Mutation

• MUTATIONS - errors in genetic sequence that can lead to changes in the amino acid sequence
• Silent mutation - amino acid produced from mutated strand is the same as the amino acid produced from original strand
• Missense mutation - amino acid produced from mutated strand is different from the amino acid produced from the original strand
• Frameshift - addition or deletion of nucleotides causes shift in reading frame, leading to production of nonfunctional proteins
• Nonsense mutations - premature stop codon introduced into mRNA, resulting in truncated protein
• Point mutation - a single nucleotide is changed in the DNA sequence of a gene.
• Insertion mutation - nucleotides are inserted, changing the set of codons and how they’re read
• deletion mutation - nucleotides are deleted, changing the set of codons and how they’re read
• Classical Breeding - mating of two species with desired qualities • natural process
• Modern Genetic Engineering - desired genes are directly introduced • genetic material is altered, cut, or inserted • examples: in vitro fertilization, cloning, recombinant DNA technology, DNA fingerprinting
• RECOMBINANT DNA TECHNOLOGY - involves cutting the DNA of interest and using a vector to propagate it
• vector – carries the designed DNA to a host cell (e.g., yeast, plasmid)
• restriction enzyme – enzyme that recognizes and cuts foreign DNA at specific sites
• ligase – enzyme used to join fragments together
• plasmids – small circular pieces of DNA found outside chromosomes; can be engineered as vectors
• selection marker gene – gene sequence that is added to differentiate a transformed plasmid from the non-transformed plasmids
• biolistics – uses a gene gun to fire DNA-coated pellets on plant tissues
• heat shock treatment – uses heat to manipulate cell pore size
• electroporation – uses an electric “shock”
• CRISPR-Cas9 - “gene editing” in living cells
• Cas9 – bacterial protein that helps in defending the bacteria against bacteriophage infections; cuts any sequence to which it is directed
• gRNA – guides the Cas9 protein to a target gene; complementary to a target gene
• GENE THERAPY - introduction of genes to an afflicted individual for therapeutic purposes
• GENE THERAPY - goal is to insert a normal allele of a defective gene into the body cells of the tissue affected by the disorder