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Biology (NCERT) - Class XI > XI Chap 10 Cell Cycle & Division > Flashcards

XI Chap 10 Cell Cycle & Division Flashcards

1
Q

Growth and reproduction are characteristics of ALL living cells. T or F?

A

True

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2
Q

All cells reproduce by diving into 2. T or F?

A

True

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3
Q

During cell division, each parental cell gives rise to __________

A

two daughter cells

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4
Q

During cell division, ________ and ________ also take place

A

DNA replication, cell growth

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5
Q

Prokaryotes do not produce ________ and ______ during cell division

A

chromosomes, spindle fibres

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6
Q

There is no mitosis or phases of division in prokaryotes. T or F?

A

True

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7
Q

What is amitosis?

A

Cell division in prokaryotes / bacteria

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8
Q

Prokaryotes and Protista divide for _________ and ____________

A

growth, reproduction

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9
Q

Multicellular organisms divide for ____________, ____________, ____________ and ____________

A

growth, repair, replacement and maintaining nucleocytoplasmic ratio

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10
Q

What is cell cycle?

A

sequence of events
cell duplicates its genome
synthesises other cell constituents
divides into 2 daughter cells

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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

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12
Q

Cell growth only takes place in G1. T or F?

A

False, continuous but most in G1

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13
Q

DNA synthesis is a continuous process in cell cycle. T or F?

A

False, occurs only in one specific stage

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14
Q

Replicated chromosomes are distributed to daughter cells by a _______ _______ series of events under _______ control

A

complex, coordinated, genetic

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15
Q

A typical __________ cell cycle is demonstrated by human cells in culture

A

eukaryotic cell cyle

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16
Q

Human cells in culture divide once in approximately every _______

A

24 hours

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17
Q

Yeast divides in ___________

A

90 minutes

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18
Q

E. Coli divides once every ___________

A

20 minutes

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19
Q

2 basic phases of cell cycle:

A

Interphase

M Phase

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20
Q

All the phases of cell cycle

A 
Gap 1,
Synthesis,
Gap 2, 
Prophase,
Metaphase, 
Anaphase, 
Telophase,
Cytokinesis
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21
Q

___________ phase represents when the actual cell division or mitosis occurs

A

M phase

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22
Q

___________ phase represents the phase between 2 successive M phases

A

Interphase

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23
Q

In 24 duration of human cell cycle, M-phase lasts only about _______

A

an hour

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24
Q

Interphase lasts for more than _____% of the cell cycle

A

95

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25
Q

In human cell in culture, time of each phase? M, G1, S, G2

A

M - 1 hour
G1 - 8-12 hours
S - 6-8 hours
G2 - 3-4 hours

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26
Q

DNA is in the form of _________ in each of the phases: M, G1, S, G2

A

M - chromosome

G1, S, G2 - chromatid

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27
Q

Cell cycle is regulated by ________ which are dependent on _________. Hence the regulators are called: __________

A

kinase (proteins)
cyclin (proteins)
CdK2 - cyclin-dependent kinase

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28
Q

M Phase starts with ________ and ends with ___________

A

nuclear division & separation of daughter chromosomes (karyokinesis);
division of cytoplasm (cytokinesis)

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29
Q

Interphase is aka _________ as cell is preparing for division

A

resting phase

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30
Q

Cell growth and DNA replication happen during the Interphase. T or F?

A

True

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31
Q

What are the 3 phases of interphase?

A

G1 (Gap 1), Synthesis and G2 (Gap 2)

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32
Q

What happens in G1 phase? (4)

A

Maximum cell/cytoplasmic growth
RNA, nucleotides, proteins, amino acids, ATPs are produced
max. cell organelles duplicated
DNA damage repair

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33
Q

What happens in S phase?

A

DNA replication in nucleus

histone synthesis and centriole duplication in cytoplasm

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34
Q

What happens in G2 phase? (4)

A

tubulin proteins synthesized (RNA and protein syn continues)
semi-autonomous organelles duplicate (mitochondria, chloroplast)
Golgi body duplicated
growth occurs but not much

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35
Q

_____ is the longest phase of interphase

_____ is the longest phase of cell cycle

A

G1, G1

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36
Q

_____ phase is shorter in frequently dividing cells (e.g. embryonic cells)

A

G1

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37
Q

What is the major checkpoint in cell cycle? What is it regulated by?

A

G1 —> S

regulated by G1 cyclin and CdK2

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38
Q

What is the minor checkpoint in cell cycle? What is it regulated by?

A

G2 —-> M

regulated by M cyclin and CdK2

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39
Q

_______ is pre-mitotic and post-synthetic

A

G2

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40
Q

_______ is post-mitotic and pre-synthetic

A

G1

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41
Q

________ phase is the interval between mitosis and initiation of replication

A

G1 phase

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42
Q

During _______ phase cell is metabolically active but doesn’t replicate DNA

A

G1

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43
Q

____chromatin replicate first and then ____chromatin

A

Euchromatin, heterochromatic

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44
Q

Amount of DNA per cell and number of chromosomes double during S phase. T or F?

A

False, amount of DNA (chromatid) doubles, but chromosome number is the same

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45
Q

Haploid cell becomes diploid after S phase of cell division. T or F?

A

False, number of chromosomes remains the same

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46
Q

In plant cells, during S phase, DNA replication begins in nucleus and centriole duplicates in the cytoplasm. T or F?

A

False, centriole only present in animal cells

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47
Q

Why is time for G1 phase so variable?

A

Because it is the only phase that depends on external factor (e.g. nutrients)

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48
Q

__________ skips G1 and G2 phase

A

Zygote in cleavage division (size doesn’t increase that much)

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49
Q

Heart cells and many others divide only occasionally, e.g. due to injury or cell death. T or F?

A

Heart cells and neurons do not divide ever, rest is accurate

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50
Q

Cells that do not divide further exit _____ phase to enter an inactive stage called _________

A

G1 phase, quiescent stage (G0)

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51
Q

Cells in G0 stage remain ________ but no longer proliferate unless called to do so.

A

metabolically active

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52
Q

Neurons remain in permanent _____ phase and do not enter ____ phase ever as they do not possess a ______

A

G1, S, centriole

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53
Q

From G1 phase, if cell goes into G0 phase its due to non-availability of _______ and ______

A

mitogen and energy-rich compounds

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54
Q

Once cell enters S phase it has to divide. T or F?

A

True

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55
Q

If a cell differentiates after G1 phase, its role becomes permanently fixed until natural death of cell. T or F?

A

True

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56
Q

Examples of cells that are constantly replaced by mitosis. (4)

A

Upper layer of epidermis,
cells of lining of gut,
blood cells,
cheek cells

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57
Q

In animals, mitotic cell division is only seen in ___________ cells

A

diploid somatic cells

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58
Q

Exceptionally, in some lower plants and social insects, ___________ cells divide by mitosis. Example?

A

haploid;

male honey bees

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59
Q

Plants show mitotic divisions in both haploid and diploid cells. T or F?

A

True

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60
Q

Tubulin protein is made in both plant and animal cell, however centriole and aster is only made in animal cell. T or F?

A

True

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61
Q

________ cell is known as amphiastral whereas ______ cell is known as anastral.

A

Animal, plant

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62
Q

__________ is the most dramatic period of the cell cycle involve reorganisation of virtually all components

A

M Phase

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63
Q

Why is M Phase division also called equational division?

A

Since the number of chromosomes is same in parents and progeny

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64
Q

Cell division is a progressive process with clear-cut lines between the various phases of M Phase. T or F?

A

False, clear cut lines cannot be drawn

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65
Q

Karyokinesis involves which 4 stages?

A

Prophase
Metaphase
Anaphase
Telophase

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66
Q

__________ is the first stage of karyokinesis of mitosis and follows the ______ phases of interphase

A

Prophase, S and G2

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67
Q

How do the new DNA molecules in S and G2 phases look?

A

Intertwined, not distinct

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68
Q

Prophase is marked by __________

A

initiation of condensation of chromosomal material

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69
Q

The centrosome undergoes duplication during which phase?

A

S phase of interphase

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70
Q

During prophase, chromosomes become _______ (tangled/untangled), and are seen to be are composed of _____ (how many?) chromatids attached at _____

A

untangled, two, centromere

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71
Q

During prophase, __________ moves towards opposite poles of the cells. Each radiates out microtubules called ______.

A

centrosome/centrioles

asters

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72
Q

The __________ together with _____________ forms the mitotic/spindle apparatus

A

two asters of centrosome

spindle fibres

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73
Q

At the end of prophase, cells show nuclear envelope, nucleolus, golgi complexes and endoplasmic reticulum. T or F?

A

False, do not show

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74
Q

_____________ marks the start of the metaphase of mitosis.

A

Complete disintegration of the nuclear envelope

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75
Q

________ is aka spireme stage

A

Early prophase

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76
Q

Chromosomes are spread through the cytoplasm of the cell during which stage?

A

Metaphase

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77
Q

In mitosis, by ______ stage condensation of the chromosomes is completed.

A

Metaphase

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78
Q

In _____ phase chromosomes can be easily observed and their morphology is most easily studied.

A

Metaphase

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79
Q

Kinetochores are ______ shaped structures made of ______ at the surface of _________.
In metaphase, what purpose do they serve?

A

Small disc-shaped structures, proteins, centromeres

serve as sites of attachment of spindle fibres

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80
Q

Chromosomes are moved to ______ aligned along the _______ during metaphase, with sister chromatids connected to ________

A

spindle equator,
metaphase plate,
one pole each (opposite poles)

81
Q

Plane of alignment of chromosomes in metaphase is referred to as _________

A

metaphasic OR equatorial plate

82
Q

Complete disintegration of the nuclear envelope is the first phase of ________

83
Q

___________ is the last event of metaphase

A

Chromosomal alignment on metaphase plate

84
Q

At the onset of anaphase, centromeres ________ and chromatids _______

A

split, separate

85
Q

In anaphase, two daughter chromatids are now referred to as ____________

A

daughter chromosomes of future daughter nuclei

86
Q

Daughter chromatids move towards same or opposite poles during anaphase?

87
Q

During anaphase, as the chromosomes move away from equatorial plate, ___________ remains directed towards the pole (at the leading edge) whereas ________ trail behind

A

centromere; arms of chromosome

88
Q

Symmetric vs asymmetric spindle?

A

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
Q

In asymmetrical spindles, chromosomal division is unequal. T or F?

A

False, cytoplasmic division is unequal BUT chromosomal division is still equal

90
Q

_________ is the best phase to observe the shape of the chromosomes

91
Q

What are the shapes of the various chromosomes?

A

metacentric - V
sub-metcentric - L
acrocentric - J
telocentric - I

92
Q

At the beginning of telophase, chromosomes …

A

decondense / lose individuality / elongate

at their respective/opposite spindle poles

93
Q

In telophase, individual chromosomes can be seen for the final time before they cytokinesis. T or F?

A

False, chromosomes can no longer be seen individually

94
Q

During which phase does the nuclear envelope develop at each pole forming daughter nuclei?

95
Q

During which phase do golgi complex, nucleolus and ER form?

96
Q

Spindle fibres degenerate in which phase of mitosis?

97
Q

Cell division is completed at the end of ___________

A

cytokinesis, two daughter cells (not just nuclei) are formed

98
Q

Describe cytokinesis in animal vs plant cell.

A

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
Q

In plants, formation of new cell wall begins with a simple precursor called ________

A

cell-plate

100
Q

Cell-plate represents the ________ between walls of two adjacent cells

A

middle lamella

101
Q

After cytokinesis, plant cells remain connected via ___________

A

plasmodesmata

102
Q

During cytokinesis, organelles get distributed between 2 daughter cells. T or F?

A

True, organelles that are not easily produced (e.g. mitochondria, plastids, chloroplasts)

103
Q

In some organisms karyokinesis is not followed by cytokinesis which results in multinucleate condition => formation of ___________. Example?

A

syncytium e.g. liquid endosperm in coconut

104
Q

In some lower plants, cleavage occurs and not cell plate formation. T or F?

Example?

A

True, unicellular algae (e.g. chlamydomonas) - cells don’t need to be connected after division

105
Q

Equational division is usually restricted to diploid cell. T or F?

A

True, key word here is USUALLY

106
Q

Meiosis is ALWAYS restricted to diploid cells only. T or F?

107
Q

___________ disturbs the ratio between nucleus and cytoplasm. _______ restores it.

A

Cell growth, cell division

108
Q

Cell repair is a significant contribution of which type of division?

109
Q

Mitotic divisions in _______ tissues in plants result in continuous growth throughout their life.

A

Meristematic (apical, lateral cambium, intercalary)

110
Q

Type of cell division that forms gametes: _______.

111
Q

In meiosis the chromosome number remains the same. T or F?

A

False, halves

112
Q

Haploid daughter cells are formed by ________ type of cell division

113
Q

__________ ensures the production of haploid phase in life cycle of sexually reproducing organisms, whereas __________ restores the diploid phase

A

Meiosis; fertilization

114
Q

Process in plants and animals that requires meiosis?

A

Gametogenesis

115
Q

Meiosis consists of ______ sequential cycles of nuclear division, ______ cycles of cell division and ______ cycles of DNA replication

A

two, two, one

116
Q

Pairing of homologous chromosomes and re-combination b/w non-sister chromosomes occurs in __________ (mitosis / meiosis)

117
Q

How many haploid cells are formed at the end of meiosis?

118
Q

Assume diploid cell with 12 chromosomes. Describe number of chromosomes, chromatids, ploidy and amount of DNA through mitosis (G1, G2, anaphase, after cytokinesis?)

A

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
Q

Assume haploid cell with 12 chromosomes. Describe number of chromosomes, chromatids, ploidy and amount of DNA through mitosis (G1, G2, anaphase, after cytokinesis?)

A

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
Q

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)

A

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
Q

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)

A

Haploid cells cannot undergo meiosis

122
Q

Prophase I of first meiotic divisions is _______ (shorter / longer) and _______ (complexity?) compared to prophase of mitosis

A

typically longer, more complex

123
Q

Prophase I is divided into how many phases? What are they?

A

5

Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis
124
Q

What happens in leptotene? (1)

A

Compaction/condensation of chromosomes (initiates and throughout)

125
Q

What happens in zygotene? (3)

A

Synapsis - homologous chromosome pairing together
Formation of synaptonemal complex
Formation of bivalent tetrad

126
Q

What happens in pachytene? (3)

A

4 chromatids become distinct and bivalents/tetrads more clearly visible
Recombination modules
Crossing over

127
Q

What happens in diplotene? (3)

A

Dissolution of synaptonemal complex
Recombined homologous chromosomes separate
Formation of chiasmata

128
Q

What happens in diakinesis? (4)

A

Terminalisation of chiasmata
Rest of prophase processes: chromosomes fully condensed, meiotic spindles assembled, ER, golgi, nucleolus and nuclear envelope disappear

129
Q

In ______ stage of prophase I, chromosomes became gradually visible under the light microscope.

130
Q

Compaction of chromosomes continues throughout leptotene. T or F?

131
Q

During ______ phase of Meiosis I, chromosomes become gradually visible under the light microscope

132
Q

What is synapsis?

A

Process of association in zygotene stage, chromosomes start pairing together (homologous chromosomes)

133
Q

What is synaptonemal complex?

A

proteinaceous complex structure

holds together homologous chromosomes

134
Q

Electron micrographs at _______ stage show synaptonemal complex

135
Q

Bivalent and/or synaptonemal complex is more clearly visible in _______ phase

A

Pachytene (even though formed in zygotene)

136
Q

Pachytene is short-lived compared to leptotene and zygotene. T or F?

A

False, reverse.

137
Q

Chromosome synapsis is accompanied by formation of synaptonemal complex. T or F?

138
Q

What are recombination nodules?

A

Enzyme complexes

Sites at which crossing over occurs between non-sister chromatids of homologous chromosomes.

139
Q

________ enzyme is responsible for crossing over

A

recombinase

140
Q

What is crossing over?

A

Exchange of genetic information between 2 homologous chromatids

141
Q

Is crossing over an enzyme-mediated process? If yes, which enzyme?

A

Yes, recombinase

142
Q

Recombination between homologous chromosomes is completed by the end of pachytene and chromosomes become unlinked. T or F?

A

False, recombination is completed but chromosomes remain linked

143
Q

Dissolution of synaptonemal complex and separation of recombinant homologous chromosomes occurs in _______ phase

144
Q

Chromosomes separate at sites of crossovers in diplotene. T or F?

A

False, separate except at the sites of crossovers.

145
Q

Chromosomes in diplotene form _____-shaped structures called ________

A

X-shaped

chiasmata

146
Q

In oocytes of some vertebrates, diplotene can last months or years. T or F?

A

True, called dictyotene

147
Q

Terminalisation of chiasmata occurs in which stage?

A

Diakinesis, final stage

148
Q

In meiosis, chromosomes are fully condensed in which stage?

A

Diakinesis

149
Q

Meiotic spindle is assembled in which phase to prepare homologous chromosomes for separation?

A

Diakinesis

150
Q

_______ represents the transition to metaphase I

A

Diakinesis

151
Q

In metaphase I, bivalent chromosomes align on ____________. The _______ from opposite poles of the spindle attach to the ___________ of homologous chromosomes.

A

equatorial plate,
microtubules,
kinetochore

152
Q

In anaphase I, _________ separate while _______ remain associated at their centromeres.

A

Homologous chromosomes, sister chromatids

153
Q

Cell goes from diploid to haploid in which stage?

A

Anaphase I

154
Q

Disjunction vs segregation?

A

Disjunction - chiasmata disappears => non-sister chromatids no longer attached
Segregation - homologous chromosomes separate => move towards opposite poles

155
Q

Disjunction and segregation occur in __________

A

anaphase I

156
Q

In telophase I, ________ and _______ re-appear

A

nuclear membrane, nucleolus

157
Q

What is univalent dyad?

A

In telophase I, after cytokinesis 2 daughter cells are formed. Each is a dyad. (1 chromosome, 2 chromatids)

158
Q

At the end of telophase I, chromosomes undergo dispersion and become extremely extended like in interphase nucleus. T or F?

A

False, they do not reach the extremely extended state of interphase nucleus.

159
Q

What is interkinesis?

A

Stage between 2 meiotic divisions,
short-lived,
chromosomes undergo some dispersion but not extended state like interphase nucleus

160
Q

During interkinesis, DNA and centrioles double. T or F?

A

False, centriole double but DNA does NOT

161
Q

Prophase I is much simpler prophase than Prophase II. T or F?

A

False, other way around

162
Q

Mendel’s Law of _________ can be observed in _______ stage of meiosis

A

Independent Assortment, anaphase I

163
Q

Meiosis II is immediately initiated after cytokinesis of Meiosis I, before chromosomes have fully elongated. T or F?

164
Q

__________ leads to aneuploidy

A

Non-disjunction in anaphase I

165
Q

Meiosis II resembles a normal mitosis. T or F?

166
Q

In metaphase I, the microtubules get attached to the kinetochore of _________.

In metaphase II, they get attached to kinetochore of _________.

A

homologous chromosomes,

sister chromatids

167
Q

In _________ simultaneous splitting occurs of ________

A

anaphase II, centromere of each chromosome

168
Q

Differentiate between anaphase I and anaphase II

A

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
Q

________ is the mechanism by which conservation of specific chromosome number of each species is achieved.

170
Q

__________ increases the genetic variability.

Mitosis / Meiosis

171
Q

Any sexually reproducing organism starts its life cycle from a single-celled zygote. T or F?

172
Q

Most of the organelle duplication happens during _____ phase

173
Q

______ is the phase where cell grows and carries out normal metabolism

174
Q

Meiosis is aka _________ division

175
Q

In _______ phase, each pole receives half the chromosome number as parent cell.

A

anaphase I

176
Q

During ___________ (anaphase I or II), sister chromatids separate.

A

Anaphase II

177
Q

In mitosis, chromosome condensation is completed in _______ whereas in meiosis I it is completed in _______

A

metaphase, prophase I

178
Q

1 chromosome is attached to 2 spindle fibres in _______ whereas a PAIR of chromosomes is attached to 2 spindle fibres in ________

A

mitosis, meiosis I

179
Q

The number of spindle fibres are same as number of chromosomes in _________ (mitosis or meiosis)

180
Q

Electron micrographs at _______ stage show synaptonemal complex

181
Q

Arrange in order of time taken: Prophase, Metaphase, Anaphase, Telophase

A

Prophase > Telophase > Metaphase > Anaphase

182
Q

What is APC?

A

anaphase promoting complex

enzyme that digests cohesin

183
Q

APC is responsible for ___________

A

digesting cohesin so that sister chromatids can separate

184
Q

What is cohesin?

A

Protein that holds sister chromatids together at centromere

185
Q

________ occurs when APC is non-functional

186
Q

___________ is responsible for polyploidy

A

Mitotic poison e.g. colcichine

187
Q

What is colcichine? What happens when it is applied to cell?

A

Mitotic poison

Sister chromatids separated by APC BUT spindle fibres not attached => chromosome number doubles

188
Q

_________ results in a whole new set of chromosomes whereas _________ results in abnormal number of chromosomes

A

Polyploidy, aneuploidy

189
Q

Types of meiosis? and in what organisms do they occur?

A

Sporic - bryophytes, pteridophytes, gymnosperms, angiosperms
Zygotic - algae
Gametic - animals e.g. humans

190
Q

Both sporic and zygotic meiosis produce spores. T or F?

191
Q

In zygotic meiosis, sporophyte is produced which undergoes meiosis to produce spores. T or F?

A

False, in zygotic meiosis there’s no sporophyte - zygote undergoes meiosis

192
Q

Sporophyte is ______cellular whereas zygote is ____cellular

A

multi, uni

193
Q

Gametophyte is _____cellular

194
Q

In what phases of meiosis does variation occur?

A

Pachytene - recombination

Anaphase I - independent assortment / chromosomes distributed into 2 different cells

195
Q

Anaphase I vs Anaphase II

A

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
Q

1 meiosis produces _____ pollen and _____ eggs

197
Q 
Ploidy and DNA amount of the following: 
oogonia
primary oocyte
secondary oocyte
first polar body
ootid
second polar body
A 
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
Q

Which ions are essential for assembly of microtubules?

A

Ca2+ and Mg2+

199
Q

Rank phases of karyokinesis from shortest to longest

A

Anaphase > Metaphase > Telophase > Prophase

Biology (NCERT) - Class XI (23 decks)

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