From Gene to Protein

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by Awroble
Last updated 4 years ago

Discipline:
Science
Subject:
Biology
Grade:
11,12

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From Gene to Protein

From Gene to Protein

-Transcription is the synthesis of RNA under the direction of DNA. Transcription is the general term for the synthesis of any kind of RNA to DNA template. Occurs in the nucleus.

Messenger RNA-Carries genetic messages from the DNA to the protein-synthesizing machinery of the cell.

Ribosomes are the site of translation. They are complex particles that facilitate the orderly linking of amino acids into polypeptide chains.

The noncoding segments of nucleic acid that lie between coding regions are called intervening sequences, or introns. The other regions are called exons, because they are eventually expressed, usually by being translated into amino acid sequences.

-Translation is the synthesis of a polypeptide, which occurs under the direction of mRNA-Translation Begins After the Assembly of a Complex Structure

The template strand, provides a template for ordering the sequence of complementary nucleotides in an RNA transcriptThe template strand is always the same strand for a given gene

One of the DNA strands

Promoter Gene-Includes within it the transcription start point-Bindind site for the RNA polymerase-Determines where transcription starts-Determines which strand of DNA will be used as the template

In Eukaryotes, a collection of proteins called transcription factors mediate the binding of RNA polymerase and the inition of transcription. The whole complex of transcription factors and RNA polumerase II bound to the promoter is called a transcription initiation complex. A crucial promoter DNA sequence is called a TATA box.

ElongationThe polymerase moves downstream, unwinding the DNA and elongating the RNA transcript 5'-3'

TerminationThe RNA transcript is released and he polymerase detaches from the DNA.

Catalyzed by RNA polymerse which unwinds the DNA strands and then attaches the RNA nucleotides

RNA synthesis

5' cap: a modified form of a guanine nucleotide added onto the 5' end after transcription of the first 20-40 nucleotides

At the 3' end, an enzyme adds 50 to 250 more adenine (A) nucleotides forming a poly-A-tail. Also known as 3' tail

P site: holds the tRNA that carriest the growing polypeptide chainA site: holds the tRNA that carries the next amino acid to be added to the chainE site: is the exit site where discharge tRNAs leave the ribosome

In the elongation stage of translation, amino acids are added one by one to the proceding amino acid

Wanna learn about mutations? Watch this Video!

The nucleotide sequence of the mRNA is composed of four different nucleotides whereas a protein is built up from 20 amino acids. To allow the four nucleotides to specify 20 different amino acids, the nucleotide sequence is interpreted in codons, groups of three nucleotides. These codons have their corresponding anticodon in the tRNA. Furthermore each anticodon is linked to one particular amino acid. Thus, each codon specifies one amino acid. This is referred to as the genetic code.

The message is a series of codons along an mRNA molecule, and the interpreter is called Transfer RNA (tRNA). The function of tRNA is to transfer amino acids from the cytplasmic pool of amino acids to a ribosome. tRNA molecules are not identical. At one end of the tRNA is an amino acid, and at the other end is an anticodon. An anticodon base-pairs with a complementary codon on mRNA. A codon are the mRNA base triplets. the tRNA colecule is a translator because it can read a nucleic acid word (the mRNA codon) and interpret it as a protein word (the amino acid).


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