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BIO CHEM EXAM 4 ACTUAL EXAM WITH QUESTIONS
AND 100% CORRECT VERIFIED ANSWERS/ Biochem
301 - Exam 4 LATEST 2025-2026 (BRAND NEW!!)
Importance of Carbs energy source, molecular recognition, protection, signaling, adhesion, biological lubrication, control of protein trafficking, maintenance of biological structure T/F - Macromolecular polysaccharides can exist as branched polymers True Carbohydrates are Organic compounds that contain an aldehyde or a ketone functional group as well as a number of hydroxyl groups Draw an aldehyde Draw a ketone Draw a carbonyl
Hydroxyl OH- Oligosaccharides sugars linked by glycosidic bonds (two to ten monomers) Polysaccharides formed when many monosaccharides are bonded together Monosaccharides have the general formula (CH2O)n (a true carbohydrate) T/F - oligosaccharides and polysaccharides are also referred to as glycans True Aldose - monosaccharide containing an aldehyde group as part ofits structure Ketose
True In terms of D configurations in fischer projections, OH are on the (BLANK) of the highest numbered chiral carbon Right hemiacetal compound that is formed by the reaction of an aldehyde with an alcohol Hemiacetals can react with alcohols to form Acetals hemiketal compound that is formed by the reaction of a ketone with an alcohol In both hemiacetal and hemiketal, the carbonyl carbon becomes a chiral center called the anomeric carbon Haworth projections --> Beta means Up
Haworth projections --> alpha means down Do we have mostly D or L sugars? D How to tell if D or L sugar? Positioning of the OH on the chiral carbon farthest from the carbonyl group - whether it is on the right or left Remember - In an aldose, the carbonyl group is located on carbon-1 (C-1) of the sugar whereas in a keto sugar the functional group is on carbon-2 (C-2) ... Deoxysugars Reduced sugars in which a hydrogen atom is substituted for one of the hydroxyl groups of the sugar Where are deoxysugars found? lipopolysaccharides, on S-layers, and on some antibiotics
Slide 39 of Carb Lecture 2 - HEMIACETAL FORMATION .. What is a Glycoside compound formed when a hemiacetal carbon reacts with an alcohol to give a full acetal Compound formed when a hemiacetal carbon reacts with an alcohol to give a full acetal
- The resulting bond of this is called a glycosidic bond Picture --> T/F - Glycosidic bonds between monosaccharide units are the basis for the formation of oligosaccharides and polysaccharides True T/F - anomeric carbon of one sugar can be bonded to any one of the OH groups on the second sugar to form an a- or b-glycosidic linkage True
Glucosamine abreviation GlcN Galactosamine abreviation GalN N-acetyl-glucosamine abreviation
- GlcNAc Glucose abreviation Glc b-glucose structure Up down up down up b-d-Galactose structure Epimer of glucose at C4 - Up rather than down
Sucrose - what makes it up a-D-glucose and b-D-fructose Is sucrose a reducing sugar? No! ⎼ both anomeric groups are involved in the glycosidic linkage Lactose - what is it made of b-D-galactose and D-glucose Is lactose a reducing sugar? Yes! The group at the anomeric carbon of the glucose portion is not involved in the glycosidic linkage Which side is the nonreducing end? LEFT HAND SIDE - can't open up What makes a sugar nonreducing? The sugar can't open up!
What makes a sugar a reducing sugar? Reducing end can open up to a linear form Which side is the reducing sugar on? RIGHT! How is maltose formed? Hydrolysis of starch Maltose - what makes it up two residues of D-glucose joined by an alpha(1 → 4) linkage How does cellobiose differ from maltose? only difference is beta notation rather than alpha T/F - Glycoproteins Contain carbohydrate residues that are noncovalently linked to specific side chains of the protein FALSE - covalent Do eukaryotic proteins typically carry attached oligosaccharide or polysaccharide chains?
Is a glycosidic bond stable? Yes - enzymes control its hydrolysis enantiomer One of two compounds that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon. T/F - Carbohydrates are compounds with the empirical formula (CH 2 O) n where as saccharides include carbohydrates and all of their derivatives. true What are the two main classes of monosaccharides? aldoses and ketoses epimer Stereoisomers that differ in stereochemistry at only one chiral carbon
- galactose is an epimer of glucose acetyl COCH
Catabolic pathway release energy by breaking down complex molecules into simpler compounds Is a catabolic pathway oxidizing or reducing? Oxidizing Anabolic pathway consume energy to build complicated molecules from simpler ones Is an anabolic pathway oxidizing or reducing? Reducing Glyceraldehyde- 3 - phosphate ATP Where does glycolysis occur?
False - decrease Carbon bonded to a carbon has an oxidation state of 0 T/F - The substance that gains electrons is reduced and is called the reducing agent False - called the oxidant/oxidizing agent What is the first stage of glucose metabolism in organisms? Glycolysis T/F - in glycolysis, 1 molecule of glucose is converted to fructose- 1 - 6 - bisphosphate, which gives rise to two moleucules of pyruvate in a 10 step pathway Absolutely true Anaerobic glycolysis pathway for conversion of glucose to lactate
- NOT glycolysis where you convert glucose to pyruvate Lactate structure
Pyruvate structure Are defects in glycolysis often found? Not really, because it is so essential for survival NAD+ structure NADH structure ATP structure NAD(H) is found in what pathways Catabolic NADP(H) is found in what pathways Anabolic
What is the primary site for regulation of glycolysis? Phosphofructokinase Do ATP levels allosterically affect PFK? Yes Step 4 of glycolysis The enzyme aldolase splits fructose 1, 6-bisphosphate into two triose phosphates that are isomers of each other. Step 5 of glycolysis Isomerization of dihydroxyacetone phosphate by triose phosphate isomerase into GAP T/F - First 5 reactions of glycolysis expend two ATP and convert 1 glucose to 2 molecules of Glyceraldehyde- 3 - phosphate (GAP) True! Step 6 of glycolysis Generates first energy-rich compound (1- 3 - bisphosphoglycerate)
- catalyzed by glyceraldehyde- 3 - phosphate dehydrogenase Step 7 of glycolysis First substrate level phosphorylation (makes 3PG and ATP)
- catalyzed by phosphoglycerate kinase Step 8 of glycolysis Prepares for synthesis of next high-energy compound
- Catalyzed by phosphoglycerate mutase Step 9 of glycolysis Synthesis of second high-energy compound (Phosphoenolpyruvate)
- Catalyzed by enolase Step 10 of glycolysis Second substrate level phosphorylation
- Catalyzed by pyruvate kinase NADH is reduced or oxidized Reduced
