BIOL 1441 1st Edition Lecture 20 Outline of Last Lecture I. The Cellular InternetII. Cell Contacta. Directb. Indirect-local vs. long distanceIII. Receptiona. Types of receptorsb. G proteinsc. Tyrosine Kinasesd. Ligand-Gated Ion ChannelIV. Transductiona. Protein Kinasesb. Protein Phosphatasesc. Phosphorylation cascaded. Second messengerse. Cyclic AMPf. Calcium ions and IP3V. Responsea. CytoplasmThese 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 cycleII. CancerIII. Two main phases of the cell cycleIV. Cellular divisionV. ChromosomesVI. Cell cycleVII. MitosisVIII. Cell cycle regulation/control systemCurrent LectureI. Cell Cyclea. Life of a cell from time 1st formed until its own division into 2 cellsb. Cell cycle regulation extremely importantII. Cancera. Cancer is the 2nd leading cause of death in the US. b. Uncontrolled cell growthc. Heritable genetic mutationsd. What causes cancer?i. Accumulation of genetic mutationsii. DNA replicationiii. Virusesiv. Carcinogensv. Radiation (UV rays)vi. *7-10 mutations in one single cellIII. Two Main Phases of the Cell Cyclea. Interphase (G1, S, G2) & Mitosisi. Most time spent in interphaseIV. Cellular Divisiona. Meiosis- sex cells (gametes)i. Gametes- egg, sperm (23 chromosomes)ii. Produce nonidentical daughter cellsb. Mitosis- somatic cells i. Body cells (46 chromosomes)ii. Every single cell in your body (except sex cells!)iii. Produces identical daughter cellsiv. Division for growth and repairv. Before cellular division, cells copy their DNAvi. Each daughter cell receives an exact copy of the genetic material (DNA)1. Doubling of chromosomes happens in interphaseV. Chromosomesa. DNA in each cell ~2 m (6 ft long!)b. You are made up of ~200 trillion cellsc. You have enough DNA if stretched end to end- it would reach the sun d. DNA strands tightly wound around positively charged proteins - histonese. DNA is negative bc of phosphate backbonei. Genome-total DNAf. Chromosomes-supercoiled DNAonly present when cell is getting ready to divideg. All other times DNA is chromatinh. DNA Replicationi. 23 pairs of chromosomes- total of 46ii. Each chromosome replicates- 92 chromosomesi. Sister Chromatids- identical DNA moleculesi. One chromosome that duplicates into TWO sister chromatidsii. Attached at centromereiii. Replicated chromosomes that are attached by protein complexes-cohesinsiv. Centromere: region of DNA on each sister chromatidVI. Cell Cyclea. Mitosis is ONE part of the whole cell cycleb. Two Main Phases of the Cell Cyclei. Mitotic (M) phase- mitosis and cytokinesis1. Mitosis- the division of the nucleus2. Cytokinesis- the division of the cytoplasmii. Interphase- cell growth & copying of DNA1. ~90% of the cell cycle2. Divided into sub-phases:a. G1 phase-cell growth and work-46 chromosomesb. S phase- copy DNA(DNA synthesis)-92 chromosomes c. G2 phase- preparing for mitosis, organelle replicationVII. Mitosis a. 5 phases:i. Prophase-92 chromosomes1. Chromatin condenses into chromosomes (now visible)2. Mitotic spindle begins to forma. Centrosomes, microtubules, asters formingb. Controls movement of chromosomes using microtubules3. Centrosomes begin to move apart4.b. Prometaphase- 92 chromosomesi. Nuclear envelope fragments (breaks down)ii. Microtubules bind to kinetochoresiii. Kinetochores-protein associated with the centromere (each sister chromatid has one)1. Chromosome has a centromere which has kinetochoresc. Metaphasei. Centrosomes opposite ends- spindle completeii. Chromosomes line upiii. All microtubules are attached to kinetochoresiv. Longest phase ~20 mind. Anaphasei. Sister chromatids part toward opposite ends of the cellii. Cell starts to lengtheniii. Shortest phase- few minutese. Telophasei. 2 daughter nuclei begin to formii. Nuclear envelopes formiii. Chromosomes become less condensediv. Cytokinesis is occurring- formation of cleavage furrow1. Cleavage furrow: groove in the cell surface near the metaphase platea. Contractile ring of actin microfilaments associated with myosinb. Furrow deepens until the cell is pinched in two2. Plants have no cleavage furrow because of cell walla. Cell plate contains vesicles make up cell wallf. Plants- mitosisi. Binary Fission- “division in half”1. Prokaryote (bacteria) reproduction2. Bacteria- most genes are on 1 circular chromosome3. Bacterial chromosome begins to replicate at the origin of replicationVIII. Cell Cycle Regulation/control systema. The frequency of cell division varies with the type of celli. Skin cell constantly dividingii. Some nerve cells never divideb. Cell cycle differences result from regulation at the molecular levelc. Events of cell cycle directed by cell cycle control systemd. Specific checkpoints where cell cycle stops until a go-ahead signal is receivedi. Critical control point to determine if cell cycle should proceedii. G1 checkpoint: cell is large enough to divide, enough nutrients are available to support the resulting daughter cells1. MOST IMPOTANT2. G0- nondividing cell phase3. If cell receives the green light, it continues on in cell cycle4. If cell receives red light, it exits the cell cycle and goes into G0iii. G2 checkpoint: DNA replication in S phase has been completed successfullyiv. M checkpoint: all of the chromosomes are attached to the mitotic spindleby a