The Genetic Code and DNA Mutations Flashcards
What are the components of the Translation Machinery?
Amino Acids
mRNA
tRNA
Ribosomes
Energy Source
Enzyme
Noncatalytic Proteins for initiation, elongation and termination
Start Codon (Nucleotide Sequence ____) codes for _____
__AUG__
__methionine__
How many of the 64 codons code for the 20 standard amino-acids?
61
What are the termination/stop/nonsense codons?
UAA
UAG
UGA
Which tRNA recognizes the initiation AUG?
tRNAi (initiator tRNA)
Base modifications exist between tRNA of initiating AUG and internal AUG
Modification of tRNAi in bacteria and mitochondria
Carries N-Formylated Methionine
What is the Wobble Hypothesis?
tRNA recognizes more than one codon for specific amino acid
Adherence to Watson-Crick rules in Wobble Hypothesis
First two bases follow Watson-Crick rules
Third base is less stringent
Reason for Wobble Hypothesis
Base at 5’-end of anticodon is not as spatially defined as other two bases
Enables nontraditional base-pairing with 3’-base of codon
What are the properties of the genetic code?
Unambiguous
Code is Degenerate
Universal
Without punctuation
Nonoverlapping
What are the types of mutations?
Point Mutation
Trinucleotide Repeat Expansion
Splice Site Mutations
Frame Shift Mutations
What is a Point Mutation?
Changing Single Nucleotide Base
What are the possible outcomes of Point Mutation?
Silent: No change in amino acid
Missense: Change of amino acid
Nonsense: Stop codon
What are the types of Missense Mutations?
Conservative: No change in protein functioning
Non-Conservative: Change in protein functioning
Diseases caused by Missense Mutation
Sickle Cell Anemia
What is a Trinucleotide Repeat Expansion?
Three bases are repeated multiple times
Diseases caused by Splice Site Mutations
Myotonic Dystrophy
What is Frame Shift Mutation?
Insertion/Deletion of one of two nucleotides which alters reading frame
Example of disease caused by Frame Shift Mutation
Cystic Fibrosis Disease (phenyl alanine for functioning of Cl- channels lost)
