Bio 201 1st Edition Final Exam Study GuideLecture 25-Bacteria have a single chromosome, and divide by fission:1. Replication of single, circular chromosome2. Segregation of chromosome and its copy3. Cytokinesis (segregation of daughter cells)-Eukaryotes divide by mitosis:1. Replication of centrosomes2. Replication of chromosomes, sister chromatids join at centromere3. Nuclear envelope breakdown and beginning of chromosome alignment4. Alignment of chromosome at equator5. Segregation of sister chromatids6. Cytokinesis and reformation of nuclear envelopeCEL CYCLE:-G1= Gap 1= Growth-G0= Gap 0= Exiting Cell Cycle-S= Synthesis= DNA replication-G2= Gap 2= Cell stops, DNA checked for error-M= Mitosis= Chromosome condensation, cytokinesis (cell division)-Maturation Promoting Factor (MPF)-The activity in the cytoplasm of progesterone- treatedoocytes that stimulates completion of M phase. -MPF found in all cells at beginning of meiosis/mitosis-MPF activity from one cell triggers entry into meiosis into mitosis in any other cell arrested in G2-MPF activity begins to appear at the end of G2 and remains high until the end of mitosis-MPF activity is a complex of 2 proteins, Cyclin B and Cdk1. Cdk1- cyclin-dependent protein kinase (cdc 2). Cyclin B- allosteric activator of Cdk1, made by cells in response to progesterone, activates Cdk1 and after a fixed time Cyclin B degrades Cdk1 inactive. -Cdk1- phosphorylates proteins involved in mitosis. Targets; Histone protein chromosome condensation, Lamin A Nuclear envelope breakdown, Microtubule associated proteins Mitotic Spindle. -Diiferentcyclins activate Cdks progression through different phases of the cycle. Lecture 26-G2/M checkpoint- Check cell size and DNA damage-Spindle Assembly Checkpoint- In M, checks for alignment and tension-G1/S Checkpoint- Cell size, DNA damage, environmental factors-Checkpoint failures tumor suppressor genes, oncogenes, and protp-oncogenes. -Tumor suppressor- genes who inhibit cell cycle. -Rb- Inhibits s-phase genes proteins is inactivated when phosphorylated by cdk. When binds to E2F, prevents S-phase transcription. But when binds to E7, Rb is turned off. -p53- prevents cell cycle at multiple checkpoints. DNA damage phosphorylation p53, may lead to apoptosis. -Apoptosis- programmed cell death, cell shrinkage, DNA laddering, cell permeabilization, loss of cell membrane asymmetry.-Necrosis- Cell death due to damage or disease, cell lysis. -Oncogenes- Genes whose normal protein products activate cell cycle progression. -Proto-oncogenes- Cellular genes whose normal protein products promote cell cycle progression, only active in certain circumstances. Lecture 27-Condensation of DNA is required for mitosis to occur without error, it prevents tangling and breakage of chromosomes when cells divide-DNA is a double stranded helix and super coiled, it wraps around histone and is wound again. -Cdk1 phosphorylates histone proteins-30nm fiber chromatin in interphase cells, and 700 nm fiber chromatin in mitosis.-Homologous chromosomes- Same chromosomes inherited from either the father or the mother (same genes, but not identical because different alleles)-Chromatid- One copy of a replicated chromosome-Sister Chromatids- 2 identical copies of a replicated chromosome-Centromere- Location somewhere within a chromosome where sister chromatids are joined-Spindle Structure-Made up of 3 microtubules-Kinetochore MT- Bind to chromosome at + end and centromere at – end.-Astral MT- Connected to membrane at + end and centrosome at – end. -Polar MT- Connected through kinesin-like motor proteins at + end and centrosome at – end. -Spindles from by MT polymerization from centrosome, MT that run into kinetochore become kinetochore MT. MT that run into the membrane become astral MT, and MT that run into other MT become polar MT. -Cohesin- A kinetochore protein that holds sister chromatids together(cohesive). At anaphase cohesion breaks down allowing the sister chromatids to separate. -MT depolymerization and motor proteins of kinetochore MTs, pull chromatids toward centrosome. Dynein-like motor proteins pull chromatids towards – ends. Kinetochore MTs depolymerize at both + and – ends  chromosomes pulled towards daughter cell centrosomes. -MT depolymerization and motor proteins of astral and polar MT push daughter cells apart.- Astral MT depolymerization at + end while dynein-like motor proteins pull on MT centrosome gets pulled towards membrane.-Polar MT polymerize at + end while kinesin-like proteins push MTs apart centrosome gets pulled apart. Lecture 28-This checkpoint is during the metaphase anaphase transition. It ensures that both sides of kinetochore have microtubules attached, before degrading the cohesin. -If anything goes wrong during the metaphase or anaphase, it can be very bad for cells.-Non-disjunction- Abnormal chromosome segregation during mitosis or meiosis. -Karyotype- #/ type of chromosome in a cell.-Aneuploidy- Cells inherit the wrong #/ type of chromosome: generally incompatible with life but often seen in cancer cells. -The kinetochore is central to preventing aneuploidy -Cohesin holds the sister chromatids together until anaphase, where it then begins to degrade. It only degrades when MTs from both poles are attached and chromosomes are aligned at the metaphase plate. -ANIMAL CYTOKINESIS: After chromatids have separated, a contractile ring forms, this ring tightens, eventually dicing parent cell into 2 daughter cells. Eukaryote cells need actin and myosin for cytokinesis. Actin and double-headed myosin are responsible for the formation and tightening of the contractile ring and cytokinesis. -PLANT CYTOKINESIS:-There is no formation of a contractile ring. After chromatids have separated, lipid vesicles invade region between 2 nuclei, this region is called the cell plate. The vesicles eventually fuse and fuse with the plasma membrane, dividing daughter cells. Plant cells divide by fusion of vesicles at the cell plate. Lecture 29-Meiosis I- Separation of homologous chromosomes, chiasma occurs. 1. Homologous chromosomes align on metaphase plate and exchange genetic information (chiasma) 2.Segregation of homologs (sister chromatids remain together) 3. Cytokinesis-Meiosis II- Separation of sister chromatids. 4. Chromosomes align on metaphase plate. 5. Separation and Segregation of sister chromatids, 6.