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What was Hippocrates explanation of inheritance?
Pangenesis: particles called pangenes travel from each part of an organism's body to the eggs or sperm and then are passed to the next generation.
The transmission of traits from one generation to the next.
- The scientific study of heredity.
- Began in the 1860's.
What did Mendel call genes?
A heritable factor "gene" that varies among individuals, such as flower color.
Each variant for a character, such as purple or white flowers.
Sperm-carrying pollen grains released from the stamens land on the egg-containing carpel of the same flower.
Fertilization of one plant by pollen from a different plant.
Varieties for which self-fertilization produced offspring all identical to the parent.
- The offspring of two different varieties.
- The cross-fertilization itself is referred to as hybridization or simply a genetic cross.
- The true-breeding parental plants.
- "P" for parental.
- The hybrid offspring.
- "F" for filial, from the Latin word for "son".
When F1 plants self-fertilize or fertilize each other.
The parent plants differ in only one character - flower color.
- The alternative versions of a gene.
- Example: the gene for flower color in pea plants exists in two versions: one for purple and the other for white.
- Two indentical allels for a gene.
- Example: BB, PP
- Two different allels for a gene.
- Example: Bb, Pp
- When one allele determines the organism's appearance.
- We use uppercase letters to represent dominant alleles.
- An allele that has no noticeable effect on the organism's appearance.
- We use lowercase letters to represent recessive alleles.
Mendel's Law of Segregation
- A sperm or egg carries only one allele for each inherited character because allele pairs seperate (segregate) from each other during the production of gametes.
- When sperm and egg unite at fertilization, each contributes its allele, restoring the paired condition in the offspring.
A table that shows the four possible combinations of alleles that could occur when gametes combine.
The expressed (physical) traits of an organism.
The genetic makeup of an organism.