Biology : DNA Questions With All Correct Answers

Biology : DNA Questions With All Correct Answers

Explain the difference in the percentage of guanine bases in the two species of
bacterium. correct answer -Different proteins;
Different genes;
Different (DNA) base sequences;

Ribonuclease is an enzyme. It is 127 amino acids long.
What is the minimum number of DNA bases needed to code for ribonuclease?
correct answer -381/384/387;

Explain how a change in a sequence of DNA bases could result in a non-
functional enzyme. correct answer -Change in (sequence of) amino
acids/primary structure;
Change in hydrogen/ionic/disulfide bonds;
Alters tertiary structure/active site (of enzyme);
Substrate cannot bind / no enzyme-substrate complexes form;

Give one advantage of DNA molecules having two strands. correct answer -
for replication / stability / protect code/bases;

Cisplatin inhibits the division of cancer cells. Suggest how. correct answer
-Prevents DNA replication/being copied;
Prevents production of proteins needed (for cell division);
Prevents transcription or a description e.g. forming mRNA;
Blocks (complementary) base pairing/hydrogen bonding;
Blocks (DNA/RNA) polymerase;
Prevents strands separating/helix or DNA unwinding/unzipping/prevents
H bonds breaking (if binds across helix);

Base pairing is important in DNA replication. Explain how. correct answer
-(Free) nucleotides bind to exposed strands;
A to T and C to G;
To produce identical copies of DNA;

DNA polymerase is involved in DNA replication. Explain how. correct
answer -Forms new strands of DNA (molecules);
By joining together (single) nucleotides bound to existing strands;