BIOL 213 1st Edition Lecture 10 Outline of Last Lecture I. Ion channelsa. Two regionsb. Are neither all the way open nor all the way closedc. There are different kinds that are triggered by different stimuliII. Membrane potentiala. Regulated by leakage of K+ ionsIII. Action potentiala. The change in membrane potential as a function of timeb. The processi. The opening and closing of Na+ and K+ ion channelsIV. Synaptic clefts and neurotransmittersa. Excitatory neurotransmittersb. Inhibitory neurotransmittersOutline of Current Lecture I. Cellular respirationa. Introductory informationII. Glycolysisa. Main pointsThese 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. Energy investment stagec. Cleavage from 6C to 3C staged. Energy production stageIII. What happens to pyruvatea. Anaerobic vs aerobic conditionsIV. What happens wherea. Glycolysis in the cytosolb. Everything else in the mitochondriaV. Citric Acid Cycle / TCA Cycle / Krebs Cyclea. Main pointsb. The processVI. Electron transport chain and oxidative phosphorylationVII. Basic reviewCurrent LectureI. Cellular respirationa. The cell breaks down (oxidizes) food to get energy from the bondsi. The byproducts are CO2 and H2Ob. This is done in three stagesi. Breakdown large macromolecules into its simple subunitsii. Breakdown subunits into acetyl CoA; this also produces some ATP and NADHiii. Completely oxidize acetyl CoA into H2O; this is when a lot of ATP molecules are made via oxidative phosphorylation1. A vast majority of ATP molecules made during cellular respiration is made in this stepc. Glucosei. More energy is retrieved from glucoseii. Most often studiedd. The cell doesn’t just retrieve all of the energy in the molecule at once, because that would be too much energyi. Instead, it converts molecules to slightly different molecules and retrievesa little bit of energy at a time ii. It usually transfers the energy retrieved from breaking down molecules into other molecules, like ATP!II. Glycolysisa. Main pointsi. One molecule of glucose (6 carbon molecule) is converted into two molecules of pyruvate (3 carbon molecule)1. It is important to remember that 1 glucose 2 pyruvateii. There are 10 enzymatic steps1. We look at some in detail2. Have to only really know a fewiii. EVERYTHING OCCURS IN THE CYTOSOLiv. ATP production1. Two molecules are put in at the beginninga. To convert glucose to fructose 1,6-bisphosphate2. Four molecules of ATP are produced later in glycolysis3. Therefore, there is a NET production of 2 ATP moleculesv. No O2 is involved, but there is oxidation of the intermediate NAD+ 1. NAD+ NADH2. A total of 2 NADHs are produced per one glucoseb. What is the net production per one glucose molecule?i. 2 pyruvateii. 2 ATPiii. 2 NADHc. Overviewi. Three main stages1. Energy investmenta. 2 ATP molecules are invested to convert one molecule of glucose into one molecule of fructose 1,6-bisphosphateb. Includes:i. Step 1ii. Step 2iii. Step 32. Cleavage of a 6-carbon sugar into two 3-carbon sugarsa. Fructose 1,6-bisphosphate is converted into 2 molecules ofglyceraldehyde 3-phospate (G3P)i. This is where you see the splitting of 6C molecule into 2 3C moleculesb. Includes:i. Step 4ii. Step 53. Energy productiona. The 2 molecules of G3P are eventually converted into 2 molecules of pyruvateb. 4 ATP are producedc. 2 NADH are producedd. Includes:i. Step 6ii. Step 7iii. Step 8iv. Step 9v. Step 10d. Energy investmenti. Step 1 (very important)1. Glucose is phosphorylated by ATP (1st) to create a glucose 6-phosphatea. This new molecule now has more energy than the original glucose 2. This phosphorylation traps the molecule inside the cella. The molecule is chargedi. This prevents it from passing through the membraneb. Because it’s no longer glucose, it can’t be transported by the glucose transporter protein out of the cell3. This phosphorylation changes the glucose concentration gradienta. Because a glucose was converted to a new molecule, the concentration of glucose inside the cell decreasedb. This causes more glucose molecules to be transported into the cell down its concentration gradientii. Step 2 (isomerization – not very important)1. Glucose 6-phospate is changed into fructose 6-phosphate in order to prepare it for step 3iii. Step 3 (most important)1. Fructose 6-phosphate is phosphorylated by phosphofructokinase (PFK) and ATP (2nd) into fructose 1,6-bisphosphate2. This further increases the amount of energy in the 6-carbon molecule3. This is most important because the enzyme in this step (and therefore the step) is regulateda. PFK is regulated by ADP and ATPb. ADP and ATP bind to the regulatory site, which is different from the active site, meaning that they can be considered as noncompetitive ligandsc. ATP is a noncompetitive inhibitori. PFK is inactive (doesn’t phosphorylate fructose 6-phosphate) when ATP is bound to itii. The whole purpose of cellular respiration is to make ATP, so when there’s enough ATP in the cell, there’s no point in going through glycolysis (which eventually leads to the production of more ATP)d. ADP is a noncompetitive activatori. PFK is active when ADP is bound to itii. A surplus of ADP means there’s not enough ATP in the celliv. Invested 2 ATPe. Cleavage from 6C to 3Ci. Step 41. This is the step when the 6-carbon molecule is split into two 3-carbon moleculesa. Fructose 1,6-bisphosphate dihydroxyacetone phosphate+ glyceraldehyde 3-phosphateii. Step 5 (isomerization – not very important)1. Dihydroxyacetone phosphate glyceraldehyde 3-phosphate2. Now have 2 G3P moleculesf. Energy productioni. First group of steps1. Step 6a. The two G3P molecules from the cleavage stage are oxidized by the addition of a phosphate groupi. G3P 1-3-bishposphoglycerateb. This increases their energyc. This creates an NADH molecule2. Step 7a. The phosphate group from the newly created 1,3-bisphosphoglycerate (from step 6) is transferred to an ADP molecule to create ATP by substrate-level phosphorylation (to create 3-phosphoglycerate)b. Substrate-level phosphorylation: this is the direct transfer of an organic phosphate group from the substrate to the ADP to create ATPi. The energy to do this comes from the bond between the organic phosphate group and the substrate – it is very high in energy: ΔG° = -11.73. Net gain: 2 NADH + 2 ATP (1 of each per 1 G3P)ii. Second group of steps1. Step
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