Translation Flashcards
mechanism of protein synthesis, via a process in which the four-letter alphabet of nucleic acids is translated into the entirely different ____alphabet of proteins.
twenty-letter
transcribed to mRNA which is translated into protein with the help of
ribosomes
They transfer amino acids from cytoplasm to the ribosomal protein synthesizing machinery;
Since they are easily soluble, they are also referred to as soluble RNA or sRNA.
tRNA are present in
They are much shorter than mRNA molecules. each molecule is only ___ to___ nucleotides in length;
RNA molecules present in the cytoplasm.
73-93
When transcribed, the tRNA molecules are large and they undergo post-transcriptional
modifications.
The transfer RNAs show ______ base pairing and acquire clover leaf like structure
extensive internal
Features of trna
Considerably shorter than mRNA
Extensive internal base pairing, clover like structure
Under goes post-trancription
Contains plenty unusual base pairing like hypoxanthine, dihydrouracil, pseudoyridine
Moreover many bases are methylated.
Acceptor Arm is at the __’ end and it carries the
3
amino acid
This area has ___ base pairs and the end sequence is ‘.
tRNA
@ acceptor arm
7
CCA-3
The 3’ end hydroxyl group is forming an ester bond with the ___
@ acceptor arm
carboxyl end of amino acids
There are 64 possible combination of nitrogenous base
61 of 74 code for amino acids AUG = methionine
Remaining 3 doesn’t code dey stop d translation process
UGA
UAA
UAG
Anticodon complementary triplets of codon
@ anticodon arm of tRNA
Function
recognizes the triplet nucleotide codon present in mRNA
The specificity of tRNA resides in the _____ site,
anticodon
which has base sequences complementary to that of mRNA codon
For example, if the mRNA has a codon with the sequence UUU, the anticodon sequence of thetRNA will be_______
In this case, the UUU codon is translated as ____
AAA, by which it base pairs with mRNA codon.
So the specific tRNA can bind correctly to the mRNA codons.
phenylalanine
The tRNA molecule will show specificity in both aspects; in recognizing the mRNA codon as well as in accepting the specific amino acid coded by that codon.
The tRNAs act as _______molecules between mRNA and the amino acids coded by it.
adapter
Do nucleotides of codons have affinity for amino acids.
NO
So the tRNA molecules act as mediator between the mRNA and amino acids
The D arm or DHU region is so named due to the presence of ____
dihydro uridine in that area
____ arm serves as the recognition site for the enzyme which adds the amino acid.
The DHU
The opposite arm is called pseudouridine arm, as it contains a pseudouridine.
It is generally denoted with the Greek alphabet “ψ”
It is involved in binding tRNA to ribosomes.
ribosomal assembly is the protein synthesizing machinery
rRNA
rRNA
______ is the area where rRNA is synthesized and ribosomal assembly is produced.
Nucleolus
Components of rRNA
Components of rRNA
mammalian ribosome has a sedimentation velocity of 80S unit
It has a larger 60S subunit and another smaller 40S subunit.
They contain different rRNAs and specific proteins.
Ribosomal RNA has catalytic activity.
Peptidyl transferase activity is carried out by ___ RNA which acts as a ribozyme.
28S
Bacterial Ribosomes are Different
T or F
How?
Bacterial ribosomes are smaller than mammalian ones
Bacteria has 70S ribosomes; with 30S and 50S subunit
The rRNA is also synthesized as a 45S precursor which is cleaved to 28S, 18S, 5.8S and 5S
rRNAs.
The large ribosomal subunit has 28S, 5.8S and 5S rRNA and small ribosomal subunit has only
18S rRNA.
Genetic Code
A triplet sequence of nucleotides on the mRNA is the codon for each amino acid.
What are the features of genetic code
Triplets code
Code is on mRNA
Each code is a conservative sequence of 3 bases on mRNA
The codes are non overlaping
They are consecutive I.e the starting point is very important
codes are read one after another in a continuous manner,
Nonpunctuated
There is no punctuation between the codons.
It is consecutive or continuous.
E. G
AUG, CAU, GAU, GCA
There are 61 codes stand for the _____ amino acids.
20
So one amino acid has more than one codon.
For example, serine has __ codons; while glycine has ___ codons
This is called ______
6
4
degeneracy of the code.
Generally speaking, if the amino acid has more than one codon, what will happen
the first two bases in the codon will be the same
It is only the third one that is different and this reduces the effect of mutations
Amino acids such as_____ , ____&____ are specified by six codons each
leucine,arginine, and serine
The number of codons for a particular amino acid correlates with its frequency of occurrence in proteins