Mutations and Gene Regulation
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Slide 1 - Mutations and Gene Regulation
Slide 2 - Review of Genetic Code
- Genes are the instructions for making specific proteins.
- Genes are made of DNA.
- A single strand of DNA contains hundreds of genes.
- Humans have 46 pieces of DNA in each cell, and 20,000-25,000 genes (still figuring that out!)
Slide 3 - DNA and the Genetic Code
Slide 4 - Examples of Human Genes
- Lactase Enzyme
Slide 5 - Lactase Enzyme
Slide 6 - GENE 1- Lactase Enzyme
- DNA Sequence 1: --CCC-CTG-GGC-
- RNA Sequence 1: --GGG-GAC-CCG
- Protein 1: -GLYCINE-ASPARTIC ACID-PROLINE
- Variation 1: Lactose Intolertant (cannot digest)
- DNA Sequence 2: -TCC-CTG-GGC
- RNA Sequence 2: -AGG-GAC-CCG
- Protein 2: -ARGININE-ASPARTIC ACID-PROLINE
- Variation 2: Lactose Tolerant (can digest)
Slide 7 - Gene 2- Hemoglobin Protein
Slide 8 - Hemoglobin Gene
- Sequence 1: --GGA-CTC-CTC-
- Protein 1: -PRO-GLT-GLT-
- Variation 1: Normal Hemoglobin
- Sequence 2: --GGA-CAC-CTC-
- Protein 2: -PRO-VAL-GLT-
- Variation 2: Abnormal Hemoglobin = SICKLE CELL
Slide 9 - BRCA-1 and Cancer
Slide 10 - Change in Sequence, Change in Trait?
- Changing the DNA sequence does not necessarily change the form of the trait
- There is ONLY a problem if the PROTEIN is affected (amino acid sequence gets changed)
- Ex: CTT CTC
- CODONS: GAA GAG
- Amino Acids = GLT = GLT
- = NOT A PROBLEM!!!
Slide 11 - MUTATIONS
- A mutation is any change in the DNA.
- Some mutations are silent (do not change the protein)
- Mutations may be harmful if they change the amino acid sequence.
- Examples of Mutations:
- GAG GAC
- GAATC GAAATC
- GAATC GATC
Slide 12 - What CAUSES Mutations?
- Many / most mutations are RANDOM
- Errors during replication (copying DNA)
- Some mutations are caused by mutagens = any substance that causes a change to DNA
- Radiation (X-rays, UV rays)
- Chemicals (many carcinogens are mutagens)
Slide 13 - Gene Regulation
- In any individual cell, only a small fraction of the total genes are working; most of the genes are silent.
- How does a cell “know” whether to turn a gene “on” or “off”?
- Certain triggers cause genes to turn “on” (start making protein) or turn “off” (stop making protein)
- Macrophage, Skin Cells
- Rods and Cones
Slide 14 - Gene Activation: Genes Turned “on” or “off”