredity and genetic variation
crossing over
metaphase 2/anaphase 2
metaphase 1/ anaphase 1
DNA replication
fertilization
148
Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of meiosis.
there would be less genetic variation among gametes
149
True or False: for crossing over to occur, homologous chromosomes must align precisely early in prophase 1 so that non-sister chromatids can exchange corresponding segments of DNA
true
150
True or False: crossing over prevents homologous chromosomes from separating during meiosis 1
false
151
True or false: as a result of crossing over, sister chromatids are no longer identical to each other
true
152
True or False: crossing over occurs at the ends of chromosomes, rather than near the centromeres
false
153
How does cellular DNA content and ploidy levels change during meiosis 1 and meiosis 2
DNA content is halved in both meiosis 1 and meiosis 2. Ploidy level changes from diploid to haploid in meiosis 1, and remains haploid in meiosis 2
154
What is the ploidy of this cell model?
haploid ( one set)
155
What is the ploidy of this cell model?
n=6
156
What is the ploidy of this cell model?
triploid
157
What is the ploidy of this cell model?
2n=6
158
Which processes lead to most genetic variation in sexually reproducing organisms?
random fertilization
independent assortment of chromosomes in meiosis
crossing over
