Post-Transcriptional Modification

Question 1

What are non-coding sequences called?

Answer 1

Introns.

Question 2

What are the coding sequences called?

Answer 2

Extons.

Question 3

When do the introns need to be removed?

Answer 3

Before the mRNA can be translated into proteins.

Removal is called Post-Transcriptional modification.

Question 4

FIRST STEP in Post-Transcriptional modification.

Answer 4

Initial mRNA that is transcribed = primary transcript or pre-mRNA.
Its an exact copy of the gene on the DNA, so it contains extons and introns.

Question 5

SECOND STEP in Post-Transcriptional modification.

Answer 5

Introns in mRNA cut out.
Exons joined together by enzymes in process called splicing.
Some splicing is done by RNA intron, acting as an RNA enzyme.
Other splicing is preformed by RNA/protein complexes called snurps.

Question 6

What does the recent discovery RNA enzymes or ribozymes illustrate?

Answer 6

What a diverse and important molecule RNA is.

Question 7

THIRD STEP in Post-Transcriptional modification.

Answer 7

The result is a shorter mature DNA containing only exons.

Introns are broken down.

Question 8

What does eukaryotic DNA contain?

Answer 8

Non-coding sequences as well as coding sequences.

Question 9

What does Prokaryotic DNA not have?

Answer 9

Introns, so mRNA processing isn’t needed.