cell cycle

51問 • 1年前

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Two genetically identical daughter cells:

DNA in each chromosome must first be replicated to produce two complete copies The replicated chromosomes must then be accurately segregated to the two daughter Duplicate their other organelles and macromolecules

The major events of the cell cycle During S phase

DNA replicates, taking 10-12 hours.

The major events of the cell cycle In M phase

chromosomes segregate into a pair of daughter nuclei(in mitosis) then the cell divides(cytokinesis) , taking less than an hour

The major events of eukaryotic cell division Prophase

DNA condenses into chromosomes

The major events of eukaryotic cell division Metaphase

nuclear envelope disassembles,chromosomes attach to mitotic fibers then align at center of cell

The major events of eukaryotic cell division Anaphase

chromosomes separate and move to opposite poles of the cell

The major events of eukaryotic cell division Telophase

the spindle disassembles, and new nuclear envelopes form around the separated chromosomes

The four phases of the cell cycle

G1, S, G2, M

G, S, and G2 are called

interphase

S Phase for

DNA replication

M phase for

mitosis and cytokinesis

Interphase might occupy While M phase

23 hours 1 hour

The control of the cell cycle Start at late G

where cell commits to cell cycle

The control of the cell cycle G2/M

triggers early mitotic events that lead to chromosome alignment on the mitotic spindle in metaphase

The control of the cell cycle Metaphase-to-anaphase

stimulates chromosomes separation, leading to the completion of mitosis and cytokinesis

Analysis of DNA content with a flow cytometer

Peak 1: cells in G1 which have 1 DNA S Phase: cells in s phase have varying amount of DNA due to being in midst of DNA replication Peak2: cells in G2 and M which have 2 DNA due to DNA replication

Cyclin-Cdk complexes of the cell-cycle control system

Cyclins and Cdks control the cell cycle. Cyclins bind to Cdks, activating them and triggering cell cycle events

Cyclin-Cdk complexes of the cell-cycle control system

The activities of these kinases rise and fall as the cell progresses through the cycle G1/S-Cdk initiates DNA replication S-Cdk prevents re-replication M-Cdk triggers mitosis

Cyclin-Cdk complexes of the cell-cycle control system G1/S-Cdk

initiates DNA replication

Cyclin-Cdk complexes of the cell-cycle control system S-Cdk

prevents re-replication

Cyclin-Cdk complexes of the cell-cycle control system M-Cdk

triggers mitosis

Cyclin-Cdk complexes of the cell-cycle control system Cyclin we're named

because undergo protein creation and degradation

The regulation for Cdk activation

Cdk needs a cyclin and a phosphate group to be fully active. Cyclin binding and phosphorylation open the Cdk's active site, allowing it to trigger cell cycle events.

The regulation for Cdk activation

In absence of cyclin, the active state of Cdk is partly hidden by protein loop

The regulation for Cdk activation

Phosphorylation of Cdk by Wee1 inhibits its activity, while dephosphorylation by Cdc25 activates it.

The inhibition of a cyclin-Cdk complex by a CKI

CKI proteins bind to cyclin-Cdk complexes, inactivating them and regulating cell cycle progression.

The inhibition of a cyclin-Cdk complex by a CKI CKI is used to

Control activities of G1/S and S-Cdks early in cell cycle

Two major proteolysis enzyme: APC/C

APC/C is a key regulator of the cell cycle. It targets securin and cyclins for degradation, allowing for chromosome separation and cell cycle progression.

Two major proteolysis enzyme: APC/C

Cdk dephosphorylation is needed to complete mitosis and cytokinesis.

Two major proteolysis enzyme: APC/C APC/C is

turned off when G1/S-Cdk is activated in late G1

Two major proteolysis enzyme: APC/C Securin

Protects protein linkage that holds together sister chromatids together

Two major proteolysis enzyme: APC/C APC/C targets

securin for degradation, allowing sister chromatid separation

Two major proteolysis enzyme: APC/C APC/C targets

S and M cyclins for degradation, stopping cell cycle progression.

Two major proteolysis enzyme:SCF

targets CKIs, for degradation by the proteasome. This helps regulate the cell cycle by controlling Cdk activity.

Two major proteolysis enzyme:SCF SCF ubiquitinates

in late G1, activating S-Cdks and initiating DNA replication

Two major proteolysis enzyme:SCF SCF activity is

constant, but its targets are regulated by phosphorylation.

Cell cycle control system G1

Cell growth and preparation

Cell cycle control system S

DNA replication

Cell cycle control system G2

Preparation for mitosis

Cell cycle control system M

Mitosis (nuclear division) and cytokinesis (cell division).

Cell cycle control system Checkpoints

Ensure correct cell division

Cell cycle control system Cyclins and Cdks

Regulate cell cycle progression

Cell cycle control system External and internal signals

Influence cell cycle decisions

Cell cycle control system External and internal signals activate

G1-Cdk, which triggers G/S and S cyclin expression, driving the cell past the Start transition

Three Major Cell Cycle Checkpoints G1 Checkpoint:

Decides if cell proceeds to DNA replication.

Three Major Cell Cycle Checkpoints G2 Checkpoint

Ensures DNA replication is complete and accurate.

Three Major Cell Cycle Checkpoints Metaphase Checkpoint

Confirms all chromosomes are attached to spindle fibers

Prereplicative complex

* Pre-RC assembly: Prepare for DNA replication. * S-Cdk activation: Initiate DNA replication. * Initiation and elongation: DNA unwinds, and new strands are created. * M-Cdk activation: Prepare for cell division. * APC/C activation: Degrade proteins for cell division. * New Pre-RC assembly: Prepare for the next cell cycle.

Prereplicative complex

group of proteins that assemble at the origin of replication on DNA to initiate DNA replication

The regulation for Cdk activation

Cyclin binding partially activates Cdk by displacing an inhibitory loop.

The regulation for Cdk activation

Full Cdk activation requires phosphorylation by CAK.

cell biology

kiler · 16問 · 1年前

cell biology