Cell Cycles – Chapters 8 & 9

Vocabulary flashcards covering major terms from Chapters 8 & 9 on cell cycles, mitosis, meiosis, and related topics

Cell cycle

Ordered sequence of events in a cell’s life, consisting of interphase and the mitotic phase

Chromosome

Long DNA molecule carrying genes; in eukaryotes wound around histone proteins

Histone proteins

Eukaryotic proteins that DNA wraps around, helping package chromosomes

Prokaryotic chromosome

Circular DNA molecule lacking histones and found in the cytoplasm

Eukaryotic chromosome

Linear DNA molecule packaged with histones inside a nucleus

Binary fission

Asexual division in prokaryotes that produces two identical daughter cells

Homologous pair (homologues)

Two chromosomes with the same genes, one inherited from each parent

Sister chromatid

Identical copies of a chromosome joined at a centromere after DNA replication

Centromere

Region where sister chromatids are held together and spindle fibers attach

DNA replication

Process that duplicates DNA, producing two identical molecules

DNA polymerase

Enzyme that adds complementary nucleotides during DNA replication

Interphase

Functional portion of the cell cycle containing G1, S, and G2 phases

G1 phase (Gap 1)

First interphase stage; cell grows and performs normal duties

S phase (DNA synthesis)

Interphase stage in which chromosomes replicate

G2 phase (Gap 2)

Second growth phase preparing the cell for division

Mitotic phase

Period that includes mitosis and cytokinesis

Mitosis

Nuclear division producing two genetically identical nuclei

Cytokinesis

Division of cytoplasm that forms two separate daughter cells

Prophase

Stage where chromosomes condense, nuclear membrane breaks down, spindle forms

Spindle fibers

Microtubules that attach to chromosomes and move them during division

Metaphase

Mitosis stage where chromosomes line up at the cell’s equator

Anaphase

Stage where sister chromatids separate and move to opposite poles

Telophase

Final mitosis stage; chromosomes uncoil and nuclei re-form

Mutation

Permanent change in DNA sequence that escapes repair

Mutagen

Physical or chemical agent that increases mutation rate

Cancer

Disease of uncontrolled cell division leading to tumor formation

Benign tumor

Non-cancerous mass that does not invade neighboring tissues

Malignant tumor

Cancerous growth that invades and destroys healthy tissue

Metastasis

Spread of cancer cells to distant sites, forming new tumors

Contact inhibition

Normal mechanism where crowded cells stop dividing; absent in cancer cells

Diploid (2n)

Cell containing two complete sets of chromosomes

Haploid (1n)

Cell containing one set of chromosomes

Gamete

Haploid sex cell such as a sperm, egg, or pollen grain

Meiosis

Cell division that produces four genetically unique haploid gametes

Allele

Alternative form of a gene

Crossing over

Exchange of genetic material between homologous chromosomes during prophase I

Independent assortment

Random distribution of maternal and paternal chromosomes to gametes during meiosis

Fertilization

Fusion of two haploid gametes forming a diploid zygote

Genetic variation

Differences in DNA sequences among individuals of a population

Asexual reproduction

Reproduction involving one parent that generates genetically identical offspring

Sexual reproduction

Reproduction involving two parents that generates genetically diverse offspring

Polyploidy

Condition of having more than two complete sets of chromosomes

Nondisjunction

Failure of chromosomes to separate properly during meiosis

Chromosomal abnormality

Any deviation from the normal number or structure of chromosomes

Homologue separation

Meiosis I event in which homologous chromosomes segregate to opposite poles

Sister chromatid separation

Meiosis II event in which chromatids segregate to opposite poles

Prophase I

Meiosis stage where homologues pair, spindle forms, and crossing over occurs

Metaphase I

Stage where paired homologues align at the cell equator

Anaphase I

Stage where homologous chromosomes move toward opposite poles

Telophase I

Stage where nuclei reform around separated homologues before cytokinesis

Prophase II

Stage where chromosomes condense again in each haploid daughter cell

Metaphase II

Stage where chromosomes line up singly at the equator during meiosis II

Anaphase II

Stage where sister chromatids separate during meiosis II

Telophase II

Stage ending meiosis; nuclei reform and four haploid cells result

Sex determination (humans)

System in which XX produces females and XY produces males; sperm decides sex

Temperature-dependent sex determination

System in some reptiles where incubation temperature decides offspring sex