Stop codons are

• AUG, GUG

• UAA, UGA, UAG

• UAC, UGG

• AGU, AGA, UAC

Which of the following is not a Pyrimidine?

• Thymine

• Uracil

• Guanine

• Cytosine

RNA is not found in

• chromosome

• plasmalemma

• nucleolus

• ribosome

Sequence of DNA (non-coding) is known as

• exon

• intron

• cistron 

• none of these

Which one of the following makes use of RNA as a template to synthesize DNA?

• Reverse transcriptase

• DNA dependant RNA polymerase

• DNA polymerase

• RNA polymerase

During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. What is that sequence called?

• CAAT box

• GGTT box

• AAAT box

• TATA box

Which one of the following hydrolysis internal phosphodiester bonds in a polynucleotide chain?

• Lipase

• Exonuclease

• Endonuclease

• Protease

E. coli cells with a mutated Z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because

• in the presence of glucose, E. coli cells do not utilize lactose

• they cannot transport lactose from the medium into the cell

• the lac operon is constitutevely active in these cells

• they cannot synthesize functional $\mathrm{\beta }$- galactosidase

What's the difference between RNA and DNA?

• Base

• Sugar

• Sugar and base

• Phosphate

300.

In split genes the coding sequences are called

• introns

• exons

• cistrons

• operons