Features Of Genetic Code Flashcards
What 3 features does genetic code have?
Its degenerate, universal and non-overlapping.
What is the start codon?
The 3 bases at the start of every gene.
What are the start codons in DNA and mRNA?
TAC and AUG.
What is the function of the start codon?
It initiates translation and codes for the amino acid methionine.
What is the stop codon?
The final triplet of bases in DNA that signals a halt to protein synthesis.
What is the function of the stop codon?
To mark the end of a polypeptide chain, causing the ribosomes to detach and stop translation.
How many amino acids does the genetic code have to be able to code for?
20
How many bases are needed to make enough combinations to code for at least 20 amino acids in DNA?
3 bases.
How many combinations is 4^3?
64
What does degenerate mean in genetic code?
Each of the 20 amino acids are coded for by more than one triplet of bases (codon).
Why is the genetic code being degenerate an advantage?
If a mutation occurs and a base is changed to another, it could still potentially code for the same amino acid.
What is a silent mutation?
A mutation that has no effect on the final protein.
What does universal mean in genetic code?
The same triplet of bases codes for the same amino acid in all organisms.
Why is genetic code being universal an advantage?
It allows genetic engineering to be possible.
What does non-overlapping mean in genetic code?
Each base is only part of one triplet that codes for one amino acid, it reads as a discrete unit.
Why is genetic code being non-overlapping an advantage?
If a mutation occurs it will only affect one codon and one amino acid, having a small impact on the final protein structure.
What are introns?
Sections of DNA that don’t code for amino acids.
How much of DNA is made of introns?
About 98%.
Where are introns found?
In eukaryotic DNA but not prokaryotic DNA or mRNA.
What happens to introns in mRNA?
They get spliced out.
What are exons?
Sections of DNA that do code for amino acids.
What is a genome?
An organism’s complete set of DNA in one cell.
What is the proteome?
The full range of proteins in one cell.
What is the difference between the genome of the cell and the proteome of the cell?
The genome should never change, whereas the proteome of the cell is constantly changing depending on the proteins currently needed.
What widely varies between organisms?
The genome.
How many base pairs does DNA have?
3 billion.
How many base pairs does bacteria have?
600,000
