Ch. 8

Question 1

Structure of RNA

Answer 1

• Ribose sugar (has OH group at 2’ carbon)
• Contain pyrimidine base Uracil (U) instead of Thymine (T)
• Usually single stranded (making it more flexible than DNA)

Question 2

Structure of DNA

Answer 2

• Deoxyribose sugar (has H group at 2’ carbon)
• Contains Thymine (T)
• Double stranded (less flexible than RNA)

Question 3

mRNA

Answer 3

Messenger RNA.
An RNA molecule transcribed from the DNA of a gene; a protein is translated from this RNA molecule by the action of ribosomes.

Question 4

Transcription

Answer 4

Information from DNA is transferred to mRNA

Question 5

Translation

Answer 5

Information from mRNA is transferred to proteins.

Question 6

Two classes of RNA

Answer 6

mRNA - encodes proteins
ncRNA - does not encode proteins

Question 7

ncRNA

Answer 7

Noncoding RNA
Does not encode proteins. The final product whose function is determined by its sequence and three-dimensional structure.

Question 8

tRNA

Answer 8

Transfer RNA
A class of small RNA molecules that carry specific amino acids to the ribosome in the course of translation; an amino acid is inserted into the growing polypeptide chain when the anticodon of the corresponding tRNA pairs with a codon on the mRNA being translated.

Question 9

rRNA

Answer 9

Ribosomal RNA
Several different noncoding RNAs that are components of the ribosome and are essential for protein synthesis (translation).

Question 10

snRNA

Answer 10

Small Nuclear RNA.
A complex containing an snRNA and proteins that resides in the nucleus.

Question 11

lncRNA

Answer 11

Long Noncoding RNA
Nonprotein-coding transcripts that are over approximately 200 nucleotides in length.

Question 12

miRNA

Answer 12

MicroRNA
A class of functional RNA that regulates the amount of protein produced by a eukaryotic gene.

Question 13

siRNA

Answer 13

Small Interfering RNA
Short double-stranded RNAs produced by the cleavage of long double-stranded RNAs by Dicer.

Question 14

Functions of ncRNAs

Answer 14

1. Protein synthesis (tRNA and rRNA)
2. RNA processing (snRNA)
3. Regulation of gene expression (siRNA and miRNA
4. genome defense (siRNA)

Question 15

Transcription bubble

Answer 15

The site at which the double helix is unwound so that RNA polymerase can use one of the DNA strands as a template for RNA synthesis.

Question 16

Template strand

Answer 16

Noncoding strand.
The strand of DNA that is copied (i.e., transcribed) by RNA polymerase.
Resulting RNA sequence is complementary to the template strand.

Question 17

Non-template strand

Answer 17

Coding strand.
Resulting RNA sequence is identical to non-template strand besides substitution of U for T.

Question 18

RNA Polymerase

Answer 18

An enzyme that catalyzes the synthesis of an RNA strand from a DNA template. Eukaryotes possess several classes of RNA polymerase; structural genes encoding proteins are transcribed by RNA polymerase II.
Moves along DNA template strand in 3’-to-5’ direction to build RNA in the 5’-to-3’ direction.

Question 19

The three stages of transcription

Answer 19

Initiation, elongation, termination