Cell cycle and cell divison

Question 1

What is chromatin?

Answer 1

long thread like DNA in non-dividing cell

Question 2

What is a chromosome?

Answer 2

2 chromatids- exact copies of each due to SCR held together at centromere

Question 3

What is the cell cycle?

Answer 3

series of events cells through as they grow and divide. INTERPHASE (G1, S1, G2), NUCLEAR DIVISION, CYTOPLASMIC DIVISION

Question 4

what is mitosis?

Answer 4

nuclear division that’s produces TWO GENETICALLY IDENTICAL DAUGHTER NUCLEI occurs in somatic body cells. for growth and repair

Question 5

state the 4 (+1) stages of mitosis

Answer 5

interphase, prophase, metaphase, anaphase, telophase

Question 6

Mitosis: interphase

Answer 6

G1= cell growth, protein synthesis. S1= replication of DNA. G2= proteins for division synthesised, prepares for division.

Question 7

Mitosis: prophase

Answer 7

chromatin-> chromosome (coil & condense), nuclear envelope & nucleolus disappear, centrioles move to opposite ends, spindle fibres form

Question 8

Mitosis: metaphase

Answer 8

chromosomes -> equator. spindle fibres connect to chromosomes

Question 9

Mitosis: anaphase

Answer 9

centromere divides in two. chromatids to opposite ends- daughter chromosomes

Question 10

Mitosis: telophase

Answer 10

daughter chromosomes uncoil -> chromatin. nuclear envelope & nucleolus appear. CYTOKINISIS- (animal) 2 nuclei form, two new cells. CYTOPLASMIC DIVISION

Question 11

how do you find the mitotic index?

Answer 11

no of cells in mitosis/ total no of cells X100

Question 12

how is cancer caused by mitosis?

Answer 12

UNCONTROLLED MITOSIS. repeatedly dividing causes irregular mass of cells that prevent other cells/ organs functioning. changes occur in genes that control cell division

Question 13

What is meiosis?

Answer 13

two stages of nuclear division that results in 4 GENETICALLY DIFFERENT HAPLOID GAMETES (1/2 no chromosomes) reproductive organs. chromosomes (HAPLOID) -> zygote (DIPLOID)

Question 14

meiosis: interphase

Answer 14

same as mitosis: G1, S1, G2

Question 15

What are diploid cells?

Answer 15

each body cell contains two each chromosome: one maternal, one paternal

Question 16

what are haploid cells?

Answer 16

gametes have half normal no of chromosomes: one chromosome from each homologous pair

Question 17

meiosis: prophase I

Answer 17

same as mitosis + crossing over (CHIASMA) between non-sister chromosomes (sections swap) = GENETIC VARIATION

Question 18

meiosis: metaphase

Answer 18

bivalents line up at equater. random assortment (LINE UP RANDOMLY) = GENETIC VARIATION

Question 19

meiosis: anaphase I

Answer 19

homologous chromosomes separate

Question 20

meiosis: telophase I

Answer 20

2 haploid cells formed- each has copy of homologous chromosomes. animals= cytokiesis

Question 21

meiosis: prophase II

Answer 21

same as mitosis but spindles form at right angles to first

Question 22

meiosis: metaphase II

Answer 22

random assortment= GENETIC VARIATION

Question 23

meiosis: anaphase II

Answer 23

chromatids pulled to opposite ends

Question 24

meiosis: telophase II

Answer 24

4 hapolid cells produced each genetically different. cytokinesis