Cell Division and Genetic Inheritance Flashcards

This set covers the vocabulary related to the cell cycle, mitosis, meiosis, genetic organization, and chromosomal disorders based on the lecture notes.

Cell Cycle

The series of events that a cell goes through as it grows and prepares to divide, consisting of interphase and the mitotic phase.

G1 Phase

A growth period for the newly formed cell where it decides whether to continue through the cycle.

S Phase

The 'synthesis' phase of the cell cycle during which replication of DNA takes place.

G2 Phase

The second growth period where the cell rebuilds energy reserves and produces proteins in preparation for mitosis.

Somatic Cells

System or body cells that arise by mitosis; in humans, they are diploid ($2n = 46$).

Walther Flemming

He dyed a specimen in 1879 and observed chromatin in the nucleus.

Binary Fission

The process of forming 2 daughter cells from a parent cell.

Cytokinesis

The division of the cytoplasm and organelles into each separate daughter cell.

DNA (Deoxyribonucleic acid)

The molecule that gives instructions and codes for traits, existing as chromatin for most of a cell's life cycle.

Chromosome

Condensed DNA (chromatid) and proteins (histones) joined by a centromere.

Histones

Proteins that DNA wraps around to help form chromosomes.

Telomere

The protective end caps found at the tips of a chromosome.

Autosomes

The 22 pairs of homologous chromosomes in humans that are not involved in gender determination.

Karyotype

A visual organization of an individual's chromosomes, paired up and arranged by length, centromere location, and staining properties.

Locus

A specific area on a chromosome with similar coding DNA.

Allele

The information present at a specific locus which can vary between homologous pairs.

Diploid

A cell containing $46$ chromosomes or 23 paired chromosomes ($2n$).

Haploid

A cell containing unpaired chromosomes, which is half the normal number ($n = 23$ in humans).

Polyploidy

A condition where a cell has more than 2 sets of one chromosome pair ($>2$).

Interphase

The phase taking up 90% of the cell cycle, focused on growth, maintenance, repair, and DNA duplication.

Prophase

The 1st phase of mitosis where chromosomes shorten and thicken, centrioles grow spindle fibers, and the nuclear membrane fades.

Metaphase

The 2nd phase of mitosis where chromosomes move towards the middle of the cell (equatorial plate) and centrioles move to the ends.

Anaphase

The mitosis phase where centromeres dissolve and chromatids move towards the centrioles guided by spindle fibers.

Telophase

The final stage of mitosis where chromatids reach opposite poles, spindle fibers dissolve, and nuclear membranes reform.

Cell Plate

A structure that begins to form between daughter cells in plants during cytokinesis and eventually becomes the cell wall.

Cancer

Uncontrollable cell duplication of non-functioning cells, often affected by hormones or nutrient levels.

Meiosis

A form of cell division producing gametes with half the number of chromosomes ($2n \rightarrow n$).

Reduction Division

The first outcome of meiosis (Meiosis I) that produces daughter cells with fewer chromosomes than the parent.

Recombination

The outcome of meiosis where chromosomes mix, producing cells with different genetic combinations than the parents.

Synapsis

The process during Prophase I where homologous chromosomes come together to form a tetrad.

Tetrad

A structure consisting of two chromosomes or four chromatids (sister and non-sister) formed during Prophase I.

Crossing-over

The exchange of segments between non-sister chromatids during Prophase I, creating genetic variation.

Independent Assortment

During Metaphase I, the random orientation of paternal and maternal homologous pairs toward the poles.

Nondisjunction

A disorder occurring when two homologous chromosomes move to the same pole during anaphase, resulting in gametes with 22 or 24 chromosomes.

Monosomy

A condition where a zygote contains 45 chromatids, such as in Turner syndrome (XO).

Trisomy

The presence of 3 homologous chromatids in every cell, such as in Down syndrome (Trisomy 21).

Spermatogenesis

The process of gamete formation in males occurring in the testes to produce sperm.

Oogenesis

The process of gamete formation in females occurring in the ovaries to produce eggs or oocytes.

Identical Twins

Twins originating from a single zygote that separates into two embryos during mitosis.

Fraternal Twins

Twins originating from two different eggs fertilized by different sperm cells.