Cell Cycle And Cell Division Flashcards
During the division of cell , ______ and ______ also takes place .
DNA replication
Cell growth
Although ______ is a continuous process , _____ occurs only during one specific stage in the cell cycle .
Cell growth
DNA synthesis
Cell growth in terms of _______is a continuous process .
Cytoplasmic increase
A typical eukaryotic human cell has a cell cycle of _____hours .
24
Cell cycle of yeast lasts for about -
90 minutes
The 2 basic phases of cell cycle -
Interphase
M Phase /Mitosis
In the average life cycle of 24 hours , cell division proper lasts for only about -
1 hour
The ______ lasts for more than 95% of the duration of the cell cycle .
Interphase
M phase of cell cycle starts with the _______division called ____ .
Nuclear
Karyokinesis
Division of cytoplasm called ______ occurs after karyokinesis .
Cytokinesis
During interphase , the cell is undergoing both ______ and _____ in an orderly manner .
Cell growth
DNA replication
Interphase is divided into -
3 sub phases -
G1
S
G2
______ phase corresponds to the interval between mitosis and DNA replication .
G1
During G1 phase , the cell is ________and _______ but DOES NOT REPLICATE ITS DNA .
METABOLICALLY ACTIVE
CONTINUOUSLY GROWS
S phase marks the period during which _______ takes place .
DNA synthesis or replication
During S phase , the amount of ______ per cell doubles .
DNA
During S phase , there is no increase in _______ .
Chromosome number .
At G1 , if the cell had 2n chromosomes , then after S phase , the number will still be 2n .
In animal cells , during the S phase , DNA replication begins in the _______ and the _______ duplicates in the cytoplasm .
Nucleus
Centriole
During G2 phase , _____ are synthesised in preparation for mitosis while ________ continues .
Proteins
Cell growth
Some cells in animals do not appear to exhibit division . Example-
Heart cells
The cells that do not divide further ______ G1 phase to enter an INACTIVE stage called QUIESCENT STAGE (G0).
Exit
G0 stage is achieved when cells exit ______.
G1
Cells in this stage remain metabolically active but no longer proliferate unless called on to do so .
Quiescent stage
In ______ , mitotic division is only seen in diploid somatic cells . Against this , ________ can show mitosis in both HAPLOID and DIPLOID cells .
Animals
Plants
Exception of a animal where mitosis is seen in haploid cells .
Male honey bees
This is the most dramatic period of the cell cycle , involving a major reorganisation of virtually all components of the cell .
M phase - mitosis
Since the number of ________ in the parent and the progeny is same , mitosis is also called _________.
equational division
Mitosis has beeen divided into 4 stages of ______ division .
Nuclear -karyokinesis
Prophase of mitosis follows ___ phases of interphase .
S and G2
In ______phases the new DNA molecules formed are not distinct but intertwined .
S and G2
Prophase is marked by the initiation of _______ .
Condensation of chromosomal materials
The centrosome which had undergone duplication in the ______ phase , begins to move towards opposite poles in prophase .
S phase
Completion of prophase is marked by -
Late prophase
Chromosomal material condenses to form chromosomes
Chromosomes are composed of 2 chromatids joined at the centromere .
Centrosomes move to opposite poles .
2 asters along with spindle fibres form mitotic apparatus .
During late prophase , each _______ radiates out MICROTUBULES called ASTERS .
Centrosome
Mitotic apparatus consists of -
2 asters together with spindle fibres
Disappearance of organelles occurs during late/early prophase .
Late
Difference between early and late prophase .state different events .
Early - initiation of chromosome condensation ; centrosome moves to opposite poles
Late- compact chromosomes formed wth sister chromatids joined at centromere ; centrosome radiates out asters ; organelles disappear ( including nucleolus and nuclear envelope )
Nucleolus and nuclear envelope disappears during -
Late prophase ( end )
______ marks the start of 2nd phase of mitosis - metaphase .
Complete disintegration of nuclear envelope
In _____ phase , chromosomes are spread throughout the cytoplasm of the cell .
Metaphase
By this stage , condensation of chromosomes is completed and they can be observed clearly under the microscope .
Metaphase
Metaphase is the best stage to study the _______ of chromosomes .
Morphology
_______ chromosome is made up of 2 sister chromatids joined at the centromere .
Metaphase
Small disc shaped structures on the surface of centromeres are called _____ ans they can be seen in ________ phase .
KINETOCHORES
Metaphase - for attachment of spindle
KINETOCHORES are formed by __________ during ________ phase
Spindle fibres
Metaphase
______ serve as sites of attachment of spindle fibres .
KINETOCHORES
_______ phase is characterised by on chromatids of each chromosome connected by its kinetochore to spindle fibres from one pole and its sister chromatid connected by its kinetochore to spindle fibres from opposite pole .
Metaphase
Arranged at equator
The plane of allignment of the chromosomes at metaphase is referred to as ______ .
Metaphase plate
Features of metaphase -
Spindle fibres attach to KINETOCHORES of chromosomes .
Chromosomes aligned at the equator
During anaphase , daughter chromatids are referred to as __________.
Daughter chromosomes of the future nuclei
What happens in early anaphase ?
Each chromosome is split simultaneously and the 2 daughter chromatids migrate towards opposite poles .
As each chromosome moves away from the equatorial plate , the _______ of each chromosome remains directed towards the POLE and hence at the LEADING EDGE , with the _______ of the chromosome trailing behind .
Centromere
Arms
Chromatids move to opposite poles during late/early anaphase .
Late
Early - chromatids separate
At the beginning of telophase , _______ that have reached opposite poles DECONDENSE and ___________ .
Chromosomes
Lose their individuality
Decondensation of chromosomes occurs in early /late telophase .
Early
In early telophase , individual chromosomes can no longer be seen and a set of ________ tends to collect at each pole
Chromatin material