QUESTION 3 (10 MARKS) (a) Describe the role of the following...

QUESTION 3 (10 MARKS) (a) Describe the role of the following enzymes in DNA replication: primase; helicase, DNA polymerase, DNA ligase. (4 MARKS) (b) Describe the process of translation, naming the key components involved in the process. Does simultaneous transcription and translation occur in bacteria, yeast or mammalian cells? (4 MARKS) (c) What is meant by codon usage, and why is it relevant when expressing human proteins in, for example, yeast or bacteria? (2 MARKS)

Transcript

00:01 Hello students, in this video i will be answering multiple questions beginning with the first one.

00:07 In first question we need to define the roles of the enzymes that are involved in dna replication.

00:13 The first one is primase.

00:15 Primase is an enzyme that synthesizes rna primers during dna replication.

00:22 It adds a short rna sequence called as primers to the template dna strand which provides a starting point for dna polymerases to begin synthesizing a new dna strand.

00:34 Next is helicase.

00:36 Helicase is an enzyme that plays a crucial role in dna replication by unwinding the double -stranded dna helix.

00:43 It breaks the hydrogen bonds present between the complementary nucleotide bases, separating the two strands and creating a replication fork.

00:53 Next dna polymerase.

00:55 Dna polymerase is an enzyme that is responsible for synthesizing new dna strands during dna replication.

01:02 It adds complementary nucleotides to the growing dna strand following the base pairing rule that is it pairs adenine with thymine and guanine with cytosine.

01:13 Dna polymerase also has proofreading capabilities to detect and correct errors in dna replication.

01:20 Next dna ligase.

01:22 Dna ligase is an enzyme that joins or ligates okazaki fragments on the lagging strand of the dna during replication.

01:30 It seals the gap between the newly synthesized dna fragments by catalyzing the formation of phosphodiester bonds.

01:38 Moving on to the next question regarding the translation.

01:41 Translation is a process by which genetic information encoded in the messenger rna is used for synthesizing proteins.

01:50 It occurs in the cytoplasm of the cell and involves several key components.

01:54 The first one is mrna.

01:56 Messenger rna carries the genetic code from the dna to the ribosomes.

02:01 It contains codons which are sequences of three nucleotides that specify the amino acids to be incorporated into the growing polypeptide chain.

02:11 Next is ribosomes.

02:13 Ribosomes are cellular structures where protein synthesis occurs.

02:18 They consist of two subunits, the larger and the smaller subunits.

02:22 These subunits come together during translation.

02:26 Ribosomes provides a site for mrna binding and facilitates the assembly of amino acids into a polypeptide chain.

02:33 Next is trna...

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