HG 3 Cytogenetics Flashcards

Vocabulary flashcards about Cytogenetics

Cytogenetics

The study of the inheritance of chromosomes, their structure, and their function.

Autosomes

Contain most of the genes for general cell functions.

Sex Chromosomes

Involved in sex determination and sexual development.

Diploid Number

The total number of chromosomes in a cell (46 in humans).

Haploid Number

The number of different chromosomes in a gamete (23 in humans).

Diploid

Containing two complete sets of chromosomes, one from each parent.

Haploid

Having a single set of unpaired chromosomes.

P arm

The shorter arm of a chromosome (P for petite).

Q arm

The longer arm of a chromosome (Q follows P in the alphabet).

Metacentric

Centromere is in the middle, so the P and Q arms are of roughly equal length.

Submetacentric

Centromere is slightly off-center, resulting in unequal arm lengths.

Acrocentric

Centromere is near one end, resulting in one very short arm and one very long arm.

Karyotype

The arrangement of all the chromosomes of a cell into pairs according to size, centromere location, and banding pattern

Colcemid

A chemical which arrests cells in metaphase. Prevents the formation of the mitotic spindle, which is necessary for cell division.

Karyotyping

The process of arranging chromosomes into a standardized format to identify chromosomal abnormalities.

Polyploidy

The entire chromosome set has been replicated, resulting in three or more copies of each chromosome.

Aneuploidy

A condition in which the number of chromosomes in the nucleus of a cell is not an exact multiple of the monoploid number of a particular species.

Monosomy

Loss of a single chromosome.

Trisomy

Gain of a single chromosome.

47XYY

A male with 47 chromosomes, possessing an extra Y chromosome.

47XX+18

Female with 47 chromosomes, possessing an extra copy of chromosome 18.

46XY del(5p)

Male with the standard 46 chromosomes but missing a portion of the short arm (p) of chromosome 5.

Non-Disjunction

Refers to the failure of chromosome separation during cell division.

Turner Syndrome

Classical characteristics: Short stature, Wide chest, Puffy hands and feet, Webbed neck, Kidney problems, Infertility, Heart problems. No impact on mental abilities.

Patau Syndrome: Trisomy 13

Occurs in about 1 in 10,000 live births; babies often die within the first month. Facial malformations (cleft palate), eye deformities, extra fingers or toes, large protruding heels, brain and nervous system problems.

Edwards Syndrome: Trisomy 18

Occurs in about 1 in 11,000 live births; mostly females. Infants are small and slow-growing, rarely surviving past four months. Mental retardation, malformed feet and hands, heart malformations.

Down Syndrome: Trisomy 21

Occurs in about 1 in 800 births. Leading cause of childhood mental retardation and heart problems. Wide variability in impact. Classical physical features (wide, flattened skull, folded eyelids, furrowed tongues).

Amniocentesis Procedure

Uses ultrasound to guide a needle through the abdominal and uterine walls into the amniotic sac to extract fluid containing fetal cells. Generally performed around 16 weeks of pregnancy.

Chorionic Villus Sampling (CVS) Procedure

Involves inserting a small catheter into the uterus to remove fetal cells from the placenta. Can be done earlier, around 8 to 10 weeks of gestation.

Duplication

Results in a small portion of a chromosome being copied and replicated alongside the original segment.

Deletion

Results in the complete loss of a segment of genetic material.

Inversion

Occurs when a part of a chromosome is flipped from its normal orientation.

Types of Inversions

Pericentric Inversions: Involve the centromere. Paracentric Inversions: Occur away from the centromere on either the P arm or the Q arm.

Reciprocal Translocations

Involve the swapping of genetic material between non-homologous chromosomes (chromosomes that are not of the same pair).

Robertsonian Translocations

Involve the exchange of genetic material between two acrocentric chromosomes, where the centromere is located at the tip of the chromosome.

Philadelphia Chromosome

Named after the city where it was discovered. Involves a translocation between chromosome 9 and chromosome 22. Speciifaclly, genetic material from the bottom of chromosome 9 and chromosome 22 are swapped, resulting in one elongated chromosome 9 and one shortened chromosome 22.

Uniparental Disomy

When an individual inherits both copies of a chromosome pair from only one parent.

Fragile Sites

Areas on chromosomes that are prone to breakage or deletion.