Ch2: Chromosomes and Cellular Reproduction - Vocabulary Flashcards

Vocabulary terms and concise definitions covering the key concepts of chromosomes and cellular reproduction from the notes.

Prokaryote

Unicellular organism lacking a nucleus; genome is usually a single circular chromosome.

Eukaryote

Organism with a nucleus and membrane-bound organelles; DNA organized into multiple linear chromosomes.

Eubacteria

True bacteria; a major group of prokaryotes with no nucleus.

Archaea

Ancient bacteria; transcription and some processes resemble eukaryotes more than eubacteria.

Nucleus

Membrane-bound organelle that houses the genetic material in eukaryotic cells.

Histone

Protein around which DNA wraps to form chromatin in eukaryotes.

Chromatin

DNA-histone complex that condenses to form chromosomes in the nucleus.

Chromosome

DNA molecule carrying genetic information; in eukaryotes usually linear and packaged with histones.

Chromatid

One copy of a replicated chromosome; sister chromatids are held together at the centromere.

Sister chromatid

The two identical copies of a replicated chromosome held together by cohesion.

Homologous chromosomes

Pairs of chromosomes that are similar in size and gene content; one from each parent.

Diploid

Cell or organism with two sets of chromosomes (2n); typically has homologous pairs.

Haploid

Cell or organism with a single set of chromosomes (n); gametes are haploid.

Polyploid

Having more than two complete sets of chromosomes.

Centromere

constricted chromosome region where sister chromatids attach and where kinetochores form.

Telomere

Protective ends of linear chromosomes that prevent degradation and fusion.

Origin of replication

Site where DNA replication begins.

Interphase

Cell growth and DNA replication phase; includes G1, S, and G2.

M phase

Mitotic phase; nuclear and cytoplasmic division occur.

Mitosis

Nuclear division producing two genetically identical diploid daughter cells.

Cytokinesis

Division of the cytoplasm and cell contents, yielding two separate cells.

Prophase

First stage of mitosis; chromatin condenses into visible chromosomes and spindle forms.

Prometaphase

Nuclear envelope breaks down; spindle attaches to kinetochores.

Metaphase

Chromosomes align on the metaphase plate; spindle checkpoint ensures proper attachment.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Chromosomes arrive at poles; nuclear envelope re-forms and chromosomes de-condense.

Kinetochore

Protein structure at the centromere where spindle fibers attach.

Spindle apparatus

Microtubule-based structure that separates chromosomes during division.

Cohesin

Protein complex that holds sister chromatids together after replication.

Separase

Protease that cleaves cohesin to allow sister chromatid separation.

Shugoshin

Protein protecting centromeric cohesin during meiosis I.

Meiosis

Cell division that reduces chromosome number by half, producing haploid gametes.

Meiosis I

Reduction division; homologous chromosomes separate; crossing over occurs.

Meiosis II

Equational division; sister chromatids separate, producing haploid cells.

Crossing over

Exchange of genetic material between nonsister chromatids during prophase I.

Chiasma

Physical site of crossing over between homologous chromosomes.

Independent assortment

Random distribution of maternal and paternal chromosomes into gametes.

Fertilization

Union of two haploid gametes to form a diploid zygote.

Zygote

Diploid cell produced after fertilization; begins a new organism.

Gamete

Haploid reproductive cell (sperm or egg) that fuses during fertilization.

Spermatogenesis

Production of sperm in the testes via meiosis.

Spermatogonium

Diploid germ cell in testes that can undergo mitosis and/or enter meiosis.

Primary spermatocyte

Diploid cell that enters meiosis I.

Secondary spermatocyte

Haploid cell produced after meiosis I.

Spermatid

Haploid product of meiosis II; matures into sperm.

Oogenesis

Production of eggs in the ovaries with unequal cytokinesis.

Oogonium

Diploid germ cell in the ovary that can undergo mitosis or enter meiosis.

Primary oocyte

Diploid cell that begins meiosis I and is arrested in prophase I until puberty.

Secondary oocyte

Haploid cell produced after meiosis I; completes meiosis II upon fertilization.

Ovum

Mature egg; haploid female gamete.

Polar body

Small haploid cell produced during female meiosis that usually disintegrates.

Megasporocyte

Diploid cell in the ovary that undergoes meiosis to produce megaspores.

Megaspore

Haploid product of megasporocyte meiosis; eight nuclei form the embryo sac.

Microsporocyte

Diploid cell in the stamen that undergoes meiosis to produce microspores.

Microspore

Haploid product that develops into pollen grain.

Pollen grain

Male gametophyte; contains a tube nucleus and a generative nucleus.

Embryo sac

Female gametophyte in flowering plants; contains egg and polar nuclei.

Endosperm

Triploid tissue formed after double fertilization; stores food for the embryo.

Double fertilization

Two fertilization events in flowering plants: one forms the zygote, the other forms endosperm.

Alternation of generations

Life cycle with alternating diploid sporophyte and haploid gametophyte generations.

Sporophyte

Diploid plant generation that produces spores by meiosis.

Gametophyte

Haploid plant generation that produces gametes by mitosis.

Karyotype

Number and appearance of chromosomes in a cell, often visualized in a stained spread.

Synapsis

Pairing of homologous chromosomes during prophase I in meiosis.

Tetrad / bivalent

Group of four chromatids formed by synapsis of homologous chromosomes.

Interkinesis

短 interval between meiosis I and II when some cells do not undergo DNA replication.

Virus

Simple infectious particle without cellular structure; consists of protein coat and nucleic acid; requires a host to replicate.