All flashcards
Flashcard 1: Which option best explains a beneficial mutation: it improves a trait that increases survival or reproduction?
Answer: It increases survival or reproduction. Enhanced traits give organisms advantages in their environment.
Flashcard 2: Identify the most likely outcome of an early stop codon: longer protein, shorter protein, or no protein?
Answer: Shorter protein. Stop codons end translation before the protein is complete.
Flashcard 3: Which type of mutation usually has the least effect on protein function: silent, missense, or frameshift?
Answer: Silent mutation. It doesn't change the amino acid, preserving protein function.
Flashcard 4: What is the main reason the same mutation can be beneficial in one environment but harmful in another?
Answer: Fitness depends on the environment. What helps in one environment may harm in another.
Flashcard 5: Which type of mutation is most likely to cause a large change in a protein: frameshift or silent?
Answer: Frameshift mutation. It alters all downstream codons, changing many amino acids.
Flashcard 6: What type of mutation adds one or more nucleotides to a DNA sequence?
Answer: Insertion mutation. Extra nucleotides are added into the sequence.
Flashcard 7: What is one reason the same mutation can be beneficial in one environment but harmful in another?
Answer: Fitness depends on the environment. What helps in one setting may harm in another.
Flashcard 8: Which cells must be mutated for the mutation to be inherited: somatic cells or gametes?
Answer: Gametes (sex cells). Only mutations in reproductive cells pass to offspring.
Flashcard 9: What is a gene mutation?
Answer: A change in the DNA sequence of a gene. Mutations alter the genetic instructions coded in DNA.
Flashcard 10: What is the most direct way a gene mutation can change an organism’s traits?
Answer: By changing the protein made from the gene. Genes code for proteins, which determine traits.
Flashcard 11: Which category describes a mutation that increases survival or reproduction in an environment?
Answer: Beneficial (positive) mutation. Helps organisms better adapt to their environment.
Flashcard 12: Which category describes a mutation that decreases survival or reproduction in an environment?
Answer: Harmful (negative) mutation. Reduces fitness and reproductive success.
Flashcard 13: Which category describes a mutation that does not change an organism’s phenotype?
Answer: Neutral mutation. No observable change in traits or function.
Flashcard 14: What type of mutation removes one or more nucleotides from a DNA sequence?
Answer: Deletion mutation. Nucleotides are lost from the sequence.
Flashcard 15: Identify the effect category: a mutation causes a nonfunctional protein that disrupts a key body process.
Answer: Harmful (negative) mutation. Loss of protein function impairs organism survival.
Flashcard 16: Identify the effect category: a mutation changes DNA but the protein and trait stay the same.
Answer: Neutral (no effect on phenotype). Redundant genetic code prevents functional change.
Flashcard 17: Which type of cell mutation affects only the individual and is not passed to offspring?
Answer: Somatic cell mutation. Body cell mutations die with the organism.
Flashcard 18: Identify the effect category: a mutation increases resistance to a disease common in the environment.
Answer: Beneficial (positive) mutation. Confers survival advantage against environmental threat.
Flashcard 19: What is the direct effect of a missense mutation on a protein?
Answer: It changes one amino acid in the protein. The new codon codes for a different amino acid.
Flashcard 20: What term describes a mutation that has no effect on the organism’s phenotype?
Answer: Neutral mutation. These mutations don't alter the organism's observable traits.
Flashcard 21: What is a silent mutation?
Answer: A DNA change that does not change the amino acid. Multiple codons can code for the same amino acid.
Flashcard 22: Which option best explains why many mutations have no effect: they occur in coding DNA or noncoding DNA?
Answer: Noncoding DNA. Most DNA doesn't code for proteins, so changes there have no effect.
Flashcard 23: What term describes a mutation that increases an organism’s fitness in a given environment?
Answer: Beneficial mutation. These mutations improve survival or reproductive success.
Flashcard 24: What term describes a mutation that decreases an organism’s fitness or survival?
Answer: Harmful (deleterious) mutation. These mutations reduce the organism's ability to survive and reproduce.
Flashcard 25: Which option is most likely neutral: a mutation in an intron or a mutation that adds an early stop codon?
Answer: A mutation in an intron. Introns are removed during RNA processing, not affecting proteins.
Flashcard 26: Identify the molecule whose sequence is changed by a gene mutation: DNA, lipid, or carbohydrate?
Answer: DNA. Gene mutations specifically alter DNA nucleotide sequences.
Flashcard 27: What is the direct effect of a nonsense mutation on a protein?
Answer: It creates an early stop codon, shortening the protein. Stop codons terminate protein synthesis prematurely.
Flashcard 28: What is a frameshift mutation?
Answer: An insertion or deletion that shifts the reading frame. Adding/removing bases changes how codons are read in groups of three.
Flashcard 29: Which option best explains why some mutations are not noticed: they are recessive and masked by a normal allele?
Answer: They are recessive and masked by a normal allele. One functional copy can compensate for the mutated copy.
Flashcard 30: Identify why a mutation in a regulatory region can affect phenotype: it changes protein shape or gene expression level?
Answer: It changes gene expression level. Regulatory regions control how much protein is made.