Cell cycle and cell division.

Question 1

Define the term cell cycle?

Answer 1

“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.”

Question 2

Define the term cell division?

Answer 2

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

Question 3

The term cell cycle was introduced by_______?

Answer 3

Howard and Pele.

Question 4

The humans cell cycle duration is________?

Answer 4

24 hours.

Question 5

What are the phases of cell cycle?

Answer 5

 Interphase
 Mitotic phase

Question 6

Interphase is also known as ________ and _______.

Answer 6

preparation phase or resting phase.

Question 7

Mention the phase of interphase.

Answer 7

 G1 phase
 S phase
 G2 phase

Question 8

Which phase is the longest in the cell cycle?

Answer 8

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

Question 9

Mention two major type of cell division?

Answer 9

 Mitosis
 Meiosis

Question 10

Which stain is used to color chromosomes?

Answer 10

Acetocarmine and Giemsa

Question 11

Division of nucleus is called as_______?

Answer 11

Karyokinesis.

Question 12

Division of cytoplasm is called as_________?

Answer 12

cytokinesis.

Question 13

Is Karyokinesis and Cytokinesis dependent on each other?

Answer 13

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

Question 14

What happens during karyokinesis?

Answer 14

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

Question 15

Describe the events of G1 phase taking place during interphase.

Answer 15

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

Question 16

Describe the events of S phase taking place during interphase

Answer 16

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.

Question 17

Describe the events of G2 phase taking place during interphase.

Answer 17

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

Question 18

Among karyokinesis and cytokinesis, which process occurs first?

Answer 18

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

Question 19

What is the significance of mitosis?

Answer 19

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

Question 20

Why is mitosis called equational division?

Answer 20

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

Question 21

What are mitocytes?

Answer 21

The cells in which mitosis occurs are called mitocytes

Question 22

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

Answer 22

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

Question 23

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

Answer 23

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.

Question 24

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

Answer 24

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.

Question 25

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

Answer 25

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.

Question 26

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

Answer 26

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

Question 27

What is the role of centrioles apart from spindle formation?

Answer 27

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.

Question 28

Where does meiosis occur?

Answer 28

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

Question 29

What are meiocytes?

Answer 29

The cells that undergo meiosis are called meiocytes

Question 30

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

Answer 30

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

Question 31

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

Answer 31

Prophase

Question 32

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

Answer 32

Telophase

Question 33

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

Answer 33

Anaphase

Question 34

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

Answer 34

S phase

Question 35

Name the different phases of meiotic prophase – I

Answer 35

 Leptotene
 Zygotene
 Pachytene
 Diplotene
 Diakinesis.

Question 36

Crossing over occurs in the _________ stage of meiosis.

Answer 36

Pachytene.

Question 37

What is crossing over?

Answer 37

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

Question 38

Crossing over is initiated and mediated by the enzyme_______________.

Answer 38

Recombinase.

Question 39

The stage between two meiotic divisions is called as ________?

Answer 39

Interkinesis.

Question 40

What is the significance of meiosis?

Answer 40

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

Question 41

Why is meiosis referred to as reductional division?

Answer 41

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

Question 42

Which cell division is concerned with cancer?

Answer 42

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

Question 43

Which cell division is concerned with cancer?

Answer 43

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

Question 44

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?

Answer 44

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.

Question 45

Define homologous chromosomes?

Answer 45

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