Biochem - DNA and RNA

Which of the following uses the RNA template to synthesise DNA?

Reverse transcriptase

Small, circular, extra chromosomal DNA molecules found in bacteria are:

Plasmids

RNA sequences that are removed during splicing are:

Introns

What enzyme involved in replication uses UTP as a substrate?

Primase

What is found exclusively in prokaryotes?

Operons

What inhibits cAMP phosphodiesterase?

Caffeine (methylated derivative of purines)

How many carbon atoms does ribose/deoxyribose contain?

5

What joins the nitric base to the sugar?

N-glycosidic bond

Wha is the function of the phosphodiester bond?

Cleaves cAMP phosphodiesterase

Which nucleic acid is resistant to the alkaline hydrolysis?

DNA

What is a genome?

Total DNA of cell, including both coding and noncoding fragments

What is an operon?

A group of genes that code the enzymes from one metabolic pathway and placed together on the chromosome along with the regulatory genes.

They are transcribed together as a long fragment of mRNA.

What is the specific effect of rifamycin?

Blocks initiation of RNA chains by binding to RNA polymerase (prevents RNA synthesis)

What is the specific effect of actinomycin D?

Binds to DNA and blocks the movement of RNA polymerase

What is the specific effect of alpha-Amantin?

Blocks mRNA synthesis by binding preferentially to RNA polymerase 2

What RNA molecule is polyA tail added to during posttranscriptional modifications?

Pre-mRNA (3’ end)

Which nucleotide bond is cleaved by cAMP phosphodiesterase?

3’-5’ phosphodiester bond forming a cyclic structure

Aminoacyl-tRNA synthetases recognises:

A specific tRNA and a specific amino acid

RNA Polymerase 2 is inhibited by:

a-amanitin

Which enzyme does not use ATP as a substrate?

DNA polymerase

Point mutation leads to the change of codon UUA. This is silent mutation because of which feature of genetic code?

Redundant

Activity of 5’-3’ nuclease is found at:

DNA Polymerase 1

Which RNA molecule contains unusual bases such as dihydrouracil?

tRNA

Methylated food xanthines are inhibitors of:

Phosphodiesterase

The enzyme required for the elongation of the polypeptide chain is:

Peptidyltransferase

What is the first amino acid of Prokaryotes in translation?

N-formylmethionine

What are isoacceptor tRNAs?

tRNA molecules which has distinct anticodons but transport the same amino acid