Regulation of Cell Division
Coordination of cell division
§ Multicellular organism
– Need to ______across different ______parts of organism
– Critical for ______growth, ______and ______
• Coordinate timing of ______
• Coordinate rates of ______
• Not all cells can have the same ______
Frequency of cell division
§ Frequency of cell division ______with cell type
– Embryo
· Cell cycle ______
– Skin cells
• Divide ______throughout life
• ______cycle
– Liver cells
• Retain ______to divide, but keep it in ______
• Divide once every ______
– Mature nerve cells and muscle cells
• ______at all after maturity
• Permanently in ______
Overview of Cell Cycle Control
§ Two ______points in cell cycle
– Replication of ______
– Separation of ______
§ Checkpoints
§ Process is ______and possibly ______
Checkpoint control system
§ Checkpoints
– Cell cycle controlled by ______chemical signals at ______points
– Signals indicate if ______have been completed correctly
§ 3 major checkpoints
– ______
• Can ______begin?
– ______
• Has ______been completed correctly?
• Commitment to ______
– ______checkpoint
• Are all ______attached to spindle?
• Can ______separate correctly?
G1/S Checkpoint
§ G1/S checkpoint is most ______
– ______decision point
• ______point
§ If cell receives go signal, it ______
· ______signals: cell growth (size), cell nutrition
· ______signals: growth factors
§ If cell does not receive go signal, cell ______cycle and switches to ______phase
– ______, working state
GO phase
§ ______state
§ ______human cells in GO phase
§ Liver cells
– In GO phase but can be ______to cell cycle by external cues
§ Nerve and muscle cells
– ______specialized
– ______in GO phase and can ______divide
Activation of cell division
§ How do cells know when to divide?
– ______signals
• Chemical signals in ______give cue
• Signals usually mean ______
– ______
– ______
Go ahead signals
§ Protein Signals that promote ______
– ______signals
– ______factors
– ______signals
• ______factors
§ Primary mechanism of control
– ______
• ______enzymes
• either activates or ______cell signals
Cell Cycle Signals
§ Cell Cycle Controls
– ______
• ______proteins
• ______cycle in the cell
– ______
• Cyclin dependent kinases
• Phosphorylates ______proteins
• ______or ______proteins
– ______
• Triggers passage through different stages of ______
Cyclins and Cdks
§ Interaction of ______and different______triggers the stages of the cell cycle
Cyclin and cyclin dependent kinases
§ ______drive cell from one phase to next in cell cycle
§ Proper regulation of cell cycle is so key to life that the genes for these regulatory proteins have been ______through evolution
§ The genes are basically the same in ______
External Signals
§ ______factors
– Coordination between ______
– Protein signals released by ______that stimulate other cells to divide
• ______inhibition
– ______cells stop dividing
– Each cell binds a bit of growth ______
– Not enough left to ______cell division
• ______dependence
– To divide cells must be attached to a ______
--______receptors
Example of a Growth Factor
§ Platelet Derived Growth Factor (PDGF)
– Made by ______(blood cells)
– Binding of PDGF to cell ______stimulates ______(connective tissue) cell division
• ______wounds
Growth Factors and Cancer
§ ______can create cancers
– Proto-oncogenes
– normally activates ______
· ______factor genes
· Become ______(cancer causing) when ______
– If switched ______can cause cancer
– Example: ______(activates ______)
§ ______genes
– ______cell division
– If switched ______can cause cancer
– Example: ______
Cancer and cell growth
§ Cancer is essentially a ______of cell division ______
– ______cell division
§ What control is lost?
– ______stops
– Gene ______plays a key role in ______restriction point
• P53 protein halts cell division if it detects ______
--Options:
– Stimulates ______to fix DNA
– Forces cell into GO ______
– Keeps cell in ______arrest
– Causes ______of damaged cell
– ______cancers have to shut down p53 activity
Development of Cancer
§ Cancer develops only after a cell experiences ~ ______(hits)
– ______growth
• Turn ______growth promoter genes
– Ignore ______
• Turn ______tumor supressor genes
– Escape ______
• Turn ______suicide genes
– Immortality = ______
• Turn ______chromosome maintenance genes
– Promotes ______
• Turn ______blood vessel growth genes
– Overcome ______dependence
• Turn ______touch censor gene
What causes these hits?
Mutations in cells can be triggered by:
§ ______
§ ______exposure
§ ______exposure
§ ______
§ ______
§ ______
§ ______
§ ______
Tumors
§ Mass of ______
§ ______tumor
– Abnormal cells ______at original site as a ______
• ______has halted cell divisions
– Most do not cause serious problems and can be removed by ______
§ ______tumors
– Cells ______original site
• Lose attachment to nearby ______
• Carried by ______system to other tissue
• Start more tumors = ______
– Impair functions of organs ______body
Traditional treatments for cancers
§ Treatments target ______cells
– High energy ______
• ______dividing cells
--Chemotherapy
· Stop ______
· Stop ______
· Stop ______
New Miracle Drugs
§ Drugs targeting ______(enzymes) found only in ______cells
§ Gleevec
– Treatment for ______(CML) and ______(GIST)
– 1st successful ______
AP Biology McClure-Ottmers
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