Mutations and Genetic Code Concepts

This lecture discusses how mutations in coding sequences can be silent or neutral, meaning they do not affect protein function. It explains the redundancy of the genetic code, where multiple codons can specify the same amino acid, allowing for silent mutations. The lecture also covers how some mutations change amino acids without affecting protein function, using examples like the Src protein. The genetic code's representation in tables and diagrams is also discussed.

What is a silent mutation?

• A mutation that always results in a non-functional protein

• A mutation that occurs outside of coding sequences

• A mutation that does not change the amino acid specified

• A mutation that changes the protein's function

How does the genetic code's redundancy contribute to silent mutations?

• By preventing any changes in the DNA sequence

• By ensuring each amino acid is specified by a unique codon

• By making all mutations result in a change of function

• By allowing multiple codons to specify the same amino acid

What is the primary reason most mutations in coding sequences are neutral?

• They are corrected by the cell's repair mechanisms

• They occur in non-coding regions

• They change the amino acid but not the protein's function

• They always result in a silent mutation

In the context of genetic coding, what does 'redundant' mean?

• Having more codons than necessary for amino acids

• Having fewer codons than necessary for amino acids

• Each codon specifies multiple amino acids

• Each amino acid is specified by a single codon

What happens when a mutation changes a codon from GAC to GAU?

• The mutation is corrected by the cell

• The protein becomes non-functional

• The amino acid remains as aspartate

• The amino acid changes from aspartate to alanine

What was the main finding of the Src protein study?

• No mutations in Src protein change its function

• All mutations in Src protein change its function

• Mutations in Src protein always enhance its function

• Some mutations in Src protein change its function, while others do not

What do red dots represent in the Src protein study?

• Positions where mutations reduce or change function

• Positions where mutations enhance function

• Positions where mutations do not affect function

• Positions where no mutations were tested

What is a neutral mutation?

• A mutation that always results in a non-functional protein

• A mutation that changes the protein function significantly

• A mutation that occurs only in non-coding regions

• A mutation that changes the DNA sequence but not the protein function

What is the significance of the third position in a codon?

• It is not involved in specifying amino acids

• It determines the start of the protein sequence

• It is the most flexible and often allows for silent mutations

• It always results in a change of amino acid

What topic will be covered next after this lecture?

• The role of introns in genetic coding

• The evolution of the genetic code

• The impact of frame shift mutations

• The process of DNA replication