Genetics Lecture 2: RNA - Structure and Function

Question 1

What does mRNA do?

Answer 1

Carries information on protein primary structure from DNA (used to make proteins).

Question 2

What does rRNA do?

Answer 2

Makes up part of the ribosome. It’s the factory which makes proteins.

Question 3

What does tRNA do?

Answer 3

helps to ‘read’ (translate) the message in mRNA and brings an appropriate amino acid to the growing peptide.

Question 4

What is RNA made of?

Answer 4

1. Sugar (Ribose)
2. Phosphate
3. Base (adenine, cytosine, guanine, uracil)

Question 5

Describe the life cycle of RNA.

Answer 5

RNA does it’s job and when it’s done, it’s broken up and recycled.

Question 6

What are the six main features of RNA?

Answer 6

1. Sugar - Ribose
2. Bases - adenine, cytosine, guanine, uracil
3. Single Stranded Helix
4. Less Stable
5. Short Lived Molecule
6. Used as Functional Molecules

Question 7

How does mRNS relate to DNA?

Answer 7

Template Strand - Also ‘antisense’ strand
Coding Strand - Also ‘sense’ strand, same as mRNA except T Replaced with U. this Sequence is usually reported when describing DNA.

Question 8

What is tRNA?

Answer 8

an adapter (transfer) molecule

Question 9

What does tRNA do?

Answer 9

It collects Amino Acids and takes them from the cytoplasm to the ribosome.

Question 10

What is the structure of tRNA?

Answer 10

Classical ‘Clover Leaf’ - Secondary Structure

Anticodon loop at opposite end carries a 3 base sequence x - y - z (5’ and 3’) termed the anticodon.

Question 11

What does rRNA stand for?

Answer 11

Ribosomal RNA

Question 12

What is rRNA?

Answer 12

• It is made of protein and has a complex structure
• It accounts for 80% of cellular RNA.
• Almost the same in ALL LIFE ON EARTH

Question 13

Explain Ribosomal Structure 1

Answer 13

Bacterial or mammalian ribosome composition.

Question 14

Explain Ribosomal Structure 2

Answer 14

They’re big (you can see them)

• Ribbons = mRNA
• Rods = tRNA

Question 15

What happens in Transcription?

Answer 15

It’s the transfer if information from DNA to RNA.

Question 16

What does Transcription require?

Answer 16

• a DNA template (mRNA is transcribed from your DNA)
• it’s catalysed by an enzyme = RNA POLYMERASE
• ribonecleotide trisphosphate which is the compound that brings the next nucleotide to be added to the mRNA chain that’s being transcribed.

Question 17

Where do the reactions occur in Transcription?

Answer 17

At the 3’ hydroxly end of the mRNA

Question 18

What are the steps in Transcription?

Answer 18

1. Transcription factors assemble at the specific promotor region along the DNA. The length of DNA following the protein is called at gene, and contains the recipe for a protein.
2. A mediator protein arrived carrying the enzyme RNA polymerase.
3. It manoeuvres the RNA polymerase, inserting it between the strands of the DNA Double Helix.
4. Activator Proteins come into contact with specific regions of the DNA called enhancer regions.
5. This contact releases the coping mechanism.
6. The RNA Polymerase unzips a small protein of the DNA helix exposing the bases on each strand. Only 1 strand is copied, like a template, matching up the bases.
7. The subunits are pulled from the nucleus and enter through the enzymes intake hole. They’re formed together to make the long messenger RNA Chain.