3.2.2 Cells - cell cycle and mitosis

Question 1

how do eukaryotic cells divide?

Answer 1

divide by mitosis or meiosis

Question 2

how do prokaryotic cells divide?

Answer 2

prokaryotic cells replicate by binary fission

Question 3

do viruses undergo cell division?

Answer 3

viruses do not undergo cell division as they are non-living

Question 4

what is the process of binary fission?

Answer 4

binary fission involves the circular DNA and plasmids (if present) replicating

then the cytoplasm splitting to create two daughter cells

each daughter cell has one copy of the circular DNA, but a variable number of plasmid copies

Question 5

where does viral replication occur?

Answer 5

inside the host cells and involves the injection of nucleic acid into the cell

Question 6

what are the three main stages of the cell cycle?

Answer 6

interphase (G1, S, G2)

nuclear division (mitosis or meiosis)

cytokinesis

Question 7

what happens during interphase?

Answer 7

the longest stage in the cell cycle

interphase is when the organelles duplicate, the cell grows and then DNA replicates

Question 8

what does mitosis create?

Answer 8

creating two identical diploid cells

mitosis creates cells with identical DNA for growth and repair

Question 9

what does meiosis create?

Answer 9

creating four genetically different haploid cells

meiosis creates gametes

Question 10

what is cytokinesis?

Answer 10

the division of the cytoplasm to create new daughter cells

Question 11

what are the 4 key stages of mitosis?

Answer 11

Prophase

Metaphase

Anaphase

Telophase

Question 12

what happens during prophase of mitosis?

Answer 12

chromatin condenses into chromosomes and the nucleolus disappears

Question 13

what happens during metaphase of mitosis?

Answer 13

chromosomes line up along the metaphase plate (imaginary plate)

Question 14

what happens during anaphase of mitosis?

Answer 14

chromosomes break at centromeres, and sister chromatids move to opposite ends of the cell

Question 15

what happens during telophase of mitosis and cytokinesis?

Answer 15

the chromosomes are now at each pole of the cell and become
longer and thinner again

The spindle fibers disintegrate, and the nucleus starts to reform.
The final stage in the cell cycle is when the cytoplasm splits in two to create the two new genetically identical cells

Question 16

what is the equation for mitotic index?

Answer 16

the number of cells in mitosis
——————————————— x100
the total number of cells

Question 17

What is the process by which eukaryotic cells divide?

Answer 17

Mitosis and meiosis

Mitosis results in two identical diploid cells, while meiosis results in four genetically different haploid cells.

Question 18

What are the three key stages of the cell cycle?

Answer 18

Interphase, nuclear division, cytokinesis

Interphase includes G1, S, and G2 phases.

Question 19

What occurs during the G1 phase of interphase?

Answer 19

Growth

This phase involves the cell growing and preparing for DNA synthesis.

Question 20

What is the S phase of interphase responsible for?

Answer 20

DNA synthesis

During this phase, the cell replicates its DNA.

Question 21

What happens in the G2 phase of interphase?

Answer 21

Growth and preparation for mitosis

This phase ensures the cell is ready for mitosis.

Question 22

What is mitosis?

Answer 22

Nuclear division creating two identical diploid cells

Mitosis is essential for growth and repair.

Question 23

What is meiosis?

Answer 23

Nuclear division creating four genetically different haploid cells

Meiosis is crucial for producing gametes.

Question 24

What is cytokinesis?

Answer 24

Division of the cytoplasm to create new daughter cells

Cytokinesis occurs after nuclear division.

Question 25

How do prokaryotic cells replicate?

Answer 25

Binary fission ## Footnote This process involves the circular DNA and plasmids replicating before the cytoplasm splits.

Question 26

What is binary fission?

Answer 26

A method of replication for prokaryotic cells ## Footnote It involves the replication of circular DNA and plasmids and subsequent division of the cytoplasm.

Question 27

Do viruses undergo cell division?

Answer 27

No ## Footnote Viruses are non-living and replicate inside host cells by injecting nucleic acid.

Question 28

What is the longest stage in the cell cycle?

Answer 28

Interphase ## Footnote This stage includes organelle duplication, cell growth, and DNA replication.

Question 29

What is mitosis?

Answer 29

Mitosis involves one round of division and results in two diploid, genetically identical daughter cells.

Question 30

What are the main purposes of mitosis?

Answer 30

Mitosis is for growth and repair.

Question 31

What is the first stage of mitosis?

Answer 31

Prophase

Question 32

What happens during prophase?

Answer 32

The chromosomes condense and become visible, and the nuclear envelope disintegrates.

Question 33

What is the role of centrioles in mitosis?

Answer 33

Centrioles separate and move to opposite poles of the cell, creating spindle fibres.

Question 34

Which cells lack centrioles but have a spindle apparatus?

Answer 34

Plant cells

Question 35

What is the second stage of mitosis?

Answer 35

Metaphase

Question 36

What is the third stage of mitosis?

Answer 36

Anaphase

Question 37

What is the fourth stage of mitosis?

Answer 37

Telophase

Question 38

Fill in the blank: Mitosis results in two _______ cells.

Answer 38

diploid

Question 39

Fill in the blank: During prophase, the nucleolus _______.

Answer 39

disappears

Question 40

True or False: Mitosis results in genetically diverse daughter cells.

Answer 40

False

Question 41

What structure attaches to the centromere and chromatids during mitosis?

Answer 41

Spindle apparatus

Question 42

What happens to chromatin during prophase?

Answer 42

Chromatin condenses into chromosomes.

Question 43

What is the significance of the spindle fibres?

Answer 43

They attach to the centromere and chromatids on the chromosome in later stages.

Question 44

What happens to chromosomes during metaphase?

Answer 44

The chromosomes align along the equator of the cell ## Footnote The spindle fibres released from the poles attach to the centromere and chromatid.

Question 45

Define 'equator' in the context of cell division.

Answer 45

The imaginary plane where chromosomes line up during metaphase ## Footnote Also referred to as the metaphase plate.

Question 46

What is the role of the centromere?

Answer 46

It is the region where sister chromatids are joined and where spindle fibres attach ## Footnote Essential for proper chromosome movement during cell division.

Question 47

What are chromatids?

Answer 47

The individual strands of a chromosome that are joined at the centromere ## Footnote Each chromatid is a copy of the chromosome.

Question 48

Fill in the blank: During anaphase, the spindle fibres start to _______.

Answer 48

retract

Question 49

What occurs to the centromere during anaphase?

Answer 49

It divides into two ## Footnote This allows sister chromatids to move towards opposite poles.

Question 50

What happens to chromatids during anaphase?

Answer 50

They are pulled to opposite poles and are now referred to as chromosomes ## Footnote This separation is crucial for ensuring each daughter cell receives the correct number of chromosomes.

Question 51

What energy source is required during anaphase?

Answer 51

ATP ## Footnote ATP is provided by respiration in the mitochondria.

Question 52

True or False: During metaphase, chromosomes are randomly distributed within the cell.

Answer 52

False ## Footnote Chromosomes align specifically along the metaphase plate.

Question 53

What is the function of spindle fibres in cell division?

Answer 53

To attach to centromeres and help separate chromatids during anaphase ## Footnote They play a critical role in chromosome movement.

Question 54

What is the final stage in the cell cycle?

Answer 54

Cytokinesis ## Footnote Cytokinesis is when the cytoplasm splits in two to create two new genetically identical cells.

Question 55

What happens to chromosomes during telophase?

Answer 55

Chromosomes unwind into chromatin ## Footnote The chromosomes become longer and thinner again.

Question 56

What reforms during telophase?

Answer 56

Nuclear membrane and nucleoli ## Footnote The nuclear membrane reforms and nucleoli reappear.

Question 57

What is the role of spindle fibres during telophase?

Answer 57

Disintegrate ## Footnote Spindle fibres disintegrate as the cell prepares for cytokinesis.

Question 58

What is the contractile ring made of?

Answer 58

Myosin II and actin filaments ## Footnote These proteins contract to cleave the cell in two.

Question 59

What is a cleavage furrow?

Answer 59

The indentation that forms during cytokinesis ## Footnote It is where the cell membrane pinches in to separate the two new cells.

Question 60

How is the mitotic index calculated?

Answer 60

Mitotic index = (Number of cells in mitosis × 100) / Total number of cells ## Footnote It indicates the proportion of cells undergoing mitosis.

Question 61

If 2 cells are in mitosis and 9 total cells are visible, what is the mitotic index?

Answer 61

22.2% ## Footnote Calculation: (2 × 100) / 9 = 22.2%

Question 62

True or False: The chromosomes become thicker during telophase.

Answer 62

False ## Footnote The chromosomes become longer and thinner during this phase.