Tag: the origin of cells and cell division

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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.

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

Telomerase is an enzyme which is a

  1. Simple protein

  2. RNA

  3. Ribonucleoprotein

  4. Repetitive DNA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Telomerase is a ribonucleoprotein enzyme which adds bases at the 3' end of one strand of telomere as directed by the RNA sequence of RNA component of this enzyme.
So, the correct answer is 'Ribonucleoprotein'
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which of the following enzymes has/have heme as a prosthetic group?
(i) Catalase                            

(ii) Carboxypeptidase
(iii) Succinic dehydrogenase 

(iv) Peroxidase

  1. (i) Only

  2. (i) and (ii)

  3. (ii) and (iii)

  4. (iii) and (iv)

  5. (i) and (iv)
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Co-enzymes tightly or covalently bonded to enzymes are called prosthetic groups, e.g., pyridoxal phosphate, heme, biotin. Heme is a prosthetic group containing ferrous ion. It is important for a number of biologically important hemoproteins such as myoglobin, cytochrome oxidase, catalase and peroxidase. Thus, the correct answer is option E.

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

Which one of the following enzyme contains 'Mn' metallic ion as the prosthetic group?

  1. Phosphatase

  2. Dehydrogenase

  3. Peptidase

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

Prosthetic groups are tightly bound cofactors. Peptidase enzymes hydrolyze peptide bonds. Peptidase enzymes require manganese ion for their activity as prosthetic group.

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

In which one of the following enzymes, is copper necessarily associated as an activator?

  1. Lactic dehydrogenase

  2. Tyrosinase

  3. Carbonic anhydrase

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

Some enzymes require metal ions for their activity. Tyrosinase is a copper containing enzyme that catalyzes the production of melanin and other pigments.

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

Most of the digestive enzymes belong to the class of

  1. Lyases

  2. Hydrolases

  3. Oxidoreductases

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

Hydrolase enzymes break large molecules into small molecules with the help of hydrogen and hydroxyl group of water molecules. The phenomenon is known as hydrolysis. Digestive enzymes in our body help to break down macromolecules of food into smaller molecules by the process of hydrolysis. So, digestive enzymes belong to the class Hydrolases. Thus, the correct option is B.

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

A simple enzyme is 

  1. Succinate dehydrogenase

  2. Urease

  3. Transaminase

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

Simple enzymes consist of only proteins and catalyze their substrate specific reactions. Urease is an enzyme which is only made up of protein and it functions to catalyze the hydrolysis of urea which results in the formation of ammonia and carbon dioxide.

Succinate dehydrogenase is an enzyme complex consisting of four polypeptides (SDH A-D) which catalyses the conversion of succinate to fumarate during cellular respiration.
Transaminase signifies a group of enzymes which catalyze transamination reaction.
Ribozymes are also called catalytic RNAs. These are RNA enzymes catalyzing peptide bonding reaction during protein synthesis.
Thus, the correct answer is 'Urease is a simple enzyme'.

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

Hydrolysis of starch occurs with the help of

  1. Sucrase

  2. Amylase

  3. Peptidase

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

Starch is used as food reserves in plants. It is a polymer of glucose. It is formed by the attachment of glucose unit by glycosidic bonds. The basic formula of starch is (C$ _6$H$ _{10}$O$ _5$)n. 

Amylase is an enzyme which helps in the digestion of the starch. It acts on the glycosidic bonds of the starch and converts into simpler compounds. It helps in the hydrolysis of this bond. It is present in the saliva and the pancreas secretion in humans and helps in intracellular digestion of starch.
So, the correct answer is option B.