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Biochemistry ACS Final Exam Questions and
Correct Answers
What is the D configuration of a sugar in a Fisher projection?
✓ ~~~ chyrol carbon furthest from the carboxyl group ✓ hydroxyl on right
What is the L configuration of a sugar in a Fisher projection?
✓ ~~~ hydroxyl on left
What is the difference between glycogen and amylopectin?
✓ ~~~ glycogen- has branches about every 10 residues (more highly branched)
amylopectin- has branches about every 25
What is amylose made up of?
✓ ~~~ glucose
What makes up starch?
✓ ~~~ amylose
amlyopectin
What is a glycosidic bond?
✓ ~~~ links two monosaccharides together at points 1 and 4
What is the difference between an alpha(1-4) and beta(1-4) linkage?
✓ ~~~ alpha: when the oxygen is pointed down in a glycosidic bond
beta: when the oxygen is pointed up in a glycosidic bond
What is the definition of a carbohydrate?
✓ ~~~ all have hydroxyl and carbonyl functional groups
Difference between aldose and ketose
✓ ~~~ aldose has an aldohyde
ketose has a ketone
What makes up sucrose?
✓ ~~~ fructose and glucose monosaccharides
What makes up lactose?
✓ ~~~ glucose and galactose monosaccharides
What makes up mannose?
proteins span the phospholipid bilayer
Why type of amino acid is present in the plasma membrane among the fatty acid
tails?
✓ ~~~ hydrophobic/nonpolar
What is passive transport (simple diffusion)?
✓ ~~~ no energy required
no protein required
move from high concentration to low concentration
water, gases, ethanol (small nonpolar) can pass through
What is facilitated diffusion?
✓ ~~~ requires protein
no energy required
molecules are two large to go through on their own
What is active transport?
✓ ~~~ energy is required
moves from low to high concentration
How many carbon atoms do most fatty acids have?
✓ ~~~ even number
What bond holds nucleotides together?
✓ ~~~ phosphodiester bond
What base pairing exists in nucleic acids? How many hydrogen bonds between
them?
✓ ~~~ G--C (3 hydrogen bonds)
A--T (2 hydrogen bonds)
What is the first amino acid always placed in a protein?
✓ ~~~ methionine (Met)
start codon
What 3 things make up a nucleotide?
✓ ~~~ nitrogen base
phosphate group
pento-sugar (ribose or deoxyribose)
What are the 3 main differences between DNA and RNA?
What does a lyase enzyme do?
✓ ~~~ catalyze removal of groups to form double bonds
What does a hydrolase enzyme do?
✓ ~~~ cleave bonds by adding water
What does a transferase enzyme do?
✓ ~~~ transfer a group from one molecule to another
What does an oxidoreductase enzyme do?
✓ ~~~ catalyze redox reactions
Where are proteins synthesized within the cell?
✓ ~~~ ribosome
Describe the 4 levels of protein structure?
✓ ~~~ primary: sequence of amino acids
secondary: hydrogen bonding between alpha-helices and beta-pleated sheets
tertiary: 3D folding
quaternary: 2 polypeptides coming together
What bond holds amino acids together?
✓ ~~~ peptide bonds
(type of amine bond)
What is an allosteric enzyme?
✓ ~~~ there are two bonding sites (active site and another)
What do enzymes do?
✓ ~~~ catalyze a reaction
What enzyme forms a bond between four molecules?
✓ ~~~ ligase
How do enzymes work?
✓ ~~~ lower the activation energy to catalyze the reaction
What is enzyme cooperativity?
✓ ~~~ when one subunit binds oxygen, it changes shape and makes it more likely for the other subunit
What is the difference between competitive and noncompetitive inhibitors?
✓ ~~~ competitive inhibitor: substrate and inhibitor compete to bind with the active site
✓ ~~~ pH
heat
What process results in the anabolism of glucose?
✓ ~~~ hydrolysis of the anhydride bonds provide energy for anabolism
What is the main function of NADH within cellular respiration?
✓ ~~~ essential electron carrier in cellular redox reactions
What is the final electron acceptor?
✓ ~~~ oxygen
What is the purpose of glycolysis?
✓ ~~~ anaerobic oxidation of glucose to give pyruvate
What are the products of glycolysis?
✓ ~~~ pyruvate
ATP
NADH
H
H
What is the purpose of the citric acid cycle?
✓ ~~~ (also called Krebb's cycle)
What is the purpose of the electron transport chain?
✓ ~~~ getting rid of ammonia in cells
What process leads to the breakdown of fatty acids within the body?
✓ ~~~ beta-oxidation
What is the main buffer in the blood?
✓ ~~~ bicarbonate carbonic acid
Ketosis generally occurs under what conditions?
✓ ~~~ starvation
Describe ketosis and ketone bodies
✓ ~~~ abnormally high levels of blood ketone bodies
Stored triaglycerols have an energy density of:
✓ ~~~ 9 kcal/g
