Tag: enzymes classification and cofactors

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

Nickel is component of

  1. PEP carboxylase

  2. Rubisco

  3. Urease

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

Urease is a nickel-containing metalloprotein which catalyzes the hydrolysis of urea into carbon dioxide and ammonia. Due to the production of ammonia, it increases the production of ammonia. Sumner crystallized an enzyme known as urease and reported that all enzymes are protein. Heliobacter pylori are microbial ureases found in the stomach.

So, 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 is false about prosthetic groups?

  1. Proteins

  2. Non-proteins

  3. Metal compounds

  4. Tightly bound to enzymes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Many enzymes show enzymatic activity only in association with certain non protein substances. Such substances are known as cofactors. Cofactors may be simple ions such as magnesium or potassium ions or complex organic compounds. An organic non-protein cofactor which is easily separable from the enzyme is called coenzyme and the non-protein organic cofactor which is tightly bound to and non-dissociable from the enzyme is termed as prosthetic group. The organic cofactors directly reduce the activation energy and thus form a functional part of active site of enzyme. They act as carriers of chemical groups, atoms or electrons removed from the substrates during reactions.

Thus, the correct answer is option A.  

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

Enzymes with heme as prosthetic group are 
(a) Catalase
(b) Carboxypeptidase
(c) Succinic dehydrogenase
(d) Peroxidase

  1. a and d

  2. a ony

  3. a and b

  4. b and c

  5. c and a
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Certain enzymes are made up of two parts - a protein part of enzyme called apoenzyme and a non-protein part called cofactor. Such enzymes are called conjugated enzymes. The working combination of apoenzyme and cofactor together form the holoenzyme. Organic cofactors are of two types- coenzymes and prosthetic groups. Coenzymes are easily separable organic cofactors while prosthetic groups are non-protein organic cofactors firmly associated with protein part of enzyme called apoenzyme. Heme is iron containing prosthetic group in hemoglobin, myoglobin, cytochrome, catalase and peroxidase. Catalase and peroxidase cause the breakdown of hydrogen peroxide to oxygen and water. Carboxypeptidase requires zinc for its activity.

Thus, the correct answer is option A.  

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

Match and find the correct option.

$(a)$ Oxidoreductases $(i)$ Linking of the compounds
$(b)$ Isomerases $(ii)$ Removal of group from substrate
$(c)$ Ligases $(iii)$ Interconversion of isomers
$(d)$ Lyases $(iv)$ Dehydrogenases
$(v)$ Hydrolysis
  1. $a - iv, b - i, c - iii, d - ii$
  2. $a - iv, b - iii, c - i, d - ii$
  3. $a - iii, b - iv, c - ii, d - v$
  4. $a - ii, b - v, c - iii, d - i$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Oxidoreductase is a dehydrogenase which acts as an acceptor of hydrogen or electrons. 
Isomerases are class of enzymes that convert a molecule from one isomer to another isomer. 
Ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond between them. 
An enzyme that forms double bonds by removing groups from a substrate other than by hydrolysis, is called lyases.
So the correct answer 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
A Correct answer
Explanation
Succinate dehydrogenase is a enzyme which is present in the inner mitochondrial membrane. It plays an important role in citric acid cycle and the electron transport chain.
It catalyzes the oxidation of succinate to fumarate. It is a conjugated protein as it has flavo protein which has FMN or FAD molecule as a prosthetic group.
So, the correct answer is option A.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Ribozyme was discovered by

  1. Kuhne

  2. Duclaux

  3. Cech et al

  4. Altman et al
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ribozymes are also known as ribonucleic acid enzymes. These are RNA molecules which helps in the catalysis of a particular reaction. It was discovered in the year 1982. The RNA can act as both genetic material and can act as a biocatalyst. It acts as a part of ribosome which attaches to the amino acid during protein synthesis. Thomas R. Cech and Sidney Altman discovered catalytic properties of RNA. So, the correct answer is option D.

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

Hydrolytic enzymes which act on low pH are called as : -

  1. Protease

  2. -Amylase

  3. Hydrolases

  4. Peroxidase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The stomach has low pH due to the secretion of HCl. Protease, an enzyme for digesting protein acts in low pH i.e. in the stomach. Amylase is a starch (carbohydrate) digesting enzyme and carbohydrate digestion does not occur in the stomach. All digestive enzymes are hydrolases. Peroxidase is an iron-containing enzyme, found mainly in plants but also present in leucocytes and milk, that catalyses the dehydrogenation (oxidation) of various substances in the presence of hydrogen peroxide.

So, the correct answer is 'Hydrolases'.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzyme urease, first crystallised by Sumner was obtained from

  1. Human urine

  2. Canavalia

  3. Pancratium

  4. Thalictrum
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Sumner crystallized an enzyme known as urease from human urine and reported that all enzymes are protein. It catalyzes the hydrolysis of urea into carbon dioxide and ammonia. John Howard Northrop and Wendell Meredith Stanley shared the noble prize with Sumner for their work on the enzyme.
Buchner in 1897, prepared a yeast extract and added sugar solution to it and observed the process of fermentation. 
So, the correct answer is option A.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Match and find the correct option.

           $I$             $II$
$(a)$ Transferases $(i)$ Epimerase
$(b)$ Hydrolases $(ii)$ Kinases
$(c)$ Lyases $(iii)$ Phosphatase
$(d)$ Isomerase $(iv)$ Fumarase
  1. $a - ii, b - iii, c - iv, d - i$
  2. $a - ii, b - iii, c - i, d - iv$
  3. $a - ii, b - i, c - iii, d - iv$
  4. $a - ii, b - iv, c - iii, d - i$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
A kinase is an enzyme that catalyzes the transfer of phosphate groups.  It belongs to the family of transferase. 
Phosphatase enzyme catalyzes the hydrolysis of its substrate,  it is a subcategory of hydrolases. 
Fumarase enzyme belongs to the family of lyases,  specifically hydro lyases, which cleave carbon-oxygen bonds. 
Epimerases are isomerase enzymes that catalyze the inversion of compounds. So the correct answer is A.