Gene Changes Affect Proteins - Middle School Life Science

1. What is a nonsense mutation's effect on the protein sequence?

   A premature stop codon causes an early, shorter protein. Creates UAA, UAG, or UGA codons that terminate translation.

2. What is the most direct way a gene change can alter protein function?

   By changing the amino acid sequence and thus the protein's shape. Different amino acids fold differently, altering protein function.

3. What is transcription?

   Copying a genes DNA sequence into mRNA. RNA polymerase reads DNA and builds a complementary RNA strand.

4. Which mutation type adds extra nucleotide(s) into a gene sequence?

   Insertion. Adds bases between existing nucleotides in the sequence.

5. What is a frameshift mutation?

   An insertion or deletion that shifts the codon reading frame. Non-multiple-of-3 changes shift how codons are read downstream.

6. Identify the most likely outcome of a frameshift early in a gene.

   Many downstream amino acids change; protein often becomes nonfunctional. Shifting the reading frame scrambles all codons after the mutation.

7. What is a frameshift mutation?

   An insertion or deletion that shifts the mRNA reading frame. Changes how codons group, altering all downstream amino acids.

8. What is the relationship between amino acid order and protein shape?

   Amino acid sequence determines folding, and folding determines shape. The sequence creates the 3D structure needed for protein function.

9. What is an allele, and how can different alleles affect proteins?

   Different versions of a gene that can produce different proteins. Alleles are gene variants; different sequences make different proteins.

10. What is the central dogma pathway from gene to protein?

    DNA is transcribed to mRNA, and mRNA is translated to protein. Information flows from DNA through RNA to make proteins.

11. What is a silent mutation's effect on the protein sequence?

    No amino acid change in the protein. Different codon still codes for the same amino acid.

12. What does a mutation mean in a gene?

    A change in the DNA nucleotide sequence. Alters the genetic code that determines protein structure.

13. Identify the best model to show how a premature stop affects a protein.

    A shortened amino acid chain ending early at a stop codon. Shows how stop codons truncate proteins, losing functional domains.

14. Identify the mutation type: one or more DNA bases are removed from a gene.

    Deletion. Missing bases shift the reading frame, altering all following codons.

15. What is a silent mutation?

    A DNA change that does not change the amino acid sequence. Multiple codons can code for the same amino acid due to redundancy.

16. What does it mean when a protein loses function after a mutation?

    The altered amino acid sequence changed folding or the active site. Mutations disrupted the 3D structure required for proper function.

17. Which mutation type changes one DNA base to another base?

    Substitution (point mutation). Replaces one nucleotide with a different nucleotide.

18. Identify the mutation type: adding 1 nucleotide shifts all later codons.

    Frameshift mutation (insertion). Single base addition disrupts triplet reading pattern.

19. Which mutation type is most likely to leave a protein unchanged in function?

    Silent mutation. The amino acid sequence remains identical despite the DNA change.

20. What is translation?

    Using mRNA codons to assemble amino acids into a polypeptide. Ribosomes read mRNA triplets to build protein chains.

21. Which model best shows how a substitution can change a protein?

    Codon chart mapping changed codon to a different amino acid. Shows how changing one base changes the codon and its amino acid.

22. What is a gene in the context of protein production?

    A DNA segment that codes for a specific protein or RNA. Genes contain instructions that cells use to build specific molecules.

23. What is transcription?

    Making an mRNA copy of a gene's DNA sequence. RNA polymerase reads DNA to create messenger RNA.

24. Identify the mutation type: a base change creates a stop codon in the mRNA.

    Nonsense mutation. UAA, UAG, or UGA replaces a normal codon, ending translation early.

25. What is translation?

    Using mRNA codons to assemble a chain of amino acids. Ribosomes read mRNA triplets and link matching amino acids together.

26. Identify the mutation type: one DNA base is replaced by another base.

    Substitution (point mutation). One base swaps for another, potentially changing one amino acid.

27. Identify the mutation type: one or more DNA bases are added to a gene.

    Insertion. Extra bases shift all downstream codons, often disrupting the protein.

28. Which mutation type removes nucleotide(s) from a gene sequence?

    Deletion. Removes bases from the original DNA sequence.

29. What is a missense mutation's effect on the protein sequence?

    One amino acid is changed to a different amino acid. Codon change results in a different amino acid substitution.

30. What is the correct flow of information in the central dogma?

    DNA rightarrow RNA rightarrow protein. Information flows from genetic material to RNA to functional proteins.

31. What is a missense mutation?

    A DNA change that substitutes one amino acid for another. The new codon specifies a different amino acid than the original.

32. What is a mutation?

    A change in the DNA nucleotide sequence. Mutations alter the genetic code, potentially changing protein structure.

33. What is a nonsense mutation?

    A DNA change that creates a premature stop codon. The mutated codon becomes UAA, UAG, or UGA, ending translation early.

34. What is a gene in the context of making proteins?

    A DNA sequence that codes for a protein or functional RNA. Contains instructions for building specific proteins or RNAs.

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