CELLDIVISION: Mitosis and Meiosis - VOCABULARY Flashcards (Video Notes)

Vocabulary flashcards covering key terms and concepts from the cell cycle, mitosis, and meiosis as presented in the lecture notes.

Interphase

Non-dividing stage of the cell cycle consisting of G1, S, and G2; cell growth and DNA replication occur here.

G1 phase

Rapid cell growth; RNA and protein production.

S phase

DNA replication.

G2 phase

RNA and protein synthesis; preparation for division; cell grows to mature size.

Mitosis

Division of somatic (body) cells into two genetically identical diploid daughter cells.

Cytokinesis

Division of cytoplasm; completes cell division; results in two separate cells.

Cell cycle

Sequence of events from one cell division to the next; includes interphase and mitotic phase.

Cell theory

All organisms are composed of cells; the cell is the structural and functional unit of life; cells arise by division from preexisting cells.

Gene

Basic unit of heredity; codes for a specific trait.

Genome

Total hereditary endowment of DNA of a cell or organism.

Somatic cell

All body cells except reproductive cells.

Gamete

Reproductive cells (sperm and eggs).

Chromosome

Elongated cellular structure composed of DNA and protein that carries genes.

Chromatid

One of two duplicated chromosomes connected at the centromere.

Centromere

Region of a chromosome where microtubules attach during mitosis and meiosis.

Diploid (2n)

Cellular condition with two sets of chromosomes; two homologous copies of each chromosome.

Haploid (n)

Cellular condition with one set of chromosomes; one copy of each chromosome.

Homologous chromosome

Chromosomes of the same size and shape carrying the same genes; pair during meiosis.

Sister chromatids

Two identical copies of a chromosome held together at the centromere; separated during mitosis or meiosis II.

Chromatin

Uncondensed DNA-protein complex; condenses into chromosomes during cell division.

Prophase

Chromosomes condense; spindle forms; nuclear envelope breaks down; centrioles move toward poles.

Metaphase

Chromosomes align at the metaphase plate; kinetochores attach to spindle fibers.

Anaphase

Sister chromatids separate and move to opposite poles; poles elongate.

Telophase

Nuclei form; chromosomes de-condense; nuclear envelopes reform.

Cleavage furrow

Animal cell cleavage groove formed by a contracting actin ring to pinch the cell membrane and split the cell.

Cell plate

Plant cell structure that forms vesicles at the center to build a separating cell wall.

Kinetochore

Protein structure at the centromere where microtubules attach during division.

Spindle apparatus

Microtubules and proteins that organize and separate chromosomes during division.

Centrioles

Organelle pair that helps organize the spindle in animal cells; move to poles.

Aster

Radial array of microtubules around each centriole during early mitosis.

Mitotic spindle

Structure composed of microtubules that separates chromosomes during mitosis.

Synapsis

Pairing of homologous chromosomes during prophase I of meiosis.

Crossing over

Exchange of chromosome segments between nonsister chromatids during prophase I; creates genetic variation.

Chiasmata

Sites where crossing over occurs between homologous non-sister chromatids.

Tetrad

Group of four chromatids (two homologous chromosomes) formed during synapsis.

Leptotene

First substage of prophase I; chromosomes begin to condense and become visible.

Zygotene

Second substage of prophase I; homologous chromosomes begin pairing (synapsis).

Pachytene

Third substage of prophase I; crossing over can occur; synaptonemal complex forms.

Diplotene

Fourth substage of prophase I; synaptonemal complex dissolves; homologs begin terminalization.

Diakinesis

Final substage of prophase I; chromosomes fully condensed and ready for metaphase I.

Meiosis I

First division of meiosis; reductional division; homologous chromosomes separate; crossing over occurs.

Meiosis II

Second division of meiosis; similar to mitosis; sister chromatids separate; four haploid gametes produced.

Independent assortment

Random orientation of homologous pairs at metaphase I; increases genetic variation.

2^n combinations

Number of possible chromosome combinations in gametes; n is haploid number; e.g., humans n = 23 ⇒ many millions.

Gametogenesis

Production of gametes; includes spermatogenesis and oogenesis.

Spermatogenesis

Production of sperm; from spermatogonium to primary, secondary spermatocytes, then spermatids and spermatozoa.

Spermatogonium

Stem cell that forms primary spermatocytes in males.

Primary spermatocyte

Diploid cell that enters Meiosis I.

Secondary spermatocyte

Haploid cell after Meiosis I; enters Meiosis II.

Spermatids

Haploid cells produced by Meiosis II; mature into spermatozoa.

Spermatozoa

Mature sperm cells.

Oogenesis

Production of egg cells; involves asymmetric cytoplasm distribution and polar bodies.

Oogonium

Stem cell that becomes the primary oocyte in females.

Primary oocyte

Diploid cell that will enter Meiosis I to begin oogenesis.

Secondary oocyte

Haploid cell after Meiosis I; will complete meiosis II upon fertilization.

Polar body

Small cells produced during meiosis that are typically not fertilized; dispose of extra genetic material.

Egg cell (ovum)

Mature female gamete produced after meiosis II.

Fertilization

Union of sperm and egg that forms a zygote.

Zygote

Diploid fertilized egg; contains a full set of chromosomes.

p53

Tumor-suppressor protein that can arrest the cell cycle or trigger apoptosis; mutation can lead to uncontrolled division.

Cancer

Disease characterized by uncontrolled cell division; often linked to defects in cell cycle regulation.

Prophase II

Second meiotic division begins with chromosomes condensing again and nuclear envelope dissolving.

Metaphase II

Chromosomes align at the equatorial plate; kinetochores attach to spindle fibers.

Anaphase II

Sister chromatids separate and move to opposite poles.

Telophase II

Nuclei reform around chromosomes; cytokinesis completes, producing four haploid cells.

Clarity on mitosis vs meiosis

Mitosis yields two genetically identical diploid cells; meiosis yields four genetically diverse haploid cells.