Chromosomes And Genetic Variation Flashcards
Cytogenetics
Use of Cytology to study heredity
Genetics
The study of Chromosomes and their importance in heredity and ‘normal’ genetic composition
Ploidy – getting the nomenclature right
n: ?
n: Number of chromosomes in the gamete
2n: ?
2n: Number of chromosomes in the zygote
x:?
x: The basal number of chromosomes, compared to a common ancestral species ie. x is the “original” set of chromosomes, from which contemporary species are derived.
Centromere
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm and a long arm on the chromatids.
Telomeres
region of repetitive DNA sequences at the end of a chromosome. Telomeres protect the ends of chromosomes from becoming frayed or tangled. Each time a cell divides, the telomeres become slightly shorter. Eventually, they become so short that the cell can no longer divide successfully, and the cell dies.
FISH
provides researchers with a way to visualize and map the genetic material in an individual’s cells, including specific genes or portions of genes. This may be used for understanding a variety of chromosomal abnormalities and other genetic mutations.
FISH
Fluorescence in situ hybridization
Kintetochore proteins
are Highly conserved
BUT
Centromere DNA sequences vary considerably
Label chromosome
Chromatid
CGH
Array Comparative Genomic Hybridisation
G–band karyotyping
Can detect Both gross and more subtle abnormalities
Many syndromes are associated with?
small (micro–) chromosomal deletions or duplications
Can Genetic and Environmental Disorders of Development Can appear to be Similar?
Yes
foetal alcohol syndrome NOT a heritable genetic disorder
