8.7 KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype!!!
mutation = change in an organism’s DNA. Some mutations affect a single gene, while others affect an entire chromosome. mutation = change in an organism’s DNA. Many kinds of mutations can occur, especially during replication!!!! mutated base
Affects a single gene point mutation = substitutes 1 nucleotide for another. frameshift mutation inserts or deletes a nucleotide in the DNA sequence!!! Remember the READING FRAME from Tuesday? A frameshift mutation SHIFTS the reading FRAME!
More details on this when we study MEIOSIS …My-Oh-Sis! Affect entire chromosome, many genes!!! @ Crossing over - exchange of unequal segments Translocation – moving of a piece of 1 chromosome to a nonhomologous part!! More details on this when we study MEIOSIS …My-Oh-Sis!
Translocation results from the exchange of DNA segments between nonhomologous chromosomes!!
Some folks have a mutation that increases cholesterol Chrom mutations tend to have a big effect…WHY? Some gene mutations change phenotype. may cause an “early” stop codon may change protein shape or active site. may change gene regulation Cystic Fibrosis is caused by a deletion – too much mucous, no cure! blockage no blockage Some folks have a mutation that increases cholesterol
ALL FOUR CODONS CODE FOR WHICH AMINO ACID?? CGU CGA CGC CGG ALL FOUR CODONS CODE FOR WHICH AMINO ACID?? LOOK IT UP!! Some gene mutations DO NOT affect phenotype. may occur in a noncoding region (you have “extra DNA” that is never transcribed…) may not affect protein folding or the active site, so the protein may still function normally SOME amino acids are coded by several codons…
Mutations can be caused by several factors. Replication errors can cause mutations. Mutagens, such as UV rays and chemicals, cause mutations. Some cancer drugs use mutagenic properties to kill cancer cells.