Question

(1)which is the initiation codon? and where is it present
(2)what are the types of RNA present inside the ribosome which triplet codent is present on it
(3)which genetic code is present on mRNA that is leaving the nucleus what must be the sequence on the DNA to have such code on mRNA​

Answer 1

Answer:

The genetic code

How is the information in an mRNA sequence decoded to make a polypeptide? Learn how groups of three nucleotides, called codons, specify amino acids (as well as start and stop signals for translation).

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Introduction

Have you ever written a secret message to one of your friends? If so, you may have used some kind of code to keep the message hidden. For instance, you may have replaced the letters of the word with numbers or symbols, following a particular set of rules. In order for your friend on the other end to understand the message, he or she would need to know the code and apply the same set of rules, in reverse, to figure out what you had written.

As it turns out, decoding messages is also a key step in gene expression, the process in which information from a gene is used to construct a protein (or other functional product). How are the instructions for building a protein encoded in DNA, and how are they deciphered by the cell? In this article, we'll take a closer look at the genetic code, which allows DNA and RNA nucleotide sequences to be translated into the amino acids they represent.

Overview: Gene expression and the genetic code

Genes that provide instructions for proteins are expressed in a two-step process.

In transcription, the DNA sequence of a gene is "rewritten" using RNA nucleotides. In eukaryotes, the RNA must go through additional processing steps to become a messenger RNA, or mRNA.

In translation, the sequence of nucleotides in the mRNA is "translated" into a sequence of amino acids in a polypeptide (protein or protein subunit).

Cells decode mRNAs by reading their nucleotides in groups of three, called codons. Each codon specifies a particular amino acid, or, in some cases, provides a "stop" signal that ends translation. In addition, the codon AUG has a special role, serving as the start codon where translation begins. The complete set of correspondences between codons and amino acids (or stop signals) is known as the genetic code.

Codon table