mitosis and meiosis

Flashcards for cell division

Cell Division

The process of cell reproduction, in which one cell divides into two cells.

Cell Cycle

A series of events that leads to cell division. For eukaryotes, it involves a series of phases in which a cell divides by mitosis or meiosis.

Cytogenetics

The field of genetics that involves the microscopic examination of chromosomes.

Karyotype

A photographic representation of the chromosomes from an actively dividing cell.

Sister Chromatids

The two duplicated chromatids that are still joined to each other after DNA replication.

Sex Chromosomes

A distinctive pair of chromosomes that are different in males and females of some species and determine the sex of an individual.

Autosomes

All of the chromosomes found in the cell nucleus of eukaryotes except for the sex chromosomes.

Diploid

Containing two sets of chromosomes; designated as 2n.

Gamete

A haploid cell that is involved with sexual reproduction, such as a sperm or egg cell

Haploid

Containing one set of chromosomes; designated as 1n.

Homolog

A member of a pair of chromosomes in a diploid organism.

Homology

A similarity that occurs due to descent from a common ancestor.

Mitosis

In eukaryotes, the process in which nuclear division results in two nuclei, each of which receives the same complement of chromosomes.

M phase

The phase of the eukaryotic cell cycle consisting of the sequential events of mitosis and cytokinesis.

Interphase

The portion of the eukaryotic cell cycle consisting of the G1, S, and G2 phases, during which the chromosomes are decondensed and found in the nucleus.

Cyclin

A protein responsible for advancing a cell through the phases of the cell cycle by binding to a cyclin-dependent kinase.

Cyclin-dependent kinase (cdk)

A protein responsible for advancing a cell through the phases of the cell cycle. Its function is dependent on the binding of a cyclin.

Mitotic Cell Division

A process whereby a eukaryotic cell divides to produce two new cells that are genetically identical to the original cell.

Asexual Reproduction

A reproductive process that occurs when offspring are produced from a single parent, without the fusion of gametes from two parents. The offspring are therefore clones of the parent.

Centromere

The region where the two sister chromatids are tightly associated; the centromere is an attachment site for kinetochore proteins.

Kinetochore

A group of proteins that bind to a centromere and are necessary for sorting the chromosomes.

Spindle Apparatus

The structure responsible for organizing and sorting eukaryotic chromosomes during cell division; it is called the mitotic spindle when used during mitosis or the meiotic spindle when used during meiosis.

Pole

A structure of the mitotic spindle defined by each centrosome.

Centrioles

A pair of structures within the centrosome of animal cells. Most plant cells and many protists lack centrioles.

Prophase

The phase of mitosis during which the chromosomes condense and the nuclear membrane begins to vesiculate (dissociate into small vesicles).

Prometaphase

The phase of mitosis during which the nuclear envelope completely fragments into small vesicles and the mitotic spindle is fully formed.

Metaphase Plate

A plane halfway between the poles of the mitotic spindle, along which the sister chromatids align during metaphase in mitosis.

Metaphase

The phase of mitosis during which the chromosomes are aligned along the metaphase plate.

Anaphase

The phase of mitosis during which the sister chromatids separate from each other and move to opposite poles; the poles themselves also move farther apart.

Telophase

The phase of mitosis during which the chromosomes decondense and the nuclear envelope re-forms.

Cleavage Furrow

In animal cells, an area that constricts like a drawstring to separate the cells during cytokinesis.

Cell Plate

In plant cells, a structure that forms a cell wall between the two daughter cells during cytokinesis.

Meiosis

The process by which haploid cells are produced from a cell that was originally diploid.

Bivalent

Homologous pairs of sister chromatids that are associated with each other, lying side by side; also called a tetrad.

Synapsis

The process of forming a bivalent.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis; allows for increased variation in the genetic information that each parent may pass to the offspring.

Meiosis I

The first division of meiosis in which homologous chromosomes are separated into different cells.

Meiosis II

The second division of meiosis in which sister chromatids are separated into different cells.

Sexual Reproduction

A process in which two haploid gametes unite in a fertilization event to produce a diploid cell called a zygote.

Genetic Recombination

The exchange of genetic material via sexual reproduction, which leads to the production of offspring with combinations of traits that differ from those found in either parent.

Life Cycle

The sequence of events that characterize the steps of development of the individuals of a given species.

Diploid-Dominant Species

Species in which the diploid organism is the multicellular organism in the life cycle. Animals are an example.

Haploid-Dominant Species

Species in which the haploid organism is the multicellular organism in the life cycle. Examples include fungi and some protists.

Alternation of Generations

The phenomenon that occurs in plants and some protists in which the life cycle alternates between diploid multicellular organisms, called sporophytes, and haploid multicellular organisms, called gametophytes.

Sporophyte

The diploid generation of plants or multicellular protists that follow a life cycle of alternation of generations; this generation produces haploid spores by the process of meiosis.

Gametophyte

In plants and many multicellular protists, the haploid stage that produces gametes by mitosis.

Metacentric

Refers to a chromosome in which the centromere is near the middle.

Submetacentric

Refers to a chromosome in which the centromere is off center.

Acrocentric

Refers to a chromosome in which the centromere is near one end.

Telocentric

Refers to a chromosome in which the centromere is at the end.

Deletion

A type of mutation in which a segment of chromosomal material has been removed.

Duplication

A type of mutation in which a section of a chromosome occurs two or more times.

Inversion

A type of mutation that involves a change in the direction of the genetic material along a single chromosome.

Translocation

A type of mutation in which one segment of a chromosome becomes attached to a different chromosome.

Simple Translocation

A type of mutation in which a single piece of chromosome is attached to another chromosome.

Reciprocal Translocation

A type of mutation in which two different types of chromosomes exchange pieces, thereby producing two abnormal chromosomes carrying translocations.

Euploid

Refers to an organism that has a chromosome number that is a multiple of a chromosome set (1n, 2n, 3n, etc.).

Polyploid

Refers to an organism or cell that has three or more sets of chromosomes.

Triploid

Refers to an organism or cell that has three sets of chromosomes.

Tetraploid

Refers to an organism or cell that has four sets of chromosomes.

Aneuploidy

Alteration of the number of a particular chromosome present in an organism or cell, so the total number of chromosomes is not an exact multiple of a set.

Nondisjunction

An event in which the chromosomes do not separate properly during cell division.