Chromosome Transmission During Cell Division and Sexual Reproduction - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes.

Chromosome

Structure within a cell that contains genetic material; in eukaryotes the DNA–protein complex is organized as chromatin.

Gene

Unit of heredity located on a chromosome that governs a trait.

DNA

Deoxyribonucleic acid; the genetic material that makes up chromosomes.

Chromatin

DNA–protein complex in eukaryotes that forms the material of chromosomes.

Non-coding RNA

RNA molecules on chromosomes that do not code for proteins.

Prokaryote

Cell type without a membrane-bound nucleus (e.g., bacteria, archaea).

Eukaryote

Cell type with a membrane-bound nucleus and organelles (protists, fungi, plants, animals).

Nucleoid

Region in a prokaryotic cell where the circular chromosome is located.

Nucleus

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

Mitochondrion

Organelle with its own DNA; site of ATP synthesis.

Golgi apparatus

Organelle involved in protein modification and trafficking.

Somatic cell

Body cell (non-gamete) in an organism.

Germ cell

Cell that gives rise to gametes (reproductive cells).

Karyotype

Organized representation of the chromosomes of a cell, usually ordered by size.

Diploid

Two complete sets of chromosomes (2n) in a cell.

Haploid

One set of chromosomes (n); typical of gametes.

Homologous chromosomes

Pair of chromosomes similar in size and gene order; carry the same genes, possibly different alleles.

Locus

Physical location of a gene on a chromosome.

Allele

Variant form of a gene.

Genotype

Genetic constitution for a gene; e.g., AA, Bb, cc.

Homozygous

Having two identical alleles for a gene.

Heterozygous

Having two different alleles for a gene.

Chromatid

One of the two identical copies of a replicated chromosome.

Dyad

Pair of sister chromatids joined at the centromere.

Sister chromatids

Two identical copies of a chromosome held together at the centromere.

Centromere

Constricted region where sister chromatids are held; site for kinetochore attachment.

Kinetochore

Protein structure at the centromere that attaches to spindle microtubules.

Centrosome

Organizes the spindle apparatus; contains two centrioles in animal cells.

Centriole

Cylindrical cell structure within the centrosome involved in organizing spindle fibers.

Spindle apparatus

Structure that separates chromosomes during cell division.

Aster microtubules

Radial microtubules around centrosomes aiding spindle positioning.

Polar microtubules

Microtubules that push the poles apart during division.

Kinetochore microtubules

Attach to kinetochores on chromosomes to move them during division.

Interphase

Cell-cycle stage (G1, S, G2) when the cell grows and DNA is replicated.

G1 phase

First gap phase; cell grows and prepares for DNA replication.

S phase

DNA synthesis phase; chromosomes are replicated.

G2 phase

Second gap phase; cell prepares for mitosis.

Mitosis

Nuclear division that distributes replicated chromosomes into two daughter nuclei.

Prophase

Chromosomes condense; nuclear envelope breaks down; spindle forms.

Prometaphase

Spindle fibers attach to kinetochores; chromosomes begin moving toward center.

Metaphase

Chromosomes align at the metaphase plate; attached to opposite poles.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Nuclei reform around separated chromosomes; chromosomes de-condense.

Cytokinesis

Division of the cytoplasm to form two separate daughter cells.

Cleavage furrow

Indentation that forms in animal cells during cytokinesis.

Cell plate

Precursor to a separating cell wall in plant cytokinesis.

Meiosis

Reduction division producing haploid gametes; two divisions (Meiosis I and II).

Meiosis I

First meiotic division; homologous chromosomes pair and cross over; reduces chromosome number.

Meiosis II

Second meiotic division; sister chromatids separate, producing four haploid cells.

Leptotene

Stage of Prophase I where chromosomes condense.

Zygotene

Stage of Prophase I where synapsis begins between homologs.

Pachytene

Stage of Prophase I where crossing over occurs and bivalents form.

Diplotene

Stage of Prophase I where synaptonemal complex dissociates.

Diakinesis

End of Prophase I; chromosomes condense further preparing for meiosis I.

Bivalent/Tetrad

Pair of homologous chromosomes during meiosis I (each with two sister chromatids).

Crossing over

Exchange of genetic material between homologous chromosomes during meiosis I.

Spermatogenesis

Production of sperm in the male reproductive system.

Spermatogonia

Diploid germ cells that divide to form primary spermatocytes.

Primary spermatocyte

Diploid cell that undergoes meiosis I.

Secondary spermatocyte

Haploid product of meiosis I that undergoes meiosis II.

Spermatids

Haploid cells that differentiate into sperm.

Sperm

Mature male gamete with haploid nucleus.

Oogenesis

Production of egg cells in the female reproductive system.

Oogonia

Diploid germ cells in ovaries that produce primary oocytes.

Primary oocyte

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

Secondary oocyte

Large haploid cell produced after meiosis I; arrests until fertilization.

Polar body

Small haploid cell produced during oogenesis that typically degenerates.

Double fertilization

In flowering plants, one sperm fertilizes the egg and another fertilizes the central cell to form endosperm.

Endosperm

Triploid tissue that nourishes the developing embryo in flowering plants.

Gametophyte

Haploid generation of plants that produces gametes by mitosis.

Sporophyte

Diploid generation of plants that produces spores by meiosis.

Spores

Haploid cells produced by meiosis in the sporophyte that develop into gametophytes.

Pollination

Transfer of pollen to the stigma; required for fertilization in plants.

Fertilization

Fusion of gametes to form a zygote; in plants, often involves double fertilization.

X-linked gene

Gene located on the X chromosome.

X-linked trait

Trait determined by an allele on the X chromosome; often shows sex-linked patterns.

Mendel’s laws and chromosomes

Mendel’s law of segregation and independent assortment explained by chromosome behavior during meiosis.

X-Y system

Males are heterogametic (XY) and females are homogametic (XX) in mammals.

X0 system

Males have one X and no Y; sex determined by X/A ratio in some insects.

Z-W system

Sex determination in birds/fish; males are ZZ and females are ZW.

Haplodiploid

Sex determination where males are haploid (from unfertilized eggs) and females are diploid.

Morgan’s experiment

Thomas Hunt Morgan’s Drosophila experiments showing X-linked inheritance with white-eyed mutation.

Punnett square

Diagram used to predict offspring genotypes from parental genotypes.

Karyotype (size order)

Arrangement of chromosomes usually from largest to smallest.