Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A gene is a heritable factor that consists of a length of and influences a specific characteristic.
A gene occupies a specific position on a type of chromosome called the locus (plural: loci).
Alleles are alternative forms of a gene that code for the variations of a specific trait. They differ from each other by only one or a few bases.
New alleles are formed by mutation. A base substitution mutation is the most common, where one base in the sequence of a gene is replaced by a different base.
The genome is the whole of the genetic information of an organism. The human genome consists of approximately base pairs.
Sickle cell anemia is a genetic disease caused by a base substitution mutation on the gene which codes for the -globin polypeptide of hemoglobin.
In sickle cell anemia, the sequence changes from to on the coding strand, resulting in the codon changing from to .
The mutation in sickle cell anemia causes the amino acid to be replaced by at the sixth position of the polypeptide chain.
📐Formulae
💡Examples
Problem 1:
Calculate the difference in the number of base pairs between the genome of () and the human genome ().
Solution:
Explanation:
The human genome is significantly larger than viral genomes. In scientific notation, the difference is approximately .
Problem 2:
Identify the change in the amino acid of the hemoglobin -chain in a patient with Sickle Cell Anemia.
Solution:
Explanation:
The replacement of a hydrophilic (polar) amino acid with a hydrophobic (non-polar) amino acid causes the hemoglobin molecules to polymerize at low oxygen concentrations, distorting the red blood cell into a sickle shape.