Mutations
55 flashcards covering Mutations for the MCAT Biology & Biochemistry section.
Mutations are changes in the DNA sequence of an organism's genome, which can occur due to errors in DNA replication, exposure to radiation, or certain chemicals. These alterations might involve a single nucleotide or larger segments of DNA, leading to effects that range from harmless to severe, such as genetic disorders or evolutionary advantages. Understanding mutations is fundamental in biology because they drive genetic diversity, natural selection, and the development of new traits, making them a key concept in genetics and evolution.
On the MCAT, mutations often appear in multiple-choice questions within the Biology and Biochemistry section, testing your ability to identify types like point mutations or insertions/deletions, predict their effects on proteins, and analyze their role in diseases or populations. Common traps include confusing similar mutation types or overlooking environmental factors, so focus on mastering mechanisms, consequences, and real-world applications like cancer genetics. Always practice linking mutations to broader biological processes for better context.
Terms (55)
- 01
Mutation
A permanent change in the DNA sequence of an organism's genome, which can alter genetic information and potentially affect phenotype.
- 02
Point Mutation
A type of mutation that involves the alteration of a single nucleotide base in the DNA sequence, often resulting from substitution.
- 03
Frameshift Mutation
A mutation caused by the insertion or deletion of nucleotides not in multiples of three, shifting the reading frame of the genetic code and usually leading to a nonfunctional protein.
- 04
Silent Mutation
A point mutation that changes a nucleotide but does not alter the amino acid sequence of the resulting protein due to the degeneracy of the genetic code.
- 05
Missense Mutation
A point mutation that results in a single nucleotide change, causing the substitution of one amino acid for another in the protein, which may affect protein function.
- 06
Nonsense Mutation
A point mutation that changes a codon for an amino acid into a stop codon, leading to a truncated protein that is often nonfunctional.
- 07
Insertion
A mutation where extra nucleotides are added to the DNA sequence, potentially causing a frameshift if not in multiples of three and disrupting the reading frame.
- 08
Deletion
A mutation involving the removal of one or more nucleotides from the DNA sequence, which can cause a frameshift and alter the protein's structure and function.
- 09
Substitution
A mutation where one nucleotide is replaced by another, potentially leading to point mutations like missense or nonsense depending on the effect.
- 10
Transversion
A substitution mutation that exchanges a purine for a pyrimidine or vice versa, such as adenine for cytosine, altering the DNA base pairing.
- 11
Transition
A substitution mutation that exchanges a purine for another purine or a pyrimidine for another pyrimidine, like adenine for guanine, which is more common in nature.
- 12
Mutagen
An agent, such as radiation or chemicals, that increases the rate of mutation by damaging DNA or interfering with replication.
- 13
Spontaneous Mutation
A mutation that occurs naturally without external agents, often due to errors in DNA replication or spontaneous chemical changes in bases.
- 14
Induced Mutation
A mutation caused by exposure to external factors like mutagens, including UV light or certain chemicals, which directly damage DNA.
- 15
DNA Repair
A cellular process that corrects errors in DNA, such as those from mutations, to maintain genomic integrity and prevent diseases like cancer.
- 16
Base Excision Repair
A DNA repair mechanism that removes and replaces a damaged or incorrect base, such as one altered by oxidation, to restore the original sequence.
- 17
Nucleotide Excision Repair
A DNA repair pathway that excises a segment of a strand containing bulky damage, like thymine dimers from UV light, and synthesizes a new segment.
- 18
Mismatch Repair
A system that corrects errors during DNA replication, such as mismatched base pairs, by removing and replacing the incorrect nucleotide.
- 19
Thymine Dimer
A type of DNA damage where two adjacent thymine bases bond together, often caused by UV radiation, leading to mutations if not repaired.
- 20
UV-Induced Mutation
A mutation resulting from ultraviolet radiation, which causes DNA damage like thymine dimers and increases the risk of skin cancer.
- 21
Chemical Mutagen
A substance, such as nitrous acid or alkylating agents, that alters DNA structure and induces mutations by modifying bases or causing strand breaks.
- 22
Somatic Mutation
A mutation that occurs in body cells and affects only the individual, not passed to offspring, potentially contributing to diseases like cancer.
- 23
Germline Mutation
A mutation in reproductive cells that can be inherited by offspring, altering the genetic makeup of future generations.
- 24
Chromosomal Mutation
A large-scale change in chromosome structure or number, such as deletions or translocations, which can lead to genetic disorders.
- 25
Inversion Mutation
A chromosomal mutation where a segment of DNA is reversed end to end, potentially disrupting gene function if it occurs within a gene.
- 26
Duplication Mutation
A mutation where a segment of DNA is copied and inserted, leading to extra genetic material that can cause gene dosage effects.
- 27
Translocation Mutation
A chromosomal mutation where a segment from one chromosome is transferred to another, possibly causing genetic disorders by fusing genes.
- 28
Deletion Syndrome
A condition resulting from a large deletion on a chromosome, leading to missing genes and symptoms like developmental delays, as in Cri du Chat syndrome.
- 29
Gene Duplication
A mutation that results in an extra copy of a gene, which can lead to new functions through evolution or cause disorders if overexpressed.
- 30
Sickle Cell Anemia Mutation
A missense mutation in the beta-globin gene where glutamic acid is replaced by valine, causing red blood cells to sickle and leading to anemia.
- 31
Frameshift in Protein Synthesis
The consequence of a frameshift mutation where the reading frame shifts, resulting in a completely different and usually nonfunctional amino acid sequence.
- 32
Neutral Mutation
A mutation that does not affect an organism's fitness, such as a silent mutation in a non-critical region, and is often invisible to natural selection.
- 33
Beneficial Mutation
A mutation that improves an organism's survival or reproduction, such as one conferring antibiotic resistance in bacteria, driving evolution.
- 34
Deleterious Mutation
A harmful mutation that reduces an organism's fitness, often leading to disease or death, and is typically selected against in populations.
- 35
Mutation Rate
The frequency at which mutations occur in a genome per generation, influenced by factors like DNA repair efficiency and exposure to mutagens.
- 36
Factors Influencing Mutation Rate
Variables such as replication errors, environmental mutagens, and DNA repair mechanisms that determine how often mutations happen in a population.
- 37
Ames Test
A method to assess the mutagenic potential of chemicals by observing their ability to cause mutations in bacteria, helping identify carcinogens.
- 38
Suppressor Mutation
A second mutation that counters the effect of a previous mutation, restoring partial or full function to a gene or protein.
- 39
Reversion Mutation
A mutation that reverses the original mutation, restoring the wild-type sequence and function, though not always exactly.
- 40
Wobble Effect on Mutations
The flexibility in the third base of a codon that allows some mutations to be silent due to tRNA's ability to pair with non-complementary bases.
- 41
Codon Redundancy and Mutations
The existence of multiple codons for the same amino acid, which means some mutations in the third position of a codon do not change the protein.
- 42
Strategy for Detecting Point Mutations
Techniques like DNA sequencing or PCR-based methods to identify single nucleotide changes by comparing sequences to a reference.
- 43
Common Trap: Silent Mutations
The misconception that silent mutations have no effect, whereas they can sometimes influence gene expression through changes in mRNA stability or splicing.
- 44
Evolutionary Role of Mutations
Mutations as the primary source of genetic variation, providing raw material for natural selection and driving species adaptation over time.
- 45
Mutation in Cancer
Accumulation of mutations in oncogenes and tumor suppressor genes that lead to uncontrolled cell growth and tumor formation.
- 46
Oncogene Activation by Mutation
A mutation that converts a proto-oncogene into an oncogene, promoting cancer by increasing cell proliferation or survival.
- 47
Tumor Suppressor Gene Mutation
A mutation that inactivates a tumor suppressor gene, removing brakes on cell division and allowing cancerous growth.
- 48
Proofreading Mechanism
The ability of DNA polymerase to check and correct errors during replication, reducing the mutation rate by excising mismatched nucleotides.
- 49
Exonuclease Activity
An enzymatic function that removes incorrect nucleotides from the DNA strand, part of the proofreading process to prevent mutations.
- 50
Polymerase Fidelity
The accuracy of DNA polymerase in incorporating the correct nucleotide, which is crucial for minimizing spontaneous mutations during replication.
- 51
Hotspot Mutations
Specific DNA sequences or regions prone to frequent mutations due to factors like repetitive elements or error-prone repair.
- 52
Microsatellite Instability
A condition where mutations occur in repetitive DNA sequences, often due to defective mismatch repair, associated with certain cancers.
- 53
Aneuploidy
A chromosomal mutation involving an abnormal number of chromosomes, such as trisomy 21, leading to genetic disorders.
- 54
Polyploidy
A mutation where an organism has more than two complete sets of chromosomes, common in plants and can lead to speciation.
- 55
Lethal Mutation
A mutation that causes the death of an organism, often by disrupting essential genes, and is usually recessive.