Chapter 12: Cell Cycle

Chapter 12: Cell CycleFigure 12.0 Mitosis

Cell DivisionReproductionGrowthrepair

GenomeChromosomesSomatic cellsGametic cellsChromatin (duplicates)CentromereSister chromatids

Figure 12.3 Chromosome duplication and distribution during mitosis

Figure 12.1a The functions of cell division: Reproduction

Figure 12.1b The functions of cell division: Growth and development

Figure 12.1c The functions of cell division: Tissue renewal

Reproduction

Growth and Development

Tissue Renewal

Mitosis vs. Meiosis

Mitosis division of nucleusCytokinesis division of cytoplasm

Meiosis produces gametesMitosis produces clones

The cell cycle

The Cell Cycle (cell growth) Interphase (90%)

G1:cell growthS:copies chromosomesG2:preps for division

Mitotic phase (M)

Figure 12.4 The cell cycle

What’s the purpose of Interphase?

Cell growth, produce proteinsHigh Metabolic ActivityPrepares for divisionSingle centrosomes replicatesCentrosomes move apartSpindle Poles form

Magnificent Mitosis!PPMAT

Prophase Prometaphase metaphase anaphase telophase

Prophase

What happens to the chromatin?What happens to the nucleolus?Sister chromatids, centromereWhat happens to the nuclear

envelope (membrane)?

Prometaphase

Nuclear envelope dissolvesMicrotubules of the spindle

contact chromosomes (kineticore)

Metaphase

“Meet in the Middle”spindle microtubulescentrioles

Anaphase

Sister chromatids separate and move to opposite poles (now called chromosomes) spindle microtubules centrioles

Telophase and Cytokinesis

Reverse of prophase chromatin nucleoli nuclear envelope

Cytokinesis

Figure 12.7 Testing a hypothesis for chromosome migration during anaphase

Cytokinesis :a closer look

Cleavage Furrow Occurs along old metaphase plate

Actin Microfilaments“pulling of drawstrings”Plants form a “cell plate” vesicles

move to middle. Cell plate fuses with plasma

membrane

Figure 12.8 Cytokinesis in animal and plant cells

Molecular ControlRegulation by internal and external

checkpoints G1 in mammals, if stop cell arrests in G0

phase. (nerve cells always in G0)

Cyclin dependent Kinases (Cdks) Cyclins bind to Cdks during G2, forming

MPF complex which initiates mitosisGrowth Factors: PDGFAnchorage Dependent

CheckpointsFigure 12.13 Mechanical analogy for the cell cycle control system

Cell Cycle Clock

Kinase Dependent: enzymes that activate or inactivate other proteins by phosphorylation.

Cyclin: protein kinase must be attached to, for enzyme to be active. Constant Conc. of Enzyme, varying conc. of cyclin

MPFs (maturation promoting factor) first Kinase discovered.

Control LinkCell Cycle Game

CancerCancer cellsBenign tumorMalignant tumor

MetastasisProto-oncogenesOncogenes

Figure 12.15 The effect of a growth factor on cell division