Cytogenetics

What is cytogenetics?

Study of chromosomes and chromosome abnormalities

What is a karyotype?

The complete chromosome complement of a cell

When are chromosomes easiest to visualize?

During metaphase of mitosis

What joins sister chromatids together?

The centromere

What are telomeres?

Repetitive DNA sequences at chromosome ends

How many chromosomes do normal human cells have?

46 chromosomes

How many pairs of autosomes do humans have?

22 pairs

What determines male sex in humans?

Presence of the Y chromosome with SRY gene

What does the 'p' arm of a chromosome mean?

The short arm (petit)

What does the 'q' arm of a chromosome mean?

The long arm (queue)

What is the diploid chromosome number in humans?

2n = 46

What is the haploid chromosome number in humans?

n = 23

Where are haploid cells found?

In gametes (sperm and egg)

What is polyploidy?

More than two complete chromosome sets

What is triploidy?

Three complete chromosome sets (3n)

What is aneuploidy?

Gain or loss of individual chromosomes

What causes aneuploidy?

Nondisjunction during meiosis

What is nondisjunction?

Failure of chromosomes to separate properly

What is a trisomy?

2n + 1 chromosomes

What is a monosomy?

2n - 1 chromosomes

Which trisomy causes Down syndrome?

Trisomy 21

What is the karyotype of Klinefelter syndrome?

47, XXY

What is the karyotype of Turner syndrome?

45, X

What does FISH stand for?

Fluorescent In Situ Hybridization

What does FISH detect?

Specific chromosome regions and abnormalities

What size abnormalities can FISH detect?

Approximately 1.5 Mb

Name a syndrome detected by FISH.

Prader-Willi, Angelman, Williams, or DiGeorge

What is a chromosome painting probe?

Probe that labels an entire chromosome

What is a locus-specific probe?

Probe targeting one chromosome region

What is a major advantage of FISH?

Works on non-dividing cells and is rapid

What does QF-PCR stand for?

Quantitative Fluorescent PCR

QF-PCR is based on what DNA markers?

Short Tandem Repeats (STRs)

What are STRs?

Repeated short DNA sequences varying between people

What is QF-PCR mainly used for?

Rapid detection of common aneuploidies

How is diploid number restored after meiosis?

Fertilization: n + n = 2n