Transcription

Question 1

Gene Expression

Answer 1

The process by which DNA directs the synthesis of proteins

Question 2

Transcription

What direction is DNA read in transcription?

Answer 2

The synthesis of mRNA using information in the DNA.

DNA is always read in 3’ to 5’ orientation.

Question 3

mRNA

Answer 3

messengerRNA carries a genetic message from the DNA to the protein-synthesizing machinery of the cell

Question 4

Ribosomes

Answer 4

The site for protein synthesis in the cell. Messenger RNA is translated here.

Question 5

Primary Transcript

Answer 5

Pre-mRNA? The initial RNA transcript from any gene.

Question 6

Codon

Answer 6

The triplet of mRNA nucleotides used to code for Amino Acids

Question 7

Template Strand

Answer 7

The strand used by RNA Polymerase as a TEMPLATE for the mRNA to be built from 5’ to 3’.

Question 8

Reading Frame

Answer 8

The reading frame is the sequence of mRNA that gets translated into amino acids. It starts from the START codon AUG and ends at the stop codons. UAA, UAG, UGA.

Question 9

RNA Polymerase

Does RNA polymerase need a primer?

Answer 9

The enzyme that pries the DNA strands apart and joins RNA nucleotides complementary to the template strand.

RNA Polymerase does not need a primer like DNA Polymerase does

Question 10

Promoter

Sequence? Why this sequence?

Answer 10

The DNA sequence where RNA polymerase attaches

TATA Box. It’s easy to open because less H-bonds

Question 11

Terminator

Answer 11

The sequence that signals the end of transcription

This is only for bacteria

Question 12

Transcription Unit

Answer 12

The portion of DNA downstream from the promoter. This is what is transcribed.

Question 13

Transcription Factor

Answer 13

Transcription Factors are proteins that bind to the DNA before RNA polymerase II can bind to the promoter.

Question 14

5’ Cap & Poly-A tail

Answer 14

The 5’ Cap is added to the 5’ end of the pre-mRNA during RNA processing and is composed of a modified guanine nucleotide. The Poly-A tail is a series of 50-250 Adenine nucleotides added to the 3’ end of the pre-mRNA during RNA processing.

They both function to facilitate the export of the mature mRNA from the nucleus and protect it from degradation by hydrolytic enzymes. Also, they help ribosomes attach to the 5’ end.

Question 15

RNA Splicing

Answer 15

This is the process during RNA processing where Introns are cut out and exons are joined together by spliceosomes

Question 16

Introns/Exons

Answer 16

Introns are the portion of the mRNA that is cut out and does not code for anything. Exons are expressed (not completely sometimes).

Question 17

Genotype vs. Phenotype?

Answer 17

An organism’s genotype is carried in its sequence of bases.
The phenotype is a consequence of the proteins that are expressed.

Question 18

How is transcription and translation different in prokaryotes when compared to eukaryotes?

Answer 18

Because bacteria lack nuclei, transcription and translation can occur simultaneously. There is also no RNA processing in bacteria.

Question 19

Start Codon: Sequence? Function? AA?

Answer 19

The START Codon says when to start reading the mRNA molecule. Its sequence is AUG and is also the amino acid methionine.

Question 20

What are the three processes in transcription and how do they work?

Answer 20

1. Initiation. Transcription factors bind to the TATA box (promoter) and RNA polymerase recognizes this and binds to it. RNA polymerase II bound to the transcription factors is known as the transcription initiation complex.
2. Elongation. RNA Polymerases move along the DNA and untwist the double helix while elongating the mRNA strand.
3. Termination. The polymerase falls off the DNA and the mRNA floats away.