Meiosis I Vocabulary Flashcards

Vocabulary flashcards covering the concepts, phases, and substages of Meiosis I as presented in the lecture transcript.

Meiosis

The process of cell division by which reproductive cells (gametes) are formed in eukaryotic cells (plants, animals, and fungi) to reproduce sexually through chromosomal reduction.

Meiosis I

The first phase of meiosis, known as reductive division.

Prophase I

The longest phase of meiosis, featuring three main events: condensation of chromatin, synapsis, and crossing-over of genetic material.

Synapsis

The physical contact between homologous chromosomes during Prophase I.

Crossing-over

The exchange of genetic material segments between non-sister chromatids of synapsed homologous chromosomes.

Leptonema

The first Prophase I event, deriving from Greek words meaning 'thin threads', where chromatin condenses and coils to form visible chromosomes.

Zygotene

The stage of Prophase I where chromosomes line up to form homologous pairs.

Pachytene

The stage of Prophase I where non-sister chromatids of homologous chromosome pairs exchange parts (crossing over) and chiasmata form.

Chiasmata

Structures that form where genetic material exchanges have occurred between non-sister chromatids during crossing over.

Diplotene

The stage of Prophase I where paired chromosomes begin to separate.

Diakinesis

The stage of Prophase I where homologous chromosomes separate.

Metaphase I

The phase of Meiosis I where tetrads align along the equator of the cell to be segregated, reducing the chromosome number by half.

Anaphase I

The phase of Meiosis I where microtubules shorten and pull one chromosome of each homologous pair to opposite poles.

Disjunction

The process during Anaphase I in which one chromosome of each homologous pair is pulled to opposite poles by shortening microtubules.

Telophase I

The final phase of Meiosis I where chromosomes arrive at opposing poles, microtubules disintegrate, and a new nuclear membrane forms around each haploid set of chromosomes.