Question

1. The enzyme responsible for recognizing damaged bases in DNA is __________ .

a. DNA glycosylase

b. DNA polymerase

c.DNA ligase exonuclease

2. What term is used to describe a species which affects the functioning of an allosteric enzyme?

a. controller

b. inhibitor

c. regulator

d. alloster

3 Which of the following statements is correct?

a. adenine and guanine are both pyrimidines

b. adenine and guanine are both purines

c. adenine is a purine and guanine is a pyrimidine

d. adenine is a pyrimidine and guanine is a purine

5 Movement of a ribosome along a mRNA is termed

a. elongation

b. lateration

c. translocation

d. translation

6 Which of the following will the cause the rate of enzyme activity to increase in a linear fashion (i.e., the activity does not level off, it continually increases)?

a. increasing the pH

b. increasing the substrate concentration

c. increasing the enzyme concentration

d. increasing the temperature

7 Which of the following is true of isozymes?

a. their amino acid sequences are mirror images of one another

b. they are a pair of enzymes which must both be present for enzyme activity to occur

c. they are different forms of the same enzyme found in different tissues

d. none of the above

Answer 1

ANS 1..DNA glycosylase

explanation: DNA glycosylase enzymes is basically involved in Base excision repair.The resynthesize of nucleotide occur with the help of DNA polymerase but the recognition or initiation of damage DNA is done by DNA glycosylase.It doesn't cleave phosphodiester bond but cleave N- glycosidic bond.The repairing process is completed with the help of DNA polymerase I and DNA ligase (helps in sealing the break).

ANS 2..Regulator

explanation:Allosteric enzymes may increase or decrease the activity of catalyst after getting some signals.It means it may be stimulatory or inhibitory.This functioning is control by a compound which is modulators or effector also called REGULATOR.

ANS..3..Adenine and Guanine are purines.

explanation:DNA and RNA are made of Nucleotides which contain sugar,base and phosphates.Bases are of two types Purine and Pyrimidines..In which purines have Adenine , Guanine and Pyrimidines have cytosine ,thymine and uracil.Thymine found in DNA whereas Uracil in RNA.

Ans 5..(c)Translocation

explanation: In protein synthesis (translation)ribosome,rRNA,mRNA and tRNA all are involved.Ribosome found in two subunits form separately before translation..but unites at the time of Translation. when translation occur they move with the mRNA in 5' to 3'having new three nucleotide called as translocation.

when one amino acid added to the nascent peptide called elongation .

Ans6..B

Explanation:: The rate of enzymes activity is directly proportional to substrate concentration..so when substrate concentration will increase enzyme activity increase.

The effect of temp and PH varies its normally works at its optimum temp.and PH.when there is low or high pH Or temperature enzymatic activity decreases.

For high enzyme concentration it must be high substrate contraction for its binding..so if enzymes are in high concentration initially rate of enzyme will increase then gets saturated ...no further reaction occur.