Genetics 5 Flashcards
(13 cards)
What is a karyotype?
Complete set of chromosomes in a cell, organised by size, shape and number.
What is an aneuploidy?
Different numbers of chromosomes
What causes an aneuploidy?
Segregation errors during meiosis.
What are the 3 examples of trisomys and the syndromes associated?
Trisomy 21 (down syndrome)
Trisomy 18 (Edward syndrome)
Trisomy 13 (Patau syndrome)
What is an example of a monosomy and the syndrome associated?
Monosomy X - Turners syndrome
Why do aneuploidies of the sex chromosomes tend to be less severe?
The Y-chromosome is non-essential and only contains a small number of genes
X-chromosome variation is well tolerated because of mechanism in place to normalise gene expression between males and females.
What is sickle cell anaemia?
Red blood cells adopt sickle cell shape under low oxygen concentrations
What does sickle cell anaemia cause?
Sickle red blood cells cant deform through narrow vessels, causing blockages. These blockages can lead to ischaemia, pain and organ damage.
What type of disease is sickle cell anaemia?
Autosomal recessive genetic disease.
What causes sickle cell anaemia?
A single base substitution in the beta-haemoglobin gene
What is the change in the codon for this mutation?
Wild type (GAA) to sickle cell allele (GTA)
How does this mutation bring around symptoms?
A complex downstream biochemical and cellular cascade.
What disease does sickle cell anaemia offer some protection of?
Malaria
