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Cellular Division. Chapters 6, 27, and 42-43. Objective 1: Structure of Chromosome. DNA is coiled around histone proteins Appears like beads on a string It is then coiled further around the existing coils Also called a “ supercoil ”. Some definitions to help understand. - PowerPoint PPT Presentation
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Cellular Division
Cellular DivisionChapters 6, 27, and 42-43Objective 1: Structure of ChromosomeDNA is coiled around histone proteinsAppears like beads on a string
It is then coiled further around the existing coilsAlso called a supercoil
Some definitions to help understandHomologous Chromosomes- chromosomes that are similar in size, shape, and genetic information.
Chromosomes are made of 2 essential parts1. Chromatid- 2 copies per chromosome2. Centromere- Protein disk that connect the two chromatids
Objective 2: TermsHaploid- 1 set of chromosomes, 23 chromosomes per cell (egg or sperm) AKA Sex cells. Symbol n
Diploid- 2 sets of chromosomes, 46 per cell, Somatic cells or body cells. Symbolized by 2n.
Gamete- Germ cell, sex cell, eggs and sperm= 23 chromosomes each.
Zygote- (Fertilized egg), sperm unites w/ egg= 46 ChromosObjective 3: Cell CycleG1- Growth and F(x) of cells. Cell prepares for DNA Replication. (Cancer cells skip this phase).S- Chromosome/DNA replicationG2- Organelles replicate to prepare for cell division by acquiring proper proteins.M- (Mitosis)(Nuclear Division) Prophase, Metaphase, Anaphase, Telophase.C- (Cytokinesis)(Cytoplasmic division) Cleavage furrow or cell plate.
90% of a cells life is spent in G1,S, and G2 phases.Objective 4: Cell Division StagesInterphaseG1, S, G2Chromatin- Uncoiled, working DNACell is functioningDNA replicationPreparations for division
ProphaseNuclear Membrane dissolves and breaks down.
Chromatin condenses and become visible Chromosomes.
Centrioles (hollow, barrel shaped cell structure) move to opposite poles and a network of spindle fibers form.
MetaphasePaired chromosomes (Chromatids) line up in the middle (equatorial plane).
Spindles attached to each chromosome at centromere, which are already connected to the centrioles.
AnaphaseCentromere divides and chromosomes physically split
Spindle fibers contract and shorten, pulling the chromosome to the opposite poles.
Mirror images- Equatorial division
TelophaseChromosomes arrive at opposite poles and spindles disappear.
Nuclear envelope reforms
Chromosomes uncoil to become working chromatin again
Cytokinesis beginsPlants= Cell wallAnimals= Cleavage furrow
Video of MitosisObjective 5: CancerCauses:4 TheoriesAll result in mutations that cause oncogenes to be turned on and tumor suppressor genes to be turned off.This messes up your DNA.
Oncogenes- Stimulate growth AKA Cell division.Tumor suppressor genes- restrain cells ability to divide.4 TheoriesStandard - result in mutations that cause oncogenes to be turned on and tumor suppressor genes to be turned off
Modified something disables the repairing of DNA leading to mutations
Early instability master genes silenced that leads to mutations
Aneuploidy too many or too few genes that leads to mutations
Molecular BiologyOncogenes and tumor suppressor genes are both types of transcription factor genes, (homeotic genes).
Transcription factors turn on or turn off lots of other genes.
Think of them as traffic lights, (oncogenes) and gates, (tumor suppressor genes)
Development of CancerInitiation- a mutation occurs to usually 1 (or more) genes. Lag time to next stage= 20-25 years.
Promotion- Anything that happens that leads to expression of the mutation. Such as cells dividing too quickly.
Progression- tumor grows larger and larger, tumor produces enzymes and polypeptides that direct blood to tumor.Cancer Characteristics6 common characteristics to all deadly cancersGrowth w/out a go signalGrowth even against stop signalsEvades autodestruct signalsAbility to stimulate blood vessel constructionImmortalityMetastasis- Ability to spread to new tissue.Cancer TreatmentsMany are specific to a particular type of cancer. Others can work on a number of cancer types. Most treatments try to work by killing cancerous cells.
Common Treatments:Radiation- malignant tumorsChemotherapy- Kills cells that rapidly divideSurgery- Removing the tumorTreatment continuedBenefits: Kill cancer cells.-RNAi siRNA Turn off Oncogenes -Potentially Perfect Cure
Drawbacks: Illness Radiation- cant pinpoint cancer cells. Chemo- targets all dividing cells. Surgery- may not get all cells.
How can cancer kill you? HandoutObjective 7: MeiosisStages:Meiosis: I, P, M, A,TM= Crossing OverMeiosis II: P, M, A, T
Overview of Meiosis I and Meiosis IIMeiosis I: Homologous chromosomes separate into 2 diploid cells. Similar to Mitosis.Meiosis II: 2 diploids become 4 haploid cells.
Purpose of MeiosisProduction of gametes or sex cells (eggs and sperm)
Each 1 contains the haploid number of chromosomesImportance of MeiosisThe offspring have the correct diploid chromosome number
Sex provides for combination of genes= better survivalAKA: Genetic Recombination
Objective 8: Mitosis vs. MeiosisMitosisMeiosis1 cell -> 2 cells
Maintain chromosome #Diploid
Produce body cells
Identical cells1 cell -> 4 sperms 1 egg (3 polar bodies)
Reduce chromosome #Haploid
Produce sex cells
Cells are different
Objective 9: Sexual vs. AsexualSexualAsexualAdvantagesDiversityGenetic recombination
DisadvantagesFew offspringEnergetically unfavorableAdvantagesTons of offspringDont need anybody else
DisadvantagesNo diversity= little evolutionLimited EnvironmentObjective 10: Evolutionary developmentsMulticellular
Tissues
Bilateral Symmetry
Body Cavity
Coelom
Segmentation
Jointed Appendages
Deuterostomes
NotochordMULTICELLULARITY cell specialization
Tissues Further Specialization
Bilateral Symmetry- Centralized Sense Receptors
Body cavity and Coelom Room to grow complex organ systems.
Segmentation- More Specialization, mostly organsSegmentation
Jointed Appendages- Better Mobility
Deuterostomes- Blastopore forms Anus
Notochord- BackboneObjective 11: Embryonic development1st Trimester (1-3 months)Week 1: Cleavage- Results in a hollow ball of calls called a blastocyst
Week 2: Gastrulation- Formation of the 3 primary tissues - Endoderm, Mesoderm, Ectoderm
Week 3: Neurulation- Formation of hollow dorsal nerve tube. - Blood vessels begin to form
Week 4: Organogenesis- Body Organs forms - The heart begins to beat and limb buds form.
2nd and 3rd Trimesters2nd Trimester (4-6 months)Morphogenesis- Miniature limbs assume their adult shapes. Organs grow and fully develop.
3rd Trimester (7-9 months)Growth- Fetus can survive if born during this stage.
Objective 12: Stem cellsWhat are they?
Omnipotent cells. They have the potential to develop into any of the cell lines in the body. The most powerful and potentially the most promising for medical are found in very young embryos. Other stem cells are found in bone marrow, umbilical cord blood and in various other places around the body.Importance of Stem cellsUse to cure degenerative (organs/tissue deteriorate over time) diseasesAlzheimer'sDiabetes mellitusMuscular dystrophy
Constructing new organs or limbsProblems with Stem cellsTo get the most potent cells currently requires the use of human embryos.STEM CELLS + CloningWhat are stem cells and why should I care?
What is Cloning and why should I care?Types of Stem cellsEmbryonic Stem Cells (ESC) Totipotent can form a new organism by becoming all the cells of the body
Adult Stem Cells (ASC) Multipotent can form many of the 220 cell types but not all (semi-differentiated)
Cancer Stem Cells (CSC) Dangerous Most difficult and evil part of any cancer
Induced Pluripotent Stem Cells (IPS) Pluripotent can form any of the 220 cell types but not a whole organism
CLONING Science or science fiction?Reproductive cloning Making an exact copy of an individual (Dolly)
Couples who cannot have childrenReproduce endangered animalsReproduce extinct organismsMake a copy of yourself
Therapeutic cloning Harvest embryonic stems cells from the blastocyst for:
Cell replacement therapyHuman disease modelingDrug therapy screening
Cloning:Problems and promisesEmbryonic Stem Cells (ESC) Totipotent can form a new organism by becoming all the cells of the body
Adult Stem Cells (ASC) Multipotent can form many of the 220 cell types but not all (semi-differentiated)
Cancer Stem Cells (CSC) Dangerous Most difficult and evil part of any cancer
Induced Pluripotent Stem Cells (IPS) Pluripotent can form any of the 220 cell types but not a whole organismShinya YamanakaDiscovered the signals necessary to turn any somatic cell into an iPS celliPS cells can be used for therapeutic cloningJust 4 signalsWhat did Dolly teach us?Dedifferentiation is possibleSo What?How would you like to cure:
Type I DiabetesSickle cell anemiaParkinsonsMuscular DystrophyAlzheimersAny disease caused by cell non-function
How would you like to study:
Lou GehrigsHuntington DiseaseDown Syndrome
Drugs on cell lines for efficacy and side effectsNO ETHICAL PROBLEMS