Lecture 1 Flashcards
What is cytogenetics?
Cytogenetics is the study of chromosomes and their structure and inheritance.
What is constitutional cytogenetic abnormality?
Constitutional cytogenetic abnormality refers to genetic make-up present at birth, found in every cell of the body, and can be inherited or passed on.
What is acquired cytogenetic abnormality?
Acquired cytogenetic abnormality usually occurs after birth, is not inherited, and is usually limited to a particular cell type.
What is karyotype?
Karyotype is the chromosomal complement of an individual or a species, including number, form, and size of the chromosomes.
What is chromosome banding?
Chromosome banding is a technique that allows identification of individual chromosomes by treating them with trypsin and Giemsa, which shows dark and pale bands.
What do pale bands on chromosomes indicate?
Pale bands on chromosomes indicate that the chromosomes are GC rich, early replicating, and gene rich.
What do dark bands on chromosomes indicate?
Dark bands on chromosomes indicate that the chromosomes are AT rich, late replicating, and gene poor.
What is FISH?
FISH (Fluorescence in situ hybridization) is a method for visualizing specific locations on a chromosome.
What are fluorescent DNA probes?
Fluorescent DNA probes are short sequences of single-stranded DNA that are complementary to the DNA sequences being labeled and examined in FISH.
What is chromosome painting?
Chromosome painting is a FISH-based technique that uses whole chromosome probes to detect differences in chromosomes based on color instead of banding patterns.
What is comparative genome hybridization- CGH?
CGH (Comparative Genome Hybridization) is a technique that identifies ranges that are amplified or lost in tumor samples by labeling reference DNA as red and tumor DNA as green.
What is ploidy?
Ploidy is the number of homologous sets of chromosomes in a cell
What is euploidy?
Euploidy is having an integral multiple of the monoploid number of chromosomes.
What is aneuploidy?
Aneuploidy is the state of not having euploidy at the level of the chromosome, such as having a pair that doesn’t match the others.
What is trisomy?
Trisomy is a condition in which one gamete with two copies of a chromosome fuses with a normal gamete, resulting in three copies of a particular chromosome.
What is monosomy?
Monosomy is a condition in which one gamete is missing a chromosome and fuses with a normal gamete, resulting in the lack of a chromosome.
What is Down syndrome?
Down syndrome is a genetic disorder caused by trisomy of all or a critical portion of chromosome 21, resulting in 47,XX+21 or 47,XY+21.
What is the main cause of Down Syndrome and how does it relate to age?
About 80% of Down Syndrome cases are due to meiosis 1 errors, while 5% are caused by non-disjunction in fathers and another 5% are due to mitosis. The risk of having a baby with Down Syndrome increases with age.
What is non-homologous end joining?
Non-homologous end joining is a repair mechanism where cells join two broken ends or add telomeres to the ends.
What causes chromosome breaks?
Chromosome breaks can be caused by DNA damage (such as chemicals or radiation) or errors in recombination.
What are acentric and dicentric joining?
Acentric joining causes the loss of a centromere, while dicentric joining causes the presence of two centromeres.
What is Cat-cry Syndrome, and what are its symptoms?
Cat-cry Syndrome is a human deletion syndrome caused by a loss of part of 5p. Symptoms include severe developmental and mental retardation, microcephaly, round face, wide-spread eyes, small chin, and most die in childhood.
How is Cat-cry Syndrome typically acquired?
Cat-cry Syndrome is mostly not inherited but rather happens by sporadic deletion during sperm/egg generation or in early fetal development.
What are the genes associated with deletions in Cat-cry Syndrome?
Deletions in Cat-cry Syndrome are associated with SEMAF and CTNND2 genes.
