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mutations. Schoonover-biology. Mutation: The Basis of Genetic Change. Mutation – a change in structure or amount of DNA Mutagens – factor that causes a mutation Radiation Chemicals. Kinds of mutations. Point mutation – one nucleotide (or base) is changed
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mutations Schoonover-biology
Mutation: The Basis of Genetic Change • Mutation – a change in structure or amount of DNA • Mutagens – factor that causes a mutation • Radiation • Chemicals
Kinds of mutations • Point mutation – one nucleotide (or base) is changed • Ex: G instead of an A • Frameshift mutation – one or more nucleotides are deleted or inserted • Ex: A GG is deleted from the DNA code • Ex: A TGG is inserted in the DNA code • Which do you think is worse?
Results of Mutations • Silent mutation – no change in amino acid • Ex: GCC becomes GCU • Both Alanine • Missencemutation – change in amino acid • Ex: CAC becomes CAA • Histidine becomes glutamine • Frameshift mutation – insertions or deletions = all new amino acids • Could result in ending protein synthesis early (stop codon)
Chromosome mutations • Deletion – a piece of the chromosome is lost • Duplication – a piece of the chromosome remains attached • Translocation – a chromosome piece ends up in a different spot
Effects of DNA change? • 3 outcomes: 1. no difference 2. harmful 3. beneficial • Is the change inherited (given to offspring)? • Somatic cell or body cell? • NO! • Germ cell or sex cell or egg or sperm cell or gamete? • YES! MAYBE!
Other interesting facts… • Genome – all the DNA in an organism’s chromosomes • DNA is universal – but codons may code for different amino acids in different organisms • DNA is made of introns (noncoding regions) and exons (coding regions) • About 80% of DNA does not code for proteins (INTRONS!!!) • DNA is not just in the nucleus • Chloroplasts have DNA • Mitochondria has DNA • About 0.1% of your DNA is in your mitochondria • This DNA comes from only mom…why?