Cellular DivisionDNA 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 Homologous Chromosomes- chromosomes that are similar in size, shape, and genetic information. Chromosomes are made of 2 essential parts 1. Chromatid- 2 copies per chromosome 2. Centromere- Protein disk that connect the two chromatids Objective 2: Terms Haploid- 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 Chromos Objective 3: Cell Cycle G1- Growth and F(x) of cells. Cell prepares for DNA Replication. (Cancer cells skip this phase). S- Chromosome/DNA replication G2- 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 cell’s life is spent in G1,S, and G2 phases. Objective 4: Cell Division Stages Interphase Nuclear 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. Metaphase Paired chromosomes (Chromatids) line up in the middle (equatorial plane). Spindles attached to each chromosome at centromere, which are already connected to the centrioles. Anaphase Centromere divides and chromosomes physically split Spindle fibers contract and shorten, pulling the chromosome to the opposite poles. Mirror images- Equatorial division Nuclear envelope reforms Cytokinesis begins 4 Theories All 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 Theories Standard - 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 Biology Oncogenes 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 Cancer Initiation- 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 Characteristics Growth w/out a go signal Growth even against stop signals Evades autodestruct signals Immortality Cancer Treatments Many 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: Surgery- Removing the tumor -Potentially Perfect Cure Chemo- targets all dividing cells. Surgery- may not get all cells. How can cancer kill you? Handout Objective 7: Meiosis Meiosis II: P, M, A, T Overview of Meiosis I and Meiosis II Meiosis I: Homologous chromosomes separate into 2 diploid cells. Similar to Mitosis. Meiosis II: 2 diploids become 4 haploid cells. Purpose of Meiosis Each 1 contains the haploid number of chromosomes Importance of Meiosis AKA: Genetic Recombination Mitosis Meiosis Reduce chromosome # Sexual Asexual Advantages Diversity Disadvantages Body cavity and Coelom – Room to grow complex organ systems. Segmentation- More Specialization, mostly organs Segmentation Objective 11: Embryonic development 1st 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 Trimesters 2nd Trimester (4-6 months) Morphogenesis- Miniature limbs assume their adult shapes. Organs grow and fully develop. 3rd Trimester (7-9 months) Objective 12: Stem cells What 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 cells Alzheimer's Problems with Stem cells To get the most potent cells currently requires the use of human embryos. STEM CELLS + Cloning What is Cloning and why should I care? Types of Stem cells Embryonic 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 children Reproduce endangered animals Reproduce extinct organisms Therapeutic cloning – Harvest embryonic stems cells from the blastocyst for: Cell replacement therapy Human disease modeling Drug therapy screening Problems and promises Embryonic 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 Shinya Yamanaka somatic cell into an iPS cell iPS cells can be used for therapeutic cloning Just 4 signals Dedifferentiation is possible Type I Diabetes Sickle cell anemia Lou Gehrig’s NO ETHICAL PROBLEMS
