Genetics and Heredity Gregor Mendel Austrian Monk Experimented

Genetics and Heredity

Gregor Mendel • Austrian Monk. • Experimented with “pea plants”. • Used pea plants because: • They were available • They reproduced quickly • They showed obvious differences in the traits Understood that there was something that carried traits from one generation to the next- “FACTOR”.

Law of Dominance • Law of Dominance: When there is a dominant allele, ONLY the dominant trait will be expressed, even if there is a recessive allele in the pair.

Alleles • Alleles are different versions of a specific gene. • A gene talks about an actual trait, while an alleles is the specific version of that trait. • For example the gene may be hair, but the hair color is the allele.

Dominant and Recessive • Dominant- traits that are expressed (shown, present). This is represented using a capital letter. For example: T= Tall, R= Red, B= Yellow • Recessive- traits that are covered up. This is represented using a lowercase letter. For example: t= Short, p= white, c= Curly

Homozygous and Heterozygous • Homozygous- two of the same alleles. (RR or rr) • RR is said: homozygous dominant • rr is said: homozygous recessive • Heterozygous- two different alleles. ( Rr) • You only have to say heterozygous, and not whether or not it is dominant or recessive.

Genotype & Phenotype • Genotype- the types of genes (Alleles) present. Represented as RR, Rr, or rr. • Phenotype- what it looks like. Represented by adjectives. Red, Skinny, tall, curly.

Punnett Squares and Probability • Punnett square: diagram showing the probabilities of the possible outcomes of a genetic cross

1. Write the genotype in each box 2. Write the phenotype in each box. 3. Tell me the probabilities for the overall box.

The Importance of the Environment The environmental influences the expression of the genotype so the phenotype is altered. Hydrangea flowers of the same genetic variety range in color from blueviolet to pink, depending on the acidity of the soil. Multifactorial; many factors, both genetic and environmental, collectively influence phenotype in examples such as skin tanning

How is it possible to maintain such genetic continuity?