Cell Cycle & Mitosis

Question 1

Define karyotype

Answer 1

Chromosomes arranged in size order, only visible in mitosis

Question 2

Cell cycle

Answer 2

G1: growth
S: DNA synthesis
G2: second growth
M: mitosis

Question 3

interphase consists of…

Answer 3

G1, S, and G2

Question 4

Location of DNA replication (S phase)

Answer 4

Begins at replication fork and needs enzymes

Question 5

DNA replication strands

Answer 5

Leading & lagging strands
Lagging strands have Okazaki fragments

Question 6

Helicase

Answer 6

Splits DNA strands apart

Question 7

Primase

Answer 7

Assembles RNA primer

Question 8

DNA polymerase III

Answer 8

Adds base at the 3’ end (reads DNA 3’ to 5’ and makes RNA 5’ to 3’)

Question 9

DNA polymerase I

Answer 9

Removes RNA primer

Question 10

DNA ligase

Answer 10

Binds Okazaki fragments together

Question 11

Regulation

Answer 11

Always make equal amounts of A and T; G and C

Question 12

Name the phases of mitosis

Answer 12

Prophase
Metaphase
Anaphase
Telophase

Question 13

Describe Prophase

Answer 13

• nuclear envelope disassembles
• nuclear membrane fragments into smaller vesicles associated with ER
• chromatin condenses into chromosomes

Question 14

what enzyme is involved in prophase?

Answer 14

lamin kinase

Question 15

Describe Metaphase

Answer 15

• some microtubules attach to kinetochores
• formation of spindle apparatus
• chromosomes align on equator of spindle

Question 16

Describe Anaphase

Answer 16

• sister chromatids separate
• occurs by breakdown of spindle microtubules

Question 17

what is the proposed mechanism for motility of sister chromatids in anaphase?

Answer 17

• protein in kinetochore contains ATPase
• force generating molecules associated with spindle microtubules

Question 18

Describe Telophase

Answer 18

• daughter chromatids segregated at opposite spindle poles
• reform nuclear envelope around each set of chromosomes (enzyme: activated lamin phosphatase)
• chromosomes decondense into chromatin
• dissolution of mitotic apparatus

Question 19

what is karyokinesis

Answer 19

break nucleus in 2

Question 20

Explain cytokinesis

Answer 20

• break cell in 2
• caused by contractile ring of actin & myosin microfilaments that encircle cortex overlying area of metaphase plate
• similar mechanism to smooth muscle contraction

Question 21

what is a chromosome?

Answer 21

• 2 sister chromatids connected by centromere (splits during division)
• kinetochore on either side of centromere region allows chromosome to attach & move on the microtubules
• telomere connects ends of chromosomes