Making predictions about future generations… Genetics Basics Making predictions about future generations…

Objective I will be able to use Punnett squares to predict the genotype and phenotype of offspring.

Gene vs. Allele Gene: A specific region of the DNA that codes for a particular trait Allele: Any of the alternative versions of a gene that occur at specific locations on a chromosome Example: The alleles for pea flowers are purple and white What are some alleles for eye color?

Introducing the Father of Genetics… Gregor Mendel! A monk that lived in Austria in the 1860s Mendel bred peas to study inheritance. He discovered the founding principles of heredity.

The technique…

The results… X Experiment 1 Purple and white makes…? Purple! Purple and purple makes…? Purple and white! X

The discovery… The dominant allele, is fully expressed in the organism’s appearance. Shown with a CAPITAL LETTER The recessive allele, has no noticeable effect on the organism’s appearance. Shown with a lowercase letter Purple = dominant = P White = recessive = p

Two Alleles for Each Trait For each trait, an organism inherits two alleles One from MOMMY one from DADDY Homozygous: When the two alleles are the same AA or aa Heterozygous: When the two alleles are different: Aa Aa AA aa

Genotype vs. Phenotype Genotype: all the organism’ genetic information that codes for traits “what’s in the DNA” Example: BB, Bb, bb Phenotype: the organisms physical characteristics “what it looks like” Example: Brown or blue eyes

Vocab. Practice… 1. If T = tall and t = short, what is the genotype of each of these: Homozygous dominant: Homozygous recessive: Heterozygous: 2. What is the phenotype for each of these? TT = Tt = tt = TT tt Tt tall tall short

More practice: N = Straight hair, n = curly hair 3. A man that is heterozygous for straight hair, marries a woman who is homozygous recessive for curly hair. Man genotype: Man phenotype: Woman genotype: Woman phenotype: Nn Straight hair nn Curly hair

B = brown eyes, b = blue eyes One more: B = brown eyes, b = blue eyes 4. A man with blue eyes marries a woman who is homozygous dominant for brown eyes. Man genotype: Man phenotype: Woman genotype: Woman phenotype: bb Blue eyes BB Brown eyes