Topic 4A - DNA, RNA and Protein Synthesis Flashcards
What is a gene?
A sequence of DNA bases that coded for either a polypeptide or functional RNA
What is a cell’s genome?
The complete set of genes in a cell
How many DNA bases code for one amino acid?
3
What is a cell’s proteome?
The full range of proteins the cell can produce
Name 2 types of non-coding DNA
Introns and multiple repeats
Name the sections within genes that code for amino acids
Exons
What is an allele?
A different form of a gene
Alleles for the same characteristic can be found at a particular fixed point on a chromosome. What is the name given to this fixed point?
A locus
What role does mRNA play in protein synthesis?
Carries the genetic code from the DNA to the ribosomes
What is an mRNA codon?
A group of 3 adjacent bases on an mRNA molecule
what does mRNA stand for?
Messenger RNA
What does tRNA stand for?
Transfer RNA
Name two stages of protein synthesis and state where each one takes place in eukaryotes
Transcription - takes place in the nucleus
Translation - takes place at the ribosomes in the cytoplasm
What is RNA polymerase and in which stage of protein synthesis is it involved?
An enzyme, transcription
Why is the mRNA that’s produced from a DNA template always a complementary copy of the DNA?
Because of complementary base parings
Explain why eukaryotic mRNA gets spliced
Eukaryotic DNA contains introns that don’t code for amino acids. These get transcribed into pre-mRNA along with the exons. Splicing removes the introns from pre-mRNA and joins together the expand to create mRNA ready for translation into a protein.
Why does prokaryotic mRNA not undergo splicing?
It doesn’t contains introns
What is a mis-sense mutation?
A base change results in a different amino acid being coded for; the significance depends on the importance of the original amino acid
What is a non-sense mutation?
A base change results in a stop codon, signalling the end of the polypeptide chain. This causes a significant difference from the original chain and it will not perform normally
What is a silent mutation?
A base change results in the same amino acid being coded for, due to degenerate nature of the DNA code. No change in polypeptide chain so no effect
What is a deletion mutation?
A base is completely deleted. This causes a “frame shift” - this completely changes the set of amino acids
Describe the function of tRNA
Carry amino acids to the ribosome during translation
