Chapter 8: The Cell Cycle Flashcards
1
Q
cell division is used for?
A
- reproduction
- growth
- regeneration
2
Q
unicellular organisms use cell division primarily for
A
reproduction
3
Q
in multicellular organisms cell division is important to
A
growth and repair of tissues
4
Q
What are the four events that must occur for cell division?
A
- reproductive signal
- replication
- segregation
- cytokinesis
5
Q
What is a reproductive signal?
A
a signal that initiates cell division
6
Q
Segregation refers to…
A
the distribution of DNA into the two new cells
7
Q
What is cytokinesis?
A
the separation of the two new cells
8
Q
In prokaryotes, what results in two new cells?
A
binary fission
9
Q
What are the signals for replication of prokaryotes?
A
external factors
10
Q
What two types of external factors signal for binary fission?
A
- nutrient concentration
2. environmental conditions
11
Q
For many bacteria what speeds up the division cycle?
A
an abundant supply of food
12
Q
Explain the 3 steps in binary fission
A
- a single circular chromosome replicates and separates
- cytokinesis
- new cell wall materials are synthesized -> separation of two cells
13
Q
What happens during cytokinesis of binary fission
A
protein fibers form a ring and pinch off the plasma membrane
14
Q
single-cell eukaryotes replicate by
A
budding
15
Q
complex eukaryotes originate from
A
a single cell, the fertilized egg (zygote)
16
Q
complex eukaryotic cells results from the union of….
A
gametes containing genetic material from both parents
17
Q
What are the two cell types?
A
- germ cells
2. somatic cells
18
Q
germ cells produce
A
gametes
19
Q
gametes only contain…
A
one set of chromosomes
20
Q
A haploid number of chromosomes is=
A
1n
21
Q
fertilization is when…
A
two haploid gametes fuse
-female egg and male sperm
22
Q
fertilization forms a
A
diploid zygote
23
Q
a diploid zygote only contain…
A
2n
24
Q
gametes are specialized for..
A
reproduction
25
gametes reside in
primary sex organs
- testis
- ovaries
26
somatic cells are NOT
specialized for reproduction
27
somatic cells contain...
23 homologous pairs of chromosomes with corresponding genes
28
each parent contributes one
homolog (23 chromosomes)
29
meiosis occurs in
germ cells
30
meiosis produces
4 haploid (1n) daughter cells genetically diff. from each other and from parent cell
31
mitosis results in
2 identical diploid (2n) sister cells identical to the parent cell
32
most of the lifetime of a cell is NOT spent doing
cell division
33
the cell cycle are a series of events that
occur to produce two eukaryotic cells from one
34
What are the phases the cell cycle consists of?
1.
| 2.
35
What are the 3 sub-phases of interphase?
1. G1
2. S phase
3. G2
36
G1 is located between
the end of mitosis and S phase
37
What occurs during the S phase?
DNA replicates; each chromosome is now a pair -> two sister chromatids
38
During G2...
the cell prepares for mitosis
39
interphase DOES NOT involve
mitosis
40
the cell remains in G1 until
a signal of replication is received
41
The M phase is where ______ and ______ occurs
mitosis and cytokinesis
42
Where does chromatin form?
forms when replicated DNA is complexed with proteins
43
What coats the DNA to make it more compact?
condensins
44
sister chromatids are held together by cohesions at the
centromere
45
what are histones?
proteins that attract phosphate groups of DNA
46
chromosomes that have histones causes the formation of
nucleosomes
47
How does chromatin appear during mitosis and meiosis?
coiled and condensed until chromatids move apart
48
kinetochores are
the area where microtubules attach to chromosomes
49
As DNA replicates the ______ doubles.
centrosome
50
centrosomes consist of
two centrioles
51
prophase is known as the ______ phase
preparation
52
during prophase cohesion _______ and ______ become visible
disappears
chromatids
53
during prophase _____ forms the centromere regions
kinetochores
54
microtubules form the
mitotic spindle
55
during prometaphase the nucleus
"disappears"
56
during prometaphase kinetochores attach to
the microtubules and push towards the equatorial plate
57
during metaphase the centromeres....
arrive at the equatorial plate
58
the centromere at the equator of the cell is critical for
equal division of chromosomes into daughter cells
59
during anaphase the sister chromatids
separate and move to opposite ends of the spindle
60
name two motor proteins
kinesin
dynein
61
motor proteins attach to
kinetochores and microtubules
62
during anaphase MT....
shorten pulling chromosomes toward poles
63
what are the four things that happen in telophase?
1. spindle breaks down
2. nuclear envelope reform
3. chromosomes uncoil
4. two daughter nuclei are formed with identical genetic information
64
cytokinesis is when
the cell membrane pinches off, separating the two newly formed daughter cells
65
how is cytokinesis distinguished in animal cells?
by the formation of a cleavage furrow
66
the cleavage furrow is formed by
actin filaments
67
cytokinesis distinguished in plant cells by the formation of
a cell plate
68
how is the cell plate formed?
vesicles containing the cell wall material align and then fuse
69
what are the two irreversible points of the cell cycle?
1. replication of DNA
| 2. separation of sister chromatids
70
what two check point can put the cycle on hold?
1. DNA checked for accuracy
| 2. cell is able to respond and make repairs
71
the cell cycle is the most highly controlled
physiological process
72
two things that happen during the G1/S checkpoint
1. cell "divides"
| 2. primary external signal influence
73
what happens during the G2/M checkpoint?
1. cell commits to mitosis
| 2. assesses success of DNA replication
74
what happens during the late metaphase (spindle) checkpoint?
ensures that all chromosomes are attached to the spindle
75
transitions of the cell cycle depend on what protein?
cyclin-dependent kinase (Cdk)
76
How is Cdk activated?
by binding to cyclin
77
the cyclin Cdk complex triggers the transition from
G1 to S
78
cyclin and Cdk act like
on/off switches
79
growth factors trigger
intracellular signaling systems
80
platelet-derived growth factor signals
cells at a wound site to divide
81
growth factor signals override...
controls that normally inhibit cell division
82
list 3 ways that cancer cells can be mutated
1. make their own growth factor
2. divide without a growth factor signal
3. bypass the cell-death control system
83
cancer is known as
uncontrolled growth of cells
84
what are the two genes that can promote cancer when mutated?
1. tumor-suppressor genes
| 2. proto-oncongenes
85
what is the function of the tumor-suppressor genes?
to stop the cell cycle if DNA is damaged leads to a repair that is stimulated
86
what are proto-oncogenes?
normal cellular genes that become oncogenes when mutated
87
what was the first tumor suppressor that was identified?
retinoblastoma
88
what is the break mechanism that launches cellular death?
p53 protein
89
asexual reproduction produces offspring that are
genetically identical to the parent
90
meiosis produces gametes that
differ genetically from the parents
91
what are the two different types of cells?
1. somatic cells
| 2. germ cells
92
in somatic cells each parent contributes one
homolog
93
germs cells only contain
one set of chromosomes
94
in most animals which state dominates?
the diploid state
95
the sexual life cycle is made up of
meiosis and fertilization
96
in meiosis DNA is ONLY
replicated once
97
the nuclear divisions of meiosis occur during
meiosis I and meiosis II
98
meiosis ensures that each gamete has
a single full set of chromosomes
99
meiosis includes two rounds of
division
100
when does synapsis occur?
during early prophase I
101
synapsis occurs the formation of
synaptonemal complexes
tetrad/ bivalents
102
what is crossing over?
genetic recombination between non-sister chromatids
103
during crossing over homologues exchange
chromosomal genetic material
104
what is chiasmata?
the site of crossing over
105
the sister chromatids remain together until after
metaphase II
106
in meiosis II the sister chromatids may not be identical due to
crossing over
107
what are the two opportunities for diversity?
1. crossing over
| 2. independent assortment
108
what are the three differences between meiosis I and mitosis?
1. synapsis and crossing over
2. sister chromatids remain joined throughout meiosis I
3. homologous pairs separate randomly at anaphase I
