701 RNA Composition and Structure

Lecture 16

RNA is bad for storage of biological information, because unlike DNA:

It is very unstable

How is RNA foundationally different from DNA?

They have different (although similar) chemical components and structural features.

Instead of a Thymine base, RNA has

Uracil, which contains an extra methyl group.

Why is RNA less stable than DNA?

RNA is single stranded and has an OH at 2’, making it more susceptible to hydrolysis. (Ribose Sugar)

RNA has the ability to modify it’s own structure because

DNA polymerases are used in:

Replication

RNA polymerases are used in:

Transcription

Which direction of nucleotides can never have anything added on to it?

5’

Nucleotides grow

Exponentially: 4^n

The OH at 2’ in RNA has the ability to act as what?

A nucleotide, which reacts against the phosphate on 3’. This separates the connected base, and leaves RNA very unstable, unlike DNA which does not have the OH at 2’.

What percent of RNA’s are mRNA’s (messenger RNA’s)?

1-5%

What is a mRNA?

Direct carrier of genetic information from DNA to translation.

What are the unique structural features of mRNA’s?

5’ Cap, Introns, Poly A tail

What percent of RNA are rRNA’s (Ribosomal RNA)

~80%

What are RNA molecules with catalytic activity?

Ribozymes

What do rRNA and tRNA have in common?

Have modified bases which give them both unique characterisitcs.

What percent of RNA are tRNA’s (Transfer RNA’s)?

15%

What are the key roles of tRNA?

Activates amino acids and recognizing codons in cellular mRNA’s.

Where is rRNA processed?

In the nucleus

What are Long non-coding RNA’s?

Non-protein coding transcripts that are longer than 200 nucleotides.

What are MicroRNA’s?

They are small non-coding RNA’s that inhibit the translation of mRNA translation or promoting the degradation of mRNA’s to prevent a certain gene expression.

Genes are very simply:

Real estate on a chromosome.

What percent of mtRNA’s make up cellular RNA?

~4%

What is reverse transcription?

When RNA is used as the blueprint for a complementary DNA sequence. Usually a virus

What is an example of the Retroviral Lifecycle?

ZDV. The virus binds to a host cell and then completes a reverse transcription.