Question

Describe the process of transcription and translation. In your answer include the major molecules involved in both the transcribing of genes and translation from nucleotide language to amino acid language. What are the major differences between transcription and translation between prokaryotes and eukaryotes?

Answer 1

Transcription is a process of formation of RNA from DNA. It takes place by the usual process of complementary base pairing, catalyzed and scruitinized by the enzyme RNA polymerase. RNA polymerase is responsible for RNA synthesis. Transcription occure unidirectionally in which RNA chain is synthesized from the 5' to 3' direction. RNA polymerase and & transcription factors can bind to specific DNA sequences called enhancer and promoter sequences and form a complex called the transcription initiation complex. This complex initiates transcription, and the RNA polymerase begins mRNA synthesis by matching complementary bases to the original DNA strand. The mRNA molecule is elongated and, once the strand is completely synthesized, transcription is terminated.

In translation mRNA is "decoded" to build a protein that contains a specific series of amino acids. Translation devided into three stages: initiation (starting off), elongation (adding on to the protein chain), and termination (finishing up).

Initiation: The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon.

Elongation: The tRNA transfers an amino acid to the tRNA corresponding to the next codon and ribosome then moves to the next mRNA codon.

Termination: When a stop codon is reached, the ribosome releases the polypeptide.

Differences between transcription and translation between prokaryotes and eukaryotes:

1. Main difference between the two is that transcription and translation occurs simultaneously in prokaryotes and in eukaryotes the RNA is first transcribed in the nucleus and then translated in the cytoplasm.

2. Prokaryotes tend to contain many different genes on a single mRNA meaning they are polycystronic. Eukaryotes contain mRNAs that are monocystronic

3. Eukaryotes have three types of RNA polymerases, I, II, and III, and prokaryotes only have one type.

4.RNAs from eukaryotes undergo post-transcriptional modifications including: polyadenylation, capping, and splicing. These events do not occur in prokaryotes