Mendel’s Peas pg. 648 Describe Mendel’s genetics experiments Identify the factors that control the inheritance of traits in organisms Explain how genetics use symbols to represent alleles

Vocabulary Heredity- purebred- gene- allele- dominant allele- recessive allele- hybrid- Genetics- Traits-

Questions: 1.What factors control the inheritance of traits in organisms? 2.What is a purebred? 3.If a pea plant has a tall stem, what possible combinations of alleles could it have?

Gregory Mendel 1851 Priest, Teacher, Gardner Pea plants have different traits - different physical characteristics similar to parents- heredity - passing of traits from parents to offspring) 10 yrs. of study & 1000’s of plants to understand heredity his work laid foundation for genetics-study of heredity

Flowering Pea Plant traits in only two forms produce many offspring able to collect much data developed method of cross pollinating

Genetics of Pea Plants

Mendel’s Experiments -wanted to cross tall with short purebred plants - always produce the same form of trait as the parent Tall purebred Tall offspring Short purebred Short offspring -self pollinate for many generations -offspring will always be identical to parent

Experiment #1 Tall Purebred parental generation=P Short Purebred parental generation=P X F1 generation filial “son” in latin

Surprise! F1 generation All Tall short trait disappeared ? Next, let grow and let self pollinate

Surprise again!!! F2 (second filial generation) Mix of tall and short no F1’s were short; shortness trait reappeared

What? I don’t get it!

Inferences made by Mendel Individual factors control inheritance of traits Factors controlling traits exist in pairs; male and female One factor can ‘mask’ (hide) another, example: Tall masked short height Scientists call factors that control traits, ‘genes’. Different form of genes are alleles.

‘Gene’ that controls ‘Stem Height’ T s T s Combination of two Dominant allele (Capitalized) -always shows up in organism when present Recessive allele (lower case) -masked or covered up when dominant allele is present alleles

Understanding Mendels Crosses 1 tall allele ‘ D’ 1 short allele ‘ r’ 1 tall, 1 short =hybrid-two different alleles for the trait TT Ts TT Tsss

Mendel’s Contribution 1866 submitted paper to Scientific Society; other scientists deemed not important, too oversimplified no phones or communication forgotten for 34 years 1900 three other scientists came upon same conclusion and recognize Mendels’ work Father of Genetics

Mendel quiz 1. Different forms of a gene. 2. An allele that is masked when a dominant allele is present 3. An organism that always produces offspring with the same form of a trait as the parent 4. An allele whose trait always shows up in the organism when the allele is present. 5. The passing of traits from parents to offspring. 6. A segment of DNA on a chromosome that codes for a specific trait. 7. An organism that has two different alleles for a trait.

Questions: 8. What factors control the inheritance of traits in organisms? 9 & 10. If a pea plant has a tall stem, what possible combinations of alleles could it have?

Answers to Mendel quiz 1 pt. each 1.Allele 2.Recessive allele 3.Purebred 4.Dominant allele 5.Heredity 6.Gene 7.Hybrid 8. Genes 9 & 10. TT, Ts. __/10