BIOL5001 Integrated Biology - Genes, Chromatin, and Chromosomes Flashcards

Vocabulary flashcards covering key terms regarding eukaryotic and viral genomes, cytogenetics, chromatin structure, and chromosomal rearrangements.

Chromosome

A discrete unit of the genome carrying many genes, consisting of a very long molecule of duplex DNA and an approximately equal mass of proteins, visible as a morphological entity only during cell division.

Nucleoid

The structure in a prokaryotic cell that contains the genome, bound to proteins and not enclosed by a membrane.

Chromatin

The state of nuclear DNA and its associated proteins during the interphase of the eukaryotic cell cycle, representing the combination of DNA and histone proteins.

Packing ratio

The ratio of the length of DNA to the unit length of the fiber containing it.

Capsid

The external protein coat of a virus particle.

Icosahedral symmetry

A viral head shell structure characterized by 60 rotational symmetries.

Nucleation center

A duplex hairpin in tobacco mosaic virus (TMV) in which the assembly of coat protein with RNA is initiated.

Genetic variation

Differences between members of the same species or those of different species.

Allelic variations

Genetic variations that are due to differences in particular genes.

Cytogenetics

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

Karyotype

A micrograph in which all of the chromosomes within a single cell are arranged in a standard fashion based on length, centromere position, and banding patterns.

G-banding

A staining technique using Giemsa dye where AT-rich regions bind heavily to create dark bands, revealing 300 bands in metaphase and 800 in prometaphase.

Euchromatin

A form of chromatin that stains lightly and consists of genes that are actively expressed.

Heterochromatin

A form of chromatin that stains darkly and is made up largely of inactive, unexpressed, repetitive DNA.

Phytohemagglutinin (PHA)

A lectin obtained from the red kidney bean that binds to the membranes of T-cells and stimulates metabolic activity and cell division.

Colchicine

An agent that arrests dividing cells in metaphase by poisoning the mitotic spindle.

Giemsa

A chromosome dye composed of methylene blue, azure, and eosin.

Ideogram

A graphical representation depicting the arms (p or q), bands, and sub-bands of chromosomes.

Deletion

Also called a deficiency, it refers to the loss of a chromosomal segment.

Duplication

The repetition of a chromosomal segment compared to a normal chromosome.

Inversion

A change in the direction of part of the genetic material along a single chromosome.

Terminal deletion

A deletion resulting from a single chromosomal break where the fragment without a centromere is lost.

Interstitial deletion

A deletion resulting from two chromosomal breaks where the central fragment is lost and the outer pieces reattach.

Nucleus

The membrane-bound organelle that contains the cell's genetic material and controls cellular activities.

Centromere

The region of a chromosome where the two sister chromatids are joined and which is critical during cell division.

Sister chromatids

Identical copies of a chromosome that are connected by a centromere and are separated during mitosis.

Telomere

The repetitive nucleotide sequences at the ends of chromosomes that protect them from deterioration.

Cell cycle

The series of phases that a cell goes through from its formation to the point of division into daughter cells.

Crossing over

The exchange of genetic material between homologous chromosomes during meiosis, leading to genetic diversity.