Cell Cycle/Intro to Cancer

Stages of the Cell Cycle

G1, S, G2, M

Interphase

G1, S, G2

What is G1

First Gap Phase

Cell growth and prep for DNA replication

what is S

Synthesis Phase

Chromosome replication, results in sister chromatitds connected at centromeres (| to X)

What is G2

Final part of interphase

Synthesis of proteins and enzymes needed for division

continued cell growth

Steps of Mitosis

Prophase- Condense choromosomes, spindle forms

Prometaphase- Nuclear envelope breaks down, chromosomes attach to spindle

Metaplase- Chromosomes align in the center of cell

Anaphase- Separate sister chromatids

Telophase- New nuclear envelopes

Cytokinesis- Starts at anaphase, cell divides. cleavage furrow

G0

Non-dividing state

Cell control system proteins

cyclins - levels rise and fall

cyclin dependant kinases (cdks)- generally constant

First Cell cycle checkpoint

restriction point

end of G1

sufficient growth?

More cells wanted?

Regulated by RB and E2F

2nd Cell cycle checkpoint

G2/M boundary

post G2, before M starts

DNA replication done?

Favorable environment?

3rd cell cycle checkpoint

metaphase-anaphase transition

during mitosis

Chromosomes attached to spindle??

Rb and E2F

Rb inhibits E2F - brake

E2F activates DNA replication gene expression - gas

Whats a growth factor

Stimulate cell growth

Stimulate cell rpoliferation

mitogens

p53

tumor suppressor

halts cell cycle by causing creation of p21 (cdk inhibitor)

Ras is a …

RB is a …

p53 is a…

Somatic mutation

gathered during life

present in that cells descendants

Germline mutation

inherited via egg/sperm

present everywhere

passed down