Eukaryote chromosomes
Eukaryote chromosomes are made of DNA and
proteins.
Definition of gene, allele and genome
Gene - a heritable factor that controls a
specific characteristic.
Allele - one specific form of a gene.
Genome - whole of the genetic information
of an organism.
Definition of gene mutation
Gene mutation - a change to the base
sequence of a gene.
Consequence of a base substitution mutation
Sickle cell anemia occurs when a \base substitution mutation converts sixth
codon of the gene from GAG to GTG. Allele with this gene is Hb5
instead of Hb4. When the Hb5 is transcribed, the amino
acid produced will be valine instead of glutamic acid. This causes hemoglobin
to stick together in tissues with low oxygen concentrations. Chains of
hemoglobin join together into bundles that are rigid to distort red blood cells
into sick shape. They also damage tissues because they become trapped in blood
capillaries, blocking/reducing blood flow. Hemoglobin cannot effectively carry
oxygen, causing individual to feel tired; it also causes anemia (low RBC
count), as sickle cells are destroyed more easily. Also, sickle cell anemia has
been known to cause malaria resistance.
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