MBLG2972 Lecture Notes - Lecture 18: Gene Duplication, Color Blindness, Angiogenesis Inhibitor
5 Jul 2018
School
Department
Course
Professor
MBLG2072
Genetics and Genomics
Monica Zanuttini !
460381099
Lecture 18 "Cytogenetics !
In animals, embryonic aneuploids have reduced viability. !
Inviability can result from: !
1. Expression of deleterious recessives. !
2. Imbalance of genetic material. !
"An extra copy of chromosome 21, humans can cope with it, leading to Down-syndrome.
"Humans can also withstand aneuploidy in chromosome 13 and 18. All other autosomal "
"aneuploids tend to be fatal. Sex chromosome aneuploidy can be tolerated too. !
Aneuploidy and cancer: !
•Many cancers contain large-scale changes in chromosome numbers. Mounting evidence
suggests that polyploid cells can be genetically unstable and act as intermediates to aneuploidy
and, ultimately, cancer.!
•Aneuploidy correlates with poor prognosis in cancer, providing adaptive advantage of cancerous
cells over healthy diploid cells. !
•Leads to instability of cells, due to chromosomal instability and mitotic errors. !
Document Summary
Inviability can result from: expression of deleterious recessives. An extra copy of chromosome 21, humans can cope with it, leading to down-syndrome. Humans can also withstand aneuploidy in chromosome 13 and 18. All other autosomal aneuploids tend to be fatal. Aneuploidy and cancer: many cancers contain large-scale changes in chromosome numbers. The gene for the precursor of endostatin resides on chromosome 21 and is expressed at a higher level because there are three copies of the precursor rather than two. Aneuploidy: advantages and disadvantages: can provide alternate functions to the cell, a quick and dirty" adaptation solution to environmental stress. Aneuploidy has been shown to facilitate increased drug resistance in pathogenic bacteria and fungi. X-inactivation applies to most but not all genes on the x. Those genes that are not inactivated are feminisation genes. Xxy - too much transcription of non- inactivated (feminisation) genes xo - not enough transcription of non-inactivated (feminisation) genes in females.
