2. Important Vocabulary  Heredity  Allele  Genetics  Hybrid  Dominant  Recessive  Punnett square  Genotype  Phenotype  Homozygous  Heterozygous

3. Inheriting Traits  Heredity: the passing of traits to offspring  An organism is a collection of traits inherited from its parent or parents

4. What is genetics?  Alleles: different forms of a trait that make up a gene pair  When a pair of chromosomes separate during meiosis, the alleles of a gene pair also separate into different sex cells  As a result, every sex cell has one allele for each trait  Genetics: the study of how traits are inherited through the interactions of alleles http://glencoe.mcgraw- hill.com/sites/0078693918/student_view0/concepts_in_motion.ht ml# (Click on Meiosis and Fertilization)

5. Mendel- The Father of Genetics  Gregor Mendel  Austrian monk who studied math and science  Became the gardener at a monastery  Predicted the types of flowers and fruits that would result from crossbreeding two plants  Began experimenting with peas in 1856  Shared results 8 years later with other scientists http://science.discovery.com/tv- shows/greatest-discoveries/videos/100- greatest-discoveries-shorts-genetics.htm

6. Mendel- The Father of Genetics  Mendel was the first scientist to trace one trait through several generations

7. Genetics in a Garden  Each time Mendel studied a plant, he crossed two plants with different expressions of the trait  He found that the new plants all looked like one of the two parents  These new plants were called “hybrids”  Hybrid: receives different genetic information, or different alleles, for a trait from each parent  Purebred: organism that always produces the same traits generation after generation

8. Dominant and Recessive Factors  Mendel found that tall plants that were crossed with short plants produced seeds that were all tall plants  Mendel called the tall form the “dominant” factor  Dominant: dominates, or covers up, another allele  Dominant alleles are written in capital letters  Ex. B = purple flower  Recessive: allele that seems to “disappear” or is covered up  Recessive alleles are written in lower case letters  Ex. b = white flower

9. Using Probability to Make Predictions  Mendel dealt with probabilities  His results were more accurate because he worked with many plants– about 30,000 pea plants!  This increased Mendel’s chances of seeing a repeatable pattern  Punnett square: tool used to predict the results in Mendelian genetics

10. Punnett Squares  In Punnett squares, letters symbolize alleles  Remember, capital letters represent dominant alleles and lowercase letters represent recessive alleles  The letters form a code for the genetic makeup an organism  Genotype: genetic make up of an organism (BB, Bb, bb)  Phenotype: the way an organism looks and behaves based on their genotype (purple flower or white flower)

11. Alleles Determine Traits  Most cells in your body have at least two alleles for every trait  Located on chromosomes within each cell’s nucleus  Homozygous: an organism that has two alleles that are the same  Example: BB or bb  Heterozygous: an organism that has two different alleles  Example: Bb

12. Making a Punnett Square  Make a grid like this one:  One parent’s alleles are placed on the top, second parent’s alleles place along the side like this (one letter per column/row):  Each square is filled in with one allele donated by each parent.  Make sure the capital (or dominant) allele is placed before the lowercase (or recessive) allele.  In this Punnett square, the probability of each genotype is:  BB: 25% or ¼  Bb: 50% or ½  bb: 25% or 1/4 Bb B b Bb BBbBbB bbBbBb Bb BBBbBb bBbBbb

13. Principles of Heredity  It took Mendel years of detailed observation, careful analysis, and repeated experimentation to conclude his ideas of heredity. The following tables sums them up in three principles:

14. Video Links  http://www.youtube.com/watch?v=xc2wbIDfO7E http://www.youtube.com/watch?v=xc2wbIDfO7E  http://learn.genetics.utah.edu/content/begin/traits/tour_t rait.html http://learn.genetics.utah.edu/content/begin/traits/tour_t rait.html  http://learn.genetics.utah.edu/content/begin/traits/tour_ heredity.html http://learn.genetics.utah.edu/content/begin/traits/tour_ heredity.html

15. Resources Florida Science Grade 8  Glencoe Science & McGraw Hill Publishing Google Images