mitosis. why mitosis? the purpose of mitosis is to generate two new cells from one cell. the...
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MitosisMitosis
Why Mitosis?Why Mitosis?
The purpose of mitosis is to The purpose of mitosis is to generate two new cells from one generate two new cells from one cell.cell. The “daughter cells” generated are The “daughter cells” generated are
exact copies of the “parent cell”exact copies of the “parent cell” Mitosis is happening in many cells Mitosis is happening in many cells
in your body as we speak!in your body as we speak! Some cells divide more frequently Some cells divide more frequently
than othersthan others
Mitosis is part of the Mitosis is part of the Cell CycleCell Cycle
Interphase
Mitosis
Cytokinesis
Key Events in the Cell Key Events in the Cell CycleCycle
The cell gets largerThe cell gets larger
Organelles are madeOrganelles are made
Genetic information is duplicatedGenetic information is duplicated
Half of the DNA and organelles go to Half of the DNA and organelles go to one end and the other half to the one end and the other half to the opposite endopposite end
The cell is split down the middle to The cell is split down the middle to make 2 new cellsmake 2 new cells
Interphase
InterphaseInterphase
Gap1 (G1)Gap1 (G1) Preparation for growthPreparation for growth Organelles, membranes, and ribosomes Organelles, membranes, and ribosomes
mademade
Synthesis (S)Synthesis (S) Chromosomes replicatedChromosomes replicated
Gap2 (G2)Gap2 (G2) Preparation for divisionPreparation for division Mitochondria divideMitochondria divide
Remember, mitochondria have their own Remember, mitochondria have their own chromosome!chromosome!
Mitosis
Cytokinesis
G1
G2
S
Q4 Part 1
Key Events in the Cell Key Events in the Cell CycleCycle
The cell gets largerThe cell gets larger
Organelles are madeOrganelles are made
Genetic information is duplicatedGenetic information is duplicated
Half of the DNA and organelles go to Half of the DNA and organelles go to one end and the other half to the one end and the other half to the opposite endopposite end
The cell is split down the middle to The cell is split down the middle to make 2 new cellsmake 2 new cells
Interphase
MitosisQ7
Chromosomes in Somatic Chromosomes in Somatic CellsCells
Nucleus of cell during G1 Chromosomes not duplicated
Nucleus of cell after S phase Chromosomes are duplicated
Nucleus of cell after mitosis Chromosomes are not duplicated
Homologous pair
Keep in Mind…Keep in Mind…
MitosisMitosis
ProphaseProphase MetaphaseMetaphase AnaphaseAnaphase TelophaseTelophase
Interphase
A
Cytokinesis
PM
T
ProphaseProphase
Pro =forward, forthPro =forward, forth Chromosomes condenseChromosomes condense Nuclear envelope breaks downNuclear envelope breaks down
Membrane surrounding the nucleusMembrane surrounding the nucleus
Centrioles move to opposite polesCentrioles move to opposite poles Spindle fibers growSpindle fibers grow
Q4 Part 2
MetaphaseMetaphase
Meta =after, withMeta =after, with Chromosomes line up at the midlineChromosomes line up at the midline Spindle attaches to chromosomes at the Spindle attaches to chromosomes at the
centromerecentromere The centromere is where the sister The centromere is where the sister
chromatids are attachedchromatids are attached
Q4 Part 2
AnaphaseAnaphase
Ana =againstAna =against Centromeres splitCentromeres split Sister chromatids are pulled to opposite Sister chromatids are pulled to opposite
poles by the shortening of spindle fiberspoles by the shortening of spindle fibers Once separated, each sister chromatid is Once separated, each sister chromatid is
now a chromosome (and each is exactly like now a chromosome (and each is exactly like the chromosome found in the original cell the chromosome found in the original cell before S of interphase)before S of interphase)
Q4 Part 2
TelophaseTelophase
Telo =completion of a goalTelo =completion of a goal Spindle breaks downSpindle breaks down Nuclear envelope forms in each Nuclear envelope forms in each
of the daughter cellsof the daughter cells Chromosomes decondenseChromosomes decondense
Q4 Part 2
Key Events in the Cell Key Events in the Cell CycleCycle
The cell gets largerThe cell gets larger
Organelles are madeOrganelles are made
Genetic information is duplicatedGenetic information is duplicated
Half of the DNA and organelles go to Half of the DNA and organelles go to one end and the other half to the one end and the other half to the opposite endopposite end
The cell is split down the middle to The cell is split down the middle to make 2 new cellsmake 2 new cells
Interphase
MitosisQ7
Cytokinesis
CytokinesisCytokinesis
““Cell-making” phaseCell-making” phase Organelles and Organelles and
cytoplasm are cytoplasm are distributed between distributed between daughter cellsdaughter cells
Microfilament band at Microfilament band at equator contracts to equator contracts to pinch apart 2 new pinch apart 2 new daughter cellsdaughter cells
Interphase
Cytokinesis
Mitosis
Summary of Cell CycleSummary of Cell Cycle
Cell growsCell grows DNA replicatesDNA replicates Organelles are madeOrganelles are made Chromosomes condenseChromosomes condense Chromosomes line up at the equatorChromosomes line up at the equator Replicated chromosomes are pulled Replicated chromosomes are pulled
apart to opposite polesapart to opposite poles Chromosomes decondenseChromosomes decondense Two daughter cells are formedTwo daughter cells are formed
G1
S
G2
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
I
A
C
PM
T
I Pee on the
MAT, See?
GGoo
Resting phaseResting phase Cell may:Cell may:
Enter S phaseEnter S phase DieDie
Cell is damaged Cell is damaged
Do nothingDo nothing NeuronNeuron
GoCell Death
Sit tight
Mitosis
Cytokinesis
G1
G2
S
Cell Cycle CheckpointsCell Cycle Checkpoints
Mitosis
Cytokinesis
G1
G2
S
DNA damage checkpoints
Spindle checkpoint
ApoptosisApoptosis
Programmed cell deathProgrammed cell death Neat and orderlyNeat and orderly
NecrosisNecrosis
Cell explodesCell explodes Not so neat and orderlyNot so neat and orderly
In response to injuryIn response to injury
TelomeresTelomeres
Consist of a repeated sequence Consist of a repeated sequence of DNAof DNA Nature’s solution to the end-replication problemNature’s solution to the end-replication problem
Very tips of chromosomes cannot be replicatedVery tips of chromosomes cannot be replicated Shortened with each mitotic divisionShortened with each mitotic division Limits # of possible cell divisionsLimits # of possible cell divisions Cell will not divide after ~50 divisionsCell will not divide after ~50 divisions Not found in eggs/sperm, bone marrow cells, cancer Not found in eggs/sperm, bone marrow cells, cancer
cellscells Shortening is hastened by chronic stressShortening is hastened by chronic stress
Cell DifferentiationCell Differentiation
The process whereby a cell becomes specializedThe process whereby a cell becomes specialized Every cell contains the exact same genetic Every cell contains the exact same genetic
information (all 23 chromosome pairs)information (all 23 chromosome pairs) One chromosome from mom and one from dadOne chromosome from mom and one from dad
Not all genetic info is being used by every cellNot all genetic info is being used by every cell Different cell types are making Different cell types are making
different proteinsdifferent proteins
The proteins being made by a cell The proteins being made by a cell
give it specialized characteristics give it specialized characteristics
((e.g. e.g. blood cell vs. brain cell) blood cell vs. brain cell)
Stem CellsStem Cells
Important for regenerating cells that are lost (Important for regenerating cells that are lost (e.g.e.g. skin skin cells) and for growthcells) and for growth
Stem cells are undifferentiatedStem cells are undifferentiated Totipotent =able give rise to any cell typeTotipotent =able give rise to any cell type
Progenitor cellsProgenitor cells Somewhat specializedSomewhat specialized Pluripotent =able to produce manyPluripotent =able to produce many different cell typesdifferent cell types
Pathways to Cell Pathways to Cell SpecializationSpecialization
Each specialized Each specialized cell type uses cell type uses only certain only certain “recipes” from “recipes” from the “cookbook”the “cookbook”
Embryonic Stem Cells -Embryonic Stem Cells -IVFIVF
Yields totipotent cellsYields totipotent cells Uses frozen embryos from Uses frozen embryos from in vitroin vitro
fertilizationfertilization in vitro in vitro =in a dish=in a dish in vivoin vivo =in the body =in the body
Embryonic Stem Cells –Embryonic Stem Cells –Nuclear TransfectionNuclear Transfection
CloningCloning
Adult Stem CellsAdult Stem Cells
Pluripotent Pluripotent Found in bone marrow, Found in bone marrow,
umbilical cord blood, umbilical cord blood, certain parts of the braincertain parts of the brain
Even I have stem
cells!