lecture 5: cell cycle

Question 1

a chromosome is…

Answer 1

made of DNA wound around proteins called histones
made of single, double stranded DNA molecule

Question 2

each sister chromatid has a

Answer 2

centromore and kinetochore

Question 3

sister chromatids held together along their length by __

Answer 3

cohesin

Question 4

in biparental inheritance, each pair of _ derived from each parent

Answer 4

loci

Question 5

allele

Answer 5

alternative forms of the same gene

Question 6

centromere

Answer 6

constricted regions on chromosomes

Question 7

karyokinesis

Answer 7

genetic material evenly divided into two daughter cells during nuclear division

Question 8

cytokinesis

Answer 8

cytoplasmic division
* parititions cellular volume into two parts and encloses each cell with a plasma membrane

Question 9

G1 phase

Answer 9

primary growth phase, longest phase

Question 10

S phase

Answer 10

synthesis
* replication of DNA

Question 11

G2 phase

Answer 11

organelles replicate, microtubules organize

Question 12

interphase

Answer 12

G1 and G2 occur
* no DNA synth occurs
* by end of G2, cell has doubled in size

Question 13

G0

Answer 13

point in G1 phase where cells withdraw from cell cycle and enter a nondividing but metabically active state

Question 14

prophase

Answer 14

chromosomes condense
nuclear envelope breaks down

Question 15

cohesin

Answer 15

protein complex that holds sister chromatids together

Question 16

prometaphase

Answer 16

period of chromosome movement

Question 17

metaphase

Answer 17

chromosome configuration following migration
* centromeres align on metaphase plate

Question 18

during prometaphase/metaphase

Answer 18

cohesin degraded by separase
sister chromatid arms disjoin except at centromere

Question 19

shugoshin

Answer 19

prevents degradation of cohesin at centromere

Question 20

anaphase

Answer 20

chromosome distribution during mitosis
* centromeres split, sister chromatids separate

Question 21

complete disjunction occurs when

Answer 21

• shugoshin degrades
• cohesin complex is cleaved by separase
• sister chromatids are pulled towards opposite poles of cell

Question 22

telophase

Answer 22

final stage of mitosis with two complete sets of chromosomes, one set at each pole

Question 23

mutations affecting the cell cycle

Answer 23

kinases - enzymes that phosphorylate proteins

Question 24

cyclins

Answer 24

proteins that bind with kinases –> activating the, at appropriate times during cell cycle

Question 25

G1 checkpoint

Answer 25

checking for DNA mistakes

Question 26

G2 checkpoint

Answer 26

checking for proper chromosome duplication

Question 27

M checkpoint

Answer 27

proper attachment of microtubules to kinetochore