Cell cycle and cell division Flashcards
The two major characteristics of living cells are
Growth and reproduction
The three important events of a cell cycle are
Cell division, DNA replication and cell growth
The sequence of events by which a cell duplicates a genome, synthesises the other constituents of cell and eventually divides into two daughter cells is termed as
Cell cycle
A cell cycle of a typical eukaryotic cell which is illustrated by human cells in culture is completed in
24 hours
A yeast cell can complete one cell cycle is about
90 minutes
A cell cycle is divided into two basic phases, namely
Interphase and M phase(Mitosis phase)
The phase of cell cycle when actual cell division occurs is?
M phase (Mitosis phase)
The phase between two successive M phases is represented by
Interphase
The % duration of interphase during the cell cycle is
more than 95%
The % duration of M phase during the cell cycle is
Less than 5%
M phase starts with the process of
nuclear division
M phase ends with the process of
cytokinesis
The process of separation of daughter chromosomes is called
Karyokinesis
The process of division of cytoplasm is termed as
Cytokinesis
Interphase is also known as
resting phase
During interphase, cell prepares itself for division by undergoing both processes, namely ____ and ____
cell growth and DNA replicaton
The phase during which cell prepares for division is
interphase
Interphase is divided into 3 phases, namely
G1 phase, S phase and G2 phase
The phase which acts as an interval between mitosis and initiation of DNA replication is
G1 phase
The phase in which cell is metabolically active and continuously grows but does not replicate its DNA is
G1 phase
The phase of cell cycle during which DNA replication takes place
Synthesis phase
During S phase, the amount of DNA per cell
doubles
If the chromosome number is 2n, then by the end of S phase, it will be
2n
If the initial amount of DNA is 2C, then by the end of S phase, it will be
4C
In animal cells, during S phase, DNA replication begins in ___
nucleus
Duplication of centriole during S phase occurs in ___
Cytoplasm
Proteins for preparation of M phase are synthesised during ____
G2 phase
The cells of adult animals which do not undergo division are
heart cells
The cells which do not divide further exit G1 phase to enter into an inactive stage are called
Quiescent stage (G0)
The phase of cell cycle in which cells remain metabolically active but donot poliferate unless called upon is
Quiescent stage (G0)
The metabolic stage of cells during G0 phase is
Active
In animals, mitotic cell division is only seen in
diploid somatic cells
In which organisms, haploid cells divide by mitosis?
male honey bees
Reorganisation of virtually all components of the cell occurs during which phase?
M phase
The phase of cell cycle which is called as an equational division is
M phase
The four stages of karyokinesis are namely
Prophase, metaphase, anaphase and telophase
The first stage of karyokinesis occuring after G2 phase is
Prophase
The stage of mitosis marked by the initiation of condensation of chromosomal materials is
Prophase
During prophase, the structure which begins to move towards opposite poles of the cell is
Centrosome
Centrosome duplicates during ____ of interphase
S phase
During prophase, chromosomal material condenses to form compact mitotic ____
chromosomes
Chromosomes are composed of two chromatids attached together at
Centromere
Asters radiating out of centrosome are structurally
microtubules
Each centrosome radiates out microtubules called
asters
Mitotic apparatus is formed by spindle fibres and
2 asters
The component which along with asters form mitotic apparatus is
spindle fibres
The complete disintegration of nuclear envelope marks the start of which phase of mitosis?
metaphase
_____ of chromosomes is completed by the beginning of metaphase
Condensation
Metaphase is the stage to study ____ completely
Morphology of chromosomes
Chromosomes are clearly visible under microscope by which stage of mitosis?
metaphase
Metaphase of chromosomes is composed of
two sister chromatids
Two sister chromatids are held together by
Centromere
Small disc shaped structures at the surface of centromere are called
Kinetochores
The structures that serve as the site for attachment of spindle fibres are
kinetochores
During metaphase, chromosomes are seen to lie at
equator
Chromatids are connected via kinetochores to their respective _____
spindle fibres
The plane of alignment of chromosomes at metaphase is referred as
metaphase plate
Spindle fibres getting attached to kinetochores of chromosomes is the characteristic feature of which phase?
metaphase
The phase of mitosis characterised by splitting of daughter chromatids in order to migrate towards two opposite poles is
anaphase
In anaphase, what migrate towards two opposite poles from equatorial plate?
Daughter chromatids
During which phase centromeres split and chromatids separate?
anaphase
The final stage of karyokinesis is
telophase
The chromosomes that have reached their respective poles decondense during which phase of mitosis?
telophase
Identity of chromosomes is lost as a discrete elements during which mitotic phase?
telophase
______, _______ and _____ are reformed during telophase
Nucleolus, golgi complex and ER
During telophase, _____ develops around chromosome clusters at each pole forming two daughter nuclei
Nuclear envelope
After karyokinesis, cell division gets completed by the process of
cytokinesis
Cytokinesis is achieved by the appearance of a furrow in the plasma membrane of _____ cells
animals
Wall formation starts in the centre of the cell and grows outward to meet the existing lateral walls in ___ cells
plant
The precursor for formation of new cell wall in plant cells is
Cell-plate
The middle lamella between the walls of adjacent plant cells is represented by
cell - plate
The cell organelles which get distributed between two daughter cells during cytokinesis are
mitochondria and plastids
Karyokinesis, when not followed by cytokinesis leads to the formation of
syncytium
Liquid endosperm in coconut is an example of
syncytium
The type of cell division which generally results in the production of diploid cells is
mitosis
Mitosis usually results in production of _____ with identical genetic compliment
diploid daughter cells
The growth of multicellular organisms is due to
mitosis
Cell division is necessary to restore the ____ ratio
nuclear-cytoplasmic
Cells are repaired by which cell division?
mitosis
Continuous growth of plants is due to meristematic tissues by the process _____
mitoss
The cell division that reduces the chromosome number by half in production of haploid in production of haploid daughter cells is
meiosis
The type of cell division which endures the production of haploid phase in life cycle of sexually reproducing organisms is
meiosis
The formation of haploid gametes in both plants and animals occur by
meiosis
Meiosis involves ____ cycles of nuclear and cell division
two sequential
Meiosis involves pairing of which chromosomes?
homologous chromosomes
Two type of cell cycle which involves recombination between non sister chromatids of homologous chromosomes is
meiosis
At the end of meiosis II ____ cells are formed
four haploid
The 5 sub phases of prophase I are
leptotene, zygotene, pachytene, diplotene and diakinesis
The stage of meiosis during which compaction of chromosomes occur is
leptotene
The process of pairing of chromosomes is called
synapsis
Synapsis occurs during which phase of meiosis I?
zygotene
The paired chromosomes are called
homologous chromosomes
Chromosome synapsis is accompained by the formation of complex structure called
synaptonemal complex
The complex formed by a pair of synapsed homologous chromosomes is called
bivalent or tetrad
The two short lived stages of prophase Iare ____ and ____
leptotene and zygotene
The phase of prophase I during which four chromatids of each bivalent chromosome become distinct and clearly appear as tetrads is _____
pachytene
The stage characterised by the appearance of recombination nodules is
pachytene
The sites at which crossing over occurs between non sister chromatids of the homologous chromosomes are called
recombination nodules
The process of the exchange of genetic material between two homologous chromosomes is called
crossing over
The process of crossing over occurs during stage of meiosis?
pachytene
The beginning of which stage is characterised by the dissolution of the synaptonemal complex?
Diplotene
The homologous chromosomes of bivalent tend to separate from each other except at the site of _____
crossovers
The X-shaped structure formed after crossing over is called
chiasmata
Diplotene can last for months or years in _____ of some vertebrates
Oocytes
The final stage of prophase I is
Diakinesis
The stage of prophase marked by terminalisation of chiasmata is
Diakinesis
By the end of diakinesis, nucleolus and nuclear envelope ____
disappears
During which phase, the chromosomes are fully condensed and the meiotic spindle is assembled to prepare the homologous chromosomes for separation?
diakinesis
The bivalent chromosomes align on equatorial plate during which phase of meiosis I?
Metaphase I
The structure which attaches spindle fibres from opposite poles of kinetochore of homologous chromosomes
microtubules
Homologous chromosomes separate while ____ remain associated during anaphase I
Sister chromatids
Dyad of cells is formed by the end of which stage of meiosis I?
telophase I
The stage between two meiotic divisions is called
Interkinesis
The stage of meiosis which is short lived and where no replication of DNA occurs is
Interkinesis
By the end of prophase II, ____membrane diappears
Nuclear
Meiosis II resembles ____
normal mitosis
During metaphase II, chromosomes align at the equator and the microtubules from opposite poles of the spindle get attached to the kinetochores of ___
Sister chromatids
The structure that holds sister chromatids together is
Centromere
The process of meiosis ends with which phase?
telophase II
After telophase II, cytokinesis results in the formation of
four daughter haploid cells/ tetrad
The significance of meiosis is that it conserves ____ of species
chromosome number
The process of meiosis results in reduction of chromosome number by
half
The process of cell division which increases the genetic variability in the population of organisms from one generation to next is
meiosis
