I. MUTATION & GENETIC VARIATION1. Mutation: a CHANGE or alteration of the DNAsequence that can cause a disruption of a geneand in turn alter the production of a protein
a. Mutation can involve the ENTIRE chromosome or a SINGLE geneb. May HELP, HARM, or have LITTLE to no effect on future generations o Changes may be SILENT or may cause phenotypic changes
c. Can occur during SEXUAL and ASEXUAL reproduction • _INHERITED mutation: occur in gametes and can be passed down to offspring cells – Happens during meiosis • _NONINHERITED mutation: occur in somatic cells which can alter the future new cells – Happens during mitosis!
II. CAUSES OF MUTATION:1. _HEREDITY2. _CARCINOGENS: chemicals, radiation, smoking, alcohol, etc.3. _CHANCE: mistakes that happen during replication but are rare
III. MAJOR EXAMPLES THAT CAUSEMUTATIONS:1. _JUMPING GENES: a TRANSPOSON or segment of DNA that can insert itself into different positions along a chromosome
2. _CROSSING OVER fails: incomplete separation ofchromosomes leads to more or less chromosomesin new progeny (happens in meiosis)
3. SINGLE GENE MUTATIONSa. SUBSTITUTION: ONE or MORE nucleotides are REPLACED by a different nucleotide in the gene sequence ex: AGA copied as AGG Results in a NEW CODON (mRNA) If codon is the same as the original, the protein will not be affected ex: UCU and UCC both code for same amino acid If codon is a “stop” or different amino acid the protein will be altered
b. DELETION: _ONE or MORE nucleotides may be DELETED from the gene sequence o More serious consequences than substitutions o The deletion of a single nucleotide cause remaining nucleotide codons to be grouped incorrectly
IV. RESULTS OF MUTATIONS• CHANGES TO DNA CAN INCREASE CHANCES OF GENETIC VARIATION THAT MAY OR MAY NOT BE HARMFUL1. Hereditary disorders: inherited mutation a. _SICKLE CELL ANEMIA b. _PKU: phenylketonuria c. _CYSTIC FIBROSIS2. Cancer: non-inherited mutation
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