RNA nucleic Acid Structure And Function and DNA

Question 1

What is RNA

Answer 1

RNA is a polymer of a nucleotide formed from a ribose, a nitrogenous base and a phosphate group
The nitrogenous base in RNA are guanine, adenine, cytosine and uracil
RNA has the base uracil instead of thymine. In comparison to the DNA polymer, the polymer is a relatively short polynucleotide chain and is single stranded
The function of RNA is to copy and transfer the genetic code from DNA in the nucleus to form the ribosomes
Some RNA is also combined with proteins to create ribosomes

Question 2

What are the three types of RNA

Answer 2

mRNA
tRNA
rRNA

Question 3

What is mRNA

Answer 3

Messenger RNA is a copy of a gene from DNA
mRNA is created in the nucleus and it then leaves the nucleus to carry the copy of the genetic code of one gene to a ribosome in the cytoplasm

Question 4

Why is mRNA used to carry the copy of the genetic code

Answer 4

DNA is too large to leave the nucleus and would be at risk of being damaged by enzymes therefore destroying the genetic code permanently. mRNA is much shorter because it is only the length of one gene and can therefore leave the nucleus
mRNA is short lived as it is only need temporarily to help create a protein therefor by the time and enzymes could break it down it would have already carried out its function. mRNA is single stranded and every 3 bases in the sequence code for a specific amino acid these three bases are therefore called codons

Question 5

explain TRNA

Answer 5

Transfer RNA is found only in the cytoplasm
It is single stranded but folded to create a shape that looks like a cloverleaf. The cloverleaf shape is held in place by hydrogen bonds
The function of tRNA is to attach to one of the 20 amino acids and transfer this amino acid to the ribosome to create the polypeptide chain. Specific amino acids attached to specific tRNA molecules and this is determined by 3 bases found on the tRNA which are complementary to the 3 bases on mRNA
These are called anticodon because they are complementary to the codon on mRNA

Question 6

explain rRNA

Answer 6

Ribosomal RNA is the type of RNA that makes up the bulk of the ribosomes

Question 7

Compare RNA and DNA

Answer 7

Differences between the DNA and RNA monomers
DNA contains thymine whereas RNA contains uracil instead
DNA contains the pentose sugar deoxyribose whereas whereas RNA contains the pentose sugar ribose

Differences between the polymers
DNA is much larger because it contains approximately 23,000 genes (the entire genome) whereas RNA is much shorter because it is only the length of one gene
DNA is double stranded whereas RNA is single stranded

Question 8

What is the function of DNA

Answer 8

DNA codes for the sequence of amino acids in the primary structure of a protein which in turn determines the final 3D structure and function of a protein
It is essential that the cells a contain a copy of this genetic code and that it can be passed on to new cells without being damaged
The DNA polymer is a double helix

Question 9

Describe the DNA nucleotide

Answer 9

The monomer that makes up DNA is called a nucleotide
It is made up of deoxyribose (a pentose sugar), a nitrogenous base and one phosphate group
The nitrogenous base can either be guanine, cytosine, adenine and thymine

Question 10

Explain a polynucleotide

Answer 10

The polymer of these nucleotides is called a polynucleotide
It is created via a condensation reaction between the deoxyribose sugar and the phosphate group, creating a phosphodiester bond
Phosphodiester bonds are strong covalent bonds and therefore help to ensure the genetic code isn’t broken down
The polynucleotide has a sugar-phosphate backbone. This describing the strong covalent bonds between the sugar and phosphate groups that hold the polymer together
The DNA polymer occurs in pairs and these pairs are joined together hydrogen bonds between the bases. This is how the double helix structure is created, as two chains twist
Hydrogen bond can only form between complementary base pairs, this is the term given to the fact that the base cytosine can only form hdyirgen bonds with guanine and that adenine can only bond with thymine
Adenine and thymine form 2 hydrogen bonds whereas cytosine and guanine form 3 hydrogen bonds. This complementary base pairing is imoortant to maintain the order of the genetic code when it replicates

Question 11

How the structure of DNA polymer relates to the function

Answer 11

Stable structure due to sugar phosphate backbone (covalent bonds) and the double helix structure
Double stranded so replication can occur using one strand as a template
Weak hydrogen bonds for easy unzipping of the two strands in a double helix during replication
Large molecule to carry lots of information
Complementary base pairing allows identical to be made