Gene expression and regulation

Question 1

What are the components of ribonucleotides

Answer 1

• Sugar Ribose
• Nitrogen Bases
• Phosphate backbone

Question 2

Name the 4 ribonucleotides that are in RNA, and state whether they are purines or pyrimidines

Answer 2

A & G : Purines

U & C : pyrimidines

Question 3

Is RNA double stranded or single stranded?

Answer 3

Single Stranded

Question 4

Does RNA have polarity?

Answer 4

yes

Question 5

Describe similarities and differences between the processes of DNA replication and transcription

Answer 5

• Similarities : Ribonucleotides are added, one by one, to the growing RNA chain; complementary base-pairing
• Transcription differs from DNA replication in several crucial respects. Unlike a newly formed DNA strand, the RNA strand does not remain hydrogen-bonded to the DNA template strand.

Question 6

What are the main differences between RNA polymerase and DNA polymerase?

Answer 6

• RNA polymerase uses ribonucleoside for phosphates as substrates, so it catalyzes the linkage of ribonucleotides, not deoxyribonucleotides.
• Second, unlike the DNA polymerase involved in DNA replication, RNA polymerases can start anRNA chain without a primer

Question 7

Messenger RNA (mRNA) Functions

Answer 7

code for proteins

Question 8

ribosomal RNAs (rRNAs) Functions

Answer 8

form the core of the ribosome’s structure and catalyze protein synthesis

Question 9

transfer RNAs (tRNAs) Functions

Answer 9

serve as adaptors between mRNA and amino acids during protein synthesis

Question 10

microRNAs (miRNAs) Functions

Answer 10

• regulate gene expression
• serve as key regulator of eukaryotic gene expression

Question 11

TATA box

Answer 11

• The TATA box is a key component of many promoters used by RNA polymerase II, and it is typically located 25 nucleotides upstream from the transcription start site.

Question 12

What allows RNA to be released from the transcription initiation complex and for transcription to begin?

Answer 12

A key step in liberating the RNA polymerase is the addition of phosphate groups to its “tail”. This liberation is initiated by the general transcription factor TFIIH, which contains a protein kinase as one of its subunits

Question 13

Why must eukaryotic RNAs go through RNA processing before translation can occur?

Answer 13

Transcription takes place in the nucleus, but protein synthesis takes place on ribosomes in the cytoplasm. So, before a eukaryotic mRNA can be translated into protein, it must be transported out of the nucleus through small pores in the nuclear envelope

Question 14

Where does RNA processing occur?

Answer 14

In the Nucleus

Question 15

Intron

Answer 15

Noncoding sequence

Question 16

Exon

Answer 16

Protein-coding sequences

Question 17

How are introns removed from mRNA?

Answer 17

Introns Are Removed From Pre-mRNAs by RNA Splicing

Question 18

Codon

Answer 18

Each group of three consecutive

nucleotides in RNA is called a codon

Question 19

Reading Frames

Answer 19

A reading frame refers to one of three possible ways of reading a nucleotide sequence.

Question 20

RNA polymerase II

Answer 20

• Eukaryotic cells
• encode proteins and miRNA’s
• require assisstance of general transcription factors to initiate

Question 21

tRNA synthetase

Answer 21

catalyzes the covalent coupling of an amino acid to a tRNA

Question 22

Large rRNA subunit

Answer 22

catalyzes the formation of peptide bonds

Question 23

small rRNA subunit

Answer 23

matches the rRNA to the codon of the mRNA