Gene Expression

Question 1

What are the two steps of gene expression?

Answer 1

Transcription and translation

Question 2

Transcription

Answer 2

Information in a DNA sequence (gene) is copied into complementary RNA sequence

Question 3

Translation

Answer 3

RNA sequence used to create amino acid sequence of a polypeptide

Question 4

Central dogma

Answer 4

DNA can be used to create a protein, but a protein can never be used to create DNA

Question 5

Central dogma process

Answer 5

DNA goes to replication or transcription — RNA— translated into protein

Question 6

What are the 3 types of RNA that have roles in the information flow of DNA to protein?

Answer 6

Messenger (mRNA)
Ribosomal (rRNA)
Transfer (tRNA)

Question 7

Messenger RNA

Answer 7

Nucleotide sequence determines ordered sequence of amino acids in a polypeptide chain

Question 8

Ribosomal RNA

Answer 8

Found in ribosome (protein synthesis factory) catalyzes peptide bond formation between amino acids to form polypeptide

Question 9

Transfer RNA

Answer 9

Bind specific amino acid, recognize mRNA sequence, recognize which amino acid should be added to polypeptide chain

Question 10

Does HIV have RNA or DNA? Describe the HIV virus in terms of RNA and DNA

Answer 10

RNA retrovirus
No transcribing, instead infects host cell and makes a DNA copy of genome- host cell transcription makes more RNA- translated and incorporated

Question 11

What does transcription need?

Answer 11

1 strand of DNA, 4 ribonucleoside triphosphates as substrates, RNA polymerase enzyme, salts and pH buffer

Question 12

Reverse transcription

Answer 12

Synthesis of DNA from RNA

Question 13

RNA polymerases

Answer 13

• catalyze the synthesis of RNA from the DNA template
• catalyze the addition of nucleotides in 5’ to 3’ direction and are processive (like DNA)
• don’t require primer

Question 14

What are the 3 steps of transcription?

Answer 14

Initiation
Elongation
Termination

Question 15

Promoter

Answer 15

Special sequence of DNA that tell RNA where to start transcription and which strand of DNA to transcribe

Question 16

Initiation site

Answer 16

Start

Question 17

Sigma factors and transcription factors

Answer 17

Proteins that help determine which specific genes are expressed at a particular time in cell

Question 18

Initiation simplified

Answer 18

RNA polymerase binds to the promoter and starts to unwind the DNA strands

Question 19

Elongation simplified

Answer 19

RNA polymerase moves along the DNA template strand from 3’ to 5’ and produces the RNA transcript by adding nucleotides complementary to the DNA template to the 3’ end of the growing RNA

Question 20

Termination simplified

Answer 20

When RNA polymerase reaches the termination site, the RNA transcript is released from the template

Question 21

Genetic code

Answer 21

Holds information for protein synthesis 
Relates genes (DNA) to mRNA and mRNA to the amino acids that make up proteins

Question 22

Codon

Answer 22

Specifies a particular amino acid

Question 23

Nirenberg and Matthale

Answer 23

Use a simple artificial polynucleotide to identify the polypeptide that the artificial messenger encoded

Question 24

What do the 64 different 3 letter codons determine?

Answer 24

20 amino acids

Question 25

Start codon

Answer 25

AUG (methionine)

Question 26

Stop codons

Answer 26

UAA, UAG, UGA

Question 27

The base sequence of the DNA strand that is transcribed to produce the mRNA is what to mRNA codons

Answer 27

Complementary and anti parallel

Question 28

What is known as the “coding strand”?

Answer 28

Non-template strand of DNA that has the same sequence as mRNA