lesson 6 translation

Question 1

what is translation

Answer 1

translation is the second stage of gene expression
it involves trnaslating the nucleic acid code of mrna into the amino acid code of a protein
occurs in cytoplasm

Question 2

what are the major components in trnaslation

Answer 2

mRNA: contains genetic info that determiens the amino acid sequence of a protein
tRNA: contains an anticodon that base paris with a codon on the mRNA and has the corresponding amino acid attached to it, according oto the genetic code
Ribosomes: composed of rRNA and proteins, involved in the process of protein synthesis
Translation factors: protein that act as accessory factors, needed at the end of translation

Question 3

transfer rna function

Answer 3

each tRNA molecule has two functional regions:
the anticodon loop which is a sequence of three nucleotides that is complementary to an mRNA codon
- the acceptor stem: a single stranded region where an amino acid is attached
the aminoacyl-trna synthease enzzyme attch to the correct aa to a tRNA
amino acids can be coded for by more than one codon and the only diff is the third base of the codon

Question 4

ribosomes structure

Answer 4

made up of one large subunit
contains binding sites one for mRNA and tRNA
the binding sites allow complemntary base pairing between tRNA anticodons and mRNA codons

Question 5

ribsomes function

Answer 5

Provide a place where the mrna, trnas that carry the amino acid molecules and translation factors involved in protein synthesis can assemble and interact

Question 6

what are the events in translation

Answer 6

TRANSLATION IS THE MOST ENERGY CONSUMING PROCESSES OF THE CELL
1. INITIATION
2. ELONGAITON
3. TERMINATION

Question 7

what undergoes in initation

Answer 7

initiation factors, mRNA, tRNA and ribosomes assmeble..
the small ribosomal subunit attaches to the mRNA near the start codon
- the initiation tRNA with the anticodon UAC bind to the start codon
- the large ribosomal subunit attaches to form an active ribosome
the start codon sets the reading frame for the gene
the reading frame establishes how subsequent codons of the mRNA will be read to produce an amino acid
– there are 3 biding sites for tRNA
– P site: contains the tRNA that carries the growing polypeptide
– A site: holds the tRNA with the next aa
– E site: the tRNA that no longer has an aa attached to it is ejeted

Question 8

elongation

Answer 8

protein synthesis occurs during elongation
- one aa is added at a time to the growing polypeptide chain
- elongation factors join to facilitate the growth of the polypeptide
- amino acids are joiend by peptide bonds

Question 9

termination

Answer 9

• begins when a stop codon on the mRNA is reached
• the polypeptide and the translation amchinery are seperated when a protein called a release factor cleaves the polypeptide from the last tRNA.
  the polypeptide is released and can fold into its 3-d shape to carry out cellular functions

Question 10

levels of protein organization

Answer 10

primary: linear sequence of amino acids
secondary: hydrogen bondings contributes to alpha helix or beta pleated structures
- tertiary: further folding based on hydrophobic and hydrophillic interactions
- quaternary: proteins composed of more than one polypeptide