Lecture 4- DNA and RNA

What are the functions of the nucleic acids? 

• DNA- stores and carries hereditary information 

• DNA- provides directions for its replication 

• RNA- has structural roles 

Describe the structure of a nucleotide.

Contains a sugar, phosphate and a base 

Describe the structure and function of a phosphodiester bond: 

Adjacent nucleotides are joined together by a phosphodiester (PO4) which creates a sugar phosphate backbone 

Describe the structure of DNA and RNA: 

• RNA- Single stranded, Thymine is replaced by Uricil 

• DNA- Double stranded, contains Thymine 

How does the form relate to the function of each nucleic acid (DNA, RNA, TRNA, MRNA)

• DNA with its double helix structure makes it so it's genetic code is protected  

• The diverse single stranded nucleic acids (e.g rNA, tRNA and mRNA) have specific functions for protein synthesis

What is meant by base pairing and how it contributes to the structure of DNA? 

• Complimentary base pairing rule: A-T( or U in rNA) G-C 

• Purine (A or G) (Double Ringed)

• Pyramidine (C or T) 

• The more G-C means the stronger as it contains 3 Hydrogen bonds rather than 2 

Why is the double-stranded structure of DNA and base pairing rules are important for DNA replication? 

Makes it so DNA can create two genetical copies of each DNA in a cell ready to divide 

Difference in base and sugar of DNA and RNA

DNA has 1 hydroxyl whereas RNA has 2. DNA contains thymine. RNA contains uricil.

How does the form relate to the function of each nucleic acid RNA?

• RNA- responsible for transcripting code from DNA to mRNA, single stranded which allows it to fold into complex 3D shapes

How does the form of tRNA help its function?

• TRNA- contains anticodons that are complimentary to mRNA and it is connected to a amino acid which is attached to growing protein chain, meaning that the correct amino acid can then be joined together to form a protein 

What is a nucleotide?

A monomer of nucleic acids.

How are nucleotides joined together and what does it form?

Joined together by a phosphodiester bond, creating the backbone of sugar-phosphate

What nucleotides are purines?

A or G

What nucleotides are pyramidines?

C or T

What kind of nucleotides are A, G, C,T?

-Purine (A or G)

-Pyramidine (C or T)

How does the form of mRNA help it function?

• MRNA- transports code from rNA to ribosome 

• Being single stranded allows for mRNA to easily pass through membranes

• Single stranded means it is readily accessible with complimentary base pairing with tRNA anticodons during translation