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Lecture

Chromosome Variation

In course

BIO-373: Genetics and genomics

The theoretical part of this course covers classical genetics and contemporary genomics. Because bioinformatics has become important for genomic research, the course also includes practical applications to genomic analyses using Python, including group pro ...

Description

This lecture covers variations in chromosome numbers, including monosomy, trisomy, euploidy, and polyploidy. It also discusses variations in chromosome structure or content, such as deletions, duplications, inversions, and translocations.

Instructors (2)

Bart Deplancke

Jacques Fellay

Jacques Fellay is a medical scientist with expertise in infectious diseases and human genomics. He obtained his MD from the University of Lausanne in 2002 and his PhD from University of Utrecht. After a clinical training in infectious diseases in Switzerland and a 4-years postdoctoral fellowship at Duke University, he joined the EPFL in April 2011 with an SNF Professorship. On top of his EPFL affiliation, Jacques is also Head of Precision Medicine at the University Hospital (CHUV) in Lausanne, Group Leader at the Swiss Institute of Bioinformatics, and Co-director of the Health2030 Genome Center at Campus Biotech in Geneva.

Official source

Ontological neighbourhood

Biology

Molecular biology: Chromosomes

Related concepts (28)

Y chromosome

The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. The other sex chromosome is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or absence of Y that determines the male or female sex of offspring produced in sexual reproduction. In mammals, the Y chromosome contains the gene SRY, which triggers male development. The DNA in the human Y chromosome is composed of about 62 million base pairs, making it similar in size to chromosome 19.

Chromosomal inversion

An inversion is a chromosome rearrangement in which a segment of a chromosome becomes inverted within its original position. An inversion occurs when a chromosome undergoes a two breaks within the chromosomal arm, and the segment between the two breaks inserts itself in the opposite direction in the same chromosome arm. The breakpoints of inversions often happen in regions of repetitive nucleotides, and the regions may be reused in other inversions. Chromosomal segments in inversions can be as small as 100 kilobases or as large as 100 megabases.

Aneuploidy

Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a euploid cell. An extra or missing chromosome is a common cause of some genetic disorders. Some cancer cells also have abnormal numbers of chromosomes. About 68% of human solid tumors are aneuploid.

Robertsonian translocation

Robertsonian translocation (ROB) is a chromosomal abnormality wherein the entire long arms of two of a certain type of a chromosome called an acrocentric chromosome become fused to each other. It is the most common form of chromosomal translocation in humans, affecting 1 out of every 1,000 babies born. It does not usually cause direct health difficulties, however such persons are almost always infertile because their chromosome count does not match that of most humans.

Homologous chromosome

A couple of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. Homologs have the same genes in the same loci where they provide points along each chromosome which enable a pair of chromosomes to align correctly with each other before separating during meiosis. This is the basis for Mendelian inheritance which characterizes inheritance patterns of genetic material from an organism to its offspring parent developmental cell at the given time and area.

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