Cell Cycle Flashcards
Yeast can progress through the cell cycle in only about……..minutes.
90
The interphase lasts more than……..of the duration of cell cycle.
95%
Statement 1: The chromosomal material becomes untangled during the process of chromatin condensation.
Statement 2: The centrosome, which had undergone duplication during S phase of interphase, now begins to move towards opposite poles of the cell.
Determine the phase of mitosis
Prophase
The completion of prophase can thus be marked by the following characteristic events:
Chromosomal material condenses to form compact mitotic chromosomes.
Chromosomes are seen to be composed of two chromatids attached together at the centromere.
Centrosome which had undergone duplication during interphase, begins to move towards opposite poles of the cell.
Each centrosome radiates out microtubules called asters. The two asters together with spindle fibres forms mitotic apparatus.
Cells at the end of………..when viewed under the microscope, do not show golgi complexes, endoplasmic reticulum, nucleolus and the nuclear envelope.
prophase
Statement 1: The complete disintegration of the nuclear envelope marks the start of the second phase of mitosis, hence the chromosomes are spread through the cytoplasm of the cell
Statement 2: By this stage, condensation of chromosomes is completed and they can be observed clearly under the microscope.
Determine the phase
Metaphase
The stage at which morphology of chromosomes is most easily studied
Metaphase
On splitting the chromosome appear of different shapes
V shape Metacentric
L shape Sub metacentric
J shape Acrocentric
I shape Telocentric
Statement 1: During leptotene stage the chromosomes become gradually visible under the light microscope. Statement 2: The compaction of chromosomes continues throughout leptotene
Both are correct
At leptotene we observe bouquet stage ie ends of chromosomes converge towards centrosomes
During this stage chromosomes start pairing together and this process of association is called synapsis.9 Such paired chromosomes are called homologous chromosomes.
Determine stage
Zygotene
Electron micrographs of stage…………..indicate that chromosome synapsis is accompanied by the formation of complex structure called synaptonemal complex
Zygotene
Statement 1: During this stage, the four chromatids of each bivalent chromosomes becomes distinct and clearly appears as tetrads.
Statement 2: This stage is characterised by the appearance of recombination nodules, the sites at which crossing over occurs between non-sister chromatids of the homologous chromosomes.
Determine stage
Pachytene
Synaptonemal complex becomes clearly visible at Zygotene stage.
True or false
False
It’s at pachytene
Statement 1: The beginning of diplotene is recognised by the dissolution of the synaptonemal complex.
Statement 2: There is tendency of the recombined homologous chromosomes of the bivalents to separate from each other except at the sites of crossovers
Both are correct
Define chiasmata
A point of physical linkage or contact between non sister chromatids of homologous chromosomes. These are X shaped structures
The final stage of meiotic prophase I is……….. This is marked by terminalisation of……….
diakinesis
chiasmata
The stage between the two meiotic divisions is called interkinesis and is generally long
True or false
False
It is short lived
Lampbrush chromosome
Decondensed diplotene chromosome
Disjunction of chromosomes
Homologous chromosomes separate while sister chromatid remain associated with their centromere
In some the telophase I and prophase II is omitted and direct jump to metaphase II
Yes, This streamlined process happens in some organisms where rapid meiotic division is advantageous, such as in certain plants and animals with specific evolutionary adaptations. This variation can help expedite the cell cycle.
Example: Trillium a plant
If cell is preparing for mitosis then it is in which phase
G2
The point in animal cell cycle at which the cell becomes committed to cell cycle or division is
G1 phase
