Zoology 101: Animal Biology Last Lecture Outline Lecture 19 1. Movie Current Lecture1. Females and the X chromosome2. Energy Processing 3. Electron transport/Chemiosmosis Females and the X chromosome • Example: hemophilia is sexlinked. Sex-linked traits are almost always found in males (females can have but it is extremely uncommon) • Females have X inactivation/dosage compensation◦ Random inactivation of one of the X chromosomes in the embryo (one of the first few stages) ▪ Barr body- condensed inactivated X chromosome ◦ Same X inactivated in each daughter cell ◦ Female mammals are mosaic for X linked gene expression Energy processing • Cellular respiration: the breakdown of organic molecules to make ATP◦ Potential energy stored in chemical bonds ◦ ATP= energy currency in cell◦ Follow the pathway of the elections originally found in our food • ATP (adenosine triphosphate) moves from ATP to ADP+P via phosphorylation◦ 2 types:▪ Substrate-Level phosphorylation▪ Oxidative phosphorylation • NAD+ and FAD are electron shuttles ◦ electrons are removed from food and transferred to shuttles ◦ NAD+ + 2e-+ 2 protons → NADH + a proton ◦ FAD + 2e- + 2 protons → FADH(2) ◦ View the overview of cellular respiration in textbook (figure 9.6, pg 167) • Glycolysis: breaking down of glucose (6 carbons; will produce 2 pyruvate ◦ Energy investment phase▪ 2 ADP + 2 P ← 2 ATP used ◦ Energy Payoff▪ 4 ADP + 4P → 4 ATP formed ▪ 2 NAD+ + 4 e- + 4 protons → 2 NADH + 2 Protons • 2 Pyruvate molecules◦ Net▪ Glucose → pyruvate and water ▪ 4 ATP formed – 2 ATP used → 2 ATP ▪ 2 NAD+ + 4 e- + 4 protons → 2 NADH and 2 protons • How is ATP made in gylcolysis?◦ Substrate level phosphorylation ▪ Enzyme transfers P to ADP and releases product and ATP • Pyruvate (in cytosol) move into mitochondria ◦ processing occurs in the matrix, modifying occurs and changes into Acetyl CoA ▪ 3 carbons goes to 2, extra carbon is turned into carbon dioxide ▪ NAD+ picks up a proton → NADH → 2 for every glucose • Citric acid cycle (Kreb's cycle) ◦ CoA go through a series of steps (bonds broken)◦ Release of 2 carbon dioxide for each turn, 3 NADH, ATP (made by substrate-level phosphorylation) and FADH(2) ◦ Net per glucose: 4 CO(2), 6 NADH, 2 ATP, 2 FADH(2) Totals per Glucose Glycolysis Pyruvate Citric Total NADH 2 2 6 10FADH(2) 0 0 2 2CO(2) 0 2 4 6ATP (substrate) 2 0 2 4• Substrate-level phosphorylation doesn't make enough ATP, we need more• All the electrons are banked in NADH and FADH(2) Electron transport/Chemiosis• Chemiosis: oxidative phosphorylation, energy stored in the form of a hydrogen ion gradient across the membrane is used to drive cellular work (ATP synthesis) • Electron transport chain: collection of molecules in inner mitochondrial membrane • Cistae increase surface area • Sequence of electron carriers → donate and accept electrons. As you move left to right, electron affinity increases. Final acceptor is oxygen • Complexes 1,3, 4 are proton pumps. Pump protons from matrix to intermembrane space. High concentration of protons in intermembrane space compared to matrix (proton gradient). Needs active transport: energy provided by movement of electrons down the electron transport chain • ATP synthase- inner mitochondrial membrane, chemiosmosis → energy stored in the form of proton gradient used to make ATP◦ Protons flow through ATP synthase → can grab an ADP and P and make ATP◦ Old data ~ 34 ATP's for every
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