Lecture 11.3

• Mitosis produces all body cells.
• Meiosis produces all reproductive cells.
• During mitosis, DNA is copied and divided equally.
• During mitosis, DNA is reduced by 50 percent
• Genes are coding regions of DNA in chromosome.
• Condensed replicated chromosomes are called sister chromatids.
• pair of condensed replicated chromosomes is called a homolog.
• Condensed unreplicated chromosomes are chromatids
• Interphase is the non-dividing stage with three distinct stages.
• Mitotic (M) phase-dividing phase.
• Synthesis phase is where replication occurs.
• The two gap phases (G1 and G2) happen before and after the S phase.
• Cells perform their functional roles in the G1 phase.
• Cells use G2 phase to prepare for M phase.
• M phase consists of Mitosis and cytokinesis.
• Cytokinesis is the division of the cytoplasm.
• Please pass me a taco compadre.
• Prophase- chromosomes condense and spindle apparatus forms.
• Prometaphase-Nuclear envelope breaks down and microtubules attach to chromosomes at the kinetochores.
• Metaphase - chromosomes complete migration to the center of the cell.
• Anaphase-sister chromosomes separate and move to their respective sides.
• Telophase-Nuclear envelope reforms and chromosomes decondense.
• Nondividing cells are permanently stuck in G1 phase (called G0).
• M-phase promoting factor (MPF) forces cells into m phase
• MPF is made up of Cyclin and CDK.
• Cyclin concentration fluctuates, it is increased during interphase, and peaks in m-phase.
• CDK remains constant throughout the cell cycle.
• When cyclin concentrations increase and they bond to CDK, and when a phosphate group is removed late in G2, MPF is turned on.
• Shut down MPF by destroying one of the proteins.
• The G1 checkpoint checks if: DNA damage, cell size, and nutrients are sufficient.
• In the G1 checkpoint, if DNA is physically damaged p53 protein pauses the cell cycle of induces apoptosis (cell death)
• The G2 checkpoint checks if chromosome replication has proceded properly.
• If a cell does not pass the G2 checkpoint, MPF does not get turned on.
• M1 checkpoint checks between metaphase and anaphase, ensures that sister chromatids don't split until all kinetochores are attached.
• M2 checkpoint between anaphase and telophase ensures chromosomes have fully separated.
• Cancer is out of control cell division that is caused by mutations either in the genes that slow, or speed up, cell division.
• Malignant tumors are cancerous and can spread to other parts of the body.
• Benign tumors are noncancerous and noninvasive.