Cell cycle and cell division. Flashcards

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1
Q

Define the term cell cycle?

A

“The sequence of coordinated, genetically controlled events by which cell duplicates its genome synthesize other constitute of the cells and eventually divides into two daughter cells.”

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2
Q

Define the term cell division?

A

“Cell division is a process by which a mature cell divides and forms two daughter cells similar to its own kind.”

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3
Q

The term cell cycle was introduced by_______?

A

Howard and Pele.

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4
Q

The humans cell cycle duration is________?

A

24 hours.

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5
Q

What are the phases of cell cycle?

A

 Interphase
 Mitotic phase

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6
Q

Interphase is also known as ________ and _______.

A

preparation phase or resting phase.

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7
Q

Mention the phase of interphase.

A

 G1 phase
 S phase
 G2 phase

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8
Q

Which phase is the longest in the cell cycle?

A

Interphase.It is thelongest phase of the cell cycle and is considered the growth phase of the cell cycle in preparation for cell division

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9
Q

Mention two major type of cell division?

A

 Mitosis
 Meiosis

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10
Q

Which stain is used to color chromosomes?

A

Acetocarmine and Giemsa

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11
Q

Division of nucleus is called as_______?

A

Karyokinesis.

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12
Q

Division of cytoplasm is called as_________?

A

cytokinesis.

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13
Q

Is Karyokinesis and Cytokinesis dependent on each other?

A

Karyokinesis is independent of cytokinesis, but cytokinesis is dependent on karyokinesis. (i.e., Karyokinesis can occur without cytokinesis, but the reverse is not possible.

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14
Q

What happens during karyokinesis?

A

During karyokinesis, the nucleus divides into two daughter nuclei. This process
occurs in four steps: -
 Prophase
 Metaphase
 Anaphase and
 Telophase

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15
Q

Describe the events of G1 phase taking place during interphase.

A

G1 phase (Gap phase 1); during this phase the cell is metabolically active and continuously grows but does not replicate its DNA.

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16
Q

Describe the events of S phase taking place during interphase

A

S or synthesis phase marks the period during which DNA synthesis or replication takes place.
During this time the amount of DNA per cell doubles but the chromosome number remain same.
If initial amount of DNA is 2C then it becomes 4C.
The chromosome number after S phase remain same.

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17
Q

Describe the events of G2 phase taking place during interphase.

A

During G2 phase proteins are synthesized in preparation for mitosis while cell growth.

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18
Q

Among karyokinesis and cytokinesis, which process occurs first?

A

Karyokinesis occurs before cytokinesis. The nucleus divides before the cytoplasm.

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19
Q

What is the significance of mitosis?

A

 Maintain the ratio of nucleoplasm and cytoplasm
 Distributes equal and identical genetic complement to daughter cells
 Growth of multicellular organisms
 Regeneration and repair

20
Q

Why is mitosis called equational division?

A

Mitosis is called equational division becauseit keeps chromosomes
number constant and genetic stability in daughter cells.

21
Q

What are mitocytes?

A

The cells in which mitosis occurs are called mitocytes

22
Q

What is the stage of cell division in which paired homologous
chromosomes get short and thick?

A

Pachytene is a stage of cell division during which paired homologous chromosomes become shorter and thicker.

23
Q

Which human body part can be used to depict the stages of mitosis?

A

Except for germinal cells, all cells in thehuman body are somatic cells.
The somatic cells divide by mitosis for regeneration and growth, which can be
used to demonstrate mitosis.

24
Q

Does meiosis occur in a variety of plant and animal tissues?

A

Yes, meiosis occurs in plants and animals. Meiosis occurs in the germ
cells or sex cells of female and male reproductive organin animals and plants,
resulting in the production of female and male gametes for sexual reproduction.

25
Q

Which cell among eukaryotes and prokaryotes has the shorter cell division
time?

A

In comparison toeukaryotic cells,prokaryotic cellshave a shorter cell cycle.
The cell division process of prokaryotes is less complicated and is a faster process than the cell division in eukaryotes.

26
Q

The asters of the spindle are formed by which animal cell structure?

A

The centrosome is the component of an animal cell that generates the spindle’s asters. The centrosome is present only in the animal cell.

27
Q

What is the role of centrioles apart from spindle formation?

A

In the centrosome, the two centrioles align perpendicular to each other, organized in a cartwheel pattern. Besides the spindle fibre formation seen in animal cell division, they form the basal body of cilia and flagella of animal or plant cells. They also assist in the formation of the sperm tail and microtubules.

28
Q

Where does meiosis occur?

A

Meiosis happens duringgametogenesis. It takes place in reproductive cells and germ cells. It occurs in germ cells as they need to grow and develop complex organ structures of its parents that results in cell division

29
Q

What are meiocytes?

A

The cells that undergo meiosis are called meiocytes

30
Q

During nuclear divisions like mitosis, what happens to the DNA of plastids
and mitochondria?

A

Chloroplastsandmitochondriacarry extrachromosomal DNA and do not participate in nuclear division. Mitosis involves just nuclear DNA.

31
Q

The disintegration of the nuclear membrane takes place in which phase of cell cycle.

A

Prophase

32
Q

The appearance of the nucleolus takes place in which phase of cell cycle.

A

Telophase

33
Q

Division of centromere takes place in which phase of cell cycle.

A

Anaphase

34
Q

Replication of DNA takes place in which phase of cell cycle.

A

S phase

35
Q

Name the different phases of meiotic prophase – I

A

 Leptotene
 Zygotene
 Pachytene
 Diplotene
 Diakinesis.

36
Q

Crossing over occurs in the _________ stage of meiosis.

A

Pachytene.

37
Q

What is crossing over?

A

Crossing over is the exchange of genetic material between two homologous chromosomes.

38
Q

Crossing over is initiated and mediated by the enzyme_______________.

A

Recombinase.

39
Q

The stage between two meiotic divisions is called as ________?

A

Interkinesis.

40
Q

What is the significance of meiosis?

A

 Maintenance or conservation of specific chromosomes number of each
species across generation
 Introduces genetic variability
 Essential for adaptation and evolution

41
Q

Why is meiosis referred to as reductional division?

A

Meiosis is called reductional division because thenumber of chromosomes in the daughter cells are half that of the parent cell.

42
Q

Which cell division is concerned with cancer?

A

Cancer is concerned withmitosis, a type of cell division. The uncontrolled division of cells allows tumours to grow and spread cancer.

43
Q

Which cell division is concerned with cancer?

A

Cancer is concerned withmitosis, a type of cell division. The uncontrolled
division of cells allows tumor to grow and spread cancer.

44
Q

If the average duplication time of E. Coli cells is 20 minutes, how long will it
take two E. Coli cells to become 32 cells?

A

Ans:It will take 1 hour and 20 minutes to complete. There are four subsequent cell divisions, each of which produces 16 cells and takes a total of 20 minutes. As a result, the total time is equal to 20 x 4 = 80 minutes, or one hour and twenty minutes. As a result, one cell can produce 16 cells in 80 minutes and twocellscan produce 32 cells in 1 hour and 20 minutes.

45
Q

Define homologous chromosomes?

A

Homologous chromosomes are defined as pairs of chromosomes that share genes that control the same set of traits.