Module 4 - RNA and protein synthesis Flashcards
What is mRNA?
It carries the genetic code from DNA to ribosomes to make a protein. mRNA contain triplets of DNA bases called codons
What is tRNA?
tRNA carries the amino acids used to make proteins. It has an anticodon on one end if the molecule which is use to bind to the mRNA during translation
What is made during transcription?
mRNA
How does transcription differ in prokaryotes compared with eukaroytes?
In eukaryotes, pre-mRNA is made which is then spliced to remove the introns to leave the exons which code for the amino acids. In prokaryotes, mRNA is made straight from the DNA
Describe simply how transcription takes place.
DNA Helicase breaks the hydrogen bonds between DNA bases. One of the strands acts as a template. RNA nucleotides align according to base pairings. Adenine joins uracil (replacing thymine). RNA polymerase joins adjacent RNA nucleotides by phosphodiester bonds via condensation reaction. pre MRNA spliced to remove introns. mRNA leaves nucleus.
What is made in translation?
Polypeptides
Describe briefly how translation works?
mRNA attaches to ribosomes. tRNA anticodon is complementary to mRNA codon. tRNA brings a specific amino acid to the ribosome. If anticdon & codon is complementary, amino acid joins a polympeptide chain forming peptide bonds using ATP. Ribosome moves along the mRNA/ there are 2 spaces available for 2 tRNA molecules at any time.
What is the difference between a codon and an anticodon?
A codon is on an mRNA molecule and consists of a triplet of a DNA sequence. An anticodon is on a tRNA molecule and consists of a triplet of a DNA sequence.
What 3 characteristics does the genetic code have?
Non-overlapping, degenerate and universal
What are start and stop codons?
These are base triplets that code for amino acid that signals when the production of a protein/polypeptide should start or stop.
What is something that must be looked out for when coding for a DNA sequence for the mRNA codon?
When there is a uracil base in a codon, it must be an A in the DNA sequence. This rule works vice versa
What is something that must be looked out for when coding for a tRNA anticodon from an mRNA codon?
Nothing because they are both RNA molecules so they are completely complementary.
If a drug meant that protein and mRNA concentration was lower than usual, what does the drug do?
Drug 1 affects the full production of the full length of mRNA
If a drug meant that mRNA production was higher than protein production, what does the drug do?
This means that the drug inhibits translation because mRNA production has already taken place in transcription but protein production hasn’t which occurs during translation
