Cell cycle and mitosis Flashcards

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1
Q

What is the cell cycle?

A

Series of events that a cell passes through until it reproduces

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2
Q

Method of prokaryotic cell division

A

Binary fission

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3
Q

Two periods of eukaryotic cell division

A

Interphase
Mitosis (M phase)

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4
Q

What is interphase?

A

Period between cell divisions

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5
Q

What occurs during the M phase

A

Cell division stage

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6
Q

What are the stages of interphase?

A

G1 phase
S phase
G2 phase

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7
Q

What occurs during the G1 phase?

A

Cell growth
Synthesis of new proteins and organelles
Regular cell functioning

Longest phase of the cell cycle

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8
Q

What occurs during the S phase?

A

Chromosomes are replicated
Centromeres are synthesized

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9
Q

What occurs during the G2 phase?

A

Centrioles and molecules for cell division are produced
Final check before mitosis

Shortest stage of interphase

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10
Q

What are the checkpoints of the cell cycle?

A

Control points where signals regulate the cycle
3 major checkpoints are G1, G2 and M

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11
Q

What regulates the movement of cells through the cell cycle?

A

Protein kinases and enzymes

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12
Q

Which proteins function as internal regulators?

A

Cyclin Dependent Kinase (CDK)
Maturation Promoting Factor (MPF)
p53
p27

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13
Q

Function of CDK

A

Adds phosphate to proteins
Along with the kinases control movment of cells from nondividing → G1 → S → G2 → M

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14
Q

Function of MPF

A

Trigger progression through the cell cycle
MPF = Mitotic CDK + Mitotic Cyclin

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15
Q

Function of p53

A

Blocks the cell cycle in case of DNA damage
If severe DNA damage occurs, p53 triggers apoptosis

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16
Q

Function of p27

A

Binds to cyclin and CDK to block entry into the S phase

17
Q

What controls the G2 checkpoint

A

Controlled by MPF
MPF phosphorylates and activates proteins involved in chromosome condensation, nuclear envelope breakdown, spindle assembly and cell death

18
Q

What controls the G1 checkpoint?

A

Controlled by the G1 CDK cyclins
Additional levels of phosphorylation and dephosphorylation regulate

19
Q

What factors regulate progression through the cell cycle?

A

Endogenous hormones: Auxin, cytokinins, abscisic acid, gibberellins and brassinosteroids (backgammon)
Environmental factors

20
Q

What are the four classes of cyclins?

A

G1-cyclins promote progression through start of restriction point in late G1
G1/S-cyclins bind CDKs at the end of G1 (cell is now committed to DNA replication)
S-cyclins bind CDKs during S phase required to initiate DNA replication
M-cyclins promote mitotic events

21
Q

What are external regulators in the cell cycle?

A

Proteins which respond to events outside the cell

22
Q

What are the functions of external regulators?

A

Speed up or slow down the cell cycle

23
Q

What are some examples of external regulators?

A

Growth factors speed up cell division
Molecules on surfaces of neighbouring cells slow down/stop the cell cycle

24
Q

What occurs in cancer cells?

A

Uncontrolled cell growth (often because of defect in p53 gene)

25
Q

Viewing cell under electron microscope during interphase

A

Chromosomes seen as chromatin under electron microscope
Nucleus in visible

26
Q

What are the events of prophase?

A

Chromatin condenses into chromosomes
Nuclei and nuclear envelope break down
Spindle fibres grow from centrioles
Centrioles migrate to opposite poles of cell

27
Q

What are the events of metaphase?

A

Chromosomes line up along the cell equator
Spindle fibres from the centrioles attach to the centromeres
Nuclear membrane has been completely degraded

28
Q

What are the events of anaphase?

A

Centromeres split
Sister chromatids separate as each is pulled to an opposite pole

29
Q

What are the events of telophase?

A

Chromosomes become longer and thinner
Nuclear membrane form
Nucleolus reappears

30
Q

What is cytokinesis?

A

Cytoplasmic division which completes mitosis