XI Chap 10 Cell Cycle & Division Flashcards
1
Q
Growth and reproduction are characteristics of ALL living cells. T or F?
A
True
2
Q
All cells reproduce by diving into 2. T or F?
A
True
3
Q
During cell division, each parental cell gives rise to __________
A
two daughter cells
4
Q
During cell division, ________ and ________ also take place
A
DNA replication, cell growth
5
Q
Prokaryotes do not produce ________ and ______ during cell division
A
chromosomes, spindle fibres
6
Q
There is no mitosis or phases of division in prokaryotes. T or F?
A
True
7
Q
What is amitosis?
A
Cell division in prokaryotes / bacteria
8
Q
Prokaryotes and Protista divide for _________ and ____________
A
growth, reproduction
9
Q
Multicellular organisms divide for ____________, ____________, ____________ and ____________
A
growth, repair, replacement and maintaining nucleocytoplasmic ratio
10
Q
What is cell cycle?
A
sequence of events
cell duplicates its genome
synthesises other cell constituents
divides into 2 daughter cells
11
Q
Cell growth in terms of cytoplasmic increase is a discontinuous process broken down into distinct stages. T or F?
A
False, cytoplasmic increase is a continuous process
12
Q
Cell growth only takes place in G1. T or F?
A
False, continuous but most in G1
13
Q
DNA synthesis is a continuous process in cell cycle. T or F?
A
False, occurs only in one specific stage
14
Q
Replicated chromosomes are distributed to daughter cells by a _______ _______ series of events under _______ control
A
complex, coordinated, genetic
15
Q
A typical __________ cell cycle is demonstrated by human cells in culture
A
eukaryotic cell cyle
16
Q
Human cells in culture divide once in approximately every _______
A
24 hours
17
Q
Yeast divides in ___________
A
90 minutes
18
Q
E. Coli divides once every ___________
A
20 minutes
19
Q
2 basic phases of cell cycle:
A
Interphase
M Phase
20
Q
All the phases of cell cycle
A
Gap 1, Synthesis, Gap 2, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
21
Q
___________ phase represents when the actual cell division or mitosis occurs
A
M phase
22
Q
___________ phase represents the phase between 2 successive M phases
A
Interphase
23
Q
In 24 duration of human cell cycle, M-phase lasts only about _______
A
an hour
24
Q
Interphase lasts for more than _____% of the cell cycle
A
95
25
In human cell in culture, time of each phase? M, G1, S, G2
M - 1 hour
G1 - 8-12 hours
S - 6-8 hours
G2 - 3-4 hours
26
DNA is in the form of _________ in each of the phases: M, G1, S, G2
M - chromosome
| G1, S, G2 - chromatid
27
Cell cycle is regulated by ________ which are dependent on _________. Hence the regulators are called: __________
kinase (proteins)
cyclin (proteins)
CdK2 - cyclin-dependent kinase
28
M Phase starts with ________ and ends with ___________
nuclear division & separation of daughter chromosomes (karyokinesis);
division of cytoplasm (cytokinesis)
29
Interphase is aka _________ as cell is preparing for division
resting phase
30
Cell growth and DNA replication happen during the Interphase. T or F?
True
31
What are the 3 phases of interphase?
G1 (Gap 1), Synthesis and G2 (Gap 2)
32
What happens in G1 phase? (4)
Maximum cell/cytoplasmic growth
RNA, nucleotides, proteins, amino acids, ATPs are produced
max. cell organelles duplicated
DNA damage repair
33
What happens in S phase?
DNA replication in nucleus
| histone synthesis and centriole duplication in cytoplasm
34
What happens in G2 phase? (4)
tubulin proteins synthesized (RNA and protein syn continues)
semi-autonomous organelles duplicate (mitochondria, chloroplast)
Golgi body duplicated
growth occurs but not much
35
_____ is the longest phase of interphase
| _____ is the longest phase of cell cycle
G1, G1
36
_____ phase is shorter in frequently dividing cells (e.g. embryonic cells)
G1
37
What is the major checkpoint in cell cycle? What is it regulated by?
G1 ---> S
| regulated by G1 cyclin and CdK2
38
What is the minor checkpoint in cell cycle? What is it regulated by?
G2 ----> M
| regulated by M cyclin and CdK2
39
_______ is pre-mitotic and post-synthetic
G2
40
_______ is post-mitotic and pre-synthetic
G1
41
________ phase is the interval between mitosis and initiation of replication
G1 phase
42
During _______ phase cell is metabolically active but doesn't replicate DNA
G1
43
____chromatin replicate first and then ____chromatin
Euchromatin, heterochromatic
44
Amount of DNA per cell and number of chromosomes double during S phase. T or F?
False, amount of DNA (chromatid) doubles, but chromosome number is the same
45
Haploid cell becomes diploid after S phase of cell division. T or F?
False, number of chromosomes remains the same
46
In plant cells, during S phase, DNA replication begins in nucleus and centriole duplicates in the cytoplasm. T or F?
False, centriole only present in animal cells
47
Why is time for G1 phase so variable?
Because it is the only phase that depends on external factor (e.g. nutrients)
48
__________ skips G1 and G2 phase
Zygote in cleavage division (size doesn't increase that much)
49
Heart cells and many others divide only occasionally, e.g. due to injury or cell death. T or F?
Heart cells and neurons do not divide ever, rest is accurate
50
Cells that do not divide further exit _____ phase to enter an inactive stage called _________
G1 phase, quiescent stage (G0)
51
Cells in G0 stage remain ________ but no longer proliferate unless called to do so.
metabolically active
52
Neurons remain in permanent _____ phase and do not enter ____ phase ever as they do not possess a ______
G1, S, centriole
53
From G1 phase, if cell goes into G0 phase its due to non-availability of _______ and ______
mitogen and energy-rich compounds
54
Once cell enters S phase it has to divide. T or F?
True
55
If a cell differentiates after G1 phase, its role becomes permanently fixed until natural death of cell. T or F?
True
56
Examples of cells that are constantly replaced by mitosis. (4)
Upper layer of epidermis,
cells of lining of gut,
blood cells,
cheek cells
57
In animals, mitotic cell division is only seen in ___________ cells
diploid somatic cells
58
Exceptionally, in some lower plants and social insects, ___________ cells divide by mitosis. Example?
haploid;
| male honey bees
59
Plants show mitotic divisions in both haploid and diploid cells. T or F?
True
60
Tubulin protein is made in both plant and animal cell, however centriole and aster is only made in animal cell. T or F?
True
61
________ cell is known as amphiastral whereas ______ cell is known as anastral.
Animal, plant
62
__________ is the most dramatic period of the cell cycle involve reorganisation of virtually all components
M Phase
63
Why is M Phase division also called equational division?
Since the number of chromosomes is same in parents and progeny
64
Cell division is a progressive process with clear-cut lines between the various phases of M Phase. T or F?
False, clear cut lines cannot be drawn
65
Karyokinesis involves which 4 stages?
Prophase
Metaphase
Anaphase
Telophase
66
__________ is the first stage of karyokinesis of mitosis and follows the ______ phases of interphase
Prophase, S and G2
67
How do the new DNA molecules in S and G2 phases look?
Intertwined, not distinct
68
Prophase is marked by __________
initiation of condensation of chromosomal material
69
The centrosome undergoes duplication during which phase?
S phase of interphase
70
During prophase, chromosomes become _______ (tangled/untangled), and are seen to be are composed of _____ (how many?) chromatids attached at _____
untangled, two, centromere
71
During prophase, __________ moves towards opposite poles of the cells. Each radiates out microtubules called ______.
centrosome/centrioles
| asters
72
The __________ together with _____________ forms the mitotic/spindle apparatus
two asters of centrosome
| spindle fibres
73
At the end of prophase, cells show nuclear envelope, nucleolus, golgi complexes and endoplasmic reticulum. T or F?
False, do not show
74
_____________ marks the start of the metaphase of mitosis.
Complete disintegration of the nuclear envelope
75
________ is aka spireme stage
Early prophase
76
Chromosomes are spread through the cytoplasm of the cell during which stage?
Metaphase
77
In mitosis, by ______ stage condensation of the chromosomes is completed.
Metaphase
78
In _____ phase chromosomes can be easily observed and their morphology is most easily studied.
Metaphase
79
Kinetochores are ______ shaped structures made of ______ at the surface of _________.
In metaphase, what purpose do they serve?
Small disc-shaped structures, proteins, centromeres
serve as sites of attachment of spindle fibres
80
Chromosomes are moved to ______ aligned along the _______ during metaphase, with sister chromatids connected to ________
spindle equator,
metaphase plate,
one pole each (opposite poles)
81
Plane of alignment of chromosomes in metaphase is referred to as _________
metaphasic OR equatorial plate
82
Complete disintegration of the nuclear envelope is the first phase of ________
metaphase
83
___________ is the last event of metaphase
Chromosomal alignment on metaphase plate
84
At the onset of anaphase, centromeres ________ and chromatids _______
split, separate
85
In anaphase, two daughter chromatids are now referred to as ____________
daughter chromosomes of future daughter nuclei
86
Daughter chromatids move towards same or opposite poles during anaphase?
Opposite
87
During anaphase, as the chromosomes move away from equatorial plate, ___________ remains directed towards the pole (at the leading edge) whereas ________ trail behind
centromere; arms of chromosome
88
Symmetric vs asymmetric spindle?
Symmetric - most common, spindle fibre equator and cell equator is the same => cells divide equally
Asymmetric - cell and spindle equators not the same (due to presence of vacuole) => unequal division (e.g. vegetative and germ cell in pollen grain)
89
In asymmetrical spindles, chromosomal division is unequal. T or F?
False, cytoplasmic division is unequal BUT chromosomal division is still equal
90
_________ is the best phase to observe the shape of the chromosomes
Anaphase
91
What are the shapes of the various chromosomes?
metacentric - V
sub-metcentric - L
acrocentric - J
telocentric - I
92
At the beginning of telophase, chromosomes ...
decondense / lose individuality / elongate
at their respective/opposite spindle poles
93
In telophase, individual chromosomes can be seen for the final time before they cytokinesis. T or F?
False, chromosomes can no longer be seen individually
94
During which phase does the nuclear envelope develop at each pole forming daughter nuclei?
Telophase
95
During which phase do golgi complex, nucleolus and ER form?
Telophase
96
Spindle fibres degenerate in which phase of mitosis?
Telophase
97
Cell division is completed at the end of ___________
cytokinesis, two daughter cells (not just nuclei) are formed
98
Describe cytokinesis in animal vs plant cell.
Animal cell - cleavage, furrow/invagination in plasma membrane, deepens gradually and joins at centre (centripetal)
Plant cell - wall formation starts in the centre and grows outward (centrifugal) to meet existing lateral walls (due to relatively inextensible cell wall) - phragmoplast deposits calcium pectate which forms the middle lamella "cell plate" after which cell wall forms on both sides and finally plasma membrane
99
In plants, formation of new cell wall begins with a simple precursor called ________
cell-plate
100
Cell-plate represents the ________ between walls of two adjacent cells
middle lamella
101
After cytokinesis, plant cells remain connected via ___________
plasmodesmata
102
During cytokinesis, organelles get distributed between 2 daughter cells. T or F?
True, organelles that are not easily produced (e.g. mitochondria, plastids, chloroplasts)
103
In some organisms karyokinesis is not followed by cytokinesis which results in multinucleate condition => formation of ___________. Example?
syncytium e.g. liquid endosperm in coconut
104
In some lower plants, cleavage occurs and not cell plate formation. T or F?
Example?
True, unicellular algae (e.g. chlamydomonas) - cells don't need to be connected after division
105
Equational division is usually restricted to diploid cell. T or F?
True, key word here is USUALLY
106
Meiosis is ALWAYS restricted to diploid cells only. T or F?
True
107
___________ disturbs the ratio between nucleus and cytoplasm. _______ restores it.
Cell growth, cell division
108
Cell repair is a significant contribution of which type of division?
mitosis
109
Mitotic divisions in _______ tissues in plants result in continuous growth throughout their life.
Meristematic (apical, lateral cambium, intercalary)
110
Type of cell division that forms gametes: _______.
Meiosis
111
In meiosis the chromosome number remains the same. T or F?
False, halves
112
Haploid daughter cells are formed by ________ type of cell division
meiosis
113
__________ ensures the production of haploid phase in life cycle of sexually reproducing organisms, whereas __________ restores the diploid phase
Meiosis; fertilization
114
Process in plants and animals that requires meiosis?
Gametogenesis
115
Meiosis consists of ______ sequential cycles of nuclear division, ______ cycles of cell division and ______ cycles of DNA replication
two, two, one
116
Pairing of homologous chromosomes and re-combination b/w non-sister chromosomes occurs in __________ (mitosis / meiosis)
Meiosis
117
How many haploid cells are formed at the end of meiosis?
4
118
Assume diploid cell with 12 chromosomes. Describe number of chromosomes, chromatids, ploidy and amount of DNA through mitosis (G1, G2, anaphase, after cytokinesis?)
G1 - 12 chromosomes, 12 chromatids, 2n, 2C
G2 - 12 chromosomes, 24 chromatids, 2n, 4C,
Anaphase - 24 chromosomes, 24 chromatids, 2n, 4C,
After cytokinesis - 2 cells each containing 12 chromosomes, 12 chromatids, 2n, 2C
119
Assume haploid cell with 12 chromosomes. Describe number of chromosomes, chromatids, ploidy and amount of DNA through mitosis (G1, G2, anaphase, after cytokinesis?)
G1 - 12 chromosomes, 12 chromatids, n, C
G2 - 12 chromosomes, 24 chromatids, n, 2C,
Anaphase - 24 chromosomes, 24 chromatids, n, 2C,
After cytokinesis - 2 cells each containing 12 chromosomes, 12 chromatids, n, C
120
Assume diploid cell with 12 chromosomes. Describe number of chromosomes, chromatids, ploidy and amount of DNA through meiosis (G1, G2, end of M1, end of M2)
G1 - 12 chromosomes, 12 chromatids, 2n, 2C
G2 - 12 chromosomes, 24 chromatids, 2n, 4C
End of M1 - 2 cells each with 6 chromosomes, 12 chromatids, n, 2C
End of M2 - 4 cells, each with 6 chromosomes, 6 chromatids, n, C
121
Assume haploid cell with 12 chromosomes. Describe number of chromosomes, chromatids, ploidy and amount of DNA through meiosis (G1, G2, end of M1, end of M2)
Haploid cells cannot undergo meiosis
122
Prophase I of first meiotic divisions is _______ (shorter / longer) and _______ (complexity?) compared to prophase of mitosis
typically longer, more complex
123
Prophase I is divided into how many phases? What are they?
5
```
Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis
```
124
What happens in leptotene? (1)
Compaction/condensation of chromosomes (initiates and throughout)
125
What happens in zygotene? (3)
Synapsis - homologous chromosome pairing together
Formation of synaptonemal complex
Formation of bivalent tetrad
126
What happens in pachytene? (3)
4 chromatids become distinct and bivalents/tetrads more clearly visible
Recombination modules
Crossing over
127
What happens in diplotene? (3)
Dissolution of synaptonemal complex
Recombined homologous chromosomes separate
Formation of chiasmata
128
What happens in diakinesis? (4)
Terminalisation of chiasmata
Rest of prophase processes: chromosomes fully condensed, meiotic spindles assembled, ER, golgi, nucleolus and nuclear envelope disappear
129
In ______ stage of prophase I, chromosomes became gradually visible under the light microscope.
Leptotene
130
Compaction of chromosomes continues throughout leptotene. T or F?
True
131
During ______ phase of Meiosis I, chromosomes become gradually visible under the light microscope
leptotene
132
What is synapsis?
Process of association in zygotene stage, chromosomes start pairing together (homologous chromosomes)
133
What is synaptonemal complex?
proteinaceous complex structure
| holds together homologous chromosomes
134
Electron micrographs at _______ stage show synaptonemal complex
zygotene
135
Bivalent and/or synaptonemal complex is more clearly visible in _______ phase
Pachytene (even though formed in zygotene)
136
Pachytene is short-lived compared to leptotene and zygotene. T or F?
False, reverse.
137
Chromosome synapsis is accompanied by formation of synaptonemal complex. T or F?
True
138
What are recombination nodules?
Enzyme complexes
| Sites at which crossing over occurs between non-sister chromatids of homologous chromosomes.
139
________ enzyme is responsible for crossing over
recombinase
140
What is crossing over?
Exchange of genetic information between 2 homologous chromatids
141
Is crossing over an enzyme-mediated process? If yes, which enzyme?
Yes, recombinase
142
Recombination between homologous chromosomes is completed by the end of pachytene and chromosomes become unlinked. T or F?
False, recombination is completed but chromosomes remain linked
143
Dissolution of synaptonemal complex and separation of recombinant homologous chromosomes occurs in _______ phase
Diplotene
144
Chromosomes separate at sites of crossovers in diplotene. T or F?
False, separate except at the sites of crossovers.
145
Chromosomes in diplotene form _____-shaped structures called ________
X-shaped
| chiasmata
146
In oocytes of some vertebrates, diplotene can last months or years. T or F?
True, called dictyotene
147
Terminalisation of chiasmata occurs in which stage?
Diakinesis, final stage
148
In meiosis, chromosomes are fully condensed in which stage?
Diakinesis
149
Meiotic spindle is assembled in which phase to prepare homologous chromosomes for separation?
Diakinesis
150
_______ represents the transition to metaphase I
Diakinesis
151
In metaphase I, bivalent chromosomes align on ____________. The _______ from opposite poles of the spindle attach to the ___________ of homologous chromosomes.
equatorial plate,
microtubules,
kinetochore
152
In anaphase I, _________ separate while _______ remain associated at their centromeres.
Homologous chromosomes, sister chromatids
153
Cell goes from diploid to haploid in which stage?
Anaphase I
154
Disjunction vs segregation?
Disjunction - chiasmata disappears => non-sister chromatids no longer attached
Segregation - homologous chromosomes separate => move towards opposite poles
155
Disjunction and segregation occur in __________
anaphase I
156
In telophase I, ________ and _______ re-appear
nuclear membrane, nucleolus
157
What is univalent dyad?
In telophase I, after cytokinesis 2 daughter cells are formed. Each is a dyad. (1 chromosome, 2 chromatids)
158
At the end of telophase I, chromosomes undergo dispersion and become extremely extended like in interphase nucleus. T or F?
False, they do not reach the extremely extended state of interphase nucleus.
159
What is interkinesis?
Stage between 2 meiotic divisions,
short-lived,
chromosomes undergo some dispersion but not extended state like interphase nucleus
160
During interkinesis, DNA and centrioles double. T or F?
False, centriole double but DNA does NOT
161
Prophase I is much simpler prophase than Prophase II. T or F?
False, other way around
162
Mendel's Law of _________ can be observed in _______ stage of meiosis
Independent Assortment, anaphase I
163
Meiosis II is immediately initiated after cytokinesis of Meiosis I, before chromosomes have fully elongated. T or F?
True
164
__________ leads to aneuploidy
Non-disjunction in anaphase I
165
Meiosis II resembles a normal mitosis. T or F?
True
166
In metaphase I, the microtubules get attached to the kinetochore of _________.
In metaphase II, they get attached to kinetochore of _________.
homologous chromosomes,
| sister chromatids
167
In _________ simultaneous splitting occurs of ________
anaphase II, centromere of each chromosome
168
Differentiate between anaphase I and anaphase II
Anaphase I - one pair of chromosomes is attached to 2 spindle fibres => homologous chromosomes separate, sister chromatids remain associated at centromere
Anaphase II - one chromosome is attached to 2 spindle fibres => splitting of centromere and each chromosome => sister chromatids separate and move to opposite poles
169
________ is the mechanism by which conservation of specific chromosome number of each species is achieved.
Meiosis
170
__________ increases the genetic variability.
Mitosis / Meiosis
Meiosis
171
Any sexually reproducing organism starts its life cycle from a single-celled zygote. T or F?
True
172
Most of the organelle duplication happens during _____ phase
G1
173
______ is the phase where cell grows and carries out normal metabolism
G1
174
Meiosis is aka _________ division
Reduction
175
In _______ phase, each pole receives half the chromosome number as parent cell.
anaphase I
176
During ___________ (anaphase I or II), sister chromatids separate.
Anaphase II
177
In mitosis, chromosome condensation is completed in _______ whereas in meiosis I it is completed in _______
metaphase, prophase I
178
1 chromosome is attached to 2 spindle fibres in _______ whereas a PAIR of chromosomes is attached to 2 spindle fibres in ________
mitosis, meiosis I
179
The number of spindle fibres are same as number of chromosomes in _________ (mitosis or meiosis)
meiosis
180
Electron micrographs at _______ stage show synaptonemal complex
zygotene
181
Arrange in order of time taken: Prophase, Metaphase, Anaphase, Telophase
Prophase > Telophase > Metaphase > Anaphase
182
What is APC?
anaphase promoting complex
| enzyme that digests cohesin
183
APC is responsible for ___________
digesting cohesin so that sister chromatids can separate
184
What is cohesin?
Protein that holds sister chromatids together at centromere
185
________ occurs when APC is non-functional
Polyteny
186
___________ is responsible for polyploidy
Mitotic poison e.g. colcichine
187
What is colcichine? What happens when it is applied to cell?
Mitotic poison
Sister chromatids separated by APC BUT spindle fibres not attached => chromosome number doubles
188
_________ results in a whole new set of chromosomes whereas _________ results in abnormal number of chromosomes
Polyploidy, aneuploidy
189
Types of meiosis? and in what organisms do they occur?
Sporic - bryophytes, pteridophytes, gymnosperms, angiosperms
Zygotic - algae
Gametic - animals e.g. humans
190
Both sporic and zygotic meiosis produce spores. T or F?
True
191
In zygotic meiosis, sporophyte is produced which undergoes meiosis to produce spores. T or F?
False, in zygotic meiosis there's no sporophyte - zygote undergoes meiosis
192
Sporophyte is ______cellular whereas zygote is ____cellular
multi, uni
193
Gametophyte is _____cellular
multi
194
In what phases of meiosis does variation occur?
Pachytene - recombination
| Anaphase I - independent assortment / chromosomes distributed into 2 different cells
195
Anaphase I vs Anaphase II
Anaphase I - homologous chromosomes separate, 1 spindle fibre per chromosome, centromeres intact
Anaphase II - sister chromatids separate, 2 spindle fibres per chromosomes, centromeres split
196
1 meiosis produces _____ pollen and _____ eggs
4, 1
197
```
Ploidy and DNA amount of the following:
oogonia
primary oocyte
secondary oocyte
first polar body
ootid
second polar body
```
```
oogonia - 2n, 4C
primary oocyte - 2n, 4C
secondary oocyte - n, 2C
first polar body - n, 2 C
ootid - n, C
second polar body - n, C
```
198
Which ions are essential for assembly of microtubules?
Ca2+ and Mg2+
199
Rank phases of karyokinesis from shortest to longest
Anaphase > Metaphase > Telophase > Prophase
