Introns interrupt exons, the protein coding parts of genes.
The Genetic Code & Protein Synthesis Flashcards | Quizlet
These rearrangement of physical location of DNA strands affects number, location, and sequence of genes coding for proteins and RNA and thus are vital for generating mutations important for evolutionary fitness of an organism.
[triplet code: the genetic code ..
The human genome has been found to contain only 5% coding sequences (genes that make proteins), while half of all non-coding portions are made of transposable elements reminiscent of viral DNA.
Part Three: Gene Expression and Protein Synthesis
Har Gobind Khorana, at the University of Wisconsin, adapted Nirenberg's experimental system, and confirmed and extended his work. Nirenberg and Khorana were awarded the 1968 Nobel Prize in Physiology or Medicine, shared with Robert W. Holley, "for their interpretation of the genetic code and its function in protein synthesis."
Gene Expression and Protein Synthesis
This code determines the type of amino acids and the order in which they are joined together to make a specific protein. The sequence of amino acids in a protein determines its structure and function.
Gene Expression - Proteins & Protein Synthesis
shows the genetic code of the messenger ribonucleic acid (mRNA), i.e. it shows all 64 possible combinations of codons composed of three nucleotide bases (tri-nucleotide units) that specify amino acids during protein assembling.
Each codon of the deoxyribonucleic acid (DNA) codes for or specifies a single amino acid and each nucleotide unit consists of a phosphate, deoxyribose sugar and one of the 4 nitrogenous nucleotide bases, adenine (A), guanine (G), cytosine (C) and thymine (T). The bases are paired and joined together by hydrogen bonds in the double helix of the DNA. mRNA corresponds to DNA (i.e. the sequence of nucleotides is the same in both chains) except that in RNA, thymine (T) is replaced by uracil (U), and the deoxyribose is substituted by ribose.
The process of translation of genetic information into the assembling of a protein requires first mRNA, which is read 5' to 3' (exactly as DNA), and then transfer ribonucleic acid (tRNA), which is read 3' to 5'. tRNA is the taxi that translates the information on the ribosome into an amino acid chain or polypeptide.
For mRNA there are 43 = 64 different nucleotide combinations possible with a triplet codon of three nucleotides. All 64 possible combinations are shown in . However, not all 64 codons of the genetic code specify a single amino acid during translation. The reason is that in humans only 20 amino acids (except selenocysteine) are involved in translation. Therefore, one amino acid can be encoded by more than one mRNA codon-triplet. Arginine and leucine are encoded by 6 triplets, isoleucine by 3, methionine and tryptophan by 1, and all other amino acids by 4 or 2 codons. The redundant codons are typically different at the 3rd base. shows the inverse codon assignment, i.e. which codon specifies which of the 20 standard amino acids involved in translation.