Gene Mutation and DNA Repair Quiz

A change in a single base pair of DNA.

A point mutation where a pyrimidine (C or T) is replaced by another pyrimidine, or a purine (A or G) replaced by another purine.

A point mutation where a pyrimidine is replaced by a purine, or vice versa.

A mutation that occurs due to the addition or deletion of nucleotides in numbers other than multiples of 3, shifting the reading frame downstream.

A mutation that does not change the amino acid sequence of a protein.

A mutation that changes the amino acid sequence of a protein.

A mutation that changes a codon specifying an amino acid to a stop codon.

A mutation involving the loss of DNA nucleotides.

A mutation that enhances an organism's survival or reproduction.

A mutation that does not affect the function of a protein.

Changes in the number or structure of chromosomes, altering gene locations or copy numbers.

Deletion, duplication, inversion, and translocation are four ways chromosomes can change.

Loss of part of a chromosome, leading to missing genetic information.

A gene's expression changes due to its new location on a chromosome.

Mutations happening naturally due to errors during DNA processes or biological abnormalities.

Mutations caused by environmental factors, like mutagens.

Cells that make gametes (eggs and sperm).

All body cells except gametes.

A common spontaneous DNA change where a purine base (adenine or guanine) breaks its link to the sugar, creating an apurinic site.

A location in DNA where a purine base is missing after depurination.

Spontaneous chemical change in a DNA base that could cause a mutation if not repaired.

A temporary change in the structure of a DNA base, potentially leading to incorrect base pairing during replication.

A type of radiation with high energy and short wavelength, capable of penetrating biological materials and causing damage by creating free radicals.

Highly reactive molecules formed by ionizing radiation, which can damage DNA by causing base deletions, single-strand and double-strand breaks, and cross-linking.

A type of radiation with lower energy and longer wavelength, unable to penetrate deeply into biological materials, but can cause the formation of thymine dimers.

Abnormal pairs of thymine bases in DNA caused by nonionizing radiation, which can lead to mutations during DNA replication.

A series of cellular processes that fix damage to DNA, involving detection, removal of damaged sections, and synthesis of new DNA.

A DNA repair system that removes an abnormal base or nucleotide and replaces it with a correct one.

A DNA repair system that removes a segment of DNA containing an abnormal nucleotide, using the complementary strand as a template to synthesize a correct replacement.

A DNA repair system that fixes mismatched base pairs in DNA, using the parental strand as a template to synthesize a correct copy.

Uracil is an unnatural base found in RNA, not DNA. Its presence in DNA usually indicates a deamination event.

A modified form of cytosine that can also undergo deamination, but produces thymine instead of uracil.

Thymine and guanine switch from their common keto form to a rare enol form, causing mispairing.

Agents that cause permanent changes to DNA structure.

Chemicals that alter DNA structure, often by modifying bases or intercalating in the DNA helix.

Chemicals that change the structure of a nucleotide by adding or removing groups, like nitrous acid.

Chemicals that attach alkyl groups (like methyl or ethyl) to bases, disrupting pairing.

Chemicals that wedge themselves between DNA base pairs, distorting the helix and causing insertions or deletions during replication.

The first step in DNA repair is recognizing and stabilizing the broken ends of the DNA molecule.

Direct Repair is a specific type of DNA repair where enzymes directly reverse the damage. Photolyase is an example, which repairs thymine dimers using light.

Nucleotide Excision Repair (NER) removes damaged DNA segments, including thymine dimers, chemically modified bases, and missing bases. It's found in most living things.

UvrA, UvrB, UvrC, and UvrD are key proteins in NER in bacteria. They work together to recognize and remove damaged DNA segments.

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are human diseases caused by defects in NER genes. These diseases make people very sensitive to sunlight.

During DNA replication, sometimes an incorrect base (mismatch) is added to the growing strand. Mismatch repair fixes these errors.

DNA polymerases have a built-in proofreading function, but if they miss any errors, mismatch repair systems come into play to fix base mismatches.

Mismatch repair systems are essential for maintaining DNA stability. Mutations in these systems are linked to certain types of cancer.