Intro to Genetics Objectives: Differentiate b/t genotype and phenotype Differentiate b/t homozygous and heterozygous

What is Genetics? The scientific study of heredity

Gregor Mendel Born in 1822 in Czechoslovakia 1843—became a monk Taught biology…  Studied at the University of Vienna

More about Mendel Loved studying the garden at the monastery Between the years of 1856 and 1863 he grew and tested of 28,000 pea plants Used pea plants b/c they are easy to grow and they have easily identifiable traits

Mendel’s Experiments Mendel created a “pure” generation or true-breeding generation (first generation) Made sure that certain plants were only able to self pollinate to eliminate unwanted traits He cut off the stamen (male part) of each flower

Genes and Dominance Trait: a characteristic Mendel studied 7 traits After he was sure the true breeding generation was “pure” he crossed plants with contrasting traits This was called the F1 generation

Pure Yellow/Pure Green All offspring were yellow Hybrids—the offspring of crosses between parents with contrasting traits

Conclusion Inheritance is determined by factors passed on from one generation to another Mendel know nothing about chromosomes, genes or DNA Why?

Mendel’s Factors Genes Each gene has different forms called alleles Mendel’s second principle stated that some alleles are dominant and some are recessive

Mendel’s Second Cross Allowed the F1 generation to self-pollinate to produce the F2 generation What happened in this cross? What would happen when he crossed two yellow pea hybrids?

Results ¾ of the peas were yellow, ¼ of the peas were green

Probabilitity The likelihood of a particular event occurring. Chance Can be expressed as a fraction or a percent

Genotypes Homozygous—when an organism possesses two identical alleles. YY or yy Heterozygous—when an organism possesses different alleles Yy

Genotype vs. Phenotype Genotype: Phenotype: Genetic makeup Symbolized with letter Tt or TT (any letter works) Phenotype: Physical appearance of the organism Expression of the trait Short, tall, yellow, smooth, etc…

A-angry B-Big C-cool D-Dense E—energetic a-happy b-small c-hot d-intelligent e--tired Genotype Phenotype Aa Bbcc BB Eebbcc Cc Happy, cool, intelligent EE Dense, hot, angry Energetic ddEeCC Happy aaCcdd aaEE Small, hot, tired, intelligent Small, dense Angry, intelligent, energetic, cool

Homozygous vs. Heterozygous BB Bb bb GG gg Gg

If a chocolate lab is dominant over a yellow lab, give the possible genotypes for the following

Traits in Humans Traits Dominant Recessive Phenotype Possible Genotypes Earlobes Free Attached Hairline Widow’s peak Straight line Eye shape Almond Round Eyelash length Long Short Tongue dexterity Can roll Unable to roll Thumb Hitchhikers Straight Lip thickness Thick Thin Hair texture Curly/wavy Inter-eye distance Close/medium Far apart Lip protrusion Protruding/slightly Not protruding Hand crossing Left over right Right over left

Rate of Frequency Observed Traits Number observed Percentage of population Tongue roller/nonrollers Free earlobes/attached Hitchhikers thumb/regular Widow’s peak/straight Almond eyes/round Long lashes/short Thick lips/thin lips Curly/straight Close eyes/far ears Protruding/not protruding Left over right/ right over left l