Topic 21: Translation Flashcards
Read a genetic code table and describe the roles of the special codons during translation.
Special Codons:
Start Codon: AUG - mRNA begins translation by looking for an AUG group
Stop Codons: UGA, UAA, UAG - stop translation and break apart the covalent bond through a hydrolysis reaction breaking apart the protein and the codon.
Describe how the linear sequence of bases in a messenger RNA corresponds to the primary structure of a polypeptide.
tRNAs recoginzie codons in the mRNA through base pairing of an anticodon and incorportar the corresponding amino acid.
Describe the relationship between the codons in the code table
a) the DNA in the gene that corresponds to the codon
b) the anticodon loop on the tRNA that recognizes the codon.
a)there will be a few mRNA codons that can attach to one amino acid.
We will have U’s instead of A’s due to RNA
b) The anticodon loop interacts with mRNA to allow the correct protein to attach to the 3’end of the tRNA.
Describe what a transfer RNA(tRNA) is and how tRNAs are used during translation.
A tRNA is a transfer RNA that codes for itself. It grows from 5’ to 3’ but it interwinds in a way where they strands make hydrogen bonds across eachother.
A tRNA has an anticodon loop that contains an anticodon fro 3’ to 5’. An mRNA codon can attach to this region and allow the correct amino acid to attach to the 3’ end of the tRNA.
This helps mRNA to translate to proteins.
Describe the properties of ribosomes.
Properties of ribosomes:
Made of protein and rRNA. They coordinate interactions between the mRNA and the tRNAs to build a protein.
Describe how each part of the ribosome is used during translation.
During translation the ribosome as we known has two subunits a large unit and a small unit. The large unit contains the 3 sites: E(exit) site, P(Peptide) site, and A(Aminoacyl) site.
The mRNA is attached between the large subunit and the small subunit.
The E site is exit region where tRNA is available to exit.
The P site is where peptide bonds are made and proteins are synthesized
The A site is where tRNA is accpeted inside the ribosome to attach to the mRNA.
Explain the steps of translation during the ribosome cycle, including the three steps of the elongation cycle and the source of energy.
Translation Steps
Initiation
Elongation
Termination
In the ribosome the **initiation **step: begins in the small subunit where our 5’ to 3’ mRNA attaches and a tRNA attaches to a start codon AUG and the large subunit attaches when 1 GTP is used.
In the **Elongation **step: Now tRNA is located in the P site. Another tRNA enters through the A site attaching next to the 1st tRNA. Peptide bond formation is occuring and 1st tRNA transfers the peptide bonds to the new tRNA. Then a GTP is released and the 1st tRNA is released and the process continues until it reaches a stop codon: UAG, UAA, UGA
In the **Termination **step: A stop codon is reached and promotes a hydrolysis rxn to break the tRNA from the protein. Then 2GTP are used to break all the componenets apart to be used again.
