11. Mention three different kinds of ribonucleic acids and functions. Tabulate the transcription and RNA processing in Bacteria and Eukaryotes.

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 11.  Mention three different kinds of ribonucleic acids and functions. Tabulate the transcription and RNA processing in Bacteria and Eukaryotes.

answer :

Introduction

Ribonucleic acid (RNA) is a molecule that is present in the majority of living organisms and viruses. It is made up of nucleotides, which are ribose sugars attached to nitrogenous bases and phosphate groups. The nitrogenous bases include adenine, guanine, uracil, and cytosine. RNA mostly exists in the single-stranded form, but there are special RNA viruses that are double-stranded. The RNA molecule can have a variety of lengths and structures. An RNA virus uses RNA instead of DNA as its genetic material and can cause many human diseases. Transcription is the process of RNA formation from DNA, and translation is the process of protein synthesis from RNA. The means of RNA synthesis and the way that it functions differs between eukaryotes and prokaryotes. Specific RNA molecules also regulate gene expression and have the potential to serve as therapeutic agents in human diseases

three different kinds of ribonucleic acids and functions :

The three major types of RNA are:

  1. mRNA (messenger RNA) : it provides the template for protein synthesis during translation .
  2. tRNA (transfer RNA) : it brings aminoacids and reads the genetic code during translation .
  3. rRNA (ribosomal RNA) : it plays a structural and catalytic role during translation.

the transcription and RNA processing in Bacteria and Eukaryotes :


Transcription:

Transcription is the cellular process by which DNA segments are copied into RNA.

Transcription in prokaryotes:

  1. Transcription in prokaryotes occurs in the cytoplasm. In prokaryotes, it occurs in three phases- Initiation, elongation, and termination.
  2. In the initiation phase, RNA polymerase recognizes a promoter site on the DNA strand. Reading a promoter sequence unwinds the DNA strand and initiates transcription.
  3. The core enzyme of RNA polymerase then proceeds to synthesize RNA in the 5'-3' direction. It uses the antisense strand of DNA as the template for RNA synthesis.
  4. The 3'-OH group of the growing RNA chain interacts with the α phosphate group of the incoming nucleotide to form a phosphodiester bond.
  5. Transcription occurs until a termination sequence on the DNA is found.
  6. When the RNA polymerase detects a termination sequence, it stops the transcription process, releases the synthesized RNA transcript, and dissociates from the DNA.

Note:

  1. The -10 sequence is referred to as the Pribnow box. It interacts with the sigma factor of RNA polymerase.
  2. The -35 sequence -TTGACA is essential for the unwinding of DNA.

Transcription in prokaryotes:

  1. Transcription is a continuous process and occurs in the cytoplasm.
  2. Only one type of RNA polymerase is used to synthesize RNA molecules.
  3. No post-transcriptional modifications occur and the mRNA is devoid of a 5' guanosine cap and a poly A tail.

Transcription in eukaryotes:

  1. Transcription is a separate process and occurs in the nucleus.
  2. Three types of RNA polymerase enzymes are involved in the eukaryotic transcription process.
  3. The mRNA produced has an RNA cap at the 5' end and a poly-A tail at the 3' end.

Transcription in prokaryotes

Transcription in eukaryotes

Transcription is a continuous process and occurs in the cytoplasm.Transcription is a separate process and occurs in the nucleus.
Only one type of RNA polymerase is used to synthesize RNA molecules.Three types of RNA polymerase enzymes are involved in the eukaryotic transcription process.
No post-transcriptional modifications occur and the mRNA is devoid of a 5' guanosine cap and a poly A tail.The mRNA produced has a RNA cap at the 5' end and a poly-A tail at the 3' end.

RNA processing in Bacteria and Eukaryotes :

The major difference in RNA processing between prokaryotes and eukaryotes is the processing of messenger RNAs. Eukaryotes splice mainly protein-coding messenger RNAs and some non-coding RNAs. Transcription occurs in the nucleus and does not occur simultaneously with translation. In prokaryotic cells, transcription takes place in the cytoplasm (in tRNAs and non-coding RNAs) and at the same time as translation.

In bacterial cells, the mRNA can be translated directly as it comes off the DNA template. In eukaryotic cells, RNA synthesis, which occurs in the nucleus, is separated from the protein synthesis machinery, which is in the cytoplasm.

conclusion :
Conclusively, the RNA is as important as DNA in molecular studies as the quantification of the gene expression is depends on the total mRNA present in the particular tissue

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