Question

The processes of transcription and DNA replication are fundamental to the metabolism of cells. Describe the major stages of each of these two processes .Although very different in terms of biochemistry they do have organizational features in common. In your answer draw attention to some of these.

Note

Detail and comprehensive is explantation is required.

Answer 1

Answer=

Major stages of transcription of DNA =there are 3 stages.

1] Initiation= is the first of transcription.it occurs when enzyme RNA polymerase binds to a region of a gene called the promoter.This signals DNA to unwind so the enzyme can read the bases in one of the DNA strands.the enzyme is now ready to make a strand of mRNA with a complementary sequence of bases.

2] Elongation= Is the addition of nucleotides to the mRNA strand.RNA polymerase reads the unwound DNA strand and builds the mRNA molecule,using complementary base pairs.

there is brief time during this process ,when the newly formed RNA is bound to the unwound DNA.During this process,an adenine in the DNA binds to an uracil in the RNA.

3] Termination= is the ending of transcription,and occurs when RNA polymerase crosses a stop sequence in the gene.The mRNA strand is complete,and is detaches from DNA.

Stages of translation

There are 3 stages .

1]Initiation= during initiation ,the mRNA ,tRNA and first amino acid all come together within the ribosome .the mRNA strand remains continuous ,but the true initiation point is the start codon,AUG.

start codon specifies the amino acid methionine.

the anticodon for AUG is UAC.The tRNA with anticodon UAC will automatically match to the codon AUG.

2] elongation = is the addition of amino acids by the formation of peptide bonds.elongation chain of amino acids grows longer and longer as more amino acids are added.this creates polypeptide.

The mRNA shifts a little through the ribosome so that the next codon is up for grabs.

3] Termination= once a stop codon i.e.UAG,UAA or UGA reaches the ribosome,translation stops,or terminates.