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 TheoriesStandard Dogma, Modified Dogma, Early Instability, All- AneuploidyAll result in mutations that cause oncogenes to be turned on and tumor suppressor genes to be turned off.

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

Early instability master genes silenced

Aneuploidy too many or too few 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 tumorHormone therapy- Manipulates endocrine systemTreatment 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.Hormone- can mess up your bodys systems.

How can cancer kill you? HandoutObjective 6: PicturesLab time baby!Objective 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 haploid cells.Meiosis II: Similar process to mitosis. 2 haploids 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

Notochord

Objective 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.