Test II QuestIons Flashcards
What are the Four ways a catalyst can speed up a reaction?
- Covalent Catalysis
- Acid-Base Catalysis
- Approximation/Entropy Reduction
- Electrostatic Catalysis
What are the three components which make up the catalytic triad and form the oxyanion hole?
- Acid
- Base
- Nucleophile
Describe the process of polypeptide cleavage with an enzyme containing an oxyanion hole?
- Polypeptide binds to active site noncovalently
- Oxyanion tetrahedral structure stabilizes with hydrogen bonding. Serine Nucleophile donates H+ to Histidine, O attacks terminal Carbon.
- H+ Transfer from Histidine residue and collapse of the tetrahedral structure causes C-N bond cleavage
- the second peptide fragment is released and enzyme returns to the initial state
- Tetrahedral oxyanion intermediate stabilized through enthalpic interactions
- H20 binds to the active site and attacks acyl ester carbonyl on peptide fragment causing release
What is the shape of an ln [S] vs time graph for a first-order kinetics reaction?
Linear
What is the shape of a 1/[S] vs time graph for a second order reaction?
Linear
Which type of inhibition results in a change of slope and no change in Y intercept to the 1/Vo vs 1/[S] graph?
Competitive Inhibition
Which type of inhibition results in a change of slope and change in Y intercept, but no change in X intercept to the 1/Vo vs 1/[S] graph?
Noncompetitive inhibition
Which type of inhibition results in no change of slope to the 1/Vo vs 1/[S] graph?
Uncompetitive
How do Isozymes work?
- Catalyze same reaction w/ Different specificities
- Mix and Match
Which of the following is a form of irreversible covalent modification?
A. Proteolytic Cleavage
B. Phosphorylation
C. y-Carboxylation
D. ADP-ribose activity
A. Proteolytic Cleavage
How many Carbons/double-bonds/locations in stearate?
18/0/0
How many Carbons/double-bonds/locations in Oleate?
18/1/9
How many Carbons/double-bonds/locations in Linoleate?
18/2/9,12
How many Carbons/double-bonds/locations in Linolenate?
18/3/9,12,15
How many Carbons/double-bonds/locations in stearidonic acid?
18/4/6,9,12,15
How many Carbons/double-bonds/locations in Docosapentaenoic acid(DPA)?
22/5/4,7,10,13,16 or 22/5/7,10,13,16,19
How many Carbons/double-bonds/locations in Eicosapentaenoic acid (EPA)?
20/5/5,8,11,14,17
How many Carbons/double-bonds/locations in Docosahexaenoic acid(DHA)?
22/6/4,7,10,13,16,19
How many Carbons/double-bonds/locations in Arachidonic acid/Arachidonate?
20/4/5,8,11,14
How many Carbons/double-bonds/locations in Laurate?
12/0/0
How many Carbons/double-bonds/locations in Myristate?
14/0/0
How many Carbons/double-bonds/locations in Palmitate?
16/0/0
How many Carbons/double-bonds/locations in Arachidate?
20/0/0
How many Carbons/double-bonds/locations in Behenate?
22/0
How many Carbons/double-bonds/locations in Lignocerate?
24/0
How many Carbons/double-bonds/locations in Palmitoleate?
16/1/9
How do Waxes differ from TAGs?
Alcohol head instead of glycerol
What is special about the lipid membrane in archaebacteria?
Contain branched fatty acids
What is the general structure of sphingomyelin?
A fatty acid connected to an amine
What type of lipid structure is important in Blood type and cell signaling?
Glycosphingolipid
Which type of transporter has an E1 state which opens inside and an E2 state which opens outward?
P-type ATPase ex. SERCA
Which type of primary active transporter uses two ATP molecules and can be a monomer or a homodimer?
ATP Binding Cassete Ex. MDR
How do Anomers differ?
by the C1 carbon and if the Hydroxyl group is a/B (up or down)
What type of isomer differs at any other carbon besides the anomeric carbon?
Epimer
When converting Fischer to Haworth, ____ goes _____, and ____ goes ____.
Left -> UP
Right -> DOWN
Describe the # Cs/Carbonyl location/ direction of hydroxides in a Glyceraldehyde?
3/1
2C - Right/Down
Describe the # Cs/Carbonyl location/ direction of hydroxides in a Ribose?
5/1
2C - R/D
3C - R/D
4C - R/D
Describe the # Cs/Carbonyl location/ direction of hydroxides in a Glucose?
6/1 2C - R/D 3C - L/U 4C - R/D 5C - R/D
Describe the # Cs/Carbonyl location/ direction of hydroxides in a Galactose?
6/1 2C - R/D 3C - L/U 4C - L/U 5C - R/D
Describe the # Cs/Carbonyl location/ direction of hydroxides in a D-Deoxyribose?
5/1
2C - NO OH
3C - R/D
4C - R/D
Describe the # Cs/Carbonyl location/ direction of hydroxides in a Ribulose?
5/2
3C - R/D
4C - R/D
Describe the # Cs/Carbonyl location/ direction of hydroxides in a Fructose?
6/2
3C - L/U
4C - R/D
5C - R/D
Describe the # Cs/Carbonyl location/ direction of hydroxides in a D-Mannose?
6/1 2C - L/U 3C - L/U 4C - R/D 5C - R/D
Which chemical is made from the substitution of a hydroxide for a methyl group at carbon 5 of Galactose?
Fucose
Describe the # Cs/Carbonyl location/ direction of hydroxides in a Xylose?
5/1
2C - R/D
3C - L/U
4C - R/D
What are the essential monosaccharides?
- Glucose
- Galactose
- Mannose
- Xylose
- Fucose
- GlcNAc
- GalNAc
- Sialic Acid
How many ATP are generated in converting 1 glucose to 2 pyruvate?
2 ATP
How much ATP is generated from converting 2 pyruvate to CO2 and H2O?
34-36 ATP
What is the location and affinity of GLUT1?
- Brain and RBCs
- High Affinity
What is the location and affinity of GLUT2?
- Liver/pancreas
- Low affinity
What is the location and affinity of GLUT3?
- Neurons
- High Affinity
What is the location and affinity of GLUT4?
- Skeletal muscle, heart, and adipose
- Insulin-dependant
What happens in the first step of stage 1 of glycolysis?
- Trapping glucose
- Hexokinase phosphorylates C6 on glucose
- ATP used
What happens in the second step of stage 1 of glycolysis?
- Trapping of glucose
- Phosphoglucose Isomerase converts G6P to F6P
What happens int he 3rd step of stage 1 of glycolysis?
- Committed step
- Phosphofructokinase phosphorylates C1 on F6P to F1,6P
- ATP used
What happens in the 4th step of stage 1 of glycolysis?
- Aldolase separates F1,6P into G3P and DHAP
What happens in the 5th step of stage 1 of glycolysis?
- TPI converts DHAP to G3P/GAP
What happens in the 1st step of stage 2 of glycolysis?
- GAP converted to 1,4 BPG via oxidative phosphorylation by GAPDH
- NAD+ Reduced to NADH
What happens in the 2nd step of stage 2 of glycolysis?
- Phosphoglycerate kinase phosphorylates 1,3BPG to become 3-Phosphoglycerate
- ATP generated
What happens in the 3rd step of stage 2 of glycolysis?
- Phosphoglycerate Mutase moves Phosphate from 3’ to 2’ carbon.
What happens in the 4th step of stage 2 of glycolysis?
- Dehydration of 2PG to form PEP via Enolase
- Generation of H20
What happens in the 5th step of stage 2 of glycolysis?
- PEP is dephosphorylated via Pyruvate kinase to Pyruvate
- ATP formed
In the absence of O2, what process regenerates NAD+?
- Conversion of Pyruvate to Lactate
What is the main inhibitor of phosphofructokinase?
- Citrate
What is the main mechanism of inhibition of Pyruvate kinase?
- Allosteric effectors
- Covalent modifications
How does excessive consumption of fructose lead to pathological conditions like obesity?
Fructose bypasses the phosphofructosekinase-catalyzed regulatory step of glycolysis. Exces Acetyl-CoA is converted to fatty Acids and form TAGs
What is the Warburg effect?
Rapidly growing tumors metabolize glucose to lactate even in the presence of oxygen
Where does gluconeogenesis occur???
Liver and kidney
Which of the following is NOT a precursor to gluconeogenesis?
A. Glycerol
B. Galactose
C. Lactate
D. Amino Acids
B. Galactose
Which of the following bypasses hexikinase in gluconeogenesis?
A. Pyruvate carbxylase
B. Phosphofructopyruvate carboxykinase
C. Glucose 6-phosphatase
D. Fructose 1/6-biphosphatase
C. Glucose 6-phophatase
Which of the following is responsible for the production of oxaloacetate?
A. Phosphoenolpyruvate carboxykinase
B. Enolase
C. PhosphoPyruvate mutase
D. Pyruvate carboxylase
D. Pyruvate carboxylase
What is produced in tandem with conversion of malate to oxaloacetate outside the mitochondria?
A. FAD+
B. NADH+
C. NAD+
D. FADH
B. NADH
Glycerol enters gluconeogenesis as:
A. Dihydroxyacetone phosphate
B. Glucose-6-phosphate
C. Fructose 1,6 biphophate
D. Glyceraldehyde 3-phosphate
A. Dyhydroxyacetone phosphate
Which of the following transporters is involved in transporting glucose-6-phosphate into the ER Lumen?
A. T2
B. T3
C. T1
D. T4
C. T1
Which of the following STRONGLY regulates glycolysis and gluconeogenesis?
A. Glucose 6-phosphate
B. Fructose 2,6-biphosphate
C. 1,3 biphosphoglycerate
D. Dihydroxyacetone phosphate
B. Fructose 2,6-phosphate
Which of the following is generated by the action of pyruvate carboxylase?
A: Glucose B: Pyruvate C: Oxaloacetate D: Glyceraldehyde - 3 - phosphate E: ATP
C. Oxaloacetate
Which of the following enzymes is the gluconeogenic partner of phospho- fructokinase?
A: Lactate dehydrogenase B: Fructose 1,6-bisphosphatase C: Pyruvate carboxylase D: Pyruvate kinase E: Hexokinase
B: Fructose 1,6-bisphosphatase
3. Which of the following is the most important substrate of the Cori cycle? A. Glucose B. Fructose C. Glycerol D. Sucrose E. Lactate
E. Lactate
What is on the reducing end of a terminal glucose monomer?
A. Hydroxyl group
B. Methyl group
C. Glycogenin
D. Phosphate group
C. Glycogenin
Which enzyme is responsible for 1-4 glycogen linkage?
Glycogen synthase
Which enzyme is responsible for a1-6 glycogen linkage?
Glycosylated transferase
Which of the. Following is responsible for reversible isomerization of glucose-6-phosphate in Glycogenesis?
A. Phosphoglucomutase
B. Phosphotranferase
C. Uridine diphosphorylase
D. Glucokinase
A. Phosphoglucomutase
To Which of the following does. Glycogen synthase Tranfer glucose to?
A. Carbon 1 of nonreducing end
B. Carbon 6 of reducing end
C. Carbon 4 of nonreducing end
D. Carbon 1 of reducing end
D. Carbon 1 of reducing end
Which of the following is NOT a direct process resulting from glycogenolysis?
A. Glycolysis
B. Release of free glucose to blood
C. Cory Cycle
D. Penthouse phosphate pathway
C. Cory Cycle
Which of the following is responsible for chain shortening of glycogen polymers?
A. Phosphoglucomutase
B. Glycogen phosphorylase
C. Hexokinase
D. 1,6 glucosidase
B. Glycogen phosphorylase
What are the two key enzymes regulating the production and breakdown of glycogen?
- Glycogen Synthase
- Glycogen phosphorylase
Which of the following correctly describes the “a” form o glycogen synthase?
A. Active phosphorylates form
B. Active non-phosphorylates form
C. Inactive phosphorylates form
D. Inactive non-phosphorylates form
B. Active non-phosphorylates form
Which enzyme is responsible for regulation of glycogen synthase?
glycogen synthase kinase
Which o the following is a potent activator of glycogen synthase?
A. Glucose-6-phosphate
B. Phosphofructokinase
C.Frustose 1,6 biphosphate
D. 3-phosphglycerate
A. G6P
Where are the primary locations of Glycogen phosphorylase?
Liver - Relaxed state
Muscle - Tense state
What are the two main mechanisms of regulation of GP?
- Allosteric effectors
- Covalent Modification (Reversible phosphorylation)
What is the pathology of Hers disease?
Mutation in lover GP
What is the pathology of McArdle Syndrome?
Mutation in muscle GP
What action does glucose have on Liver GP?
Glucose binds to active site and stabilizes inactive T state
What are the main negative allosteric regulators of GP in the muscle?
- ATP
- G6P
Where does Glucagon NOT act?
Muscle
How does the fate of G1P in the liver differ from in the muscle?
- G1P in the liver is converted to glucose and released in the blood stream
- In muscle, no G6-phosphatase results in energy via glycolysis and TCA cycle
Which of the following statements is correct?
A. Type I GSD primarily affects muscle cells
B. Type II GSD is characterized by defective Phosphorylase enzyme
C. Type IV GSD primarily affects the spleen and liver
D. Type III GSD is characterized by defects in a-1,4-glucosidase
C. Type IV GSD primarily affects the spleen and liver