Tag: classification of enzyme

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

Enzymes that catalyse endergonic synthesis, coupled with exergonic hydrolysis of ATP are

  1. Ligases

  2. Isomerases

  3. Lyases

  4. Transferases
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
There are six major classes of enzymes, as follows:
(1) Oxidoreductases - Catalyze oxidationreduction reactions.
(2) Transferases - Catalyze the transfer of a functional group from a donor molecule to an acceptor molecule.
(3) Hydrolases - Catalyze hydrolysis reactions. 
(4) Isomerases - Catalyze conversion of a molecule from one isomeric form to another.
(5) Ligases - Ligases or synthetases are enzymes that catalyse endergonic synthesis, coupled with the exergonic hydrolysis of ATP
(6) Lyases - Catalyze certain reactions in which double bonds form or break.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which enzyme act as chromosomal breaks?

  1. DNA polymerase

  2. DNase

  3. DNA ligase

  4. DNA polymerase II
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The enzyme that cause chromosomal breaks are DNase. A deoxyribonuclease or DNase, is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. Deoxyribonucleases are one type of nuclease, a generic term for enzymes capable of hydrolising phosphodiester bonds that link nucleotides.

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

Enzyme were discovered for the first time in

  1. Bacteria

  2. Yeast

  3. Algae

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

Enzymes are biological catalysts, which activate various biochemical reactions of a living cell in a highly specific and precise manner. Enzymology is the study of enzymes. The name enzyme was coined by Kuhne in 1878. Pasteur recognised that some microorganisms like yeasts have got a capacity to cause fermentation in wine. In 1897, Buchner discovered that yeast extract could bring about fermentation of grape juice, like the living yeast cells. He also observed that the extract has lost its catalytic activity on boiling. He coined the word zymase for the active principle involved in the fermentation. The substance on which the enzyme acts is called substrate. Enzymes are essentially proteins but all proteins are not enzymes.

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

Who coined the term zymase? 

  1. Pasteur

  2. Buchner

  3. Kuhne

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

Buchner coined the term zymase for the complex of biocatalysts extracted from yeast and taking part in alcoholic fermentation. Pasteur is responsible for the process of pasteurization and Kuhne is best known today for coining the word enzyme.

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

Which of the following set of three items are true, as each set belongs to the category mentioned against them?

  1. Lysine, glycine, thiamine - Amino acids

  2. Myosin, oxytocin and gastrin - Hormones

  3. Rennin, helicase and hyaluronidase - Enzyme

  4. Optic nerve, oculomotor, vagus - Sensory nerves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rennin is a protease found in rennet. It is produced by newborn ruminant animals in the lining of the fourth stomach to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese.

Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
Hyaluronidase is a protein enzyme. It works by causing rapid spreading of injected fluid into the body, which increases the absorption of injected fluids.
Therefore, the correct answer is option C.

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

Enzyme concerned with transfer of electrons are

  1. Hydrolase

  2. Dehydrogenase

  3. Transaminase

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

Dehydrogenases are the enzymes which catalyze oxidation-reduction reactions by addition or removal of electrons. These reactions are used to synthesize reduced coenzymes like NADH$ _2$ and FADH$ _2$. For example phosphoglyceraldehyde dehydrogenase.

So, the correct answer is 'Dehydrogenase'.

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

Which enzyme shows greatest substrate specificity?

  1. Nuclease

  2. Trypsin

  3. Sucrase

  4. Pepsin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Enzymes are highly specific catalysts and show high degree of substrate specificity. Some enzymes names are general and these enzymes act on a type of biomolecules. For example: nucleases means enzymes acting on nucleic acids. Nuclease is a general class of enzyme. Similarly, pepsin and trypsin are protein metabolising enzymes. These enzymes will act on any proteins and not on some specific protein. Sucrase is, however, a specific enzyme which will act on sucrose only.
So, the correct answer 'Sucrase'
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Non-proteinaceous enzyme that acts as a catalyst for the formation of peptide bond is
OR
"All enzymes are proteins." This statement is now modified because an apparent exception to this biological truth is

  1. Spliceosome

  2. Ribozyme

  3. RNA polymerase I

  4. RNA polymerase III
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ribozymes or RNA enzymes are catalytic RNA molecules. The first ribozyme discovered was self splicing group I intron. The second catalytic RNA was RNAase P which separates tRNA from hn RNA at their 5' ends. Peptidyl transferase involved in translation of proteins is also catalytic RNA. Telomerase is a ribonulceoprotein  enzyme. It is involved in replication of terminal DNA or telomeres.

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

Molecular scissors which cut DNA at specific site is known as

  1. Pectinase

  2. Polymerase

  3. Restriction endonuclease

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

A restriction enzyme or restriction endonuclease or molecular scissors is an enzyme used in genetic engineering that splices DNA at or near specific recognition nucleotide sequences, known as restriction sites. Thus, the correct answer is option C.

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

Which of the following enzyme is not of protein origin?

  1. Hexokinase

  2. Synthetase

  3. Endonuclease

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

Enzymes are biological catalysts which catalyse the biochemical reactions in living systems. Majority of enzymes are proteins. A small minority of enzymes are catalytic RNA molecules. These catalytic RNA molecules are called ribozymes. These catalytic RNA molecules catalyze reactions like splicing of introns during processing of RNA in eukaryotic mRNA.