Cell Cycle, Mitosis, and Meiosis Vocabulary

Flashcards covering key terms and definitions regarding chromatin structure, mitosis, meiosis phases, and gametogenesis from the lecture notes.

Chromatin

A complex of DNA and protein that condenses during cell division to form chromosomes.

Nucleosome

A structure formed every $200$ nucleotide pairs when DNA wraps twice around a group of $8$ histone proteins.

Karyotype

An ordered, visual representation of the chromosomes in a cell, photographed when highly condensed and arranged in order of decreasing size.

Homologous Chromosomes

Pairs of chromosomes in a diploid cell that look the same, control the same traits, and originate from different parents.

Sex Chromosomes

Chromosomes represented as $X$ and $Y$ that determine the sex of an individual, with $XX$ being female and $XY$ being male.

Diploid Cell

A cell possessing two copies or sets of each chromosome, represented as $2n$ (e.g., $2n = 46$ in human somatic cells).

Haploid Cell

A cell possessing a single set or copy of each chromosome, represented as $n$ or $1n$, such as human sex cells.

Sister Chromatids

Two identical copies of a duplicated chromosome connected at the centromere, containing identical genetic information.

Kinetochores

Two discs of protein bound to the centromere region of a chromosome that serve as points of attachment for microtubules during cell division.

Interphase

The majority stage of the cell cycle dedicated to cell growth and DNA replication prior to cell division.

Telomeres

Structures located at the ends of condensed chromosomes that protect DNA and do not contain genes.

Prophase

The phase of mitosis characterized by chromosome condensation, disappearance of the nuclear membrane, separation of centrioles to opposite poles, and formation of spindle fibers.

Metaphase

The shortest phase of mitosis, characterized by chromosomes lining up across the middle of the cell and spindle fibers attaching to centromeres.

Anaphase

The phase of mitosis in which centromeres split and sister chromatids separate to move to opposite poles of the cell.

Telophase

The final phase of mitosis where single-chromatid chromosomes uncoil, new nuclear envelopes assemble, spindle fibers break down, and cytokinesis begins.

Cytokinesis

The process of dividing the cell cytoplasm to produce two individual daughter cells.

Cleavage Furrow

A constriction formed in the cell membrane of animal cells during cytokinesis that pinches the cell into two nearly equal parts.

Leptotene

The first phase of Prophase I in Meiosis I during which chromosomes start to condense.

Zygotene

The phase of Prophase I in which homologous chromosomes become closely associated through synapsis to form bivalents or tetrads.

Pachytene

The phase of Prophase I during which crossing over occurs between pairs of homologous chromosomes to form chiasmata.

Diplotene

The phase of Prophase I where homologous chromosomes begin to separate but remain attached at chiasmata.

Diakinesis

The final phase of Prophase I where homologous chromosomes continue to separate and chiasmata shift to the ends of the chromosomes.

Synapsis

The pairing and close association of homologous chromosomes during Prophase I to form a tetrad.

Crossing-Over

The exchange of chromosome pieces or genes between homologous chromosomes in a tetrad during Prophase I, producing genetic recombination.

Spermatogenesis

The process of gamete formation occurring in the testes of males that produces sperm cells.

Oogenesis

The process of gamete formation occurring in the ovaries of females that produces eggs.

Polar Body

A non-functional haploid cell formed during oogenesis that eventually degenerates and dies.