Cell cycle, mitosis, meiosis

Question 1

define cell cycle

Answer 1

cyclic process of duplication of cell contents and division to produce daughter cells

Question 2

importance of cell cycle

Answer 2

allows for coordination of DNA synthesis, organelle biosynthesis, macromolecule synthesis, such that each daughter cell has its own cell components and organelles

Question 3

G1 phase cell cycle

Answer 3

growth, normal metabolism, prepares for S phase

Question 4

G0 phase cell cycle

Answer 4

cell gets regulatory signals and exits the cell cycle, maintains constant size
can enter and leave G0 back to G1 with regulatory signals

Question 5

S phase cell cycle

Answer 5

DNA repilcation, centrosomes finish replication, nucleus enlarges

Question 6

G2 phase cell cycle

Answer 6

growth, protein synthesis, prepare for mitosis

Question 7

how are sister chromatids joined

Answer 7

joined by cohesin proteins at the centromere (more for meiosis)

Question 8

convert heterochromatin to euchromatin

Answer 8

modify histones by adding acetyl group, more negative, DNA repeled away, less densely packed, more accessible

Question 9

kinetochores structure and function

Answer 9

spindle fibres (microtubules) binding structure, on opposite sides of the centromere, 1 per chromatid

Question 10

centrosome structure and function

Answer 10

groups of 2 centrioles perpendicular to each other
replicated during S phase, each daughter cell gets 1 centrosome
centrioles produce the microtubules, centrosome organises them

Question 11

kinetochore microtubule vs astral microtubule

Answer 11

kinetochore: contract to enable segregation of sister chromatids (microtubules lengthen and shorten at both ends)

astral: enables correct spindle orientation and polarity by interacting with the actin fibres in the cell cortex (part of cytoskeleton)

Question 12

mitosis definition

Answer 12

somatic cell division, 2 genetically identical diploid daughter cells produced

Question 13

prophase

Answer 13

chromatin condenses into chromosome
spindle fibres form

Question 14

prometaphase

Answer 14

nuclear membrane disintegrates
spindle fibures attach to chromatids at kinetochores

Question 15

metaphase

Answer 15

chromosomes line up on the metaphase plate

Question 16

anaphase

Answer 16

spindle retraction occurs, breakdown of cohesin proteins, sister chromatids separate and move towards opposite poles

Question 17

telophase

Answer 17

nuclear membrane reforms
chromosomes uncondense into chromatin

Question 18

Meiosis definition

Answer 18

produces 4 genetically different haploid daughter cells

Question 19

Meiosis I and Meiosis II type of division

Answer 19

I - reduction division, centromere number halved in each cell
II - equational division, centromere number remains equal in each cell

Question 20

prophase I

Answer 20

chromatin condenses to form chromosomes
spindle fibres form
nuclear membrane disappears
homologous chromosomes pair (synapsis), forming a tetrad
crossing over occurs

Question 21

allele definition, variation of chromosomes

Answer 21

different forms of the same gene
minor differences in base sequence of chromosomes will give variation

Question 22

crossing over process and function

Answer 22

exchange of genetic material at chiasma between homologous pair
new combinations of genetic material, increase variation

Question 23

metaphase I

Answer 23

homologous chromosome pairs line up along metaphase plate, independent assortment occurs

Question 24

anaphase I

Answer 24

spindle fibres retract, cohesin proteins break down, except the ones protected by shugosin at centromere
chromosomes move to opposite poles of cell

independent distribution occurs

Question 25

differences between mitosis and meiosis

Answer 25

tetrad pairing in meiosis crossing over in meiosis reduction division to give haploid cells in meiosis mitosis is cyclic 2 vs 4 daughter cells

Question 26

mitotic spindle, microtubules, spindle fibres, aster definition

Answer 26

overall structure that forms in mitosis, responsible for organising and separating chromosomes spindle fibres and microtubules are interchangeable, just know that there are kinetochore and astral star shaped structure made of astral fibres forming around centrosome, orientation of spindle fibres

Question 27

segregation and non disjunction

Answer 27

separation of chromosomes incorrect segregation causing incorrect chromosome number in daughter cells