mitosis

Question 1

what is the point of cell division?

Answer 1

continuity of life

Question 2

what is a chromatid?

Answer 2

half the chromosome

Question 3

what is a sister chromatid?

Answer 3

replicated chromosomes

Question 4

what is the product of mitosis?

Answer 4

2 identical, diploid, daughter cells

Question 5

what is the product of meiosis?

Answer 5

4 haploid, non-identical, daughter cells

Question 6

what is mitosis used for?

Answer 6

growth and repair, cell proliferation and asexual reproduction

Question 7

what is meiosis used for?

Answer 7

gametes (sexual reproduction)

Question 8

what is the first stage of cell division, synonymous to both mitosis and meiosis, and how does it work?

Answer 8

• DNA replication
• homologous pair of chromosomes replicated and joined sister chromatids attached at centromere
• 2 chromosomes!

Question 9

what is the meaning homologous?

Answer 9

same genes but different alleles i.e. same gene coding for eye colour but one blue and one brown

Question 10

what is the role of cohesin?

Answer 10

fibrous protein loop that attaches sister chromatids at centrosome

Question 11

what is the condensation of DNA?

Answer 11

DNA is wrapped around histones, it is supercoiled, chromosome shorter and fatter

Question 12

why is it important for chromosomes to condense?

Answer 12

they are able to move around which is essential to both mitosis and meiosis

Question 13

how are chromosomes moved around?

Answer 13

by microtubules called spindle fibres

Question 14

what are microtubules?

Answer 14

hollow cylinders of tubulin proteins which can be assembled and dissembled

Question 15

what is the purpose of kinetochores?

Answer 15

attach spindle fibre to chromosomes

Question 16

what are the characteristics of the cell during interphase?

Answer 16

uncondensed but duplicated DNA, duplicated centrioles

Question 17

what are the characteristics of the cell during prophase?

Answer 17

• chromosomes condense
• chromatids joined at
  centromere
• spindle fibres beginning to
  form
• centrioles migrate to poles
• nuclear membrane break
  down

Question 18

what are the characteristics of the cell during metaphhase?

Answer 18

• chromosomes line up at equator
• randomly attach to certain spindle fibres at centromeres

Question 19

what are the characteristics of the cell during anaphase?

Answer 19

• cohesin loops broken
• sister chromatids split
• pulled to poles by microtubules
• then s-fibres break down
• new nuclear envelope round
  each group of chromatids

Question 20

what are the characteristics of the cell during telophase?

Answer 20

• cell constricts inwards till membrane physically splits

Question 21

what is equal cytokinesis?

Answer 21

parent cell -> equally sized daughter cells (growth and repair of tissues)

Question 22

what is unequal cytokinesis?

Answer 22

daughter cells different size - smaller cells can die (oogenesis) or survive (yeast budding)

Question 23

what occurs in G1 of cell cycle?

Answer 23

growth: increase cytoplasm vol, synthesis of new organelles, increase SFA of cytoplasm

Question 24

what occurs in S of cell cycle?

Answer 24

DNA replication: chromosomes replicated to form sister chromatids

Question 25

what occurs in G2 of cell cycle?

Answer 25

further synthesis of proteins and organelles, prep for mitosis

Question 26

what is the role of cyclins?

Answer 26

to control cell cycle

Question 27

how do cyclins work?

Answer 27

activate proteins called cyclin dependent protein kinases CDKs phosphorylate other proteins, activating them 4 mains types unless each reaches a particular level, cell will not move into next stage of the cycle each cyclin activates a different group of proteins, which carry out actions required in a specific stage of cell cycle

Question 28

what are the repercussions of mutations in genes controlling cell cycle?

Answer 28

cell cycle controlled by genes when control lost, division can become uncontrollable, forming a mass or tumour either oncogene or tumour suppressor gene

Question 29

how can tumour be formed?

Answer 29

too much proto-oncogene or inactivated tumour suppressor gene

Question 30

what is a primary tumour?

Answer 30

a mass of cells

Question 31

what is metastasis?

Answer 31

tumour has moved from primary site through lymphatic system to secondary site

Question 32

how could mitotic index be used to identify cancerous tissues?

Answer 32

high mitotic index as significantly higher rate of cell division