Structure And Propertires Of RNA

Question 1

What codes for proteins

Answer 1

Genes DNA doesn’t express proteins

Question 2

What expresses proteins

Answer 2

RNA

Question 3

Differences between DNA and RNA

Answer 3

DNA has 2-deoxyribose and RNA has ribose which is less stable
RNA has uracil instead of thymine
DNA is double stranded RNA is single stranded
Both have complementary base pairing however RNA is within the same strand and DNA is between different strands

Question 4

Difference between thymine and uracil

Answer 4

Thymine has a methyl group whereas uracil has a hydrogen group so it is less stable

Question 5

How do you write RNA

Answer 5

5’ to 3’ direction

Question 6

What is the shape of RNA in space? How is this shape formed? and what is the function of this shape?

Answer 6

Hairpin loop that forms a stem where there is complementary base pairing between the nitrogenous bases

This give it a stability allowing it to perform its function

Question 7

Structure of transfer RNA

Answer 7

Single stranded
3 hairpin loops and 1 variable loop
3’ end is the acceptor stem place where an amino acid will bind that has been coded for in the anticodon loop, the anticodon loop will have 3 bases that have the information for the amino acid that is required at the acceptor stem

Question 8

Structure and function of messenger RNA

Answer 8

Protein coding RNA allows proteins to be made
Must be stable enough to allow translation to happen
It is a single stranded molecule
4 domains made of hairpin loops that gives it a stability so it can remain in the nucleus so translation can happen
4 domains will differ and are unique to the length and complexities of the RNA transcript unique to gene

Question 9

What determines how long RNA will remain in the nucleus

Answer 9

The amount of hair pin loops and stems it has more the longer it will last as it is more stable

Question 10

Why is it important that RNA remains in the nucleus for longer

Answer 10

Because when expressing a protein you need to express enough protein for it to carry out its function.
Genes are not constantly transcribed they are only actively transcribed when they are needed.
RNA is still present in the nucleus so you can still make proteins from that transcript and transcription doesn’t need to happen repeatedly.

Question 11

The Centeral dogma of molecular biology

Answer 11

The two step process of transcription and translation by which the information in genes flows into proteins through DNA to RNA to proteins

Question 12

Transcription

Answer 12

The synthesis of RNA from DNA

Question 13

Translation

Answer 13

The synthesis of a protein under direction of the RNA

Question 14

What can happen if DNA is changed within a protein coding region

Answer 14

Can lead to the manifestation of a different phenotype, if beneficial it will remain and become the dominant characteristic over time, this is evolution

Question 15

Process of transcription

Answer 15

Helicase unwinds the DNA
RNA polymerase binds and moves in 5’ to 3’ direction so uses the 3’ to 5’ parental strand as the template and makes an RNA transcript complementary to the DNA coding region
This chain that is formed contains uracil and ribose sugars
RNA polymerase reaches the end of the DNA coding region and the pre mRNA is released and moves into the nucleons
This process will repeat until sufficient amounts of transcript are formed for the amount of protein that is needed

Question 16

Process of RNA processing

Answer 16

Pre mRNA which is the same length as the DNA coding region is processed into mature mRNA transcript that is then transported out of the nucleus

Question 17

Where does transcription take place

Answer 17

Within the nucleus

Question 18

Where does translation take place

Answer 18

Within the cytoplasm at the rough endoplasmic reticulum on ribosomes

Question 19

4 RNA’s involved in gene expression and synthesis of proteins

Answer 19

Messenger RNA
Transfer RNA
Ribosomal RNA
Small nuclear RNA

Question 20

What are introns and exons

Answer 20

Introns are non coding regions
Exons are protein coding regions
These can both be transcribed however intron regions can give rise to RNA that is involved in the regulation of the gene being expressed

Question 21

How does transcription differ from replication?

Answer 21

Transcription doesn’t require a primer for RNA polymerase to bind however replication requires an RNA primer
In transcription,as the RNA polymerase moves along the gene the helix is reformed behind it it is not held open DNA remains in a compact structure

Question 22

How does RNA polymerase bind without a primer

Answer 22

The DNA coding region has a sequence at the 5’ end which has specific DNA sequences called the promoter, this allows for specific transcription facts to bind which form a complex to signal the RNA polymerase to bind

Question 23

Where does the RNA polymerase start from on the gene during transcription

Answer 23

The promoter region this region specifies where transcription begins, transcription doesn’t start in the promotor region

Question 24

What comes after the promoter on a gene

Answer 24

The RNA coding sequence

Question 25

What is at the end of the coding sequence

Answer 25

A sequence that is not transcribed and protects the gene this is called the terminal sequence this is where pre mRNA is released

Question 26

Which strand is the template strand during transcription | Which strand is the coding strand

Answer 26

The 3’ to 5’ strand as RNA polymerase works in a 5’ to 3’ direction The coding strand is the 5’ to 3’ strand of DNA

Question 27

Eukaryotes mRNA

Answer 27

The mature mRNA is shorter than the gene

Question 28

What happens to pre mRNA as soon as it has been made

Answer 28

A GTP cap is placed on the mRNA at the 6’ end to keep it in tact as soon as it is made At the 3’ is a polyA tail to keep the transcript undamaged and increase the stability

Question 29

How are the introns removed from pre mRNA

Answer 29

Process called RNA processing How the introns are removed is determined by splicing there can be different splice variants of a protein that will allow different functions to a family of proteins

Question 30

How does splicing work

Answer 30

Small nuclear RNA make a snRNA protein which are able to identify a specific sequence at the boundaries of an intron and an exon and will bind at the sequences and force the intron to loop out, this is then stabilised by two more snRNA proteins that will stabilise the intron forming the splicasome. Two exons will join together.

Question 31

What happens to mature mRNA once RNA processing is complete

Answer 31

It is exported out through nuclear pores to the cytoplasm