Week 10

Nucleotide excision repair

A repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide.

Nonhomologous end joining

Brings together 2 ends of DNA fragments. a way of repairing a DNA double-strand break and is often error-prone

Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of individual large cells. Predict what is different about the cell cycle in a muscle cell. The G1 and G2 phases are extended. S phase happens twice. M phase is inhibited. Cytokinesis does not occur.

Cytokinesis does not occur.

Which of the statements most accurately describes the benefits of the proofreading function of DNA polymerase? DNA polymerase is always present in the nucleus and can repair all mutations when they occur. All DNA mutations can be detected and repaired during DNA replication. DNA polymerase can repair most mutations as they occur during DNA replication. DNA polymerase can be recruited to recently mutated sites to repair mutations.

DNA polymerase can repair most mutations as they occur during DNA replication.

Base excision repair

DNA repair that first excises modified bases and then replaces the entire nucleotide

Unrepaired single-stranded DNA breaks can lead to double-stranded DNA breaks during the next round of replication. Which repair pathway would be most appropriate for repairing double-stranded DNA breaks? DNA proofreading Mismatch repair Nonhomologous end joining Base excision repair

Nonhomologous end joining

What would happen to the daughter cells if the G2 phase of the parent cell is shortened? The cells would be smaller than normal. The cells would be larger than normal. The cells would be missing chromosomes. The cells would not undergo cytokinesis.

The cells would be smaller than normal.

Mismatch repair

The cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides.

Which one of the choices would most likely contribute to uncontrolled cell proliferation (that is, cancer)? a mutant enzyme needed for microtubule synthesis/polymerization a mutant cyclin that cannot bind to its normal CDK binding partner a mutant kinetochore protein that causes reduced microtubule attachment a mutant CDK that was active in the absence of its cyclin binding partner a mutant DNA synthesis mechanism causing blocked chromosome replication

a mutant CDK that was active in the absence of its cyclin binding partner

DNA proofreading

mismatched bases are corrected during replication

A gene that normally has the sequence CAGAGCCTATTAGGC is replicated as CAGAGCTGACGAGGC. Which of the repair mechanisms would most likely be employed to fix this replication error? base excision repair nucleotide excision repair None of the answer options is correct. DNA polymerase proofreading base excision repair and/or nucleotide excision repair

nucleotide excision repair

Homologous recombination

process by which a cell replaces a stretch of DNA with a segment that has a similar nucleotide sequence

Colchicine is a drug that blocks the assembly of microtubules. If dividing cells are treated with colchicine, at what stage of mitosis would you predict the arrest would occur? prophase metaphase G1 of interphase late anaphase telophase

Prophase

Mismatch repair, base excision repair, and nucleotide excision repair are similar in that each: repairs a single mismatched base. uses an undamaged segment of DNA as the template to repair a damaged segment of DNA. None of the other answer options is correct. repairs a short strand of mismatched nucleotides. repairs multiple mismatched or damaged bases across a region.

uses an undamaged segment of DNA as the template to repair a damaged segment of DNA.