Chromosomes and Replication Vocabulary

Flashcards on Chromosomes and Replication

Chromosome Theory of Heredity

The theory that genes are located on specific chromosomes, supported by sex chromosome studies in Drosophila and mammals.

Dosage Compensation

Ensures that cells in males and females produce the same amount of protein encoded by X-linked genes, achieved through X chromosome inactivation.

Barr Body

The inactive X chromosome in female cells, ensuring proper dosage compensation.

Chromatin

Complex of DNA and protein found in the nucleus of a cell.

Chromosomes

Separate pieces of chromatin that behave as a unit during cell division.

Nucleosome

Basic structural unit of chromatin, composed of histones and DNA.

Histones

Small proteins that are highly conserved among different organisms and help compact DNA within chromatin.

Linker DNA

A stretch of ~40 base pairs of DNA that connects one nucleosome with the next.

Condensins

Protein complexes that help shape loop structures in DNA.

G bands

Alternating dark and light segments of a chromosome as seen under a microscope after staining with Giemsa dye.

p arm and q arm

Short (p) and long (q) arms of human chromosomes. (An arm is the interval between a telomere and the centromere.)

Heterochromatin

Compact and heavily stained regions of chromatin, mainly consisting of highly repeated noncoding DNA sequences (satellite DNA).

Euchromatin

The rest of the chromatin, which becomes visible only after chromosome condensation in mitosis or meiosis.

Telomeres

Specialized terminal structures that ensure the maintenance and accurate replication of the two ends of each linear chromosome in eukaryotes.

Telomerase

An enzyme crucial to the successful replication of telomeres.

Centromere

A specialized chromosome region at which chromatids are most tightly connected and which elaborates the kinetochores to which spindle fibers attach during cell division

Kinetochore

A specialized chromosomal structure located at the centromere that is composed of DNA and proteins and that functions as the site at which chromosomes attach to the spindle fibers.

Cohesin

A multisubunit protein complex that holds the sister chromatids of eukaryotic chromosomes together until anaphase; cohesin can be found at both the centromere and along the chromosome arms.

Separase

An enzyme that cleaves the cohesin complexes at anaphase, allowing the sister chromatids to separate.

Shugoshin

A protein that protects the cohesin complex from separase cleavage during meiosis I.