DNA Mutations
DNA Mutations
Mutations
• A mutation is a permanent change in DNA.• Since DNA determines all aspects of an
organism, even small changes can have big effects on the organism.
• Some mutations alter one gene while some alter an entire chromosome.
Table Talk!
• Talk to your neighbor for 2 minutes about the following question:
• What kinds of problems do you think a DNA mutation might cause? Do you think they could be life threatening problems?
DNA code is like a recipe, remember?Ingredients•2 sticks of unsalted butter•1 cup light brown sugar•1/3 cup granulated sugar•2 large eggs•2 teaspoons vanilla extract•2 1/2 cups all-purpose flour•1 teaspoon baking powder•1 teaspoon baking soda•3/4 teaspoon salt•2 cups milk chocolate chips
1. Preheat the oven to 350 degrees Fahrenheit
2. Whisk together all ingredients in a separate mixing bowl. Stir in the chocolate chips. Portion 2 tablespoons of dough for each cookie and roll together to form a ball, spacing the dough balls 2 inches apart on the baking sheet.
3. Bake until the edges just start to brown, 12 to 14 minutes. Transfer to a wire rack to cool.
General Types of Mutations
SpontaneousProblem arises in DNA replication or gamete formation.
Ex: Strand slippage
InducedCaused by our environment causes mutation
Ex: Cigarettes, Radiation, Chemicals
Gene Mutations
1. Point Mutations– Mutations that occur in one nucleotide– Substitution: When one nucleotide is substituted for anotherFor example: C-G A-T
Insertions and Deletions
1. Deletion: when a nucleotide is removed (CGC CC)
2. Insertion: when a nucleotide is added (CGC CGAC)
Examples
Table Talk!
• Talk to your neighbor about what kind of mutation this is, and how you know.
• What is the result?
• ACG CCG UAU GUG GGC UAU CUC• Thr Pro Tyr Val Gly Tyr Leu
• ACG CCG UAU GAG GGC UAU CUC• Thr Pro Tyr Glu Gly Tyr Leu
Frameshift Mutations • When an insertion or deletion causes the
“reading frame” to shift• Since nucleotides are read in groups of three
(codons), a reading frame shift causes all of the following amino acids to be changed
• ATG GAA GCA CGT• Met Glu Ala Gly
• ATG AAG CAC GT• Met Lys His
Frameshift Mutation
http://www.youtube.com/watch?v=OS1F54RFD3M
Chromosomal Mutations
• Changes in the number or structure of chromosomes
• 4 types:– Deletion (1 or more genes are deleted)– Duplication (1 or more genes have two copies)– Inversion ( the location of the genes is switched)
– ABCD DCBA
– Translocation (one segment of the chromosome breaks off and attaches to another chromosome
The Good and The Bad
• Good:– Mutations provide genetic variation in species
which increase their chances of survival– Some mutations can fix genetic problems if they
alter a diseased gene and make it normal – EX. Changes in the gene for bone density can
cause individuals to have increased bone density
The Good and The Bad
• Bad:– Many mutations cause genetic diseases– Cancer is usually caused by mutations – Down Syndrome is caused by a chromosomal
mutation where an individual has two copies of chromosome 21
How do mutations occur?
• Two ways:– Given to offspring by parent– Acquired during the organism’s lifetime• UV radiation from the sun• Problems during DNA replication/ cell division• Tobacco • Chemicals