Introduction to Molecular Biology 4 Lecture Flashcards
07/11/24
How is DNA converted into usable form?
Replication, Transcription, Translation
How many bases code for 1 amino acid?
3
What does it mean if the genetic code is degenerate?
Each amino acid can be coded for by multiple codons/triplets.
What is the consequence of an insertion/deletion mutation?
Frameshift of bases
How can a substitution mutation have no effect?
The genetic code is degenerate so a change in one base may lead to the triplet coding for the same amino acid, this is known as a silent mutation.
What makes a mutation different from a polymorphism?
A mutation leads to a change in phenotype.
A polymorphism is more common and does not affect gene function, and does not contribute to disease.
What marks the starting point of translation?
The “initiation codon”
What marks the end of translation?
The “stop codon”
What is the role of tRNA?
The anticodon on tRNA binds to its complementary codon on the mRNA and brings the respective amino acids to form peptide bonds and begin a polypeptide chain.
What is aminoacyl-tRNA synthetases?
There are 20 different aminoacyl-tRNA synthetases, each one recognises only one amino acid and all its compatible tRNAs. Binds tRNA to amino acids by an esterification reaction.
What make up ribosomes?
Large and small rRNAs are found in the large and small ribosomal units.
How many binding sites does a ribosome have?
The small unit has 1 for mRNA and the large unit has 3: E, P and A for tRNA molecules.
What is initiation?
Ribosomes bind to mRNA and scan through 5’ non-coding region for the initiation codon. Requires initiation codon.
What is elongation?
Correct charged tRNAs bind and a peptide bond forms between amino acids. Once the peptide bond forms, the ribosome moves along the mRNA one codon, and the deacylated tRNA exits the complex and a new charged tRNA binds.
What is termination?
When the termination codon is encountered at the end of the open reading frame, the finished protein is released. This requires termination factors and the whole complex dissociates.
