Cell division

Question 1

What is the cell cycle?

Answer 1

The cell cycle is the series of events through which a cell grows, duplicates its DNA, and divides to produce two daughter cells.

Question 2

What are the types of cells and their division frequency?

Answer 2

Rapidly dividing cells: Skin cells, intestinal lining cells.
Rarely dividing cells: Nerve cells, muscle cells.

Question 3

What is mitosis, and what is its function?

Answer 3

Mitosis is the process of nuclear division in somatic cells that ensures each daughter cell receives an identical set of chromosomes. Its main function is growth, repair, and replacement of cells.

Question 4

How many daughter cells are produced during mitosis?

Answer 4

Two daughter cells.

Question 5

What is the chromosomal content of daughter cells after mitosis?

Answer 5

Daughter cells are diploid (2n), with the same number of chromosomes as the parent cell.

Question 6

What are the key events of prophase?

Answer 6

— Chromatin condenses into visible chromosomes.
— The nuclear membrane breaks down.
— The mitotic spindle begins to form.

Question 7

What is the role of centrioles in mitosis?

Answer 7

Centrioles organize the spindle fibers, which help separate sister chromatids during mitosis.

Question 8

What is a parent cell?

Answer 8

The original cell that divides to produce daughter cells.

Question 9

What is a daughter cell?

Answer 9

The two genetically identical cells produced from a parent cell during mitosis.

Question 10

What are sister chromatids?

Answer 10

The two identical copies of a chromosome connected by a centromere after DNA replication.

Question 11

What is a centromere?

Answer 11

The region of a chromosome where sister chromatids are joined and where spindle fibers attach during mitosis.

Question 12

How many cells are produced during meiosis?

Answer 12

Four daughter cells.

Question 13

What is the chromosomal content of daughter cells after meiosis?

Answer 13

Daughter cells are haploid (n), containing half the number of chromosomes as the parent cell.

Question 14

How many divisions occur during meiosis?

Answer 14

Two divisions: meiosis I and meiosis II.

Question 15

Does synapsis and crossing over occur in mitosis or meiosis?

Answer 15

Synapsis and crossing over occur only in meiosis during prophase I, not in mitosis.

Question 16

What is the relationship between DNA, chromosomes, and chromatin?

Answer 16

— DNA is the genetic material that carries instructions for life.
— Chromosomes are condensed structures of DNA and proteins visible during cell division.
— Chromatin is the uncondensed form of DNA found in the nucleus during interphase.

Question 17

What regulates the progression of the cell cycle?

Answer 17

Cyclins and cyclin-dependent kinases (CDKs) regulate the cell cycle by ensuring proper progression through checkpoints.

Question 18

What happens when the cell cycle is not properly regulated?

Answer 18

Unregulated cell division can lead to cancer, where cells divide uncontrollably and invade other tissues.

Question 19

What happens during the G1 phase of interphase?

Answer 19

The cell grows, produces organelles, and performs its normal functions.

Question 20

What happens during the S phase of interphase?

Answer 20

DNA replication occurs, and each chromosome duplicates to form sister chromatids.

Question 21

What happens during the G2 phase of interphase?

Answer 21

The cell prepares for mitosis by synthesizing proteins and ensuring that all DNA is properly replicated.

Question 22

How does cytokinesis differ in plant and animal cells?

Answer 22

— In animal cells, cytokinesis occurs through the formation of a cleavage furrow.
— In plant cells, cytokinesis occurs through the formation of a cell plate.

Question 23

Do plant cells have centrioles?

Answer 23

No, plant cells do not have centrioles, but they can still form a spindle apparatus.

Question 24

What is independent assortment, and when does it occur?

Answer 24

Independent assortment is the random orientation of homologous chromosomes during metaphase I of meiosis, leading to genetic variability.

Question 25

What is crossing over, and when does it occur?

Answer 25

Crossing over is the exchange of genetic material between homologous chromosomes during prophase I, resulting in new allele combinations.

Question 26

What are homologous chromosomes?

Answer 26

Pairs of chromosomes, one from each parent, that have the same genes but may carry different alleles.

Question 27

What is nondisjunction, and what does it cause?

Answer 27

Nondisjunction is the failure of chromosomes to separate properly during meiosis, leading to cells with abnormal numbers of chromosomes (e.g., trisomy 21 causes Down syndrome).

Question 28

What is aneuploidy?

Answer 28

A condition where cells have an abnormal number of chromosomes, often caused by nondisjunction.

Question 29

What is the key difference between asexual and sexual reproduction?

Answer 29

• Asexual reproduction produces offspring genetically identical to the parent.
• Sexual reproduction produces genetically diverse offspring through the combination of gametes.

Question 30

What are some advantages of asexual reproduction?

Answer 30

It is faster, requires only one parent, and produces large numbers of offspring.

Question 31

What are some advantages of sexual reproduction?

Answer 31

It promotes genetic diversity, which increases adaptability to changing environments.

Question 32

What is ploidy?

Answer 32

Ploidy refers to the number of sets of chromosomes in a cell (e.g., diploid = 2n, haploid = n)

Question 33

What is the difference between a haploid and diploid cell?

Answer 33

Haploid (n): One set of chromosomes (e.g., gametes).
Diploid (2n): Two sets of chromosomes, one from each parent (e.g., somatic cells).

Question 34

What is a karyotype?

Answer 34

A karyotype is an organized profile of an individual’s chromosomes, used to identify chromosomal abnormalities.

Question 35

What are two methods for collecting cells to prepare a karyotype?

Answer 35

Amniocentesis and chorionic villus sampling.

Question 36

What are the sources of genetic variability in meiosis?

Answer 36

— Independent assortment of chromosomes.
— Crossing over during prophase I.
— Random fertilization of gametes.