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Biochem 1 > T1 | Test 2 Chap. 6-8 > Flashcards

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

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2
Q

Only ___ - Carbohydrates are found in natural and biologically active

A

D

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3
Q

What are the cyclic structures of monosaccharides?

A

Hemiacetal and Hemiketal

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4
Q

What is a hemicetal structure of a monosaccharide?

A

Functional group resulting from reaction between an aldehyde and an alcohol

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5
Q

What is a hemiketal structure of monosaccharides?

A

Functional group resulting from reaction between a ketone and an alcohol

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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)

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7
Q

What is lactase?

A

Hydrolytic enzyme in digestive tract that breaks bond between galactose and glucose

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8
Q

What is maltose?
(Building block, configuration, connection)

A

-Building block: Glucose
-Configuration: alpha
-Connection: 1->4

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9
Q

What is lactose? (Building block, configuration, connection)

A

-Building block: Galactose, glucose
-Configuration: Beta
-Connection: 1->4

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10
Q

What is sucrose? (Building block, configuration, connection)

A

-Building block: glucose, fructose
-Configuration: alpha-1, beta-2
-Connection: alpha-1<—>beta-2

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11
Q

Reaction partners of hemiacetal?

A

Carbonyl (aldehyde or keytone) and hydroxyl

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12
Q

Reactions partners of acetal?

A

Hemiacetal and hydroxyl

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13
Q

Examples of Glucose-based homopolysaccharides?

A

Starch, glycogen, and cellulose

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14
Q

Mannose is a(n) _______ of glucose

A

Epimer

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15
Q

Starch is an _____ polysaccharide

A

Branched homo-

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16
Q

Cellulose consists of ____ in ____ connection

A

Glucose; beta 1-4

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17
Q

Hyaluronate is a _____________ polysaccharide?

A

Unbranched hetero-

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18
Q

A glycosidic bond is a _____________ bond.

A

Acetal or ketal

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19
Q

Which of the following is a non-reducing sugar?

A. Fructose
B. Sucrose
C. Galactose
D. Maltose

A

B. Sucrose

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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

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21
Q

Which ion is reduced in the Benedict’s test (Fehling’s reaction)?

A

Cu2+

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22
Q

The function of peptidoglycan is to…

A

Protect and give structure to bacteria cells.

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23
Q

The glycocalyx of cells consists of oligosaccharides connected to:

A

Proteins and lipids

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24
Q

The sugar code is about…

A

The many oligosaccharides available for communication

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25
Q

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

A

C. The removal of the C- or N- terminus

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26
Q

A glycosidic bond is a _______________ bond.

A

acetal or ketal

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27
Q

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

A. excess amounts of the final product of a certain pathway are present and inhibit the enzyme catalyzing the first step of that pathway.

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28
Q

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

A

B. They are (beta) 1–> 4 connected

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29
Q

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

A

Proteoglycans - D. Extracellular Space

Glycoproteins - B. Cytoplasmic membrane

Lipopolysaccharides - C. Outer membrane of gram-negative bacteria

Glycolipids - B. Cytoplasmic membrane,

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30
Q

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

A. Binds reversibly at the active site.

31
Q

Carbohydrates are poly _________ _________ compounds.

A. -hydroxy carbonyl
B. - amino carboxyl
C. -hydroxy amino
D. - carbonyl hydroxyl
E. -amino alcohol

A

A. -hydroxy carbonyl

32
Q

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

A

D. hemiacetal

33
Q

Fructose is released when __________ is hydrolyzed.

A. Sucrose
B. Prothrombin
C. Lactose
D. Maltose
E. Trypsinogen

A

A. Sucrose

34
Q

Which of the following structures in an epimer of D-glucose?

A

A

35
Q

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

A

B. neither Km Nor Vmax

36
Q

The carbonyl group in the depicted monosaccharide is located on carbon #__.

A. 1
B. 2
C. 3
D. 4
E. 5

A

B. 2

37
Q

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

A. disaccharide consisting of glucose.

38
Q

Feedback inhibition is an example of _______ inhibition.

A. Reversible noncovalent
B. reversible covalent
C. nonreversible noncovalent
D. nonreversible covalent

A

A. Reversible noncovalent

39
Q

Match the double reciprocal graphs with the correct type of inhibition.

A. Uncompetitive
B. Mixed
C. Competitive

A

C. Competitive
B. Mixed
A. Uncompetitive

40
Q

Phosphorylation is an example of _____________ enzyme regulation.

A. Covalent reversible
B. Non-covalent irreversible
C. Covalent irreversible
D. Non-Covalent reversible

A

A. Covalent reversible

41
Q

_____________ is a non-reducing sugar.

A. Lactose
B. Galactose
C. Mannose
D. Amylose
E. Maltose

A

D. Amylose

42
Q

Which of the structures below is the enantiomer of D-glucose?

A

E.

43
Q

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

A

C. allosteric inhibitor

44
Q

Two​ ​different​ ​enzymes​ ​are​ ​able​ ​to​ ​catalyze​ ​the​ ​same​ ​reaction,​ ​A​ ​→​ ​B.​ ​​ ​They​ ​both​ ​have​ ​the​ ​same​ ​Vm​ ax,​ ​ ​but​ ​differ​ ​in their​ ​K​m​​ ​for​ ​the​ ​substrate​ ​A.​ ​​ ​For​ ​enzyme​ ​1,​ ​the​ ​K​m​​ ​is​ ​1.0​ ​mM;​ ​for​ ​enzyme​ ​2,​ ​the​ ​K​m​​ ​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

A

E. 0.022​ ​mmoles/minute

45
Q

The stereoisomers formed through the cyclization of monosacccharides in soultion are called

A. enantomers
B. anomers
C. epimers
D. monomers
E. diastereomers

A

B. anomers

46
Q

Hyaluronate is an ___________________ polysaccharide.

A. branched homo-
B. unbranched homo-
C. branched hetero-
D. unbranched hetero-

A

D. unbranched hetero-

47
Q

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.

A

B. Calculating the inverse value of the y-intercept.

48
Q

Galactose is an ________________.

A. aldopentose
B. aldohexose
C. ketopentose
D. ketohexose
E. aldoheptose

A

B. aldohexose

49
Q

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

A

C. at very high [S], the velocity curve becomes a horizontal line that intersecds the y-axis at Km

50
Q

In Michaelis-Menten graphs, the independent variable is ___________.

A. [S]
B. V0
C. Km
D. 1/[S]
E. 1/V0

A

A. [S]

51
Q

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

A. Protect bacteria cells

52
Q

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

A

D. is an inhibitor of natural blood thinners

53
Q

Match the structures with the correct name:

Mannose
Fructose
Galactose

A

Mannose: D

Fructose: E

Galactose: C

54
Q

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.

A

C. The higher Km, the lower the affinity for the substrate.

55
Q

In the Lineweaver-Burke plot, the slope =

A. 1/[S]
B. 1/Vmax
C. Km/Vmax
D. Vmax/2
E. -1/Km

A

C. Km/Vmax

56
Q

Which carbon is carrying the amino group?

A. 1
B. 2
C. 3
D. 4
E. 5

A

B. 2

57
Q

Which of the following is NOT a function of carbohydrates?

A. Protection and shape
B. Energy carrier
C. Communication
D. Catalysis
E. Joint Lubrication

A

D. Catalysis

58
Q

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

A. Is the active precursor of the enzyme thrombin

59
Q

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

A

E. Ketohexose; glucose

60
Q

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

A

-Cleaving of the N-Terminus: Covalent, non-reversible
-Allosteric regulation: non-covalent, reversible

61
Q

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

A

B. Involves the downstream products inhibiting their synthesis through feedback inhibition

62
Q

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

A. Preventing vitamin K from binding to its binding site as a coenzyme in glutamate carboxylase

63
Q

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

A

B. Phosphorylation/dephosphorylation

64
Q

The higher the activation energy the __________ the probability of the reaction occurring spontaneously

A

Lower

65
Q

An enzyme _______ activation energy

A

Lowers

66
Q

What format does the Lineweaver-Burke equation follow?

A

Y=Mx + b
-Y= 1/Vo
-m=km/vmax
-x= 1/[S]
-b=1/vmax

67
Q

What is the Michaelis-Menton Equation?

A

Vo=Vmax[S]/Km + [S]
-Vo=1/2max)
-Km=[S]

68
Q

How does competitive inhibition appear in MM-plot and LB-Plot?

A

-MM-plot: Hyperbola is flatter, but trends toward the same Vmax
-LB-Plot: Lines intersect on the Y-Intercept

69
Q

How does Uncompetitive Inhibition appear in both the MM-Plot and LB-Plot?

A

-MM-Plot: Curve starts out on the same track but plateaus @ lower Vmax
-LB-Plot: Lines do not intersect (parallel lines)

70
Q

How does Mixed Inhibition appear on an MM-plot and LB-plot?

A

MM-Plot: Runs flatter and plateaus at a lower v-max
(More than uncompetitive)
-LB-Plot: Lines intersect in the 2nd quadrant

71
Q

How does Competitive Inhibition work with Vmax and Km?

A

-Vmax:unchanged
-Km:Increases

72
Q

How does uncompetitive inhibition correlate with Vmax and Km?

A

Vmax: Decreases
Km: Decreases

73
Q

How does mixed inhibition correlate with Vmax and Km?

A

-Vmax: Decreases
-Km: Increases

74
Q

There is a huge variety of oligosaccharides that aid in communication. Name four variables that contribute to this:

A

-Building Blocks
-Size
-Variability in Bonds
-Variability in Branching

Biochem 1 (7 decks)

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