Cell Cycle, Cell Division, and Chromosome Abnormalities

Flashcards covering key vocabulary related to the cell cycle, cell division (mitosis and meiosis), chromosome morphology, and various numerical and structural chromosome abnormalities and their consequences in animals.

Metacentric Chromosome

A chromosome with its centromere located in the middle, resulting in arms of approximately equal length.

Submetacentric Chromosome

A chromosome with its centromere located between the middle and the end, resulting in arms of unequal length.

Acrocentric Chromosome

A chromosome with its centromere located close to the end, resulting in one very short arm and one long arm.

Telocentric Chromosome

A chromosome with its centromere located at the very end.

Centromere

The constricted region of a chromosome, joining sister chromatids, which is essential for chromosome segregation during cell division.

Sister Chromatids

Two identical copies of a chromosome joined together by a centromere, formed during DNA replication.

Heterogametic

An individual that produces two different types of gametes with respect to sex chromosomes (e.g., males in mammals - XY, females in birds - ZW).

Homogametic

An individual that produces only one type of gamete with respect to sex chromosomes (e.g., females in mammals - XX, males in birds - ZZ).

Karyotype

The number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

Mitosis

A type of somatic cell division resulting in two daughter cells each having the same number and kind of chromosomes (2n) as the parent nucleus.

Meiosis

A type of germ cell division resulting in four daughter cells each with half the number of chromosomes (n) of the parent cell, as in the production of gametes.

Diploid Cell (2n)

A cell containing two complete sets of chromosomes, one from each parent.

Haploid Gamete (n)

A cell containing a single set of chromosomes, produced by meiosis, such as sperm or egg cells.

Interphase

The phase of the Eukaryotic cell cycle in which the cell grows and makes a copy of its DNA, comprising G1, S, and G2 phases.

G1 Phase

The first growth phase of interphase, where the cell grows and synthesizes proteins.

S Phase

The synthesis phase of interphase, where DNA replication occurs, and chromosomes are duplicated.

G2 Phase

The second growth phase of interphase, where the cell prepares for mitosis or meiosis.

M Phase

The mitotic phase, which includes nuclear division (mitosis or meiosis) and cytoplasmic division (cytokinesis).

Prophase (Mitosis)

Stage of mitosis where chromosomes coil up, condense, and centrioles divide and move apart.

Metaphase (Mitosis)

Stage of mitosis where centromeres of sister chromatids align on the metaphase plate.

Anaphase (Mitosis)

Stage of mitosis where centromeres split, and daughter chromosomes migrate to opposite poles.

Telophase (Mitosis)

Stage of mitosis where daughter chromosomes arrive at the poles, and cytokinesis commences.

Cytokinesis

The cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.

Meiotic Prophase I

The longest and most complex stage of meiosis, involving processes like synapsis, tetrad formation, and crossing over.

Synapsis

The pairing of homologous chromosomes during prophase I of meiosis.

Tetrad

A structure formed during prophase I of meiosis, consisting of two homologous chromosomes, each with two sister chromatids (four chromatids total).

Chiasma

The point of contact and physical link between two homologous non-sister chromatids where chromosomal crossover occurs.

Chromatin Crossover

The exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis prophase I, generating genetic recombination.

Gametogenesis

The biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes.

Spermatogenesis

The process of sperm formation in males, involving meiosis and differentiation of spermatids into spermatozoa.

Oogenesis

The process of ovum (egg) formation in females, involving meiosis and the production of a single ovum and polar bodies.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during anaphase of cell division, leading to an unequal distribution of chromosomes in daughter cells.

Chromosome Abnormalities

Deviations from the normal number or structure of chromosomes, which can arise from errors during cell division or environmental factors.

Euploidy

A variation in chromosome number that involves complete sets of chromosomes (e.g., monoploidy, polyploidy).

Monoploidy (n)

A condition in which an organism or cell has a single set of chromosomes.

Polyploidy

A condition in which an organism or cell has more than two complete sets of chromosomes (e.g., triploidy 3n, tetraploidy 4n).

Aneuploidy

A variation in chromosome number involving one or more individual chromosomes either in excess or fewer than the normal diploid set (e.g., monosomy, trisomy).

Monosomy (2n-1)

An aneuploid condition where an organism has only one copy of a particular chromosome instead of the usual two.

Trisomy (2n+1)

An aneuploid condition where an organism has three copies of a particular chromosome instead of the usual two.

Structural Rearrangement

Changes in the structure of individual chromosomes, such as deletions, duplications, inversions, or translocations.

Deletion

A type of structural chromosome abnormality where a segment of a chromosome is lost.

Duplication

A type of structural chromosome abnormality where a segment of a chromosome is repeated.

Inversion

A type of structural chromosome abnormality where a segment of a chromosome is reversed end to end.

Pericentric Inversion

An inversion that includes the centromere within the inverted segment.

Paracentric Inversion

An inversion that does not include the centromere within the inverted segment.

Translocation

A type of structural chromosome abnormality where a segment of a chromosome is transferred to another non-homologous chromosome.

Reciprocal Translocation

An exchange of segments between two non-homologous chromosomes.

Robertsonian Translocation (Centric Fusion)

A specific type of translocation where two acrocentric chromosomes fuse at their centromeres, with the loss of their short arms and centromeres.

Teratogens

Substances or agents that can cause birth defects or developmental abnormalities in an embryo or fetus.

X Monosomy (XO)

An aneuploidy where an individual has only one X chromosome, commonly leading to sterility or abnormal reproductive development.

XXX Trisomy

An aneuploidy where an individual has three X chromosomes, often associated with infertility or irregular estrus cycles.

XXY Trisomy

An aneuploidy where an individual has two X chromosomes and one Y chromosome, typically leading to small, hypoplastic testes and abnormal spermatogenesis (sterility).

XYY Trisomy

An aneuploidy where an individual has one X chromosome and two Y chromosomes, often presenting with normal phenotype but sometimes infertility due to small testes.