6 Solved Questions on Metabolism, ATP and Glycolysis - Study Guide | BIOLCHEM 212, Study notes of Biochemistry

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Biological Chemistry 212 Problem set 6: Metabolism and ATP , Carbohydrates, Glycolysis Due 11/10/

1. Explain the following terms: a. Anabolism - Processes that require energy to build large molecules from small ones. b. Catabolism - Processes that breakdown food (lipids, carbohydrates and proteins) to produce energy. c. Spiral sequence - One enzyme or group of enzymes breakdown a polymer one monomer at a time. d. Coenzyme - is an organic compound required for catalysis and are derivatives of water soluble vitamins
2. Is photosynthesis an example for an endergonic/ exergonic process? Explain. Write the overall reaction of photosynthesis. What is the ∆G value for this reaction? Photosynthesis is an endergonic reaction because the reactions require energy, and don’t occur spontaneously. 6CO 2 + 6H 2 O  C 6 H 12 O 6 + O 2 ∆G = 686 kcal which is a positive value
3. State if the following reactions are exergonic/ endergonic. a. Acetyl phosphate ---> Acetate + phosphate ion ∆G= -10.3Kcal/mol – (exergonic) b. ADP + Phosphate ion ---> ATP ∆G= + 7.3 Kcal/mol (endergonic) Write the overall reaction and state if the coupled reaction is spontaneous or not. Acetyl phosphate ---> Acetate + phosphate ion ∆G= -10.3Kcal/mol ADP + Phosphate ion ---> ATP ∆G= + 7.3 Kcal/mol = Acetyl phosphate + ADP  Acetate + ATP ∆G = -3.0 Kcal/mol which is spontaneous
4. Give four reasons why ATP is the preferred energy store in cells. a. ATP hydrolysis produces a medium amount of energy, isn’t costly to make and doesn’t waste too much energy when hydrolyzed. b. Stable at pH 7. c. Precursor to other High Energy molecules d. Requires an enzyme for hydrolysis. While other anhydrides automatically breakdown in water.
5. How many isomers can the following compounds form? a. Glyceraldehyde b. Erythrose c. Furctose a. has 2 isomers b. has 4 isomers c. has 16 isomers
6. Answer the following questions about the disaccharide pictured to the right.

a. Name this disaccharide and mention two naturally occurring sources of this.

• Sucrose, sugar beats and sugar cane. b. Name the constituent monosaccharides of this disaccharide. Draw their structures in Fischer projection and circle all the chiral carbons.
• –D-Glucose and –D-Fructose c. State whether the monosaccharides are a ketose or an aldose.
• Aldose d. Is this a reducing sugar? Explain your answer.
• No, because it doesn’t have a lone OH left, for a hemiacetal. e. Indicate the positions of the anomeric carbon(s).
• The position of the D-Glucose anomeric carbon is going down, the -D-Fructose anomeric carbon is positioned upward. f. Name the type of glycosidic linkage.
• The anomeric carbons are 1, and 2 or a  1,  2 linkage) g. Name the two monosaccharides that make up lactose.
• D-Glucose, and D-Glucose. It is the same monosaccharide, just two of them. h. Name the two monosaccharides that make up maltose.
• D-Galactose and D-Glucose.

a. What are glycoproteins?

• Sugars covalently bonded to proteins. b. (i) If a person has blood type O, he can receive blood from a person with blood type B. True or False. (ii) A man with blood type AB wishes to donate blood. Name the blood type(s) of possible recipients.
• He can give blood to only AB recipients. e. What is the difference between amylose and amylopectin?
• Amylose accounts for 20% of starch while amylopectin accounts for 80% of starch. Amylopectin is comprised of larger molecules about 100,000 glucose units per molecule, while amylose is comprised of several hundred to a thousand glucose units. Ones straight and one is branched on is alpha f1,4 and the branched alpha 1,4 + 6

a. Where in the cell, does glycolysis occur? Is it an aerobic or anaerobic process?

• It occurs in the cytosol, it is an anaerobic process. b. For every glucose molecule that undergoes glycolysis, how many molecules of ATP are generated? How many ATP molecules are consumed?

• Four ATP molecules are generated, the process began with two ATP molecules which were consumed. c. What is the committed step of glycolysis? Write the substrate(s), enzyme and product(s) of this step. Why is this step called, “committed”? What are the molecules that positively and negatively regulate this enzyme?
• The third step is the committed step, where glucose becomes committed to the process of glucose. Fructose + ATP  fructose 1,6 biphosphate + ADP. The enzyme is Phosphofructokinase. (Finish answer) (three pathways as a phosphate, it doesn’t have anyother place to go, no other branch point, highly exergonic. Molecules are: they are negatively regulated shuts off to stop reaction from occurring, it would burn extra energy. (citrates builds up metabolates that shut off other enzyme. (positively turns it on (ADP & AMP d. Name the coenzyme that is consumed in glycolysis. From what vitamin is this coenzyme obtained? NAD+ is the conenzyme that is consumed in glycolysis. It is obtained from the vitamin Niacin (B3). e. Explain how glycolysis traps glucose within cells.
• A phosphate is added which gives a negative charge which doesn’t allow the molecule to escape the cellular membrane. f. Give two examples of enzymes in glycolysis that fall under the category of transferases.
• Phosphoglycerate kinase
• Pyruvate kinase g. Under anaerobic conditions, (in RBCs, highly active muscles, etc) what is the fate of pyruvate produced from glycolysis? Why is this step important for glycolysis to continue?
• Located in mitochondria, and RBC have no mitochondria. Converted to lactate oxidizes goenzyme important for NADP+ to be released n is needed in step 6 of glycolysis

9. Name at least three roles for carbohydrates in humans and nature.

• Carbohydrates are a source of energy in the human body.
• Carbohydrates function as an anticoagulant and joint lubricants.
• Carbohydrates form polysaccharides that provide structural stability in plants.

10. It is important to avoid air when making wine, so a novice winemaker added yeast to fresh grape juice and placed in a sealed bottle to avoid air. Several days later, the lid exploded off the bottle. Explain the biochemistry responsible for the exploding lid.

• Expansion occurred, the sealed glass bottle didn’t allow for any expansion. If there had been a hole in the lid to allow Co2 from fermentation to escape then there wouldn’t be an “explosion”. Air can’t be used to start with for the fermentation because it is a anaerobic process. (ethanol + CO2)