5.1 Mendelian Inheritance

Monks are known for many things…

Gregor Mendel ( ) Austrian monk “the father of modern genetics” tv-shows/greatest- discoveries/videos/100- greatest-discoveries-shorts- genetics.htmhttp://science.discovery.com/ tv-shows/greatest- discoveries/videos/100- greatest-discoveries-shorts- genetics.htm

Pea Plant Experiments Mendel crossed true-breeding plants (the P generation) to form hybrids (the F 1 generation) F1 generation were monohybrids because they differed only in 1 characteristic

Mendel’s conclusions organisms carry 2 “factors” for each trait, one from each parent factors can be dominant or recessive law of segregation explains how only one copy of each gene is in gametes

Take a look at yourself…

Which characteristics do you think are dominant or recessive?

Cheek Dimples cheek dimples are dominant

Brown/black eyes? brown/black eyes are dominant over blue/green eyes

Attached Earlobes? attached earlobes are recessive

Widow’s Peak? pointed hairline is dominant over straight hairline

Hitchhiker’s thumb? a straight thumb is dominant over a bent thumb

Tongue roller? the ability to roll your tongue is dominant

Left thumb on top? when you fold your hands, the left thumb on top is dominant over the right thumb on top

6 fingers? polydactyly is dominant

How are these traits inherited? Back to Mendel…

More terms… alleles are specific forms of genes; some alleles are dominant, some recessive phenotype is the outward appearance of the genotype, which is the set of alleles an individual has genotypes can be homozygous or heterozygous

Punnett square chart that organizes the possible combination of “factors” in offspring See this website for a simple animation on creating a Punnett square: enepool/genepool%20think.htmlhttp:// enepool/genepool%20think.html

Test Cross An individual has the dominant phenotype for a trait. How can you determine if the individual’s genotype is homozygous or heterozygous? Do a test cross…