Mitotic Cell Cycle

Question 1

describe the structure of chromosomes (5)

Answer 1

two identical structures = chromatids
held by centromere
one chromatid contains one DNA molecule
ends have telomeres
made of chromatin

Question 2

describe the structure of chromatin

Answer 2

made of DNA and proteins
DNA coiled tightly
euchromatin (loose)
heterochromatin (tightly)

Question 3

how can chromatin be stained

Answer 3

when its tightly coiled

Question 4

when are chromosomes in their most condensed state

Answer 4

metaphase

Question 5

definition of mitosis

Answer 5

nuclear division that produces two genetically identical daughter nuclei, each containing the same number of chromosomes from parent cell

Question 6

stages in interphase

Answer 6

G1 –> S phase –> G2

Question 7

process in G1 phase

Answer 7

preparation for the cell (making RNA, enzymes and proteins) - decision to mitosis

Question 8

process in S phase

Answer 8

synthesis of DNA by semi-conservative replication
assembly of nucleotides
old strand acts as template
complementary base pairing

Question 9

process in G2 phase

Answer 9

sharp increase in tubulin for spindle fibres and cell continues to grow

Question 10

stages in mitosis

Answer 10

PMAT

Question 11

stages in early prophase (2)

Answer 11

chromosomes become shorter and thicker

centrosomes replicate

Question 12

stages in late prophase (4)

Answer 12

formation of chromatids
nuclear envelope breaks down
nucleolus disappears
mitotic spindle extend to opposite poles

Question 13

stages in metaphase (2)

Answer 13

chromosomes line up

chromatids attach to the spindle fibres

Question 14

stages in anaphase (2)

Answer 14

spindle fibres attached to kinetochore on centromere

spindle fibres shorten and pull apart chromatids to opposite poles

Question 15

stages in telophase (4)

Answer 15

spindle fibres break down
nuclear envelope reforms
nucleolus in each cell reforming
chromatids uncoil

Question 16

stages in cytokinesis

Answer 16

division of cytoplasm
reproducing structures
(cell wall for plants)

Question 17

significance of mitosis (4)

Answer 17

growth, repair tissues, asexual reproduction in eukaroytes, immune response

Question 18

why it is important mitosis results in identical cells (3)

Answer 18

need the same number of chromosomes
produces genetic stability in cells
produce genetically identical cells

Question 19

describe telomeres

Answer 19

structures made of DNA and short repeated base sequences to seal ends of chromosomes

Question 20

purpose of telomeres

Answer 20

allows replication of entire strand

prevent loss of genes

Question 21

what happens to cell cycle when telomeres cannot replicate

Answer 21

stay in G1 phase

Question 22

describe stem cell

Answer 22

cell that can divide unlimited number of times and can turn into specialised cell

Question 23

definition of potency

Answer 23

ability to produce any type of cell

Question 24

describe totipotent cell

Answer 24

total potency (zygote)

Question 25

describe pluripotent cell

Answer 25

cell can only turn to three germ layers in embryo (embryonic stem cell)

Question 26

describe multipotent cell

Answer 26

cell can turn into some cells only (blood cell) found in bone marrow

Question 27

describe cancer

Answer 27

uncontrolled cell division

Question 28

describe process of cancer (7)

Answer 28

``` carcinogen causes mutation oncogene transformed by carcinogen rapid mitosis uncontrolled cell division tumour formed blood vessels supply ```

Question 29

what is metatasis

Answer 29

tumour breaks off from origin and spread to other sites

Question 30

benign tumour

Answer 30

isn't cancerous