Molecular Genetics

Gene expression

The conversion of a gene into a specific trait.

Where does transcription occur?

In the nucleus.

Where does translation occur?

In the cytoplasm.

What type of sugar does RNA contain?

Ribose.

How many strands does RNA have?

Single stranded.

Which base pairs with adenine in RNA?

Uracil (U).

What are the three types of RNA?

Messenger RNA (mRNA), Transfer RNA (tRNA), Ribosomal RNA (rRNA).

What is the function of RNA polymerase in transcription?

Binds to open the double helix at the beginning of a gene and transcribes DNA into mRNA.

What indicates where transcription should start?

The promoter sequence.

In which direction does RNA polymerase build the mRNA strand?

In the 5’ to 3’ direction.

What happens during termination of transcription?

RNA polymerase passes the end of a gene, comes to a stop, and mRNA is released.

What does mRNA translate into?

A chain of amino acids (polypeptides).

What does a codon consist of?

A triplet of RNA nucleotides.

How many possible codons are there?

64 possible codon codes.

What is the start codon for translation?

AUG.

What is the role of tRNA?

Carries a specific amino acid and has an anticodon that connects to the mRNA.

What must be done to introns before mRNA is translated?

They must be spliced out by a spliceosome.

How many tRNAs can attach to a ribosome at one time?

Two tRNAs can attach at one time as the ribosome has 3 binding sites.

What are exons?

Sections of coding DNA that are expressed in the final mRNA.