Cell Division, Mitosis, and Meiosis Flashcards

Vocabulary flashcards covering cell cycle phases, mitosis, meiosis, gametogenesis, and chromosomal abnormalities based on the lecture notes.

Zygote

A single cell containing $2n$ (46) chromosomes formed when an egg ($n$, 23 chromosomes) and a sperm ($n$, 23 chromosomes) fuse during fertilization.

Gametes

Specialized sex cells, specifically egg or sperm cells, that contain 23 chromosomes ($n$).

Soma Cells

Identical body cells that make up all tissues except sex cells, containing a complete diploid set of 46 chromosomes.

Histones

Specialized proteins that support DNA structure and help control gene expression.

Autosomes

All chromosomes in a cell excluding sex chromosomes that determine which non-sex traits and genes are expressed.

Interphase

The major preparatory phase of the cell cycle consisting of G1, S, and G2 phases, during which cell growth, DNA purification, and replication occur.

G1 Phase

The first gap phase of interphase where the majority of cell growth occurs, organelles and proteins are synthesized, and DNA is checked for errors or mutations before replication.

S Phase

The synthesis phase of interphase during which DNA replicates to produce identical sister chromatids attached at the centromere.

G2 Phase

The second gap phase of interphase where growth continues and DNA replication is double-checked for errors before entering mitosis.

G0 Phase

A resting state outside the active cell cycle where cells stop replicating if damage or improper conditions are detected.

G1 Checkpoint

A regulatory checkpoint in interphase that assesses growth factors and DNA damage; passing this checkpoint commits the cell to division.

G2 Checkpoint

A checkpoint after DNA synthesis that checks cell size and verifies error-free DNA replication before allowing mitosis to proceed.

M Checkpoint

A cell cycle checkpoint occurring during metaphase that monitors correct spindle fiber assembly and attachment.

Spindle Fibers

Tiny protein fibers that attach to chromosomes and facilitate their movement and separation toward opposite cell poles during cell division.

Mitosis

Nuclear division in body cells that splits one nucleus into two genetically identical daughter nuclei.

Cytokinesis

The division of the cytoplasm that begins during telophase and splits a single cell into two distinct daughter cells.

Prophase

The first stage of mitosis where chromatin condenses into visible chromosomes around histones, the nuclear membrane breaks down, and mitotic spindles form.

Metaphase

The second stage of mitosis where chromosomes line up along the equator (middle) of the cell and spindle fibers fully assemble and attach.

Anaphase

The third stage of mitosis where sister chromatids are pulled apart at the centromeres toward opposite poles of the cell, doubling the separate chromosome count.

Telophase

The final stage of mitosis where separated chromosomes reach opposite poles, decondense into chromatin, nuclear envelopes reform, and nucleoli reappear.

Meiosis

A specialized cell division process consisting of eight phases across two divisions (Meiosis I and Meiosis II) that produces four genetically unique haploid gametes.

Crossing Over

The swapping of genetic material between paired homologous chromosomes during Prophase I of Meiosis I, creating new genetic combinations and diversity.

Independent Assortment

The random arrangement and alignment of maternal and paternal homologous chromosome pairs at the cell equator during Metaphase I of Meiosis I.

Spermatogenesis

The production process of sperm cells in the testes, which yields approximately 400,000,000 sperm per day.

Oogenesis

The production process of egg cells in females, producing a lifetime total of approximately 400 to 500 mature eggs created prior to birth.

Karyotype

A visual display showing the number, size, and structural appearance of chromosomes in an organism's cell nucleus.

Trisomy 21

The scientific term for Down syndrome, caused by the presence of an extra third chromosome at chromosome pair 21.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during meiosis I or meiosis II, leading to abnormal chromosome numbers in gametes.

Turner Syndrome

A chromosomal disorder in females characterized by a monosomy where one X chromosome is missing or incomplete, leading to webbed neck, amenorrhea, and infertility.

Klinefelter Syndrome

A chromosomal disorder where a biological male possesses an extra X chromosome (XXY), causing low testosterone, enlarged breasts, sparse body hair, and small testes.