Mutations and Their Effects on Proteins

Mutations are changes in the DNA sequence that can affect protein structure and function. They can lead to diseases like sickle cell anemia. Common mutations include base substitutions, silent mutations, and premature stop codons. Base substitutions involve swapping one base for another, potentially altering protein function. Silent mutations do not affect protein sequences due to genetic code redundancy. Premature stop codons result in incomplete, non-functional proteins, leading to health issues.

What is the primary consequence of a mutation in the DNA base sequence?

• It always leads to a disease.

• It has no effect on the organism.

• It only affects the organism's appearance.

• It changes the mRNA sequence, which may alter the protein sequence.

Which of the following is NOT a type of mutation discussed?

• Premature stop codon

• Base substitution mutation

• Silent mutation

• Frame shift mutation

What is the role of tRNA in protein synthesis?

• It forms the ribosome structure.

• It transcribes DNA into mRNA.

• It degrades mRNA after translation.

• It carries amino acids to the ribosome.

In a base substitution mutation, what happens at the molecular level?

• A base is added to the DNA sequence.

• A base is deleted from the DNA sequence.

• One base is exchanged for another in the DNA sequence.

• The entire DNA sequence is reversed.

What happens when a base substitution mutation changes a codon to CAA?

• The codon is deleted.

• The amino acid arginine is replaced by glutamine.

• The protein becomes longer.

• The protein becomes non-functional.

What is the effect of substituting a G for an A in the third base of codon 129?

• It causes the protein to be non-functional.

• It creates a new protein.

• It results in a silent mutation with no change in the protein.

• It changes the amino acid sequence.

What is a silent mutation?

• A mutation that stops protein synthesis.

• A mutation that has no effect on the protein sequence.

• A mutation that deletes a base pair.

• A mutation that changes the protein sequence.

What is the result of a premature stop codon in a gene?

• A non-functional protein is produced.

• A longer protein is produced.

• The gene is deleted.

• The protein is unaffected.

Which codon is NOT a stop codon?

• CGA

• UGA

• UAG

• UAA

How does a premature stop codon affect protein synthesis?

• It enhances the protein's function.

• It results in an abnormally short and non-functional protein.

• It has no effect on the protein.

• It causes the protein to be synthesized longer than usual.