Question

Answer the following genetics questions:

a. In detail describe the process of DNA replication. Be sure to include all the major enzymes (gyrase, helicase, ligase, polymerase, primase), SSBs, replication fork, Okazaki fragments, and strand types (leading v. lagging). Draw and label a diagram of a replication bubble and replication forks.

b. Describe and differentiate among the primary, secondary, and tertiary structures of a protein. To what
   kinds of interactions can each of these stages be ascribed?

c. What are the functions of the 5' cap and poly(A) tail of mature mRNAs in eukaryotes?

Answer 1

Replication

Parental DNA double helix is denatured by helicase enzyme and single stranded proteins hold them in single strand condition. Supercoil that builds during this phase will be relaxed by the gyrase enzyme

Once dentaured primer will be added by primase at the 5' end and polymerase starts to add nucleotides and replication bubble move on. In leading strand tbere will be continous strand synthesis and in lagging strand it will produced in patch that is called as ogazaki fragments and they are ligated by ligase enzyme

2. Protein structures

Primary structure :

It is made up of amino acids that are bound by peptide bonds

Secondary structure : it is made up alpha helix beta sheets and beta turns that are made from aminoacid sequence

Tertiary structure : it has hydrogen , ionic and disulfide bonds that makes the protein confirmations

3. Role of 5' cap and poly a tail

Both 5' cap and poly a tail protects the mRNA from degradation by enzymes when it is taken to the cytoplasm