Question

translation Key Terms 

Term 

 Translation

 Triplet code

 Codon

 Template strand

 start codon

 stop codon

 TRNA

 Anticodon

 Aminoacyl-tRNA synthetase

 Ribosomal subunits

 RNA

 A site

 P site

 E site

 Initiation

 Elongation

 Termination

 Direction of translation

 Free ribosomes vs. bound ribosomes

 Polyribosome

Answer 1

1) Translation :-

It is a mechanism by which the triplet base sequence of an mRNA guides the linking of a specific sequence of amino acids to form a polypeptide (protein) on ribosomes.All the proteins a ceel needs are synthesized by the cell within itself.

2) Triplet Code:-

In DNA or mRNA, the sequence of three nucleotides that is the code for a particular amino acid.

The triplet sequence controls the amino acid sequence during protein synthesis.

3) Codon :-

A base Triplet on mRNA chain.

4) Template Strand :-

The noncoding strand of a DNA molecule that is used as a template for RNA synthesis.

5) Start codon :- It is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and a modified Met (fMet) in prokaryotes. The most common start codon is AUG. The start codon is often preceded by a 5' untranslated region (5' UTR).

6) Stop codon :- They are sequences of DNA and RNA that are needed to stop translation or the making of proteins by stringing amino acids together. There are three RNA stop codons: UAG, UAA, and UGA. In DNA, the uracil (U) is replaced by thymine (T).

7) tRNA :- Transfer ribonucleic acid (tRNA) is a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. tRNAs function at specific sites in the ribosome during translation, which is a process that synthesizes a protein from an mRNA molecule.

8) Anticodon :- A base triplet at the recognition end of tRNA molecule.

9) Aminoacyl-tRNA synthetase :- It also called tRNA-ligase, is an enzyme that attaches the appropriate amino acid onto its tRNA. It does so by catalyzing the esterification of a specific cognate amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA.

10) Ribosomal subunits :- Ribosomes are large nucleoprotein particles, and consist of two subunits, denoted small (or 30S) and large (or 50S) in bacteria. They have a mass of about 2.5 MDa, and are about 2/3 RNA by mass.

11) rRNA :- Also known as Ribosomal ribonucleic acid (rRNA) .It is the RNA component of the ribosome, and is essential for protein synthesis in all living organisms. It constitutes the predominant material within the ribosome, which is approximately 60% rRNA and 40% protein by weight, or 3/5 of ribosome mass. Ribosomes contain two major rRNAs and 50 or more proteins.

12) A Site :- The A site (acceptor site), binds to the aminoacyl tRNA, which holds the new amino acid to be added to the polypeptide chain.

13) P Site :- The P site, called the peptidyl site, binds to the tRNA holding the growing polypeptide chain of amino acids.

14 ) E Site :- The E site (exite site), serves as a threshold, the final transitory step before a tRNA now bereft of its amino acid is let go by the ribosome.

15) Initiation :- ("beginning") in this stage, the ribosome gets together with the mRNA and the first tRNA so translation can begin.

16) Elongation :- ("middle") in this stage, amino acids are brought to the ribosome by tRNAs and linked together to form a chain.

17) Termination :- ("end") in the last stage, the finished polypeptide is released to go and do its job in the cell.

18) Direction of Translation :- translation begins at the 5' end of the mRNA while the 3' end is still attached to DNA.

19) Free ribosomes vs bound ribosomes :- Free ribosomes are located in the cytoplasm, and the bound ribosomes are attached to the endoplasmic reticulum. Free ribosomes produce proteins for the cell, while bound ribosomes produce proteins that are transported out of the cell.

20) Polyribosome:- A cluster of ribosomes connected with messenger RNA; they play a role in peptide synthesis.

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