BIOL110s05-16 - BIOL 110: Principles of Biology Spring 2005...

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Unformatted text preview: BIOL 110: Principles of Biology Spring 2005 Lecture 16, W 3/2/05 • Midterm #1: Average 75%, Median 82%; 3 at 100%+ Average – See me THIS WEEK, if you scored < 70%. (Don’t panic!!) (Don’ – Extra Credit if <70%: Rewrite wrong multiple choice questions, explaining why your choice was wrong, and the correct answer is right. (earn-back (earnup to 50% of lost points on M/C) • If you scored <20/40 on the Essays, you may rewrite them THIS ONE TIME (for 50% of difference)! • All exam extra credit is due by Noon TODAY!! • Return Lab Quiz #1 to me by TODAY. • Journal Article reports –Topics due 3/7 or 3/9 in lab. – Go to the library, online, or newspaper Science sections – Look through Discover, National Geographic, Scientific American, Discover, JAMA, NEJM, Science News for topics for • (be as specific as possible! – include possible reference) • Skipping Ch. 24 for now. Read Ch’s 7 & 8! Ch’ – (Cell Division & Genetics) REVIEW: • Ch. 6: How Cells Release Chemical Energy – Aerobic: • Glycolysis (6C 2x 3C): 2 net ATP; 2 NADH. 2x • Pyruvate Oxidation (2x 3C 2x 2C + 2CO2). 2 NADH 2x • Krebs Cycle (2X 2C 4 CO2 ). 6 NADH, 2 FADH2, 2 ATP CO ). – Totals: 4 ATP, 10 NADH, 2 FADH2 (LOTS OF ENERGY!) TODAY: • Ch. 6: How Cells Release Chemical Energy – Aerobic: Electron Transport Phosphorylation (Chemiosmosis) ATP!!!! ATP!!!! – Anaerobic: Fermentation • Ch. 7: How Cells Reproduce – Eukaryotes: Cell cycle, Mitosis, Meiosis (& sex) – Cancer 1 III. Electron Transport Phosphorylation (Oxidative Phosphorylation; Chemiosimosis) 1. Occurs in the mitochondria 2. Coenzymes deliver electrons to electron transport systems electron 3. Electron transport sets up H+ ion gradients 4. Flow of H+ down gradients powers ATP formation ATP Electron Transport 1. ETS’s are embedded in inner mito. membrane 2. NADH and FADH2 give up electrons to ETS give • Electrons were picked up in earlier stages 3. Electrons are transported through the system • Pumps H+ into outer mito. space mito. 4. The final electron acceptor is Oxygen Oxygen 2 Creating an H+ Gradient OUTER COMPARTMENT NADH INNER COMPARTMENT Making ATP: Chemiosmotic Model Only way out for H+ protons is thru ATP Synthase enzyme ATP Exergonic H+ flow out drives Endergonic ATP synthesis Exergonic Endergonic = ENERGETIC COUPLING!!!!!!! ENERGETIC ATP INNER COMPARTMENT ADP + Pi Diffusion Gradient (conc’n & charge) conc’ 3 Importance of Oxygen • Electron transport phosphorylation requires the presence of oxygen • Oxygen withdraws spent electrons from the electron transport system – combines with H+ to form water – So ravenous for electrons, it takes even the wimpiest ones!!! ** Summary of Energy Harvest ** (per molecule of glucose) 1. Glycolysis – 2 ATP formed by substrate-level phosphorylation substrate• 2 NADH 2. Krebs cycle and preparatory reactions (Pyr. Ox’n) – 2 ATP formed by substrate-level phosphorylation substrate• 8 NADH, 2 FADH2 3. Electron transport phosphorylation – 32 net ATP formed (~3 ATP/NADH, 2 ATP/FADH2) (~3 4. NET = 36 ATP from AEROBIC RESPIRATION!! 4 IV. Fermentation Pathways 1. Begin with glycolysis 2. Are anaerobic: don’t require oxygen don’ 3. Do not break glucose down completely to carbon dioxide and water (lots of energy left!!) 4. Yield only the 2 ATP from glycolysis only 5. Steps that follow glycolysis serve only to regenerate regenerate NAD+ NAD • Lots of Energy left in the resulting reduced product (Lactic Acid, or Ethanol) A. Lactate Fermentation GLYCOLYSIS C6H12O6 2 ATP energy input 2 ADP 2 4 ATP energy output 2 NAD+ NADH 2 pyruvate (3C) 2 ATP net LACTATE FORMATION FORMATION 2 lactate (3C) electrons, hydrogen from NADH 5 B. Alcoholic Fermentation GLYCOLYSIS C6H12O6 2 ATP energy input 2 ADP 2 4 ATP 2 pyruvate 2 NAD+ NADH energy output 2 ATP net ETHANOL FORMATION FORMATION 2 H2O 2 CO2 2 acetaldehyde (2C) electrons, hydrogen from NADH 2 ethanol (2C) How Cells Reproduce Chapter 7 HeLa cells 6 Understanding Cell Division 1. What instructions are necessary for inheritance? 2. How are those instructions duplicated for distribution into daughter cells? 3. By what mechanisms are instructions parceled out to daughter cells? Reproduction • Parents produce a new generation of cells or multicelled individuals like themselves • Parents must provide daughter cells with – hereditary instructions, encoded in DNA – and enough metabolic machinery to start up their own operation 7 ** Division Mechanisms 1. Eukaryotic organisms 1. 1. Mitosis 1. 2. Meiosis identical products!! identical generates diversity!! generates 2. Prokaryotic organisms – Prokaryotic fission PART 1: Mitosis Roles of Mitosis: 1. Multicelled organisms 1. Growth 2. Cell replacement 2. Some protistans, fungi, plants, animals – Asexual reproduction 8 Chromosome • A DNA molecule & attached proteins • Duplicated in preparation for mitosis one chromosome (unduplicated) one chromosome (duplicated) DNA DNA and proteins arranged as cylindrical fiber one nucleosome histone Chromosome Number • Sum total of chromosomes in a cell • Somatic cells – Chromosome number is diploid (2n) diploid – Two of each type of chromosome • Gametes – Chromosome number is haploid (n) haploid – One of each chromosome type 9 Human Chromosome Number • Diploid chromosome number (2n) = 46 – 2 meters of DNA! • Two sets of 23 chromosomes each – One set from father – One set from mother • Mitosis produces cells with 46 chromosomes – two of each type I. Cell Cycle • Cycle starts when a new cell forms • During cycle, cell increases in mass and duplicates its chromosomes • Cycle ends when the new cell divides 10 A. Interphase 1. Usually longest part of the cycle 2. Cell increases in mass 3. Number of cytoplasmic components doubles – (mitochondria, ribosomes, etc.) ribosomes, 4. DNA is duplicated – (“S” synthesis phase) Stages of Interphase 1. G1: – Interval or gap after cell division (before DNA replication) 2. S: – Time of DNA synthesis (replication) 3. G2: – Interval or gap after DNA replication CELL CYCLE CONTROL: 1. Once S begins, the cycle usually runs through G2 and mitosis 2. The cycle has a built-in molecular brake in builtG1 3. Cancer involves a loss of control over the cycle, malfunction of the “brakes” brakes” 11 B. Mitosis • • Period of nuclear nuclear division division Usually followed followed by cytoplasmic division Four stages: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase chromosome (unduplicated) in a daughter cell at interphase chromosome (unduplicated) in a daughter cell at interphase chromosome (unduplicated) in a cell at interphase • same chromosome (duplicated) in interphase prior to mitosis mitosis, cytoplasmic division The Spindle Apparatus 1. = two distinct sets of microtubules 1. Each set extends from one of the cell poles 2. Two sets overlap at spindle equator 2. Moves chromosomes during mitosis one spindle pole one of the condensed chromosomes spindle equator microtubules organized as a spindle apparatus one spindle pole 12 ...
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