BCHM 3050 Lecture 30 Outline of Last Lecture I. MonosaccharidesII. Enantiomers and DiastereomersIII. Chemical Reactions of MonosaccharidesIV. Important MonosaccharidesV. DisaccharidesOutline of Current Lecture I. PolysaccharidesII. ATP (Adenosine triphosphate)III. Glycolysis: OverviewIV. Step 1V. Step 2VI. Step 3VII. Step 4VIII. Step 5IX. Step 6X. Step 7Current LectureI. Polysaccharidesa. Starch is the most common polysaccharide (alpha-glucose + alpha-glucose)b. Starch is our #1 food sourcec. Starch is all alpha-glucose unitsd. Glycogen is identical to starch in terms of the chemical composition, just with more branched chainsi. Takes more energy to break down glycogenii. Alpha-glucose units connected by alpha 1, 4 glycosidic linkagese. Cellulose is beta-glucose units i. Creates a 3D mesh connected by hydrogen bondsii. Humans do not have the enzyme to digest cellulosef. Chitin – beta 1, 4 linkages; a modified form of glucose, but not glucoseg. Peptidoglycen is present in the cell wall of bacteria – beta 1, 4 linkage connecting sugarsII. ATP (Adenosine triphosphate)a. Contains adenine, ribose, and 3 phosphate groupsThese 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 currencyc. Obtain from foodd. Energy from ATP used to carry out other functions in your bodyIII. Glycolysis: Overviewa. Glycolysis - The most ancient known reaction – from times on earth when only anaerobic organisms were present (before the amount of oxygen was sufficient)b. Present in virtually all organisms on earthc. Harvest 2 molecules of ATP in the first step of glycolysisd. NADH is made, but not used until later one. NADH is an energy investment in the cellIV. Step 1a. As soon are we consume glucose, the body attacks itb. Be able to write out this pathway from memoryc. Hexokinase – adds a phosphate group to glucose à glucose 6-phosphated. This is an energy investment phase because ATP is investede. When hexokinase meets glucose, it is committing glucose to go through glycolysisf. Exothermic reactions are spontaneous à irreversibleg. Glucose 6-phosphate inhibits/regulates hexokinaseV. Step 2a. The enzyme is also called phosphohexoseisomerase, the carbonyl oxygen in G6P is shifted from C1 to C2, an aldose to a ketose isomerization. The next step, 3, is Phophorylation at C1 and the hemiacetyl OH group of glucose would be harder to phosphorylate compared to the primary OH group in fructose.b. - Not much is happening hereVI. Step 3a. Adds 2 phosphate groups onto fructoseb. Bis – 2 phosphate groups on difference carbon atomsc. Di – 2 phosphate groups on the same carbon atom (ex: adenosine-diphosphate)d. Irreversible e. Enzyme activated by AMP and ADP f. ATP is a universal inhibitor of glycolysisg. ATP is a substrate for phosphofructokinase as well as an inhibitorVII. Step 4:a. This step is why the process is called glycolysis because of the lysis (splitting) of the F1,6bisphosphate. b. Splitting catalyzed by aldolasec. This is the step where breaking down happens – lyse reaction as it breaks down a6 carbon compound into two 3 carbon compoundsd. Not exothermicVIII. Step 5:a. In the presence of the enzyme TPI, dihydroxyacetone phosphate gets converted into glyceraldehyde 3-phosphateb. Started with one glucose and ended up with 2 molecules of glyceraldehyde 3-phosphate by the end of step 5IX. Step 6:a. This is the start of the energy payback stageb. Generation of the reducing agent NADH (2 molecules of NADH generated)c. The source of NADH is NAD+ d. NAD+ is reduced to NADHe. NADH is an electron carrier, a reduced form of NAD+f. Always an oxidation reaction coupled with reduction reactionsg. Only enzyme in this process involved in oxidation+phosphorylation reactions is glyceraldehyde 3-phosphate dehydrogenaseh. This is the only step where both oxidation and phosphorylation (adding phosphate group from inorganic molecule) are occurringi. NADH can donate its electrons later on in the processX. Step 7:a. 1,3-bisphosphoglycerate is a very high energy moleculeb. Substrate level phosphorylationc. Here the ATP is maded. 3 ways ATP can be formed in cells – substrate level, oxydative phosphorylation and photo phosphorylation (in plants)e. Phosphoglycerate kinasef. Broken even – two ATP that was consumed has now being generated back.g. Standard free energies of hydrolysis of some phosphorylated compoundsh. This is the first step where we get energy
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