Biochemistry Quiz 2 and Exam 2 supplements

Platelet-activating factor \[PAF\] plays a role in allergic and inflammatory responses, as well as toxic shock syndrome. The structure of PAF is shown below__.__ __**How does it match/differ f**__**rom the structure of the commonly referred phospholipids**?

**The C16 alkyl chain is attached by and ether linkage. The C-2 carbon atom of**

**glycerol has only an acetyl group attached by and ether linkage of fatty acids, as**

**in the case with most lipids.**

**(2/4) points**

**PAF has a long chain alkyl group which merges with glycerol back bonne in ether**

**linkage at position one and at acetyl group at a position 2**

**PAF represents a family of phospholipids and that is because the alkyl group is in**

Name these Fatty acids and arrange their melting temp in increasing order ( lowest to highest)

1. palmitoleic acid
2. oleic acid
3. linoleic acid
4. linolenic acid
5. arachidonic acid

1. The value of KM for the enzyme depicted by curve **A i**s:

* 5 mM
* 1 mM
* 0.5 mM
* 0.5 μmol min-1 mg-1
* 10 μmol min-1 mg-1

.5mM

2. The value of Vmax for enzyme depicted by curve **A** is:

* 1 μmol min-1 mg-1
* 1 μmol min-1 mg-1
* 10 μmol min-1 mg-1
* 5 μM
* 2mM

* 10 μmol min-1 mg-1

3. Curve **B** depicts the effect of an inhibitor on the system described by curve **A**. This inhibitor:

* Is a competitive inhibitor
* Is a non competitive inhibitor
* Increases the Vmax
* Decreases the KM
* None

Is a competitive inhibitor

4. Curve **C** depicts the effect of a different inhibitor of the system described by curve **A**. This second inhibitor :

* Is a competitive inhibitor
* Is a non-competitive inhibitor
* Increases the Vmax
* Decreases the KM
* None

non competitive inhibitor

A recently diagnosed “hypersensitive patient” has been prescribed an ACE inhibitor \[Angiotensin Concerting Enzyme inhibitor\] which is known to act by __lowering Vmax without altering Km__, what is the possible mechanism of inhibition of this drug?

non-competitive inhibition

Consider a reaction catalyzed by enzyme A with a Km value of **5 x10-6 M** and Vmax of **20 mmol. min**. At a concentration of **5 x10-6M** substrate, the rate of the reaction will be:

10mM/sec

The structure of an unsaturated fatty acid:

A. is one in which all the carbons are saturated with hydrogen atoms

B. contains three fatty acids and one glycerol

C. contains double bonds between carbons

D. is made with interconnected rings of carbon atoms

C. contains double bonds between carbons

Linoleic acid and linolenic acid are known as __________ because the body cannot synthesize them.

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A. eicosanoids

B. trans-unsaturated fatty acids

C. cis-unsaturated fatty acids

D. essential fatty acids

D. essential fatty acids

Which blood lipoproteins (increased levels) appear to increase the risk of plaque formation the most?

A. LDL

B. HDL

C. VLDL

D. chylomicrons

A. LDL

True or false: One method of determining if a fat is saturated or unsaturated is to observe if the fat is solid or liquid at room temperature.

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True

False

True

True or false: The letter B in this diagram represents a fatty acid molecule.

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True

False

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What does A represent?

False

fatty acid molecules

Which of the following describes the fatty acid depicted in this \n diagram?

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saturated

trans fat

monosaturated

polyunsaturated

polyunsaturated

The process whereby hydrogen atoms are added to the carbon-carbon double bonds making them more saturated is called?

hydrogenation

Identify the molecule in this diagram of a lipid labeled C

phosphate group

Good sources of omega-3 fatty acids include all of the following except

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salmon

walnuts

flaxseeds

tilapia

tilapia

Which of the following is a phospholipid?

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Sphingosine

glycogen

oleic acid

cardiolipin

cardiolipin

The maximum number of doubles in an unsaturated fatty acid is?

4

Example of monounsaturated fatty acid:

\
oleic acid

palmitic acid

linoleic acid

arachidic acid

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the number of carbons and double bonds? draw structure

oleic acid 18C, double bond on carbon 9

Which of the following is a glycerol-based phospholipid? Draw its structure and list carbons/double bonds.

Sphingomyelin

Cerebroside

Sphingosine

cardiolipin

cardiolipin

Which of the following is a glycolipid? Draw its structure and list carbons/double bonds.

\
Sphingomyelin

Cerebroside

Sphingosine

Arachidonate

arachidonate??

Which is the backbone of a glycolipid? Draw its structure and list carbons/double bonds.

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Sphingomyelin

Cerebroside

Sphingosine

Arachidonate

Sphingosine, 18C, DB on 5

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QUIZ 2 BELOW

what is the slope (m) of a double rciprocal plot?

km/Vmax

Enzymes, serving as catalysts require small modules for a catalytic activity known as cofactors. An enzyme with a cofactor is referred to as:

Apoenzyme

Holoenzyme

Abzyme

Coenzyme

Ribozyme

**Holoenzyme**

Enzymes are quite specific. Trypsin is partially specific in its catalysis, What terminus of what amino acids does it cleave at?

C terminus of Arginine R or Lysine K

Among A,B, and C, these two have the same Km value

\

A and C (0.5mM)

In the following inhibition plot, these two could represent the "Uncompetitive inhibition "

\
all of them

B and C

A and B

none of them represent it

A and C

B and C

As per Michalis Menten's relationship, what will be the rate of catalysis, if the \[S\] and K M are the same and V max is 20 nmol/sec?

10

Km=S means that Vmax/2 = Vo

what is the Vmax of inhibitor A in micromol/min/mg?

10

As per Michalis Menten relationship, what will be the rate of catalysis, if the \[S\] = 1mM and K M 0.5 mM with value V max is 1.5 mM/sec

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*  3.0 mM/sec
*  1.0mM/sec
* Can not compute from given data sets
*  1.0 mM/sec
*  2.5 mM/sec

1mM/sec

in Lineweaverplot (1/S X-axis) and 1/V o \[as Y-a axis), the linear equation is: Y = 0.25X + 0.02 The numerical value of K M will be \[ Hint the Vmax=50\]

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*  0.02
*  can not compute from a given data set
*  0.25
*  12.5
*  0.25

12\.5

Enzymes are quite specific. Thrombin is highly specific for its catalysis, how many location will it cleave the given peptide with a sequence of: Gly-Ala- Lys-Glu- Arg -Lys-Val -Ser-Arg-Val-Gly

NONE

What does thrombin cut?

Arginine-Glycine bonds

this enzyme cuts any peptide bond

papain

True or False: The free energy changes provides information about the spontaneity but not the rate of reaction. A reaction can take place spontaneously only if delta G is negative reaction is exergonic ).

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True

False

True

Among the following unsaturated fatty acids, this will have **higher** melting point compared to others

oleic acid , 2

Thiamine pyrophosphate TPP) serves as a coenzyme for the following enzyme.

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Succinate dehydrogenase

Pyruvate carboxylase

Glycogen phosphorylase

Pyruvate dehydrogenase

Lactate dehydrogenase

Pyruvate dehydrogenase

The physiological consequence of K M is linked to the sensitivity of certain group of people to the alcohol. Most people has two form of aldehyde dehydrogenase , the KM ----form less active in susceptible persons .

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* high, mitochondrial
* low, mitochondrial
* low, cytoplasmic

low, mitochondrial

True or false: According to chemical kinetics, **reactions that are directly proportional to the reactant concentration** are called **zero-order reactions**, with a typical rate constant unit of sec^ -1

False, this is a first order reaction

The active site of enzymes has some standard and specific features, which is NOT a common feature of the active site.

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* usually water is present at active site
* usually involves multiple weaker interactions
* usually relatively smaller compared to total volume
* usually three-dimensional cleft
* usually water is excluded from active site

usually water is present at active site

what kind of enzyme inhibition does this depict?

\

Non competitive inhibition

Which of the following is NOT a common feature of membranes?

\
* are noncovalent assemblies
* are covalent assemblies
* are asymmetric
* electrically polarized
* are sheetlike structures

are covalent assemblies

Enzymes, serving as catalysts requires small modules for catalytic activity known as cofactors . Divalent cation Mg^ 2+ is NOT an essential cofactor for…

carbonic anhydrase

Among the following unsaturated fatty acids, this will have the lowest melting point compared to others

arachidonic acid \n 5 or E

Notes

\

what side of the fatty acid do you count carbons from?

\

carboxyl side

what is the carbon:double bond name for arachidonate?

20:4

what is the carbon: double bond name for arachidate (arachidic acid)?

20:0

Where is the omega carbon found?

the opposite end of the carboxyl side of the fatty acid

this ratio of body lipids are phospholipids

2/3

What fatty acid tail is always unsaturated?

first

What glycerol based phospholipid is PS?

Phosphatudlyserine

this phospholipid contains serine (NH3 and COO-)

Phosphatudlyserine

What glycerol based phospholipid is PC?

phosphatidylcholine

this phospholipid contains multiple methyl groups

phosphatidylcholine

What glycerol based phospholipid is PE?

phosphatidylethanolamine

this phospholipid contains NH3 and 2(CH2)

phosphatidylethanolamine

What glycerol based phospholipid is PI?

phosphatidylinositol

this phospholipid has a chair confirmation and a bunch of OH

phosphatidylinositol

What phospholipid is DPG?

diphosphatidylglycerol

what is another name for the phospholipid diphosphatidylglycerol

cardiolipin

this phospholipid is very large and has two symmetrical sides

diphosphatidylglycerol (cardiolipin)

True or false: Sphingosine is a backbone for both non-glycerol phospholipids and glycerol based phospholipids

True

What are three features of sphingosine

long chain

has amino group

has a double bond

this phospholipid is phosphatidylcholine with a sphingosine replacing glycerol

sphingomyelin

this type of bond connects amino acids

amide bond

what is an example of a simple glycolipid?

cerebroside

what is an example of a complex glycolipid?

ganglioside

What is the chemical formula for cholesterol?

C27H45OH or C27H46O

True or false: Bacteria have cholesterol

False

How does degrees of unsaturation influence melting point and membrane fluidity?

higher degrees of unsaturation means increased membrane fluidity due to double bonds creating more space between lipids, and this lowers the melting point as well

which of the following structures is a 20:2 ^ (◬4,9) fatty acid ?

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CH3(CH2)1OCH=CH(CH2)3CH=CH CH2 COOH

CHS(CH2)2CH=CH(CH2)3CH=CH(CH2)9COOH

CH3(CH2)9CH=CH(CH2)3CH=CH(CH2)2C COOH

CH3CH2CH CH=CH(CH2)3C=CH(CH2)10COOH

CH3(CH2)9CH=CH(CH2)3CH=CH(CH2)2C COOH

**Which of the following is/ are represented by a phospholipid?**

**sphingosine**

**cardiolipin**

**Gasolio Side** \n **Cerebroside** \n **Cardiolipin and and sphingosine both**

cardiolipin

**In the following inhibition plot, these two could represent the competitive inhibition**

\

A and B

**Following glucose transporters GLUT-) family in mammalian tissues is present in ----- and pancreas in with very high Km of value of 2----**

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**GLUT -2 in liver 1- 5mM**

**GLUT -4 in liver 15=20 mM**

**GLUT -2 in muscle 15-20mM**

**GLUT -2 in liver 15-20mM**

**GLUT -1 in muscle 15-20mM**

**GLUT -2 in liver 15-20mM**

**which of the following is not true of glycolysis?**

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The glycolytic pathway is tightly controlled

The 10 reactions of glycolysis take place in the cytoplasm

Glycolysis is the set of reactions that convert glucose into pyruvate

The pathway does not require oxygen

The pathway oxidizes two moles of NADH and NAD+ for each mole of glucose

The pathway oxidizes two moles of NADH and NAD+ for each mole of glucose

At psychological PH, the carboxyl group is readily ionized, rendering a negative charge onto fatty acids in bodily fluids

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True

False

True

which of the epimer pair given below for monosaccharide is INCORRECT?

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D- fructose and D-psicose

D-glucose and D-galactose

D-Ribose and D- Arabinose

D- Erythrose and D-threose

D-glucose and D-mannose

D-glucose and D-galactose

in gluconeogenesis, the conversion of pyruvate into phosphoenol pyruvate \[PEP\] begins with the enzyme -----

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Phosphoenolpyruvate carboxylase

Pyruvate carboxylase

Enolase

Triose phosphate isomerase

Pyruvate dehydrogenase

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Pyruvate carboxylase

Cardiolipin is a glycolipid that contains sphingosine"amino alcohol that contains a long unsaturated hydrocarbon chain as the backbone

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**True**

**False**

False. cardiolipin is phospholpid not glycolipid

In Micheli- enzyme kinetics, when \[s\] is much higher compared to the reaction is represented as the FIRST order

\
**True**

**False**

False, this would be a zero order reaction

Certain enzyme requires metal ion small organic molecule etc such as cofactor. An Enzyme with a cofactor is known as APOENZYME

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True

False

False

the stereoisomer of D- Erythrulose is represented by the following:

\
D-arabinose

D-Ribose

D- Threose

L- threose

L- Erythrulose

L- Erythrulose

CH3( C=0)COOH
2 molecules of CH3(C=0)CO0H
2 molecules of CH3(CH2)COOH CH3(CH0H) COOH CH30H(CH2)COOH

2 molecules of CH3(C=0)CO0H

Error in glycosylation leads to pathological conditions . The N linked protein glycosylation begins in Endoplasmic reticulum and completes in golgi complex

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**True**

**False**

True

Which of the following given statements is incorrect to glycolysis?

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Unlike TCA, glycolysis does not produce any electron carrier

\
Glycolysis connected to TCA cycle using pyruvate

\
The glycolytic pathway is tightly controlled

\
Glycolysis uses 2 ATP and produces 4 ATP per glucose

\
Glycolysis is the set of reactions that converts to glucose in pyruvate

Unlike TCA, glycolysis does not produce any electron carrier

why does the glycolytic pathway continue in the direction of glucose catabolism?

There are three irreversible reactions that stop the process from recreating glucose

Amylose is a branched polysaccharide while amylopectin is an unbranched polysaccharide (plant starch)

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True

False

False, amylopectin is highly branched

Glycolysis \[ a ten step metabolic pathway that oxidizes glucose to produce two pyruvate molecules \] produces very little ATP but produces several molecules of NADH and FADH 2

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True

False

false

The unique enzymatic process/step in glycolysis involves removal of water

\
Aldolase

Pyruvate carboxylase

None of the listed options

Triose phosphate isomerase

Pyruvate kinase

None of the listed options

In model bacteria, membrane fluidity is controlled by the fatty acid composition and cholesterol content

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True

False

false

In gluconeogenesis , conversion of pyruvate into phosphoenol pyruvate |PEP| begins with formation of---------------

\
2-phosphoglycerate

3-phosphoglycerate

Acetyl CoA \n Lactase

Oxaloacetate

**Oxaloacetate**

Enzyme Aldolase catalyzes the readily reversible splitting of fructose 1,6-bisphosphate (F-1,6-BP), into the products glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP)

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True

False

True

The free energy changes provides information about the spontaneity but not the of reaction A reaction can take place spontaneously only if delta G is negative ( reaction is exergonic )

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True

False

True

In------------- the amino group of the sphingosine backbone is linked to a fatty acid by an amide bond. The primary hydroxyl group estered to phosphorylcholine.

\

Sphingomyelin

following fatty acid is characterized and identified commonly as a polyunsaturated fatty acid. Provide its common and positions of double bonds by numbering system

Arachidonic acid, 20:4 (5,8,11,14)

observe the given scheme and predict the mode of inhibition

\

noncompetitive inhibition

**Enzyme........... Traps glucose in the cell and begins glycolysis: Glucose enters cells through specific transport proteins GLUT) and has one principal fate: it is phosphorylated by ATP to form glucose 6-phosphate**

Hint: name the enzyme

Hexokinase