BIOL 1441 1st Edition Lecture 20 Outline of Last Lecture I The Cellular Internet II Cell Contact a Direct b Indirect local vs long distance III Reception a Types of receptors b G proteins c Tyrosine Kinases d Ligand Gated Ion Channel IV Transduction a Protein Kinases b Protein Phosphatases c Phosphorylation cascade d Second messengers e Cyclic AMP f V Calcium ions and IP3 Response a Cytoplasm These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute b Nucleus Outline of Current Lecture I Cell cycle II Cancer III Two main phases of the cell cycle IV Cellular division V Chromosomes VI Cell cycle VII Mitosis VIII Cell cycle regulation control system Current Lecture I II III IV Cell Cycle a Life of a cell from time 1st formed until its own division into 2 cells b Cell cycle regulation extremely important Cancer a Cancer is the 2nd leading cause of death in the US b Uncontrolled cell growth c Heritable genetic mutations d What causes cancer i Accumulation of genetic mutations ii DNA replication iii Viruses iv Carcinogens v Radiation UV rays vi 7 10 mutations in one single cell Two Main Phases of the Cell Cycle a Interphase G1 S G2 Mitosis i Most time spent in interphase Cellular Division a Meiosis sex cells gametes i Gametes egg sperm 23 chromosomes ii Produce nonidentical daughter cells b Mitosis somatic cells i Body cells 46 chromosomes ii iii iv v vi V VI VII Every single cell in your body except sex cells Produces identical daughter cells Division for growth and repair Before cellular division cells copy their DNA Each daughter cell receives an exact copy of the genetic material DNA 1 Doubling of chromosomes happens in interphase Chromosomes a DNA in each cell 2 m 6 ft long b You are made up of 200 trillion cells c You have enough DNA if stretched end to end it would reach the sun d DNA strands tightly wound around positively charged proteins histones e DNA is negative bc of phosphate backbone i Genome total DNA f Chromosomes supercoiled DNA only present when cell is getting ready to divide g All other times DNA is chromatin h DNA Replication i 23 pairs of chromosomes total of 46 ii Each chromosome replicates 92 chromosomes i Sister Chromatids identical DNA molecules i One chromosome that duplicates into TWO sister chromatids ii Attached at centromere iii Replicated chromosomes that are attached by protein complexescohesins iv Centromere region of DNA on each sister chromatid Cell Cycle a Mitosis is ONE part of the whole cell cycle b Two Main Phases of the Cell Cycle i Mitotic M phase mitosis and cytokinesis 1 Mitosis the division of the nucleus 2 Cytokinesis the division of the cytoplasm ii Interphase cell growth copying of DNA 1 90 of the cell cycle 2 Divided into sub phases a G1 phase cell growth and work 46 chromosomes b S phase copy DNA DNA synthesis 92 chromosomes c G2 phase preparing for mitosis organelle replication Mitosis a 5 phases i Prophase 92 chromosomes 1 Chromatin condenses into chromosomes now visible 2 Mitotic spindle begins to form a Centrosomes microtubules asters forming VIII b Controls movement of chromosomes using microtubules 3 Centrosomes begin to move apart 4 b Prometaphase 92 chromosomes i Nuclear envelope fragments breaks down ii Microtubules bind to kinetochores iii Kinetochores protein associated with the centromere each sister chromatid has one 1 Chromosome has a centromere which has kinetochores c Metaphase i Centrosomes opposite ends spindle complete ii Chromosomes line up iii All microtubules are attached to kinetochores iv Longest phase 20 min d Anaphase i Sister chromatids part toward opposite ends of the cell ii Cell starts to lengthen iii Shortest phase few minutes e Telophase i 2 daughter nuclei begin to form ii Nuclear envelopes form iii Chromosomes become less condensed iv Cytokinesis is occurring formation of cleavage furrow 1 Cleavage furrow groove in the cell surface near the metaphase plate a Contractile ring of actin microfilaments associated with myosin b Furrow deepens until the cell is pinched in two 2 Plants have no cleavage furrow because of cell wall a Cell plate contains vesicles make up cell wall f Plants mitosis i Binary Fission division in half 1 Prokaryote bacteria reproduction 2 Bacteria most genes are on 1 circular chromosome 3 Bacterial chromosome begins to replicate at the origin of replication Cell Cycle Regulation control system a The frequency of cell division varies with the type of cell i Skin cell constantly dividing ii Some nerve cells never divide b Cell cycle differences result from regulation at the molecular level c Events of cell cycle directed by cell cycle control system d Specific checkpoints where cell cycle stops until a go ahead signal is received i Critical control point to determine if cell cycle should proceed ii G1 checkpoint cell is large enough to divide enough nutrients are available to support the resulting daughter cells 1 MOST IMPOTANT 2 G0 nondividing cell phase 3 If cell receives the green light it continues on in cell cycle 4 If cell receives red light it exits the cell cycle and goes into G0 iii G2 checkpoint DNA replication in S phase has been completed successfully iv M checkpoint all of the chromosomes are attached to the mitotic spindle by a kinetochore