Genetics and Heredity

Heredity The passing of traits from parent to offspring.

Heredity 1. Genes on chromosomes control the traits that show up in an organism

Heredity 1. Genes on chromosomes control the traits that show up in an organism 2. The different forms of a trait that a gene may have are alleles

Heredity 3. During Meiosis a pair of chromosomes separates and the alleles move into separate cells

Heredity 3. During Meiosis a pair of chromosomes separates and the alleles move into separate cells 4. Each chromosome now contains one gene for each trait.

Heredity 5. The study of how traits are inherited is genetics

B. Gregor Mendel Known as the father of genetics Austrian monk Studied mathematics and science Began experimenting with garden peas in 1856

B. Gregor Mendel 1. Mendel was the first to use the mathematics of probability to explain heredity and to trace one trait for several generations

B2 Hybrid 2. A hybrid receives different genetic information for a trait from each parent

B2 Hybrid 2. A hybrid receives different genetic information for a trait from each parent a. Dominant allele- covers up or dominates the other trait

B2 Hybrid 2. A hybrid receives different genetic information for a trait from each parent a. Dominant allele- covers up or dominates the other trait b. Recessive allele- trait that seems to disappear

B3 Probability 3. Probability helps you predict that chance that something will happen

B4 Punnett Square 4. A Punnett square can help you predict what an offspring will look like

B4 Punnett Square 4. A Punnett square can help you predict what an offspring will look like a. Uppercase letters stand for dominant alleles

B4 Punnett Square 4. A Punnett square can help you predict what an offspring will look like a. Uppercase letters stand for dominant alleles b. Lowercase letters stand for recessive alleles

B5 Genotype 5. Genotype is the genetic makeup of an organism

B5 Genotype Genotype is the genetic makeup of an organism a. Homozygous- an organism with two alleles for one trait that are the same (Ex. Written TT, or tt) – (Mendel would have called it purebred)

B5 Genotype Genotype is the genetic makeup of an organism a. Homozygous- an organism with two alleles for one trait that are the same (Ex. Written TT, or tt) – Mendel would have called it purebred b. Heterozygous- an organism with two alleles for one trait that are different (ex. Written Tt) – Mendel would have called it hybrid

B6 Phenotype 6. Phenotype – the way an organism looks or behaves as a result of its genotype.

Punnett Practice This animated punnett square shows a cross between a homozygous brown eyed father (BB) and a homozygous blue-eyed mother (bb) All of the children will be heterozygous for Brown eyes (Bb)

Punnett Practice The orange bird has two dominant A genes. We put two A s along the top of the square. The blue bird has two recessive a genes.   We put two a s down along the left side of the square. All the offspring have the genes Aa. They will all have orange feathers, but will carry a recessive gene for blue feathers. This is called the F1 generation

Punnett Practice Now suppose that two individuals from the F1 generation become parents.   Here they are!   The baby birds are called the F2 generation.   You can see how their genes work out.-- The offspring are coded in the squares. One bird will be orange with two AA genes. Two birds will be orange with genes coded Aa. One bird will be blue and will have two recessive aa genes. Individual nests of birds may not turn out exactly like this, but if there are many baby birds, they will work out genetically with the ratios 1:2:1.