Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Genetic Dosage and Chromosome 21

In course

BIO-105: Cellular biology and biochemistry for engineers

Basic course in biochemistry as well as cellular and molecular biology for non-life science students enrolling at the Master or PhD thesis level from various engineering disciplines. It reviews essential notions necessary for a training in biology-related ...

Description

This lecture discusses the importance of genetic dosage, focusing on Trisomy 21 and the protein concentration in disomic and trisomic cells. It explores Chromosome 21, the X chromosome, X-inactivation, Barr bodies, and X-linked inheritance.

Instructor

Romain Zufferey

Official source

Ontological neighbourhood

Biology

Molecular biology: Chromosomes

Related concepts (25)

X chromosome

The X chromosome is one of the two sex chromosomes in many organisms, including mammals, and is found in both males and females. It is a part of the XY sex-determination system and XO sex-determination system. The X chromosome was named for its unique properties by early researchers, which resulted in the naming of its counterpart Y chromosome, for the next letter in the alphabet, following its subsequent discovery. It was first noted that the X chromosome was special in 1890 by Hermann Henking in Leipzig.

Chromosome

A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation.

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.

X-inactivation

X-inactivation (also called Lyonization, after English geneticist Mary Lyon) is a process by which one of the copies of the X chromosome is inactivated in therian female mammals. The inactive X chromosome is silenced by being packaged into a transcriptionally inactive structure called heterochromatin. As nearly all female mammals have two X chromosomes, X-inactivation prevents them from having twice as many X chromosome gene products as males, who only possess a single copy of the X chromosome (see dosage compensation).

Chromosome 21

Chromosome 21 is one of the 23 pairs of chromosomes in humans. Chromosome 21 is both the smallest human autosome and chromosome, with 45 million base pairs (the building material of DNA) representing about 1.5 percent of the total DNA in cells. Most people have two copies of chromosome 21, while those with three copies of chromosome 21 have Down syndrome, also called "trisomy 21". Researchers working on the Human Genome Project announced in May 2000 that they had determined the sequence of base pairs that make up this chromosome.

Related lectures (32)

Genetic Dosage and Chromosome Abnormalities

Explores genetic dosage, X chromosome inactivation, and chromosome abnormalities, illustrated by real-life examples and genetic concepts.

Chromosomal Dosage and Genetic Disorders

Explores chromosomal dosage, genetic disorders, inheritance patterns, and X chromosome inactivation.

Genetic Expression and Chromosome Dosage

Explores genetic expression, chromosome characteristics, X chromosome inactivation, and DNA methylation impact.

Cellular Biology: Mitosis and Meiosis Overview

Covers cellular biology, focusing on mitosis, meiosis, and the cell cycle processes.

Chromosome Variation