BCHM 4611 Exam 3 Questions with Correct Answers Fully Solved
How are ABO blood types produced in the cell? - Answers Presence of a small O-linked oligosaccharide
on the cell surface; a glycosyl transferase enzyme adds the final sugar residue to the oligosaccharide;
mutations in the enzyme active site cause different residues to be added in A or B type individuals; O
type individuals lack a functional version of this enzyme, so no sugar is added
How is blood type compatibility determined? - Answers By the antigens present in the donor's blood and
the antibodies present in the recipient's blood; antigens must not be targeted by the antibodies of the
recipient's blood, causing the blood to agglutinate
Anabolism - Answers Building complex molecules at the expense of
energy
Catabolism - Answers Breaking down larger molecules, releasing energy
In what order are available fuels are utilized for energy in the body? - Answers Glycogen first, then fats,
then proteins
Which proteins are degraded by the lysosome? - Answers Primarily extracellular or membrane proteins
Which proteins are degraded by the proteasome? - Answers Intracellular proteins
Protein degradation by proteasome steps - Answers 1. Chain of ubiquitin molecules targets a protein to
the proteasome
2. Polypeptide is unfolded as it enters the proteasome
3. Protease active sites inside the proteasome cleave the polypeptide into small peptides that diffuse
away
Vitamin B1 (thiamine) physiological role - Answers Cofactor for the pyruvate dehydrogenase complex
and alpha-ketoglutarate dehydrogenase
Vitamin B1 (thiamine) deficiency - Answers Causes beriberi which is characterized by weakness and leg
swelling
Vitamin B3 (niacin) physiological role - Answers Precursor for NADP+ and NADPH
Vitamin B3 (niacin) deficiency - Answers Causes pellagra
Vitamin C (ascorbic acid) physiological role - Answers Antioxidant and acts as a cofactor for the enzyme
that hydroxylates proline residues in collagen
Vitamin C (ascorbic acid) deficiency - Answers Causes scurvy
NAD+/NADH - Answers Water soluble 2e- carrier (redox cofactor)
, NADP+/NADPH - Answers Redox cofactor in biosynthetic pathways; phosphorylated form of
NAD+/NADH
Q/QH2 - Answers Ubiquinone or coenzyme Q is a lipid-soluble 1 e- (QH•) carrier or 2 e- (QH2) carrier
FMN/FMNH2 and FAD/FADH2 - Answers Flavins - prosthetic groups that can carry 1 or 2 e-; ubiquinone
is a mobile e- carrier that often receives electrons from FMNH2 or FADH2; derived from riboflavin
(vitamin B2)
What molecules are used as energy currency by the cell? - Answers Energy may be stored in reduced
cofactors,
phosphoanhydride bonds (eg. ATP), or thioester bonds (eg. Acetyl-CoA)
Why is it advantageous to have hexokinase phosphorylate glucose? - Answers Hexokinase is irreversible,
so phosphorylating 6 carbon sugars prevents the sugars from leaving the cell and reduces the sugar so
that the gradient favors sugar import into the cell
Fates of pyruvate - Answers Acetyl-CoA, oxaloacetate, lactate, or ethanol + CO2
What happens to pyruvate under anaerobic conditions in animals? - Answers Pyruvate is reduced to
lactate so that NADH can be
reoxidized to NAD+; NAD+ is then used in the GAPDH
reaction to continue glycolysis
What happens to pyruvate under anaerobic conditions in yeast? - Answers Pyruvate is decarboxylated to
acetaldehyde which is then reduced to ethanol so that NADH can be reoxidized to NAD+; NAD+ is then
used in the GAPDH
reaction to continue glycolysis
Pyruvate to acetyl-CoA - Answers Pyruvate may be converted to acetyl-CoA which is then
oxidized further in the citric acid cycle or used in lipid
synthesis
Pyruvate to oxaloacetate - Answers Pyruvate may be converted to oxaloacetate which can be used for
amino acid or glucose biosynthesis
Glycogen synthesis steps - Answers 1. Phosphoglucomutase interconverts G6P and G1P
2. G1P is activated by UTP to form UPD-glucose and PPi; subsequent hydrolysis of PPi drives the reaction
forward
3. Glycogen synthase links glucose units via alpha(1,4) and UDP functions as a leaving group
How are ABO blood types produced in the cell? - Answers Presence of a small O-linked oligosaccharide
on the cell surface; a glycosyl transferase enzyme adds the final sugar residue to the oligosaccharide;
mutations in the enzyme active site cause different residues to be added in A or B type individuals; O
type individuals lack a functional version of this enzyme, so no sugar is added
How is blood type compatibility determined? - Answers By the antigens present in the donor's blood and
the antibodies present in the recipient's blood; antigens must not be targeted by the antibodies of the
recipient's blood, causing the blood to agglutinate
Anabolism - Answers Building complex molecules at the expense of
energy
Catabolism - Answers Breaking down larger molecules, releasing energy
In what order are available fuels are utilized for energy in the body? - Answers Glycogen first, then fats,
then proteins
Which proteins are degraded by the lysosome? - Answers Primarily extracellular or membrane proteins
Which proteins are degraded by the proteasome? - Answers Intracellular proteins
Protein degradation by proteasome steps - Answers 1. Chain of ubiquitin molecules targets a protein to
the proteasome
2. Polypeptide is unfolded as it enters the proteasome
3. Protease active sites inside the proteasome cleave the polypeptide into small peptides that diffuse
away
Vitamin B1 (thiamine) physiological role - Answers Cofactor for the pyruvate dehydrogenase complex
and alpha-ketoglutarate dehydrogenase
Vitamin B1 (thiamine) deficiency - Answers Causes beriberi which is characterized by weakness and leg
swelling
Vitamin B3 (niacin) physiological role - Answers Precursor for NADP+ and NADPH
Vitamin B3 (niacin) deficiency - Answers Causes pellagra
Vitamin C (ascorbic acid) physiological role - Answers Antioxidant and acts as a cofactor for the enzyme
that hydroxylates proline residues in collagen
Vitamin C (ascorbic acid) deficiency - Answers Causes scurvy
NAD+/NADH - Answers Water soluble 2e- carrier (redox cofactor)
, NADP+/NADPH - Answers Redox cofactor in biosynthetic pathways; phosphorylated form of
NAD+/NADH
Q/QH2 - Answers Ubiquinone or coenzyme Q is a lipid-soluble 1 e- (QH•) carrier or 2 e- (QH2) carrier
FMN/FMNH2 and FAD/FADH2 - Answers Flavins - prosthetic groups that can carry 1 or 2 e-; ubiquinone
is a mobile e- carrier that often receives electrons from FMNH2 or FADH2; derived from riboflavin
(vitamin B2)
What molecules are used as energy currency by the cell? - Answers Energy may be stored in reduced
cofactors,
phosphoanhydride bonds (eg. ATP), or thioester bonds (eg. Acetyl-CoA)
Why is it advantageous to have hexokinase phosphorylate glucose? - Answers Hexokinase is irreversible,
so phosphorylating 6 carbon sugars prevents the sugars from leaving the cell and reduces the sugar so
that the gradient favors sugar import into the cell
Fates of pyruvate - Answers Acetyl-CoA, oxaloacetate, lactate, or ethanol + CO2
What happens to pyruvate under anaerobic conditions in animals? - Answers Pyruvate is reduced to
lactate so that NADH can be
reoxidized to NAD+; NAD+ is then used in the GAPDH
reaction to continue glycolysis
What happens to pyruvate under anaerobic conditions in yeast? - Answers Pyruvate is decarboxylated to
acetaldehyde which is then reduced to ethanol so that NADH can be reoxidized to NAD+; NAD+ is then
used in the GAPDH
reaction to continue glycolysis
Pyruvate to acetyl-CoA - Answers Pyruvate may be converted to acetyl-CoA which is then
oxidized further in the citric acid cycle or used in lipid
synthesis
Pyruvate to oxaloacetate - Answers Pyruvate may be converted to oxaloacetate which can be used for
amino acid or glucose biosynthesis
Glycogen synthesis steps - Answers 1. Phosphoglucomutase interconverts G6P and G1P
2. G1P is activated by UTP to form UPD-glucose and PPi; subsequent hydrolysis of PPi drives the reaction
forward
3. Glycogen synthase links glucose units via alpha(1,4) and UDP functions as a leaving group
