BIO CHEM 3 Flashcards by ROLLIE ESTEVES

The allosteric inhibitor of an enzymE

Causes the enzyme to work faster
Binds to the active site
Participates in feedback regulation
Denatures the enzyme

Participates in feedback regulation

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Which of the following is false about allosteric feedback inhibition?

Bacterial enzyme system is the first known example

Conversion of L-leucine to L-isoleucine

Threonine dehydratase is inhibited by isoleucine

If the isoleucine concentration decreases, the rate of threonine dehydration increases

Conversion of L-leucine to L-isoleucine

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Which of the following is false?

Methyl, phosphoryl, adenyl, uridylyl and adenosine diphosphate ribosyl groups are the modifying groups

An example of an enzyme regulated by methylation is the methyl-donating chemo taxis protein of bacteria

The protein is a part of the system that permits a bacterium to swim towards attractant

The methylating agent is S- adenosylmethionine

An example of an enzyme regulated by methylation is the methyl-donating chemo taxis protein of bacteria

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Which of the following enzyme is responsible for the regulation of biological nitrogen fixation?

Dinitrogenase reductase
Dinitrogenase oxidase
Phosphatase
Kinase

Dinitrogenase reductase

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Which of the following enzymes catalyze the ADP-ribosylation of key cellular enzymes or proteins?

Diphteria toxin and cholera toxin
Dinitrogenase reductase
Protein phosphatases
Kinase

Diphteria toxin and cholera toxin

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Removal of phosphoryl groups is catalyzed by

Diphteria toxin and cholera toxin
Dinitrogenase reductase
Protein phosphatases
Protein kinases

Protein phosphatases

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The attachment of phosphoryl groups to specific amino acid residues is catalyzed by

Diphteria toxin and cholera toxin
Dinitrogenase reductase
Protein phosphatases
Protein kinases

Protein kinases

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Phosphorylase a +2H2O → phosphorylase b + 2Pi
Which of the following is false about this reaction?

Phosphorylase a is less active and phosphorylase b is more active

Glycogen phosphorylase catalyzes this reaction

Phosphorylase b can be transformed back into phosphorylase a by phosphorylase kinase

Phosphorylase kinase catalyzes the transfer of phosphoryl groups from ATP to Phosphorylase b

Phosphorylase a is less active and phosphorylase b is more active

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Which of the following takes place due to phosphorylation of isocitrate dehydrogenase?

Inhibits the binding of citrate at active site
Degrades the enzyme
Enhances the substrate-binding affinity
No reaction

Inhibits the binding of citrate at active site

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Which of the following enzyme catalyzes a reaction that introduces reduced nitrogen ito cellular metabolism?

Bacterial glutamine synthase
Bacterial dinitrogenase reductase
Bacterial dinitrogenase oxidase
Phosphatase

Bacterial glutamine synthase

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Which of the following is false about feedback regulation?

It is a type of enzymatic activity regulation

The synthesis of concerned enzyme is inhibited by interfering with the gene of that enzyme

Concentration of enzyme is reduced by the end product

The best example is the biosynthesis of L-isoleucine from L-threonine in bacteria

NO ANSWER, PLEASE CHECK OTHER REFERENCE

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Which of the following is false?

Allosteric modulators may be inhibitory or stimulatory

Based on the nature of modulator, allosteric enzymes are of two types

Homotropic allosteric enzymes have the substrate and modulator same

Heterotropic allosteric enzymes have the substrate and modulator same

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In the case of allosteric enzymes what is the graphical representation when initial velocity is plotted against substrate concentration?

Straight line with negative slope
Hyperbola
Sigmoid curve
Parabola

Sigmoid curve

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How many types of enzymatic regulation mechanism occurs in the cells?

2
3
4
5

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Which is the enzyme that acts as a regulatory enzyme in a four-step metabolic pathway?

First enzyme
Fourth enzyme
Second enzyme
Third enzyme

First enzyme

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Anthrone method is preferred in the determination of

Carbohydrates
Proteins
Vitamins
Fats

Carbohydrates

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Which of the following are an example of epimers?

Glucose & Galactose
Glucose & Ribose
Mannose & Glucose
a & c

Glucose & Galactose

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One of the following has reducing properties

Glucuronic acid
Gluconic acid
Glucaric acid
Mucic acid

Glucuronic acid

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The red precipitate formed when glucose is heated with “Benedict’s reagent” is

Cupric hydroxide
Cuprous hydroxide
Cupric oxide
Cuprous oxide

Cuprous oxide

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Fructose and Glucose can be distinguished by

Selwinoff’s reagent
Benedict’s reagent
Fehling’s reagent
Barfoed’s reagent

Selwinoff’s reagent

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Which of the following is an example of monosaccharide?

Galactose
Sucrose
Lactose
Maltose

Galactose

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Which of the following is an example of disaccharide?

Glucose
Fructose
Galactose
Maltose

Maltose

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In maltose, between which of the following carbons there is a linkage?

C1, C2
C2, C3
C1, C4
C2, C4

C1, C4

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Which of the following carbohydrates is a triose?

Glucose
Ribose
Ribulose
Glyceraldehyde

Glyceraldehyde

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Lactose is a disaccharide of which of the following sugar units? Glucose and fructose Glucose and galactose Glucose and sucrose Glucose and ribose

Glucose and galactose

Which of the following is an example of bacterial and yeast polysaccharide? Starch Glycogen Cellulose Dextrans

Dextrans

In which of the following, glucose residues are linked by β1 - 4 glycosidic bonds? Amylose Starch Cellulose Glycogen

Cellulose

What is the chemical difference between cellulose and chitin? Replacement of the hydroxyl group at C2 with an acetylated amino group Replacement of the hydroxyl group at C3 with an acetylated amino group Replacement of the hydroxyl group at C4 with an acetylated amino group Replacement of the hydroxyl group at C5 with an acetylated amino group

Replacement of the hydroxyl group at C2 with an acetylated amino group

When all the monosaccharides in a polysaccharide are same type, such type of a polysaccharide is called a Glycogen Homoglycan Heteroglycan Oligosaccharide

Homoglycan

In which of the following forms, glucose is stored in plants? Glycogen Starch Dextrin Cellulose

Starch

In which of the following forms, glucose is stored in liver? Glycogen Starch Dextrin Cellulose

Glycogen

Which of the following are the storage polysaccharides? Glycogen Cellulose Chitin Glucose

Glycogen

Which of the following are the structural polysaccharides? Glycogen Starch Chitin Glucose

Chitin

Which of the following is an analogous to starch? Cellulose Glycogen Sucrose Chitin

Glycogen

Which of the following is not a monosaccharide with 5 carbon atoms? Arabinose Xylulose Trehalose Ribulose

Trehalose

Which of the following are found in connective tissues? Glycosamineglycans Proteoglycans Gycoproteins Glycolipids

Proteoglycans

Which of the following statements is false about proteoglacans? They hold less amount of water Chondroitin sulfate is a proteoglycan They possess charge They are made of amino acids and sugars

They hold less amount of water

In cell membrane, carbohydrates in glycoproteins or glycolipids are oriented? Towards outside Towards inside Towards outside and inside Randomly distributed

Towards outside

Which of the following is an oligosaccharide linked to protein? Glycolipid Glycoprotein Ganglioside Galactoside

Glycolipid

The protein core of proteoglycan is rich in Serine and threonine Serine and methionine Threonine and methionine Alanine and serine

Serine and threonine

Which of the following are included in the types of glycolipids? N-acetylgalactosamine N-acetylglucosamine Xylose Cerebrosides

Cerebrosides

Which of the following blood group individuals have N-acetylgalactosamine sugar attachment? A B AB O

Which of the following blood group individuals have galactose ? A B AB O

Which of the following glycoprotein functions as a lubricant and protective agent? Collagens Mucins Transferrins Immunoglobulins

Mucins

Which of the following are important for white blood cell recognition? Glycosamineglycans Proteoglycans Gycoproteins Glycolipids

Gycoproteins

Identify the purine base of nucleic acids in the following Cytosine Thymine Uracil Adenine

Adenine

Which of the following are not the components of RNA? Thymine Adenine Guanine Cytosine

Thymine

Which of the following statements is true? Sugar component of a nucleotide is ribose Sugar component of a nucleotide is deoxyribose The bases in nucleotides are attached to a pentose sugar moiety by a glycosidic linkage The sugar molecule of the nucleotide is in L-configuration

The bases in nucleotides are attached to a pentose sugar moiety by a glycosidic linkage

What is the composition of nucleoside? a sugar + a phosphate a base + a sugar a base + a phosphate a base + a sugar + phosphate

a base + a sugar

What is the composition of nucleotide? a sugar + a phosphate a base + a sugar a base + a phosphate a base + a sugar + phosphate

a base + a sugar + phosphate

Group of adjacent nucleotides are joined by Phosphodiester bond Peptide bond Ionic bond Covalent bond

Phosphodiester bond

The sugar molecule in a nucleotide is Pentose Hexose Tetrose Triose

Pentose

Which of the following is true about phosphodiester linkage? 5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide 3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide 5’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide 3’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide

5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide

Which of the following is false about purine and pyrimidine bases? They are hydrophobic and relatively insoluble in water at the near-neutral pH of the cell At acidic or alkaline pH the bases become charged and their solubility in water increases Purines have two rings in their structure, but pyrimidine bases have only one ring At acidic or alkaline pH the bases become charged and their solubility in water decreases

At acidic or alkaline pH the bases become charged and their solubility in water decreases

Building blocks of nucleic acids are Nucleotides Nucleosides Amino acids Histones

Nucleotides

Number of hydrogen bonds between adenine and thymine? 1 2 3 4

Number of hydrogen bonds between guanine and cytosine? 1 2 3 4

Which ratio is constant for DNA? A + G / T + C A + T / G + C A + C / U + G A + U / G + C

A + G / T + C

According to Chargaff’s rule, in a DNA molecule The amount of adenine and thymine is equal to the amount of guanine and cytosine The amount of adenine and guanine is equal to the amount of thymine and cytosine The amount of adenine and uracil is equal to the amount of guanine and cytosine The amount of adenine and guanine is equal to the amount of uracil and cytosine

The amount of adenine and thymine is equal to the amount of guanine and cytosine

Arrangement of nucleotides in DNA can be seen by Ultracentrifuge X-Ray crystallography Light microscope Electron microscope

X-Ray crystallography

Which of the following leads to disruption of nucleosomal structure? Acetylation Carboxylation Phosphorylation Methylation

Methylation

One of the following nucleic acids has a left handed helix M-RNA T-RNA A-DNA Z-DNA

Z-DNA

Which of the following statements is not true about RNA? Does not have a double stranded structure Thymine is present Does not obey Chargaff’s rule The sugar contained in RNA is a ribose

Thymine is present

Which of the following is true about Z-DNA helix? It has alternating GC sequences It is a permanent conformation of DNA It tends to be found at the 3’ end of the genes It has fewer base pairs per turn than B-DNA

It has alternating GC sequences

Which of the following statements is true? The template strand matches the sequence of the RNA transcript The two strands of DNA run parallel to each other G-C bonds are much more resistant to denaturation than A-T rich regions The common form of DNA is left handed

G-C bonds are much more resistant to denaturation than A-T rich regions

What happens in hypochromicity? When DNA is in bound form, there is decrease in absorption of UV light When DNA is in bound form, there is increase in absorption of UV light When DNA is in unbound form, it is more stable When DNA is in unbound form, there is decrease in absorption of UV light

When DNA is in bound form, there is decrease in absorption of UV light

What happens in hyperchromicity? When DNA is in bound form, there is decrease in absorption of UV light When DNA is in bound form, there is increase in absorption of UV light When DNA is in unbound form, it is more stable When DNA is in unbound form, there is increase in absorption of UV light

When DNA is in unbound form, there is increase in absorption of UV light

Which of the following is true about tm? It can be termed as renaturation temperature The higher the content of G ≡ C base pairs, the higher the tm The higher the content of A = T base pairs, the higher the tm The higher the content of G ≡ C base pairs, the lower the tm

The higher the content of G ≡ C base pairs, the higher the tm

Which of the following is false? The stability of an RNA-DNA hybrid is generally intermediate between that of RNA and DNA RNA duplexes are more stable than DNA duplexes DNA duplexes are more stable than RNA duplexes DNA duplexes are less stable than RNA- DNA hybrid

DNA duplexes are more stable than RNA duplexes

DNA denaturation is measured by absorbance at 220nm 230nm 250nm 260nm

260nm

Which of the following is false about denaturation? Disruption of hydrogen bonds Disruption of phosphodiester linkage Loss of helical structure of DNA It is resulted as a result of change in pH or increase in temperature

Disruption of phosphodiester linkage

Which of the following nucleotides is not present in RNA? AMP GMP CMP TMP

TMP

Which of the following nucleotides is not present in DNA? AMP GMP CMP UMP

UMP

Which of the following is false? RNA does not obey Chargaff’s rule DNAs can be identified by Orcinol color reaction In RNA OH group is present at 2’ position Alkali hydrolyses RNA to 2’3’-cyclic diesters

DNAs can be identified by Orcinol color reaction

Which of the following involves in carrying genetic information from DNA for protein synthesis? m-RNA t-RNA r-RNA sn-RNA

m-RNA

Which of the following does not act as a restriction enzyme? EcorI BamHI HindIII polydeoxyribonucleotide synthase

polydeoxyribonucleotide synthase

Which of the following enzyme is responsible for making a DNA copy from RNA? Reverse transcriptase DNA polymerase RNA polI RNA polII

Reverse transcriptase

Which of the following statements is true? Exonuclease III removes nucleotide residues from the 3’ ends of a DNA strand Bacteriophage lambda exonuclease removes terminal phosphates Alkaline phosphatase removes nucleotides from 5‘ends Kinase adds homopolymer tails to the 3’ –OH ends of a linear duplex

Exonuclease III removes nucleotide residues from the 3’ ends of a DNA strand

Which of the following can be termed as a restriction modification system? Restriction endonuclease + methylase DNA ligase + methylase Restriction endonuclease + acetylase DNA ligase + acetylase

a. Restriction endonuclease + methylase

Which of the following is true about restriction endonucleases? Type I and II requires ATP to move along DNA Type I, II and III requires ATP to move along DNA Type II requires no ATP and cleaves DNA within recognition sequence Type II requires ATP and cleaves DNA within recognition sequence

Type II requires no ATP and cleaves DNA within recognition sequence

Which of the following enzymes’ combined action leads to the generation of sticky ends in plasmid vector? Alkaline phosphatase and terminal transferase Exonuclease III and alkaline phosphatase Bacteriophage lambda exonuclease and terminal transferase Exonuclease III and terminal transferase

Bacteriophage lambda exonuclease and terminal | transferase

Generally a plasmid vector contains how many elements? 1 2 3 4

To make the recombinant plasmid permeable to DNA molecules, which of the chemicals is added? MgCl2 CaCl2 NaCl HCl

CaCl2

Which of the following statements is false? The cells which take up recombinant plasmids are drug resistant The cells with no recombinant plasmids are drug resistant Plasmid replication is independent of cell’s division The cells containing recombinant plasmid are called transformed cells

The cells which take up recombinant plasmids are drug resistant

The extra chromosomal, self-replicating, closed, double stranded and circular DNA molecule is generally termed as Chromosome Plasmid Genomic DNA Bacteriophage

Plasmid

E.cor1 is a DNA ligase enzyme Restriction endonuclease A vector used for insulin synthesis A plasmid used as a vector

Restriction endonuclease

In which stage of genetic engineering a probe is used? Cleaving DNA Recombining DNA Cloning Screening

Screening

A DNA library is a A DNA fragment inserted into a vector. A general collection of all genes sequenced thus far. All DNA fragments identified with a probe. A collection of DNA fragments that make up the entire genome of a particular organism.

A collection of DNA fragments that make up the entire genome of a particular organism.

Which of the following enzyme is required for end to end joining of DNA? DNA ligase Restriction endonuclease RNA polymerase DNA polymerase

DNA ligase

Repressor molecules bind to Operator Promoter Enhancer Hormone response element

Operator

Generally YAC contains how many elements? 1 2 3 4

Which of the following endonuclease removes a length of DNA between two telomere sequences? EcoR1 EcoR2 BamHI HindIII

BamHI

In hybridization method, which of the following is pressed onto agar? Silicon paper Nitrocellulose paper Filter paper PVDF

Nitrocellulose paper

Which of the following temperature best suits for the growth and multiplication of transformed cells? 35°C 36°C 37°C 30°C

37°C

Which of the following is a DNA element that instructs RNA polymerase where to bind on DNA? Operator Promoter Enhancer Hormone response element

Promoter

Site directed mutagenesis facilitated research on Carbohydrates Proteins Lipids Fats

Proteins

Recombinant DNA molecule is produced by ligating Two DNA segments Two m-RNA molecules One m-RNA with one t-RNA One m-RNA with DNA segment

Two DNA segments

Arrange the following steps involved in Gene cloning in the correct order i. Isolation of desired gene ii. Insertion of isolated gene to the vector iii. Introduction of recombinant vector to the host iv. Expression of recombinant gene in host v. Extraction of recombinant gene product i, ii, iii, iv, v v, iv, iii, ii, i i, iii, ii, iv, v iv, v, ii, i, iii

i, ii, iii, iv, v

Where does a restriction endonuclease cuts DNA? Ligation site Recognition sequence Ori Replication site

Recognition sequence

Which of the following statements is true about a vector? Plasmids, phages can be used as vectors All vectors are plasmids Cyanobacteria can also be used as vectors Fungi can also be used as vectors

Plasmids, phages can be used as vectors

Which of the following is true about plasmids? They are present in all organisms They are present in bacteria only They are present in bacteria and phages They are present in plants and animals

They are present in bacteria and phages

DNA Ligase, used in recombinant DNA technology is obtained from E.coli only E.coli and also Ligase encoded by T4 phage Saccharomyces Retroviruses

E.coli and also Ligase encoded by T4 phage

The main aim of human genome project is To identify and sequence of all the genes present in the human body To introduce new genes to human beings To remove disease causing genes from humans To improve techniques of finger printing

To identify and sequence of all the genes present in the human body

The work ‘Hybridization’ in DNA finger printing means Pairing between the nucleotides of DNA sample with probe Pairing between the nucleotides of DNA and mRNA Pairing between the nucleotides of probe with mRNA Pairing between the nucleosides with mRNA

Pairing between the nucleotides of DNA sample with probe

Agar is extracted from Fungi Bacteria Algae Virus

Algae

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