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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
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The major events of the cell cycle During S phase
DNA replicates, taking 10-12 hours.
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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
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The major events of eukaryotic cell division Prophase
DNA condenses into chromosomes
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The major events of eukaryotic cell division Metaphase
nuclear envelope disassembles,chromosomes attach to mitotic fibers then align at center of cell
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The major events of eukaryotic cell division Anaphase
chromosomes separate and move to opposite poles of the cell
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The major events of eukaryotic cell division Telophase
the spindle disassembles, and new nuclear envelopes form around the separated chromosomes
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The four phases of the cell cycle
G1, S, G2, M
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G, S, and G2 are called
interphase
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S Phase for
DNA replication
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M phase for
mitosis and cytokinesis
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Interphase might occupy While M phase
23 hours 1 hour
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The control of the cell cycle Start at late G
where cell commits to cell cycle
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The control of the cell cycle G2/M
triggers early mitotic events that lead to chromosome alignment on the mitotic spindle in metaphase
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The control of the cell cycle Metaphase-to-anaphase
stimulates chromosomes separation, leading to the completion of mitosis and cytokinesis
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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
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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
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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
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Cyclin-Cdk complexes of the cell-cycle control system G1/S-Cdk
initiates DNA replication
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Cyclin-Cdk complexes of the cell-cycle control system S-Cdk
prevents re-replication
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Cyclin-Cdk complexes of the cell-cycle control system M-Cdk
triggers mitosis
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Cyclin-Cdk complexes of the cell-cycle control system Cyclin we're named
because undergo protein creation and degradation
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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.
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The regulation for Cdk activation
In absence of cyclin, the active state of Cdk is partly hidden by protein loop
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The regulation for Cdk activation
Phosphorylation of Cdk by Wee1 inhibits its activity, while dephosphorylation by Cdc25 activates it.
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The inhibition of a cyclin-Cdk complex by a CKI
CKI proteins bind to cyclin-Cdk complexes, inactivating them and regulating cell cycle progression.
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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
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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.
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Two major proteolysis enzyme: APC/C
Cdk dephosphorylation is needed to complete mitosis and cytokinesis.
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Two major proteolysis enzyme: APC/C APC/C is
turned off when G1/S-Cdk is activated in late G1
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Two major proteolysis enzyme: APC/C Securin
Protects protein linkage that holds together sister chromatids together
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Two major proteolysis enzyme: APC/C APC/C targets
securin for degradation, allowing sister chromatid separation
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Two major proteolysis enzyme: APC/C APC/C targets
S and M cyclins for degradation, stopping cell cycle progression.
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Two major proteolysis enzyme:SCF
targets CKIs, for degradation by the proteasome. This helps regulate the cell cycle by controlling Cdk activity.
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Two major proteolysis enzyme:SCF SCF ubiquitinates
in late G1, activating S-Cdks and initiating DNA replication
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Two major proteolysis enzyme:SCF SCF activity is
constant, but its targets are regulated by phosphorylation.
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Cell cycle control system G1
Cell growth and preparation
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Cell cycle control system S
DNA replication
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Cell cycle control system G2
Preparation for mitosis
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Cell cycle control system M
Mitosis (nuclear division) and cytokinesis (cell division).
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Cell cycle control system Checkpoints
Ensure correct cell division
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Cell cycle control system Cyclins and Cdks
Regulate cell cycle progression
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Cell cycle control system External and internal signals
Influence cell cycle decisions
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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
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Three Major Cell Cycle Checkpoints G1 Checkpoint:
Decides if cell proceeds to DNA replication.
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Three Major Cell Cycle Checkpoints G2 Checkpoint
Ensures DNA replication is complete and accurate.
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Three Major Cell Cycle Checkpoints Metaphase Checkpoint
Confirms all chromosomes are attached to spindle fibers
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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.
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Prereplicative complex
group of proteins that assemble at the origin of replication on DNA to initiate DNA replication
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The regulation for Cdk activation
Cyclin binding partially activates Cdk by displacing an inhibitory loop.
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The regulation for Cdk activation
Full Cdk activation requires phosphorylation by CAK.