T1 | Test 2 Chap. 6-8 Flashcards
1
Q
What are the functions of carbohydrates?
A
-Source of Energy
-Nutritional Fiber (Cellulose)
-Glycocalyx (Oligosaccharides): Cell Adherence/Communication
-Extracellular Matrix: Structure and H20 balance
2
Q
Only ___ - Carbohydrates are found in natural and biologically active
A
D
3
Q
What are the cyclic structures of monosaccharides?
A
Hemiacetal and Hemiketal
4
Q
What is a hemicetal structure of a monosaccharide?
A
Functional group resulting from reaction between an aldehyde and an alcohol
5
Q
What is a hemiketal structure of monosaccharides?
A
Functional group resulting from reaction between a ketone and an alcohol
6
Q
Difference between alpha and beta-anomers?
A
Alpha: CH2OH- points in the opposite direction of newly formed OH- group (pointing down)
Beta: The two functional groups point in the same direction (pointing up)
7
Q
What is lactase?
A
Hydrolytic enzyme in digestive tract that breaks bond between galactose and glucose
8
Q
What is maltose?
(Building block, configuration, connection)
A
-Building block: Glucose
-Configuration: alpha
-Connection: 1->4
9
Q
What is lactose? (Building block, configuration, connection)
A
-Building block: Galactose, glucose
-Configuration: Beta
-Connection: 1->4
10
Q
What is sucrose? (Building block, configuration, connection)
A
-Building block: glucose, fructose
-Configuration: alpha-1, beta-2
-Connection: alpha-1<—>beta-2
11
Q
Reaction partners of hemiacetal?
A
Carbonyl (aldehyde or keytone) and hydroxyl
12
Q
Reactions partners of acetal?
A
Hemiacetal and hydroxyl
13
Q
Examples of Glucose-based homopolysaccharides?
A
Starch, glycogen, and cellulose
14
Q
Mannose is a(n) _______ of glucose
A
Epimer
15
Q
Starch is an _____ polysaccharide
A
Branched homo-
16
Q
Cellulose consists of ____ in ____ connection
A
Glucose; beta 1-4
17
Q
Hyaluronate is a _____________ polysaccharide?
A
Unbranched hetero-
18
Q
A glycosidic bond is a _____________ bond.
A
Acetal or ketal
19
Q
Which of the following is a non-reducing sugar?
A. Fructose
B. Sucrose
C. Galactose
D. Maltose
A
B. Sucrose
20
Q
Which of the following is a reducing carbohydrate?
A. Hyaluronate
B. Starch
C. Mannose
D. Cellulose
A
C. Mannose -
Monosaccharide - always reducing
Polysaccharide - always non-reducing
21
Q
Which ion is reduced in the Benedict’s test (Fehling’s reaction)?
A
Cu2+
22
Q
The function of peptidoglycan is to…
A
Protect and give structure to bacteria cells.
23
Q
The glycocalyx of cells consists of oligosaccharides connected to:
A
Proteins and lipids
24
Q
The sugar code is about…
A
The many oligosaccharides available for communication
25
Enzyme regulation through irreversible modification typically involves...
A. an increase in modulator concentration.
B. The removal of the a methyl group.
C. The removal of the C- or N- terminus
D. The attachment of a phosphate group
E. All of the above are correct answers
C. The removal of the C- or N- terminus
26
A glycosidic bond is a _______________ bond.
acetal or ketal
27
Feedback inhibition means that...
A. excess amounts of the final product of a certain pathway are present and inhibit the enzyme catalyzing the first step of that pathway.
B. An inhibited reaction feeds back on the last step of a certain pathway.
C. Inhibition of a particular enzyme reaction occurs in response to one pathway feeding back into another.
D. An enzyme is irreversibly altered as a result of proteolytic cleavage.
E. None of the above is correct.
A. excess amounts of the final product of a certain pathway are present and inhibit the enzyme catalyzing the first step of that pathway.
28
Cellulose is indigestible for all humans and lactose is indigiestible for many humans. What do these two carbohydrates have in common?
A. They are (alpha) 1 --> 4 connected
B. They are (beta) 1--> 4 connected
C. Their building block is glucose.
D. They are disaccharides.
E. They are non-reducing sugars
B. They are (beta) 1--> 4 connected
29
Match the glycoconjugates with the site where their larger component is located
A. Cystol
B. Cytoplasmic membrane,
C. Outer membrane of gram-negative bacteria
D. Extracellular space
Proteoglycans
Glycoproteins
Lipoprolysaccharides
Glycolipids
Proteoglycans - D. Extracellular Space
Glycoproteins - B. Cytoplasmic membrane
Lipopolysaccharides - C. Outer membrane of gram-negative bacteria
Glycolipids - B. Cytoplasmic membrane,
30
in competitive inhibition, an inhibitor...
A. Binds reversibly at the active site.
B. does not change the characteristic [Km] of the enzyme
C. binds at several different sites on an enzyme
D. binds covalently to the enzyme.
E. binds only to the ES complex
A. Binds reversibly at the active site.
31
Carbohydrates are poly _________ _________ compounds.
A. -hydroxy carbonyl
B. - amino carboxyl
C. -hydroxy amino
D. - carbonyl hydroxyl
E. -amino alcohol
A. -hydroxy carbonyl
32
A covalent bond formed by the reaction between an aldehyde and a hydroxy group is called a __________ bond.
A. ester
B. peptide
C. acetal
D. hemiacetal
E. amide
D. hemiacetal
33
Fructose is released when __________ is hydrolyzed.
A. Sucrose
B. Prothrombin
C. Lactose
D. Maltose
E. Trypsinogen
A. Sucrose
34
Which of the following structures in an epimer of D-glucose?
A
35
An enzyme follows Michaelis-Menten kinetics. When [S] is doubled ___________-is/are altered.
A. Km and Vmax
B. neither Km Nor Vmax
C. Km
D. Vmax
B. neither Km Nor Vmax
36
The carbonyl group in the depicted monosaccharide is located on carbon #__.
A. 1
B. 2
C. 3
D. 4
E. 5
B. 2
37
Maltose is a
A. disaccharide consisting of glucose.
B. polysaccharide consisting of glucose.
C. disaccharide consisting of glucose and fructose.
D. polysaccharide consisting of mannose.
E. Disaccharide consisting of galactose and glucose
A. disaccharide consisting of glucose.
38
Feedback inhibition is an example of _______ inhibition.
A. Reversible noncovalent
B. reversible covalent
C. nonreversible noncovalent
D. nonreversible covalent
A. Reversible noncovalent
39
Match the double reciprocal graphs with the correct type of inhibition.
A. Uncompetitive
B. Mixed
C. Competitive
C. Competitive
B. Mixed
A. Uncompetitive
40
Phosphorylation is an example of _____________ enzyme regulation.
A. Covalent reversible
B. Non-covalent irreversible
C. Covalent irreversible
D. Non-Covalent reversible
A. Covalent reversible
41
_____________ is a non-reducing sugar.
A. Lactose
B. Galactose
C. Mannose
D. Amylose
E. Maltose
D. Amylose
42
Which of the structures below is the enantiomer of D-glucose?
E.
43
A small molecule that decreases the activity of an enzyme by binding to a site other than the catalytic site is termed an ______________.
A stereospecific agent
B. transition-state analog
C. allosteric inhibitor
D. alternative inhibitor
E. competitive inhibitor
C. allosteric inhibitor
44
Two different enzymes are able to catalyze the same reaction, A → B. They both have the same Vm ax, but differ in their Km for the substrate A. For enzyme 1, the Km is 1.0 mM; for enzyme 2, the Km is 10 mM. When enzyme 1 was incubated with 0.1 mM A, it was observed that B was produced at a rate of 0.0020 mmoles/minute. Vm ax was determined to be 0.022 mmoles/min. What will be the rate of production of B when enzyme 2 is incubated with 0.1mM Substrate? (Hint: use Michaelis-Menten)
A. 0.0020 mmoles/minute
B. 0.020 mmoles/minute
C. 0.00022 mmoles/minute
D. 0.0022 mmoles/minute
E. 0.022 mmoles/minute
E. 0.022 mmoles/minute
45
The stereoisomers formed through the cyclization of monosacccharides in soultion are called
A. enantomers
B. anomers
C. epimers
D. monomers
E. diastereomers
B. anomers
46
Hyaluronate is an ___________________ polysaccharide.
A. branched homo-
B. unbranched homo-
C. branched hetero-
D. unbranched hetero-
D. unbranched hetero-
47
Using the Lineweaver-Burke approach, Km can be determined by
A. Calculating the negative inverse value of the x-intercept
B. Calculating the inverse value of the y-intercept.
C. Dividing the slope by Vmax.
D. Dividing the x-intercept by Vmax.
B. Calculating the inverse value of the y-intercept.
48
Galactose is an ________________.
A. aldopentose
B. aldohexose
C. ketopentose
D. ketohexose
E. aldoheptose
B. aldohexose
49
Which of the following statements about a plot of V0 vs. [S] for an enzyme that follows Michaelis-Menten kinetics is FALSE.
A. the y-axis is a rate term with units of mM/min.
B. as [S] increases, the initial velocity of reacdtion to V0 also increases.
C. at very high [S], the velocity curve becomes a horizontal line that intersecds the y-axis at Km
D. Km is the [S] at which V0=1/2Vmax
E. the shape of the curve is a hyperbola
C. at very high [S], the velocity curve becomes a horizontal line that intersecds the y-axis at Km
50
In Michaelis-Menten graphs, the independent variable is ___________.
A. [S]
B. V0
C. Km
D. 1/[S]
E. 1/V0
A. [S]
51
The function of peptidoglycan is to _____________________.
A. Protect bacteria cells
B. Activate the blood clotting cascade.
C. digest proteins in the small intestine.
D. Inhibit glycogen phospahorylase.
E. Form glycosidic bonds.
A. Protect bacteria cells
52
Vitamin K is essential for blood clotting because it
A. can chelate Ca2+ ions.
B. removes N- and C-termini from proteases of the blood clotting cascade.
C. is a coenzyme of protease carboxylase
D. is an inhibitor of natural blood thinners
E. triggers the blood clotting cascade
D. is an inhibitor of natural blood thinners
53
Match the structures with the correct name:
Mannose
Fructose
Galactose
Mannose: D
Fructose: E
Galactose: C
54
Which of the following statements about enzymes is correcdt?
A. Enzymes are fibrous proteins.
B. Vmax is twice the value of Km.
C. The higher Km, the lower the affinity for the substrate.
D. All enzymes follow Michaelis-Menten kinetics
E. All enzymes need a cofactor, a coenzyme and a prosthetic group.
C. The higher Km, the lower the affinity for the substrate.
55
In the Lineweaver-Burke plot, the slope =
A. 1/[S]
B. 1/Vmax
C. Km/Vmax
D. Vmax/2
E. -1/Km
C. Km/Vmax
56
Which carbon is carrying the amino group?
A. 1
B. 2
C. 3
D. 4
E. 5
B. 2
57
Which of the following is NOT a function of carbohydrates?
A. Protection and shape
B. Energy carrier
C. Communication
D. Catalysis
E. Joint Lubrication
D. Catalysis
58
Prothrombin
A. Is the inactive precursor or the enzyme thrombin
B. Is the protease that activates thrombin through proteolytic cleavage
C. Is a promoter of glutamate Carboxylase
D. Is a drug given to individuals with bleeding disorders
A. Is the active precursor of the enzyme thrombin
59
Fructose is a(n) __________ and is most closely related (stereochemistry) to ______________
A. Aldohexose; galactose
B. Aldopentose; ribose
C. Aldoheptose; glucose
D. Ketopentose; ribose
E. Ketohexose; glucose
E. Ketohexose; glucose
60
Match the types of regulation with the correct category of regulation (answers can only be chosen once)
-Cleaving of N-Terminus
-Allosteric Regulation
-Covalent, reversible
-Covalent, non-reversible
-Non-covalent, reversible
-non-covalent, non-reversible
-Cleaving of the N-Terminus: Covalent, non-reversible
-Allosteric regulation: non-covalent, reversible
61
Allosteric Regulation
A. Is non-covalent and non-reversible
B. Often involves downstream products inhibiting their synthesis through feedback inhibition
C. Is the scientific term of proteologic cleavage of C- and N-termini
D. Refers to the process of phosphorylation/dephosphorylation triggered the hormones insulin and glucagon
B. Involves the downstream products inhibiting their synthesis through feedback inhibition
62
Blood thinners containing warfarin diminish blood clotting by:
A. Preventing vitamin K from binding to its binding site as a coenzyme in glutamate carboxylase
B. Reversibly inhibiting the action of thrombin (the last protease in the blood thinning cascade).
C. Phosphorylating fibrin
D. Non-reversibly inhibiting the action of all proteases involved in blood clotting
E. Preventing Ca2+ from binding to its site as a cofactor in calcium dependent proteases
A. Preventing vitamin K from binding to its binding site as a coenzyme in glutamate carboxylase
63
The regulation of glycogen phosphorylase (in response changing levels of insulin and glucagon) happens through ______________.
A. Competitive inhibition
B. Phosphorylation/dephosphorylation
C. Methylation/demethylation
D. Cleaving of the C-terminus
E. Vitamin K-dependent carboxylation
B. Phosphorylation/dephosphorylation
64
The higher the activation energy the __________ the probability of the reaction occurring spontaneously
Lower
65
An enzyme _______ activation energy
Lowers
66
What format does the Lineweaver-Burke equation follow?
Y=Mx + b
-Y= 1/Vo
-m=km/vmax
-x= 1/[S]
-b=1/vmax
67
What is the Michaelis-Menton Equation?
Vo=Vmax[S]/Km + [S]
-Vo=1/2max)
-Km=[S]
68
How does competitive inhibition appear in MM-plot and LB-Plot?
-MM-plot: Hyperbola is flatter, but trends toward the same Vmax
-LB-Plot: Lines intersect on the Y-Intercept
69
How does Uncompetitive Inhibition appear in both the MM-Plot and LB-Plot?
-MM-Plot: Curve starts out on the same track but plateaus @ lower Vmax
-LB-Plot: Lines do not intersect (parallel lines)
70
How does Mixed Inhibition appear on an MM-plot and LB-plot?
MM-Plot: Runs flatter and plateaus at a lower v-max
(More than uncompetitive)
-LB-Plot: Lines intersect in the 2nd quadrant
71
How does Competitive Inhibition work with Vmax and Km?
-Vmax:unchanged
-Km:Increases
72
How does uncompetitive inhibition correlate with Vmax and Km?
Vmax: Decreases
Km: Decreases
73
How does mixed inhibition correlate with Vmax and Km?
-Vmax: Decreases
-Km: Increases
74
There is a huge variety of oligosaccharides that aid in communication. Name four variables that contribute to this:
-Building Blocks
-Size
-Variability in Bonds
-Variability in Branching
