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Flashcards in Cell cycle Deck (22)
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1
Q

What is oriC

A

Single origin of replication

2
Q

How does replication occur in prokaryote

A

Has single circular chromosomes
Two DNA strands
Replication forks move bidirectionally to terminus - away from oriC in bigger loops

3
Q

What triggers chromosome replication

A

Cell growth

Cells can sense when cell DNA:mass very low - new chromosome replication triggered

4
Q

What happens when chromosome replication has occured

A

DNA doubles

Cell must double in size before divides again

5
Q

How long does the replication of a chromosome take, what is this period called

A

40 mins

C period

6
Q

What occurs after chromosome replication, how long it takes and the name of this period

A

20 minute preparation to divide

D period

7
Q

Why may a cell take over 60 minutes to double in size

A

Resting period B will occur between divisions and next DNA synthesis

8
Q

Why does E. coli have a generation time of less than 60 minutes

A

Cell cycles overlap

9
Q

What are the two goals that eukaryotes must alternate between for controlled cell cycle

A

Growth - copying cellular components (interphase)

Division - dividing cell so components distributed evenly to daughter cells (mitosis)

10
Q

What does the cell check before divisions

A

All chromosomes at cell centre

Centromeres attached to microtubules

11
Q

What happens if some chromosomes not attached by microtubules

A

Chromosomes may not separate as need to - one daughter cell may get an extra chromosome

12
Q

Cytokinesis in animal cells

A

Cell membrane pulls inward from edges and pinches off

13
Q

Cytokinesis in plant cells

A

Phragmoplast grows out from cell centre, form new cell membrane, cell wall - combine with existing cell wall

14
Q

Where is the DNA replication check point

A

Between G2 and M

15
Q

Where is the spindle check point

A

Between M and G1

16
Q

Where is the restriction point

A

Between G1 and S

17
Q

How did Howard and Pelc find where DNA synthesis was occuring in the cell cycle

A

Fed cells radioactive nucleotides for short periods
Extracted DNA see if radioactive
If radioactive, cell must’ve been making DNA

18
Q

Why is the S phase longer in eukaryotes than prokaryotes

A

Eukaryotes have more than one chromosome to replicate

19
Q

When is the cell committed to mitosis

A

When enters S phase

20
Q

What is the G2 phase

A

Prepares for mitosis

21
Q

What is the G1 phase

A

Cell growth
Preparation of chromosomes for replication
Cellular components duplicate

22
Q

What is the restriction point

A

Cell stop dividing