Transcription and Translation

Transcription

is the synthesis of RNA from a DNA Template.

single gene (DNA)

A _______ is transcribed using only one of the two DNA strands, the coding strand. Its complement, the silent strand, is not used.

RNA polymerase

The two DNA strands of the gene move apart to provide access by?

RNA polymerase

An enzyme attaches to the initiation site at the 3’ end of the coding strand of the gene (DNA).

RNA polymerase

An enzyme moves along the coding strand, inserting the appropriate RNA nucleotides in place as dictated by the nucleotide sequence of the gene.

initiation, elongation, termination

What are the 3 steps of Transcription

Initiation

occurs at an initiation site at the 3’ end of the gene. The initiation site is part of a larger promoter. Each gene has its own promoter. The promoter consists of a TATA box of about 100 nucleotides, mostly T and A, and an initiation sequence. The TATA box is upstream of the initiation sequence. Proteinaceous transcription factors attach to the promoter and help the polymerase find and attach to the initiation site. RNA polymerase attaches to the initiation sequence.

initiation site, promoter

The _____ is part of a larger promoter. Each gene has its own ____.

TATA box

The promoter consists of a _____.

100

How many nucleotides consists of a TATA box

T and A

What kinds nucleotides mostly are in the initiation sequence

TATA box

is upstream of the initiation sequence.

Proteinaceous transcription

factors attach to the promoter and help the polymerase find and attach to the initiation site

RNA polymerase

This attaches to the initiation sequence

Elongation

RNA polymerase moves along, unwinding one turn of the double helix at a time thus exposing about 10 bases. New RNA nucleotides are added to the 3’ end of the growing mRNA molecule at a rate of about 60 sec-1. The double helix reforms behind the enzyme. Many RNA polymerase molecules can transcribe simultaneously (remember, the gene is hundreds of thousands of nucleotides long). Only one DNA strand, the coding strand, is transcribed. The other strand is not used (silent). But, which strand is coding and which silent varies from gene to gene. The reading direction is 3’ to 5’ along the coding strand.

1

How many DNA strand which is the coding strand is transcribed?

gene to gene

which strand is coding and which silent varies from?

3 to 5

The reading direction of the mRNA is ____ along the coding strand

Termination

When the RNA polymerase reaches the 5’ end of the coding strand of the gene it encounters a termination site, usually AATAAA. Here the enzyme falls off the coding strand and releases the pre mRNA strand (which must now be modified).

AATAAA

When the RNA polymerase reaches the 5’ end of the coding strand of the gene it encounters a termination site, usually?

The termination phase has produced a strand of pre mRNA which contains many areas of nonsense known as _________ between useful areas known as exons.

introns

The pre RNA must be modified to remove the ____?

Translation

is the process of converting the mRNA codon sequences into an amino acid sequence.

Genes

This will determine phenotype through the synthesis of proteins

AUG

No transcription occurs without the _____ codon

translation

This is where the nucleotide sequence of the mRNA strand is translated into an amino acid sequence. This is accomplished by tRNA and ribosomes.

f-Met

is always the first amino acid in a polypeptide chain, although frequently it is removed after translation.

initiation complex

The intitator tRNA/mRNA/small ribosomal unit is called the?

larger subunit

What subunit attaches to the initiation complex