Genetics 4.1

1. Genetics 4.1

2. 4.1.1 Eukaryotic Chromosomes • Long chains of DNA molecules • Eukaryotic chromosomes are made of DNA and proteins • Typical chromosome contains about 1000 genes arranged in particular linear sequence. Why?

3. 4.1.2 Genes • Gene – basic unit of inheritance; located on chromosome in specific location (called locus) • Heritable Factor that controls a specific characteristic(s) by controlling the specific order of amino acids used to make protein

4. 4.1.2 Alleles • Chromosomes all have the same gene loci in the same order, but there can be different versions of the genes (alleles) • Simply a difference in a couple of base pairs which code for a different protein to be produced • For example, one of the genes that determines eye color has two different alleles, one the codes for brown eyes and one that codes for non-brown eyes (the actual color would be determined by a different gene)

5. 4.1.2 Genome • All genes of a particular organism • The whole of the genetic information of an organism • Not just genes that are expressed, but also genes that are simply carried by the organism

6. 4.1.3 Gene Mutations • A change in DNA sequence that creates genetic diversity • Caused by DNA copying errors or mutagens (anything that can alter the base pair sequence of a gene) • Mutagens include any form of high energy radiation (UV, X-ray, Gamma) and certain chemicals (like benzene)

7. 4.1.4 Base substitution mutation • This type of mutation is when one base is mistakenly substituted for another. • Sickle cell anemia is caused by this type of mutation • GAG codon is mutated to GTG causing valine to be produced instead of glutamic acid (causes sickle cell anemia) • This causes the hemoglobin to cyrstallize (form clumps) in the cell, distorting the shape of the cell into a curved form. • The cell cannot carry as much oxygen so the person is tired and weak all the time