BIG PICTURE: MAKING PROTEINS DNA  RNA  PROTEIN Nucleus  Cytoplasm  Ribosomes

WHY PROTEINS?? Proteins are polymers = CHON –Proteins make up ENZYMES, muscles, hair, nails, and code for traits Amino acids held together by peptide bonds –There are 20 amino acids in nature Function of the protein depend on the twists and folds

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Mutations Any mistake or change in the DNA sequence –Accuracy of DNA is important to ensure genetic continuity of new cells and offspring

3 types of mutations: 1. Point mutations: change in ONE DNA base –This would change the meaning of the codon on the mRNA –Example: THE DOG BIT THE CAT THE DOG BIT THE CAR = mutation mutate d base

3 types of mutations: 2. Frameshift mutations: a single base is added or deleted from DNA –This would cause every codon to be wrong from that point on in protein coding –Example: THE CAT ATE THE FAT RAT THE ATA TET HEF ATR ATT

3 types of mutations: 3. Chromosomal mutations: –Affects the entire chromosome –If a chromosome is missing= monosomy Monosomy on Sex Chromsomes = Turner Syndrome –45 chromosomes in humans –May involve an extra chromosome = trisomy Trisomy on Chromosome 21 is Down Syndrome –47 chromosomes in humans

CAUSES OF MUTATIONS Mutations can be good, bad or nothing –They are usually random events but…. Errors in DNA provide the variation that must be present for the evolution of species