Understanding Mutations in DNA and Their Effects
Mutations in DNA are changes that can occur in body cells or gametes, leading to alterations in the genetic code. Not all mutations are harmful, but they can impact protein structure and function. Different types of mutations, such as substitutions, insertions, and deletions, can result from various factors including mutagens in the environment. Point mutations, like missense changes, can have significant consequences, like in the case of sickle cell anemia. Frameshift mutations, which alter the reading frame of genes, can cause significant downstream effects. Understanding these mutations is crucial in comprehending genetic disorders and inheritance patterns.
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Notes on Mutations A change in DNA
Mutations Mutation Mutation: a change in DNA -not all mutations are harmful -can happen in body cells and in gametes. ** **mutations are passed down to offspring only when they are in the gametes ** ** Types of Mutations Types of Mutations Substitution: one base is substituted for another ACTTAGGC ACATAGGC Insertion: a base is added ACTTAGGC ACTTAGGCT Deletion: a base is removed ACTTAGGC ACTTAGG__
Mutagens: Mutagens: factors in the environment that cause mutations Ex: x-rays, UV light, radiation, chemicals, smoking, sun ta https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQAazMOfKKyRFeYB_ZTfV4jWedLtNM9wAFm5xzbnV2FEIWylj2txkdgea1D https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTHeWDfxdiK1ALAO0HqhZEWMDd1XlPGJOukbGhJFxZvg3EKkwI29HZEKQ71 https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQT5cWEqb9yYmyaOzE3gYrfMrV24gY7rW9a2cNfAOaal8rnX7VetwPaCw
Mutations Mutations are changes in DNA sequences changes to the order of A, T, C & G different order = different amino acid in protein different protein structure = different protein function BB Bb bb
Mutations Point mutations single base change silent mutation no amino acid change redundancy in code missense change amino acid nonsense change to stop codon
Point mutation leads to Sickle cell anemia What kind of mutation? Missense!
Sickle cell anemia Primarily Africans recessive inheritance pattern strikes 1 out of 400 African Americans
Mutations Frameshift shift in the reading frame changes everything downstream insertions adding base(s) deletions losing base(s) Where would this mutation cause the most change: beginning or end of gene?
Frameshift mutations THERATANDTHECATATETHEREDBAT THERATANDTHECATATETHEREDBAT Deletion THERTANDTHECATATETHEREDBAT THERTANDTHECATATETHEREDBAT Insertion THERAATANDTHECATATETHEREDBAT THERAATANDTHECATATETHEREDBAT
Cystic fibrosis Primarily whites of European descent strikes 1 in 2500 births 1 in 25 whites is a carrier (Aa) normal allele codes for a membrane protein that moves Cl- across cell membrane mutant channel limit movement of Cl- (& H2O) across cell membrane thicker & stickier mucus coats cells mucus build-up in the pancreas, lungs, digestive tract & causes bacterial infections without treatment children die before 5; with treatment can live past their late 20s