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Bioscience > Cell Cycle and Communication > Flashcards

Cell Cycle and Communication Flashcards

1
Q

Phases of the cell cycle

A

G1
S
G2
M

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2
Q

G1

A

Growth phase 1
Cell is metabolically active
Organelles and centrosomes are replicated
DNA and nucleus are NOT replicated

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3
Q

S

A

Synthesis (of DNA)
DNA strands separate by breaking of hydrogen bonds
New strands of DNA synthesised opposite old strands

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4
Q

G2

A

Growth phase 2
Prepares for mitotic phase
Centrosome replication is completed

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5
Q

M

A

Mitosis
Nuclear membrane is dismantled
2 copies of DNA separate from each other
2 nuclei formed each containing 1 copy of DNA

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6
Q

Phases of mitosis

A 
Interphase
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis
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7
Q

Interphase

A

G1, S, G2
Chromosomes replicate, each containing 2 sister chromatids
Centrosomes containing centrioles have finished replication

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8
Q

Prophase

A

Chromatin condenses into chromosomes
Copies are held together by centromeres
Microtubules extend from centrosomes towards the mitotic spindle

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9
Q

Prometaphase

A

Nucleolus disappears
Nuclear envelope breaks down
Spindle fibres attach to kinetochores at centromere of sister chromatids

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10
Q

Metaphase

A

Kinetochore microtubules of mitotic spindle align centromeres along the metaphase plate

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11
Q

Anaphase

A

Centromeres split

Microtubules drag each chromatid away from metaphase plate towards centrosome at each end of cell

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12
Q

Telophase

A

Chromosomes revert to chromatin
Nuclear envelope and nucleolus reform
Mitotic spindle breaks down

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13
Q

Cytokinesis

A

Cytoplasm division

Actin-myosin run causes plasma membrane to pinch inwards and separate into two distinct cells

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14
Q

Cell cycle checkpoints

A

G1: Allows to pass if the cell is of adequate size, has sufficient nutrients and undamaged DNA
G2: Allows to pass if the cell has correctly replicated chromosomes, undamaged DNA and an activated MPF
M: Allows to pass if the cell has all chromosomes attached to the spindle apparatus

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15
Q

MPF

A

Mitotic promotion factor
Induces mitosis in eukaryotes
M phase cytoplasm contains regulatory molecule that induces M phase in interphase cells
CDK/cyclin complex

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16
Q

CDK

A

Cyclin dependent kinase
Catalyses phosphorylation of target protein using ATP
Constant concentration
Active only when bound to cyclin subunit

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17
Q

Cyclin

A

Regulatory molecule that binds CDK

Concentration varies throughout the cell cycle to maintain appropriate mitosis levels

18
Q

Cyclin/CDK mechanism

A

M-cyclin binds inactive CDK1 molecule
M-CDK complex formed but is inactive
CDK-activating kinase (CAK) adds an activating phosphate to the CDK molecule
Wee1 adds an inhibitory phosphate to the CDK molecule
To be active, CDK must have ONE phosphate so the inhibitory phosphate is removed by CDC25

19
Q

4 effects of MPF

A

Phosphorylate chrmosomal proteins to initiate M
Phosphorylate lamins to initiate nuclear envelope breakdown
Phosphorylate microtubule associated proteins to activate mitotic spindle
Phosphorylate cyclin degradation enzyme to decrease cyclin concentration

20
Q

5 targets of MPF

A 
Condensins
Microtubule associated proteins
Lamins
Histones
Golgi matrix
21
Q

APC disassembly

A

Anaphase promoting complex
APC polyubiquitinates cyclin to mark it for degradation in a negative feedback loop
Concentration of cyclin/CDK complex increases and this heterodimer promotes APC to polyubiquitinate cyclin

22
Q

Proto-oncogene

A

Gene that produces a protein that promotes progress through the cell cycle
Functions normally
Expressed for a short time at a specific point in the cell cycle then degraded

23
Q

Oncogene

A

Gene that produces at protein such as RAS that promotes progress through the cell cycle but functions abnormally
Expressed at inappropriate time or for too long

24
Q

4 pathways activated by RAS

A

RAF
PI3K
RALGDS
PLC

25
Q

RAF pathway

A

Phospholipase A
Cell cycle progression
Transcription

26
Q

PI3K pathway

A 
Inhibition of GSK3
Protein Kinase C
Survival
Transcription
Cytoskeletal signals
Translation
27
Q

RALGDS pathway

A

Phospholipase D
Transcription
Vesicle trasnport
Cell cycle progression

28
Q

PLC pathway

A

Protein Kinase C

Calcium signalling

29
Q

3 types of oncogene mutation

A

Point - hyperactive growth stimulating protein
Duplication - normal growth stimulating protein in excess
Translocation - normal growth stimulating protein in excess

30
Q

4 stages of cell-cell communication

A

Signal reception
Signal processing
Signal response
Signal deactivation

31
Q

Signal reception

A

Intracellular signals bind specific receptors

Binding of signal to protein causes conformational change indicating signal has been received

32
Q

Intracellular signal

A

Typically hormones, always a small molecule

33
Q

Steroid hormones

A

Direct effect
Bind to cytosolic receptors
Transported to nucleus to alter gene expression

34
Q

Small, hydrophobic primary messengers bind to…

A

Cytosolic and nuclear receptors

35
Q

Large, hydrophilic primary messengers bind to…

A

Membrane and cell surface receptors

36
Q

Signal processing

A

G proteins are activated by GTP binding
GTP binding triggers rapid production of large quantities of secondary messengers to amplify original signal
These diffuse rapidly and spread hormone throughout the cell

37
Q

Signal transduction

A

A type of signal processing where the intracellular secondary messenger links activated enzyme with signalling cascade

38
Q

G proteins

A

Intracellular peripheral membrane proteins activated by GTP binding

39
Q

RTKs

A

Transmembrane proteins that bind a hormone signal at tyrosine site
Phosphorylate each other to carry out cellular processes

40
Q

IP3 gated calcium channels

A 
IP3 activated by G protein bound to GTP
Phospholipase C activated
PIP2 activated
IP3 activated
IP3 binds calcium pump which causes it to open
Calcium is released into the cytosol
41
Q

Regulation of calcium pump

A

Calcium becomes own negative feedback loop initiator by binding to the IP3 gated calcium pump. When enough calcium is bound to the pump the IP3 dissociates and the channel closes

42
Q

Signal response

A

Gene expression
Protein activity
Metabolism

Bioscience (10 decks)

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