Cell cycle and mitosis

Question 1

Mitosis

Answer 1

cell division that produces 2 daugther cells (diploid) that have the same number of chromosomes as the parent cell and each other

Question 2

Stages of mitosis

Answer 2

(interphase)
1. Prophase
2. Anaphase
3. Metaphase
4. Telophase

Question 3

Interphase

Answer 3

the longest period of the cell cycle where cell is not dividing
* cellular activity that includes replication of DNA
* cell spends most of its life here
* copies cell DNA for in preparation for mitosis
* each chromosome is double-stranded, 2 chromatids joined in the centre by a centromere

Question 4

Prophase

Answer 4

first stage in mitosis
* nuclear membrane breaks down and nucleolus disappears
* chromosomes condense and become visible, they shorten and thicken
* centrioles move to opposite poles of the cell and begin to form spindle fibres which span from pole to pole

Question 5

Metaphase

Answer 5

• chromosomes are made of 2 chromaids
• each chromatid is an identical copy of DNA from parent cell
• chromatids are attached by the centromere
• chromosomes are pulled by spindle fibres and line up along the equator of the cell

Question 6

Anaphase

Answer 6

• centromeres splitand chromatides seperate
• spindle fibres pull chromatids apart to opposite poles of the cell
• each chromatid becomes an individual chromosome at new pole
• mitochondria provides energy for this process

Question 7

Telophase

Answer 7

• chromosomes reach their respective poles and uncoil
• chromosomes become longer and thinner, diappearing altogether
• spindle fibres disintergrate
• nucleuar membrane reforms

Question 8

Cytokinesis

Answer 8

• cytoplasm divides forming 2 new daughter cells with 2 distinct nuclei

Question 9

How do cells divide in prokaryotes?

Answer 9

• Binary fission

Question 10

Binary fission

Answer 10

division of prokaryotic cells
1. Circular DNA replicates and both copies attach to cell membrane
2. Plasmids replicate
3. Cell membrane begins to grow between the 2 DNA molecules and begins to pich forward- dividing cytoplasm into 2
4. New cell wall forms between the 2 molecules DNA, 2 identical daughter cells formed, each with a single copy of circular DNA

Question 11

Replication of viruses

Answer 11

viruses are non-living and they cannot undergo cell division
* replicate by attaching to their host cell with their attachment proteins on thei surface
* inject their nucleic acid into the host cell

Question 12

Why is mitosis important?

Answer 12

1. Growth- increases the size of a tissue during development
2. Repair- if cells are damaged or dead new cells produced have an identical structure and function
3. Reproduction- single-celled organisms divide to give 2 new organisms

Question 13

Stages of the cell cycle:

Answer 13

1. Interphase
2. Nuclear divison (nucleus divides into 2, mitosis, or 4, meiosis)
3. Cytokenesis (division of cytplasm to produce 2 or 4 new daughter cells

Question 14

Stages of Interphase

Answer 14

G1- organelles replicate
S- DNA replicates
G2- DNA is repaired and cell is prepared for division