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Biology > Cell Cycle and cell division > Flashcards

Cell Cycle and cell division Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is cell cycle?

A

sequence of events in which a cell duplicates its genome, synthesis other constituents and divides into two daughter cells.

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2
Q

At what rate does the human cell divide?

A

every 24 hours
( 23 hrs - interphase)
(1 hr - M-phase)

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3
Q

What is interphase?

A

Phase where the preparation of the cell for division takes place (or) phase between two successive m-phase

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4
Q

What happens in interphase?

A

cell growth and dna replication

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5
Q

What are the 3 phases of interphase?

A

G1 PHASE
S PHASE
G2 PHASE

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6
Q

What happens in g1 phase?

A

Cell grows
remains metabolically active
Synthesis of rna and proteins
preparation for dna replication

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7
Q

what happens in s phase?

A

DNA synthesis or replication in nucleus.
Amount of DNA doubles
amount of chromosomes remains the same.
Centrioles divides in cytoplasm.

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8
Q

What happens in g2 phase?

A

preparation for mitosis.
synthesis of rna and proteins.
cell growth.

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9
Q

What is G0 phase?

A

Cells that do not divide exits g1 phase and enters an inactive phase called quiescent phase. it is metabolically active but divides only if said so.

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10
Q

What is m-phase?

A

phase where the actual cell division occurs.
Divided into two:
1. karyokinesis
2. cytokinesis

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11
Q

What are the 4 phases of karyokinesis?

A
  1. prophase
  2. metaphase
  3. anaphase
  4. telophase
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12
Q

Explain prophase

A
  1. chromosomal materials gets condensed into chrmosomes
  2. Centrosomes moves towards opposite poles and radiate microtubules called the aster along with spindle fiber.
  3. Nucleolus, nuclear envelop, golgi and er disappears
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13
Q

Explain metaphase.

A
  1. complete condensation takes place.
  2. complete disintegration of nuclear envelop takes place.
  3. kinetochores get attached to the spindle fibers.
  4. chromosomes move to the equator or align at the metaphase plate.
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14
Q

Explain anaphase.

A
  1. centrioles get split and chromosomes seperate and move towards the poles with its arms trailing behind.
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15
Q

Explain telophase.

A
  1. Chromosomes decondenses and loses their individuality.
  2. nucleolus and nuclear envelop reappears.
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16
Q

Explain cytokinesis in both plants and animals.

A

it is the division of cytoplasm.
animals - furrow developing from outwards to the center
plants - wall formation (cell plate) from center to outwards

17
Q

What is the significance of mitosis?

A
  1. the no of chromosomes is maintained.
  2. the genome is the same.
  3. cell repair and replacement.
  4. nucleo-cytoplasmic ratio is maintained.
18
Q

what is meiosis?

A

specialized division by which the chromosomes are reduced in to half and produces haploid daughter cells. eg : gametogenesis in sexual reproduction.

19
Q

what are the features of meiotic division?

A
  1. 2 sequence cycle - meiosis 1 and meiosis 2
  2. meiosis 1 initiates after the production of sister chromatids at s-phase.
  3. pairing of homogenous chromatids and recombination between 2 non-sister chromosomes
  4. 4 haploid cells formed at the end of meiosis 2.
20
Q

Explain prophase 1.

A
  1. Leptotene -chromosomes formation
  2. Zygotene - Chromosomes starts to pair ( synapse ) ( aka bivalent )
  3. pachytene - crossing over occurs and recombination of genetic material takes place.
  4. diplotene - desynapsis begins and bivalent chromosomes seperate. but they are held together by the site of cross over ( chiasmata )
  5. diakinesis - chromosomes are fully condensed and meiotic spindles starts to assemble.
21
Q

Explain metaphase 1.

A

bivalent chromosomes align on the metaphase plate. spindle gets attached to kinetochores

22
Q

Explain anaphase 1.

A

homologous chromosome seperates while sister chromatids remain with centromere.

23
Q

Explain telophase 1.

A

nuclear membrane reappears and results in dyad of cells. dna replication does not take place.

24
Q

Explain prophase 2.

A

chromosomes become compact and nuclear envelop disappears.

25
Q

Explain metaphase 2.

A

chromosomes align with the equatorial plate and spindle attaches to kinetochores.

26
Q

Explain anaphase 2.

A

splitting of chromosomes and moving near the poles.

27
Q

Explain telophase 2.

A

nuclear envelop reappears followed by cytokinesis and forms tetrad of cells.

28
Q

What is the significance of meiosis.

A
  1. Gamete formation
  2. maintains the no of chromosomes
  3. new combinations of genes and variations
  4. becomes diploid after fertilisation.

Biology (4 decks)

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