cell division

Question 1

The cell cycle has three phases what are they

Answer 1

interphase, mitosis(nuclear division), cell division (cytokinesis)

Question 2

what happens during interphase

Answer 2

During Interphase the cell increases in mass and size and carries out its normal cellular functions (eg. synthesising proteins and replicating its DNA ready for mitosis)

Question 3

what are the 3 phases of interphase

Answer 3

G1 phase, S-phase, G2 phase

Question 4

what happens during G1

Answer 4

Cell grows and receives a signal to divide,

Question 5

what happens during S-phase

Answer 5

Synthesis of new DNA, DNA replicate in nucleus( resulting in each chromosome consisting of 2 identical sister chromatids)

Question 6

what happens during G2 phase

Answer 6

Further cell growth
Error checking of newly synthesised DNA

Question 7

in mitosis the movement from one phase to another is triggered by chemical signals is called what

Answer 7

cyclins

Question 8

what occurs after interphrase

Answer 8

nuclear division- mitosis- referred to as the m phase, cell growth stops

Question 9

what happens after mitosis

Answer 9

cytokenisis- cell split into 2 identical individual cells

Question 10

how is DNA stored

Answer 10

DNA is stored as chromosomes

Question 11

what are chromosmes

Answer 11

thread like structure which constist of DNA tightly coiled around proteins called histone proteins.

Question 12

how much chrosomes do the human haves

Answer 12

46 chromosmes- 23 pairs

Question 13

what is a homologous pair

Answer 13

a chromosome inherited from paternal and one chromosome inherited from maternal

Question 14

what is a chromotid

Answer 14

a half of a chromosome- sister chromotid

Question 15

what is a chromotid in a chromosome held together by

Answer 15

a centomere

Question 16

what are diploid cells

Answer 16

a complete double set of a chromosome

Question 17

what are haploids

Answer 17

a single set of chromosomes

Question 18

what is cancer

Answer 18

uncontrollable cell division- mitosis

Question 19

what does cancer lead to

Answer 19

tumours- irregular mass of cells

Question 20

how do cancer start

Answer 20

when changes occur in the genes that control cell division

Question 21

what are the 2 types of cancer

Answer 21

benign and malignant

Question 22

what are benign tumours

Answer 22

they do not spread from their original site- don’t cause cancer- often in a capsule

Question 23

what are malignant tumours

Answer 23

cancer that burst from its capsule and spread to rest of body destroying and invading other tissues- spread from site of origin

Question 24

how does malignant tumours spread

Answer 24

via the bloodstream or lymphatic system

Question 25

what does malignant tumours interfere with

Answer 25

normal function of the organ.

Question 26

what is metastasis

Answer 26

spreading of cancer- malignant

Question 27

how do most cancer treatment stop cancer

Answer 27

they control the rate of mitosis.

Question 28

what do most people who have cancer posses.

Answer 28

the p53 gene.

Question 29

what is mitosis

Answer 29

when the nucleus divides- type of cell division which produces 2 identical daughter cells.

Question 30

what does mitosis do

Answer 30

increase the number of cells during growth

Question 31

does the daughter cells have the same exact DNA as the parent cell

Answer 31

yes

Question 32

what are 3 importances of mitosis

Answer 32

growth, repair and for asexual reproduction

Question 33

how many stages does mitosis have and what are they

Answer 33

4- prophase, metaphase, anaphase,telophase

Question 34

what happens during prophase

Answer 34

chromosomes condense and become thicker and are now visible under a microscope. Centrioles seperate and move to opposite poles of cell. Each centriole forms spindle fibres. Chromotin condenses into chromosomes and the nucleolus disappears- chromosomes free in cytoplasm.

Question 35

what are centrioles

Answer 35

bundles of proteins

Question 36

what is metaphase

Answer 36

longest phase of mitosis- there is no longer a nucleus- chromosomes line up along the equator of the cell-Each chromosome attaches to the spindle by their centromere and chromotid.

Question 37

what is anaphase

Answer 37

The centromeres divide to separate each pair of sister chromatids. -The spindle fibres contract and shorten to pull the chromatids to opposite poles of the cell. -Each chromatid is pulled by its centromere.

Question 38

what happens in telophase

Answer 38

The chromatids reach the opposite poles of the cell where they uncoil to become long and thin chromosomes again. -A nuclear envelope forms around each set of chromosomes to form two nuclei and the nucleolus starts to reform.

Question 39

what type of cells don't divide

Answer 39

specialised cells once they differentiate from stem cells.

Question 40

why can't neurones divide

Answer 40

they lack centrioles- cannot divide- also division would lead to loss of memories and connection.

Question 41

why can't red blood cells divide

Answer 41

they lack a nucleus and other organelles need for division to maximise haemoglobin. They must be continually produced from stem cells.

Question 42

how many chromotids may a chromosome have

Answer 42

1 or 2 depending on the cell cycle.

Question 43

what type of cells are involved in meoisis

Answer 43

gamete cells- sexual reproduction

Question 44

how many nuclear divisions does it have and what are they called

Answer 44

2- meiosis 1 and meiosis 2

Question 45

what is the significance of meiosis

Answer 45

it increases variation by combing the genetic variation of 2 organisms by a process of random fertlisation