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MUTATIONS Mistakes in DNA. The Big Picture. Chromosome. DNA double helix. Coils. Supercoils. Proteins. Chromosomes are made up of super coiled strands of DNA Genes are sections of your chromosome made up of DNA. Mutations. Mutations are changes in genetic material.
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The Big Picture Chromosome DNA double helix Coils Supercoils Proteins • Chromosomes are made up of super coiledstrands of DNA • Genes are • sections of your chromosome • made up of DNA
Mutations • Mutations are changes in genetic material. • There are two major mistakes that can happen: • Chromosomal Mutations • Gene Mutations
Type 1: Chromosomal Mutations • Whole chromosome is affected. • Large sections of DNA can be • Removed from a chromosome • Added to a chromosome • Rearranged within a chromosome • Switched with DNA from another chromosome. • These mutations are usually very harmful
Chromosomal Mutations Deletion loss of material Duplicationaddition of material Inversionrearrangement of material Translocation switching material with another chromosome
Type 2: Gene Mutations • Changes that occur in a single gene. • Change occurs at the DNA nucleotide level Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)
Two Types of Gene Mutations • Point mutations: one nucleotide that affects one amino acid. Example: Substitution C changes to G
Two Types of Gene Mutations 2. Frameshift mutations: • involve the reading of the DNA or m-RNA strand • many amino acids are affected. Examples: Insertion Deletion
Mutation Can Be… • Neutral (a.k.a. Silent) • Example: Substitution • UCU = Serine if the last U is changed to C, A or G the mRNA will still make Serine • Harmful • Example: Substitution • Sickle Cell Anemia • There is a change 17th nucleotide in the code for hemoglobin • A is changed to a T - GAG changes to GTG • How does this change the amino acid? • GLU changes to VAL • This changes hemoglobin’s shape from round to sickle shaped
Mutation Can Be… 3. Harmful (more harmful) • Example: Frameshift - Deletion • Shifts the whole reading frame • Changes the amino acids produced • Harmful (even more harmful!) • Example: Chronic myelogenous leukemia • Translocation • Pieces of 2 chromosomes switch • Causes white blood cells to divide and reproduce improperly.