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Chapter 9 How Cells Reproduce. Start with 3 questions: What kind of information guides inheritance? How is the information copied in a parent cell before being passed to the daughter cell? What kind of mechanisms actually parcel out info to daughter cells?. 9-1 Overview. - PowerPoint PPT Presentation
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Chapter 9 How Cells ReproduceChapter 9 How Cells Reproduce
Start with 3 questions:Start with 3 questions:– What kind of information guides inheritance?What kind of information guides inheritance?– How is the information copied in a parent cell How is the information copied in a parent cell
before being passed to the daughter cell?before being passed to the daughter cell?– What kind of mechanisms actually parcel out info What kind of mechanisms actually parcel out info
to daughter cells?to daughter cells?
9-1 Overview9-1 Overview
Mitosis – nuclear division in somatic cellsMitosis – nuclear division in somatic cells– Growth, replacing cells, tissue repairGrowth, replacing cells, tissue repair– Plants, animals, fungi, protistsPlants, animals, fungi, protists
Meiosis – formation of gametes/sporesMeiosis – formation of gametes/spores– Basis of sexual reproductionBasis of sexual reproduction– Develop from germ cellsDevelop from germ cells
Prokaryotes?Prokaryotes?– Binary fission (p. 336)Binary fission (p. 336)
ChromosomesChromosomes
Characteristic Characteristic numbernumber
Orderly coilingOrderly coiling DNA winds 2x DNA winds 2x
around histones to around histones to make nucleosomesmake nucleosomes
CentromereCentromere Kinetochore Kinetochore
one chromosome(one dispersed DNAmolecule + proteins;
not duplicated)
one chromosome(threadlike and nowduplicated; two DNAmolecules + proteins)
one chromosome(duplicated and also condensed
tightly)p.61
Nuclear DNA
9.2 Cell Cycle9.2 Cell Cycle
Series of events Series of events from one cell from one cell division to the nextdivision to the next
InterphaseInterphase
G1G1– Growth/functionalGrowth/functional
SS– Synthesis of DNASynthesis of DNA
G2G2– Prepare for divisionPrepare for division
Mitosis and Mitosis and C-some #C-some #
DiploidDiploid– 2n2n– 2 of each type2 of each type
9.3 Closer look9.3 Closer look
ProphaseProphase– C-somes visibleC-somes visible– Centrioles duplicateCentrioles duplicate– Nuclear envelopeNuclear envelope– MT docks at MT docks at
kinetochoreskinetochores
MetaphaseMetaphase
Alignment of c-Alignment of c-somes between somes between spindle polesspindle poles
AnaphaseAnaphase
Sister chromatids Sister chromatids move to opposite move to opposite spindle poles by spindle poles by motor proteinsmotor proteins
TelophaseTelophase
C-somes reach polesC-somes reach poles DecondenseDecondense Vesicles reform Vesicles reform
envelopeenvelope
9.4 Cytokinesis9.4 Cytokinesis
AnimalsAnimals– Contractile ringContractile ring– Cleavage furrowCleavage furrow
PlantsPlants– New fibers made before New fibers made before
prophaseprophase
– Vesicles from Golgi fuse and Vesicles from Golgi fuse and deposit materials for cell platedeposit materials for cell plate
Identifying phases of MitosisIdentifying phases of Mitosis
Phase Determination
9.5 When Control is lost9.5 When Control is lost
Cell cycle Cell cycle checkpointscheckpoints– Proteins monitor Proteins monitor
DNA structureDNA structure– Proteins monitor Proteins monitor
proceeding phasesproceeding phases– Favorable Favorable
conditions?conditions?– Kinases Kinases – Growth factorsGrowth factors
Architecture of control systemArchitecture of control system
Growth assessed at G1 checkpointGrowth assessed at G1 checkpoint DNA replication success assessed at G2DNA replication success assessed at G2 Mitosis assessed at M checkpointMitosis assessed at M checkpoint
Molecular MechanismsMolecular Mechanisms
Cyclin dependent protein kinases (Cdks)Cyclin dependent protein kinases (Cdks)– Cyclins – bind to Cdks, allow them to work as Cyclins – bind to Cdks, allow them to work as
enzymesenzymes– G2 - MPFG2 - MPF
Growth factors – stimulateGrowth factors – stimulate– Usually everyone gets equal amountsUsually everyone gets equal amounts– Specific cell surface receptorsSpecific cell surface receptors– Broad or specificBroad or specific
Tumor supressorsTumor supressors
InhibitInhibit Prevent binding of Prevent binding of
cyclins to CdKscyclins to CdKs Recessive Recessive Gene p53 – role in Gene p53 – role in
G1 checkpoint, G1 checkpoint, checks for DNA checks for DNA errorserrors– Repair or notRepair or not
Figure 2: p53 re-enforces G1 and G2 cell cycle arrest after DNA damage through the cyclin-dependent kinase inhibitor p21WAF1/CIPI Mdm2 and Bax are other p53 transcriptional targets, with Mdm2 regulating p53 levels and Bax mediating apoptosis
Proto-oncogenesProto-oncogenes
StimulateStimulate Mutation = oncogeneMutation = oncogene DominantDominant Changes in surface receptorsChanges in surface receptors
Figure 2. A modified receptor. Under normal circumstances membrane-bound receptors require the binding of their ligand to be in an activated state. In contrast, receptors encoded by oncogenes do not require the regulatory step of ligand binding to be active.
CancersCancers
4 characteristics4 characteristics– Grow & divide abnormallyGrow & divide abnormally– Cytoplasm & membrane alteredCytoplasm & membrane altered– Weakened capacity for adhesionWeakened capacity for adhesion– Lethal effectsLethal effects
http://nobelprize.org/educational_games/medicine/2001/
Control of the cell cycle gameControl of the cell cycle game