Chapter 20 Mutation

Interphase

The phase of the cell cycle between cell divisions

S Phase

The phase of the cell cycle during which DNA is replicated.

Aneuploidy

A condition in which the number of chromosomes in a cell is not a multiple of the haploid number.

Chromosome-Level Mutation

A large-scale alteration affecting entire chromosomes rather than individual nucleotides.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Chemical Mutagens

Substances that chemically modify DNA bases

Mutation Rate

The frequency with which new changes occur in DNA sequences.

DNA Polymerase

An enzyme that synthesizes new DNA strands using an existing strand as a template.

G2 Phase

The second growth phase of the cell cycle

Cell Cycle

The series of events that take place in a cell leading to its division and duplication.

Frameshift Mutation

An insertion or deletion of nucleotides that shifts the reading frame of the genetic code.

G1 Checkpoint

A control point in the cell cycle that ensures the cell is ready to proceed to DNA replication.

Malignant Tumor

A cancerous mass of cells that can invade surrounding tissues and metastasize to other parts of the body.

DNA Repair Efficiency

The ability of a cell to correct errors and damage in its DNA.

Kinetochores

Protein structures on chromosomes where spindle fibers attach during cell division.

Nonsense Mutation

A substitution that creates a premature stop codon

M Checkpoint (Spindle Checkpoint)

A control point in the cell cycle that ensures proper attachment of microtubules to kinetochores before chromosome segregation.

Metastasis

The spread of cancer cells from the primary tumor to distant sites in the body.

Silent Mutation

A nucleotide substitution that does not change the amino acid sequence.

Replication Errors

Mistakes made by DNA polymerase during DNA replication

Cyclins

Proteins that regulate the cell cycle by activating cyclin-dependent kinases (CDKs).

Meiosis II Nondisjunction

The failure of sister chromatids to separate during the second meiotic division.

G2 Checkpoint

A control point in the cell cycle that ensures DNA replication is complete and accurate before mitosis begins.

Insertion Mutation

The addition of one or more nucleotide base pairs into a DNA sequence.

Mitosis (M Phase)

The process of cell division that results in two identical daughter cells.

Point Mutation

A change at a single nucleotide base within a DNA sequence.

G1 Phase

The first growth phase of the cell cycle

Deletion Mutation

The removal of one or more nucleotide base pairs from a DNA sequence.

Meiosis I Nondisjunction

The failure of homologous chromosomes to separate during the first meiotic division.

Benign Tumor

A non-cancerous mass of cells that does not invade surrounding tissues.

Pyrimidine Dimers

Covalent linkages between adjacent pyrimidine bases on a DNA strand

Tumor-Suppressor Genes

Genes that regulate cell division and prevent uncontrolled growth; their inactivation can lead to cancer.

Spindle Fibers

Structures formed during cell division that segregate chromosomes to daughter cells.

Missense Mutation

A substitution that results in one amino acid being replaced by a different amino acid.

Angiogenesis

The formation of new blood vessels