5- mitotic cell cycle

Question 1

Importance of mitosis:

Answer 1

Growth of multicellular organisms: production of genetically identical cells ensures all new cells have same genetic material as original, maintaining organism’s characteristics
Replacement of dead/damaged cells: ensures functionality of tissues maintained without altering DNA composition
Tissue repair by cell replacement
Asexual reproduction: organisms reproduce without need for gametes/fertilisation. Produces offspring genetically identical to parent, ensuring survival in stable environments

Question 2

Telomeres:

Answer 2

repetitive sequences of non-coding DNA found at ends of eukaryotic chromosomes

Question 3

Role of telomeres:

Answer 3

• prevent loss of genes during division
• allow continued cell division
• prevent shortening of chromosomes

Question 4

When are chromatids formed?

Answer 4

during the interphase of the replication of the DNA strand.

Question 5

prophase

Answer 5

• chromosomes condense+become visible
• nuclear envelope breaks down, nucleolus disappears
• centrioles move to opposite poles of cell

Question 6

metaphase

Answer 6

chromosomes line up on equator of cell + centromeres attach to spindle fibres

Question 7

anaphase

Answer 7

chromatids continue moving to opposite poles, centromeres first and
- they are pulled by the shortening of the microtubules

Question 8

telophase

Answer 8

chromatids reach opposite poles of cell+uncoil.
nuclear envelope forms around each chromosome set+nucleoli form

Question 9

cytokinesis

Answer 9

cytoplasm divides to form 2 new daughter cells

Question 10

how can cancer drugs prevent mutations occuring

Answer 10

prevent DNA replication in interphase
interfere with formation of spindle fibres in prophase

Question 11

stem cell features

Answer 11

divide by mitosis to form more cells
differentiate into diff types of specialised cell

Question 12

types of stem cell:

Answer 12

• embryonic=pluripotent, can differentiate into any type of cell
• adult=multipotent. responsible for tissue+repair
• totipotent=embryonic(placenta) can develop into any organism

Question 13

Toti

Answer 13

diff into any type of cell+produce whole organisms

Question 14

pluri

Answer 14

most cell types, but not produce whole organisms

Question 15

multi

Answer 15

few cell types, growth+repair

Question 16

meristem

Answer 16

plant tissue continually growing+contain stem cells