Biology · Chemistry

Biomolecules and Enzymes

1,501 Questions

This topic focuses on biomolecules, specifically proteins, enzymes, and amino acids. It includes questions on enzyme structures, protein folding, and catalysis. These concepts are crucial for medical and biology competitive exams.

Enzyme catalysisProtein structuresAmino acid synthesisPolypeptide chainsBiomolecule properties

Biomolecules and Enzymes Questions

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Arginosuccinase is a .............. enzyme.

  1. Hydrolase

  2. Ligase

  3. Lyase

  4. Oxido-reductase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hydrolase is a class of enzyme which act as biochemical catalysts that use water to break chemical bonds.

Ligase is an enzyme which catalyses the joining of two large molecules by forming a new bond generally accompanied by hydrolysis of a small chemical group.
Lyase is an enzyme which catalyses the breaking of C-C, C-O and C-N bonds by any methods other than hydrolysis or oxidation. Arginosuccinase is an enzyme which catalyses the breakdown of argininosuccinate producing arginine and fumarate.
Oxido-reductase is an enzyme which catalyses the transfer of electrons from the molecule of the reductant which acts as the electron donor to another molecule of the oxidant which accepts the electron.
So, the correct answer is 'Lyase'.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Match List I with List II and select the correct answer.

List-I(Enzymes) List-II(Characteristic Activity)
a. Terminal transferees $1$. Stable above $90$ degrees C
b. Polynucleotide kinesis $2$. Cleave the ends of linear DNA
c. Taq DNA polymerases $3$ Adds phosphate to $5$ OH end of DNA or RNA
d. Exonucleases $4$. Adds a number of nucleotides to $3'$ end of DNA or RNA
$5$. Regulate the level of super coiling of DNA molecule
  1. A-$5$, B-$4$, C-$1$, D-$2$
  2. A-$4$, B-$3$, C-$1$, D-$2$
  3. A-$3$, B-$4$, C-$5$, D-$1$
  4. A-$4$, B-$3$, C-$2$, D-$1$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

The fastest acting enzyme in the biological kingdom is

  1. Lipase

  2. Amylase

  3. Carboxypeptidase

  4. Carbonic anhydrase
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In enzymology, turnover number is the number of substrate molecules converted to products in a given unit of time on a single enzyme molecule when the enzyme is saturated with substrate. The enzyme catalase has highest turnover number value of 40,000,000 (per second per molecule of enzyme), followed by Carbonic anhydrase 400,000 (per second per molecule of enzyme), followed by acetylcholinesterase 140,000 (per second per molecule of enzyme), followed by $\beta$-lactamase 2000 (per second per molecule of enzyme).

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

In recent years, pre-soaked laundry agent (detergent) contains an enzyme

  1. Pepsin

  2. Flavin

  3. Amylase

  4. Subtilin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Natural source of subtilin is bacteria Bacillus subtilis. Subtilisins are proteolytic enzymes mainly used in detergents and house hold cleaning products to remove proteinaceous deposits and stains.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Histones associated with the genetic material apart from maintaining its also act as

  1. Modulators

  2. Apozymes

  3. Isozymes

  4. Activators
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Histone proteins are rich in basic amino acids and form the core around which the DNA is wound giving rise to nucleosome particles. DNA is wound around histones because basic amino acids are positively charged at physiological pH which facilitates winding of acidic or negatively charged DNA. Neutralization of positive charge, on basic amino acids of histone proteins, by chemical processes like reversible acetylation will lead to neutralization of attractive force between nucleosome core and DNA molecule. This will in turn lead to transcriptional activation (histone proteins are acetylated) and after transcription once again the histone proteins will be deacetylated restoring there positive charge, thus facilitating the tight binding between (negatively charged) DNA and (positively charged) histone core. Apart from reversible acetylation, histone proteins also undergo a number of other chemical modifications. Thus, acting as modulators for DNA metabolism.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

The first enzyme isolated in crystalline form was 

  1. Catalase

  2. Urease

  3. Peroxidase

  4. Amylase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

in 1897, Eduard Buchner discovered that yeast extracts could ferment sugar to alcohol, proving that fermentation was promoted by molecules that continued to function when removed from cells. Frederick W. Khne called these molecules as enzymes. The isolation and crystallization of urease by James Sumner, in 1926, provided a breakthrough in early enzyme studies. Sumner found that urease crystals consisted entirely of protein, and he postulated that all enzymes are proteins. In the absence of other examples, this idea remained controversial for some time. Only in the 1930s, was Sumners conclusion widely accepted, after John Northrop and Moses Kunitz crystallized pepsin, trypsin, and other digestive enzymes and found them also to be proteins.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which one of the following is not true for an iso-enzymes?

  1. Iso enzymes are quartenary proteins.

  2. All forms synthesized by different genes.

  3. Increase activation energy of substrate.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Isoenzymes are an unique example in which the same reaction may be catalyzed by two or more different molecular forms of an enzyme. The multiple forms, called isozymes or isoenzymes, may occur in the same species, in the same tissue, or even in the same cell. The different forms of the enzyme generally differ in kinetic or regulatory properties, in the cofactor they use (NADH or NADPH for dehydrogenase isozymes, for example), or in their subcellular distribution (soluble or membrane-bound). Isozymes may have similar, but not identical, amino acid sequences, and in many cases they clearly share a common evolutionary origin. One of the first enzymes found to have isozymes was lactate dehydrogenase (LDH), which, in vertebrate tissues, exists as at least five different isozymes separable by electrophoresis. However, isoenzymes follow the same general mechanism of enzyme action, i.e., decreasing the activation energy of substrates for a reaction.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Proteinaceous nature of enzyme was suggested by

  1. T. Cech

  2. Kuhne

  3. E. Buchner

  4. Northrop
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are biological catalysts. The multitude of biochemical reactions that make cellular metabolism possible are due to enzymes. The isolation and crystallization of urease by James Sumner in 1926 provided a breakthrough in early enzyme studies. Sumner found that urease crystals consisted entirely of protein, and he postulated that all enzymes are proteins. In the absence of other examples, this idea remained controversial for some time. Only in the1930s, was Sumners conclusion widely accepted, after John Northrop and Moses Kunitz crystallized pepsin, trypsin, and other digestive enzymes and found them also to be proteins.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

The enzyme which combines with a nonprotein prosthetic group to form a functional enzyme is called

  1. Apoenzyme

  2. Holoenzyme

  3. Coenzyme

  4. Proenzyme.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The non-protein component or prosthetic group along with the protein component or apoenzyme is called the holoenzyme. The prosthetic group may be metal ion or a co-enzyme that may be firmly or losely bound to the enzyme.
So, the correct answer is option B.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzymes generally have

  1. Same pH and temperature optima

  2. Same pH but different temperature optima

  3. Different pH but same temperature optima

  4. Different pH and different temperature optima
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes are biocatalyst that affects the rate of biochemical reactions they generally have the same pH and temperature Optima at which they work efficiently. 

So, the correct option is 'Same pH and temperature optima'. 

Multiple choice enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which is not a hydrolase?

  1. Protease

  2. Dehydrogenase

  3. Sucrase

  4. Amylase

  5. Esterase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation


A dehydrogenase is an enzyme that oxidizes a substrate by reducing an electron acceptor, usually a flavin coenzyme known as FMN.
While all other are hydrolases because they take part in the hydrolysis. 
So the correct answer is C.

Multiple choice enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Endopeptidase of plant kingdom is

  1. Trypsin

  2. Pepsin

  3. Papain

  4. Urease
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Endopeptidase are the proteolytic enzymes which cleave the peptide chain at internal locations. They break peptide bonds of non terminal amino acids (i.e. within the molecule), in contrast to exopeptidases, which break peptide bonds from their end-pieces. One example is papain obtained from unripe papaya.