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DNA, genes, and mutations

DNA, genes, and mutations. DNA and genes. The nucleotide sequences are used to encode information that is used to make proteins and enzymes The order of the base pairs can be read my strands of RNA and carried to ribosomes to make molecules. Codons to Protiens.

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DNA, genes, and mutations

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  1. DNA, genes, and mutations

  2. DNA and genes • The nucleotide sequences are used to encode information that is used to make proteins and enzymes • The order of the base pairs can be read my strands of RNA and carried to ribosomes to make molecules

  3. Codons to Protiens • A DNA sequence is lumped into sections of 3 base-pairs called a codon ACGATGCGGTACGTAC . . . is the sequence, broken into codons looks like . . . ACG ATG CGG TAC GTA C . . .

  4. Codons to proteins cont’d • The sequence is read by strands of RNA called messenger RNA (mRNA) and translated into proteins by transfer RNA (tRNA) • Each codon is read and associated with an amino acid (amino acid chains are protiens)

  5. Reading the Sequence . . . ACG ATG CGG TAC GTA C Becomes: Thr-Met-Arg-Tyr-Val . . . However, the sequence starts with a start codon (ATG) and ends with a stop codon (TAA TAG TGA)

  6. Mutations • 3 basic types: • Substitution: swapping one nucleotide for another • Insertion: adding an extra nucleotide • Deletion: removing a nucleotide • Chromosome mutations also occur, but are usually a result of non-disjunction which we already learned

  7. Mutations and Inheritance • Most errors in the DNA code are found and corrected by RNA strands • As we age, the telomeres of the DNA shorten which increases chances for harmful mutations (telomeres are the long ends of a chromosome which contain few genes) • If mutation is persistent and expressed in gametes, it can be passed on

  8. Sickle Cell Anemia • Genetic disorder where red blood cells become sickled in shape (C-shaped) • Mutation causes less oxygen carrying potential for RBC’s (by definition = anemia) • Harmful disorder for most of the world as it causes pain and reduced O2 in blood • HOWEVER. . .

  9. Benefit of SCA • Malaria is a blood borne pathogen (carried in blood transmitted by mosquitos) • Normal RBC’s get infected by parasite and can cause death (over 1 million deaths/year in Africa alone) • SCA will not allow parasite infection as easily due to low O2 levels • SCA-individuals have higher survival rates (and thereby see more SCA cases in Africa and malarial regions of the world)

  10. Methods of Mutations • Spontaneous – mutations that occur naturally and suddenly • Occur by incorrect copying of DNA • Induced – mutations that occur by exposure to physical or chemical agents causing change • Sunlight and UV rays, environmental carcinogens, etc

  11. Moving Genes • Genes can relocate on a chromatid • Transposon – a gene that can jump to new locations on chromatids or to new DNA strands • Transposition – the process of moving a gene

  12. Some haemophiliacs arise as a means of a clotting gene transposon moving into the region for normal blood clotting

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