Structure and properties of RNA?

Question 1

What is RNA made of?

Answer 1

Nucleic acid but has ribose instead of deoxyribose

Question 2

Is RNA single or double stranded?

Answer 2

Single

Question 3

What are the two parts to the RNA structure?

Answer 3

Hairpin

Stem

Question 4

Are there hydrogen bonds in an RNA molecule?

Answer 4

Yes, at the stem between the two sides of the strand

Question 5

What is transcription?

Answer 5

Making RNA from DNA

Question 6

What is translation?

Answer 6

Making protein from RNA

Question 7

Name the four types of RNA

Answer 7

mRNA
tRNA
rRNA
snRNA

Question 8

What does mRNA do?

Answer 8

Messenger RNA

Encodes amino acid sequence of a polypeptide

Question 9

What does tRNA do?

Answer 9

Transfer RNA

Brings amino acids to ribosomes during translation

Question 10

What does rRNA do?

Answer 10

Ribosomal RNA
Makes up the ribosome
Organelle that translates the mRNA

Question 11

What does snRNA do?

Answer 11

Small nuclear RNA
Forms protein complexes that process RNA
Eukaryotes only

Question 12

What are the three parts of a protein-coding gene?

Answer 12

Promoter
Coding sequence
Terminator

Question 13

What is the promoter?

Answer 13

A base-pair sequence that specifies where transcription begins

Question 14

What is the coding sequence?

Answer 14

A base-pair sequence that includes coding information for the polypeptide chain specified by the gene

Question 15

What is the terminator sequence?

Answer 15

A sequence that specifies the end of the mRNA transcript

Question 16

What is pre-mRNA?

Answer 16

RNA made directly from the DNA
Contains introns
Requires splicing

Question 17

Describe the stages of transcription

Answer 17

DNA helicase unwinds the DNA forming the replication fork.
RNA polymerase comes in using transcription factors and recognises the promoter to begin transcription
Pre-mRNA is made in a 5’ to 3’ direction
RNA released and DNA helix reforms as RNA polymerase moves along
When terminator is reached, RNA polymerase stops and full pre-mRNA transcript is released

Question 18

How does prokaryotic and eukaryotic mRNA differ?

Answer 18

Prokaryotic mRNA is said to be colinear with the protein sequence
It requires no splicing

Question 19

In eukaryotic cells, what is added to the 5’ end of mRNA?

Answer 19

A cap of modified GTP
This occurs at the beginning of transcription
A signal for ribosomes to bind to the mRNA

Question 20

In eukaryotic cells, what is added to the 3’ end of mRNA

Answer 20

A poly(A) tail of 150 or more adenine nucleotides is added
It is needed for stability of the mRNA

Question 21

What are the stages to removing introns from pre-mRNA?

Answer 21

The intron loops out as snRNPs, snRNAs and proteins bind to form a spliceosome
The intron is excised and the exons spliced together

Question 22

What happens if introns are left in the mRNA transcript?

Answer 22

They will be translated and a variant of the protein will be produced which may or may not be functional.