RNA Processing

Question 1

Colinearity

Answer 1

In prokaryotes, the coding region of a gene is uninterrupted
The sequence of the gene corresponds to the amino acid sequence
They are colinear
Number of nucleotides is proportional to the number of amino acids (3:1)

Question 2

3 primary regions of mature mRNA

Answer 2

5’ UTR
Protein coding region
3’ UTR

Question 3

5’ UTR

Answer 3

5’ untranslated region
Does not code for amino acids
Binds the ribosomal complex

Question 4

Protein coding region

Answer 4

Comprises the codons that specify the amino acids
Begins with a start codon and ends with a stop codon

Question 5

3’ UTR

Answer 5

3’ untranslated region
Does not code for amino acids
Affects the stability of the mRNA and regulates its translation

Question 6

Where do translation and transcription occur in prokaryotes

Answer 6

In cytoplasm and can occur simultaneously
The mRNA sequence direction corresponds to the DNA (no processing between)

Question 7

Eukaryotes rna processing

Answer 7

The mRNA is extensively modified before translation and must be transported out of the nucleus

Question 8

Pre-mRNA

Answer 8

Result of Transcription of the entire template strand of the gene in eukaryotes
is then processed to make mature mRNA that can be translated into protein

Question 9

How are genes interrupted

Answer 9

By introns

Question 10

exons

Answer 10

are protein coding segments,

Question 11

Introns

Answer 11

are intervening (non-coding) segments
Need to be removed by splicing

Question 12

Exons - more detail abt length and order

Answer 12

Can vary in length and relative position on the gene
However, the order of exons is always maintained in the spliced mRNA

Question 13

Where does splicing take place?

Answer 13

The nucleus

Question 14

snRNAs

Answer 14

Small nuclear RNAs are required to remove the intron
Compose a spliceosomal complex

Question 15

Introns

Answer 15

Only present in eukaryotes DNA and can vary in nucleotide length, and there are different types.
Some have self splicing capabilities as in mitochondrial jeans they are removed from pre-mRNA by the action of us places on.

Question 16

What is the function of an addition of a 5 prime cap?

Answer 16

It facilitates the binding of ribosome to the five prime end of mRNA
increases mRNA

Question 17

What is the function of the three prime, cleavage, and addition of Polly a tail?

Answer 17

Increases the stability of mRNA facilitates binding of ribosome to mRNA

Question 18

What is the function of RNA splicing?

Answer 18

Removes the non-coding entrance from pre-mRNA facilitates the export of mRNA to cytoplasm and allows for multiple proteins to be produced through alternative splicing

Question 19

What are the steps to add the five prime cap?

Answer 19

One of the phosphate groups at the five prime end of the mRNA is removed
A guanine nucleotide with its phosphate group is added
Methyl groups are added to position seven of the base of the terminal guanine nucleotide
Metal groups are also added to the to prime position of the sugar in the second and sometimes the third nucleotides, and if the base on the second nucleotide is a that basement also be methylated

Question 20

For the five prime cap, methyl groups are added to what?

Answer 20

Seven prime position of the terminal guanine that was added
Two prime OH group of the sugar of the first and sometimes second nucleotide
To adenine if it is the second nucleotide sometimes

Question 21

Can methyl guanosine be transcribed?

Answer 21

Nope

Question 22

Three prime Polly a tail

Answer 22

50 to 250 A’s are added to the three prime end of the mRNA
The A’s are added without a template
This is termed polyadenylation
Poly a consensus sequence is the polyadenylation signal located 11 to 30 nucleotides upstream of the cleavage site

Question 23

Poly a consensus sequence

Answer 23

Is the polyadenylation signal located at 11 to 30 nucleotides upstream of the cleavage site

Question 24

What are the different parts of the intron?

Answer 24

5’ spice site - containing junction sequence GU

Branch point - conserved A residue located 18-40 nt upstream of 3’ splice site

3’ splice site - containing the junction sequence AF

Question 25

Spliceosome

Answer 25

It’s an rna/protein structure
It contains five small nuclear RNAs (U1, U2, U4, U5, U6)
The snRNAs associate with about 300 small proteins to form small nuclear ribonuvleopriteins (snRNPs)

Question 26

Spliceosome assembly

Answer 26

U1 attatches to the 5’ splice site
U2 attatches to the branch point A
A complex of U4, U5 and U6 joins the Spliceosome
U1 and U4 are released
Base pairing btw sequences in the mRNA and the snRNAs hood the sliceosome together
The exons are joined together and the intron is released as a lariat

Question 27

Why is glucose the preferred source of energy for bacteria

Answer 27

It requires less energy to metabolize glucose than lactose