Variation What is variation Variation Lab Day 1
Variation What is variation? Variation Lab – Day 1 Variation Lab – Day 2 How does variation arise?
Variation - a difference or deviation in structure or character from others of the same species or group
Single-gene Traits – traits controlled by a single gene that has two alleles p Examples – cleft chin, hitchhiker’s thumb, tongue rolling, attached/unattached earlobes
Polygenic Traits– traits controlled by two or more genes p Range of phenotypes p More than two genes p Examples – height, performance on IQ tests, skin color, eye color
Variation Lab – Definitions p Species - a group of organisms capable of interbreeding and producing fertile offspring p Population – groups of individuals of the same species that interbreed p Gene Pool – all genes that are present in a population
Variation Lab – What will you be doing? p Mealworms – LENGTH of mealworm (mm) p. Peanuts – LENGTH of inside nut, or cotyledon (mm) p Hand – LENGTH of hand spread from thumb to little finger
Variation Lab - Predictions
Variation Lab - Graphing
Variation Lab – Graphing Instructions p Label the x-axis (independent variable) and the y-axis (relative frequency). p Determine the maximum and minimum values for each variable and a standard width for each bar and set them on your axes. p Draw a bar for each range of values that shows how many organisms have a trait that measures within that range. Repeat this for all ranges of measurements.
Mealworm (mm) Size <9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 >28 Number Peanut (mm) Size <9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 >28 Number Hand Size (mm) Size <14 15 16 17 18 19 20 21 22 23 24 25 >26 Number
Genetic Variations p Mutations n p Due to mistakes in the replication of DNA or radiation or chemicals in the environment Gene Shuffling n Occurs during meiosis
Genetic Variations – Mutations: Sickle Cell Anemia
Sickle Cell Anemia Mutation – Harmful or Beneficial? NN – normal round blood cells p NS – normal round blood cells; immune to malaria p SS – sickle-celled blood cells p
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