i cant understand it from my book or teacher...she talks too fast
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I am a retired AP biology teacher, and I know Mendel's Laws as two, but I think I might know why your teacher divided them into three. At any rate, I'll give it a shot and you can decide if this is a usable answer for you.
The first law is the Law of Segregation.
Mendel realized, by crossing many generations of pea plants with various physical characteristics, that every individual has a pair of what he called "particles" for a given trait, and that each of the two parents pass on only one of these 'particles' to the offspring, and they are randomly passed on to the offspring. There are mathematical probabilities, but that's all they are. It's possible for recessive traits, for example, to be passed along from one parent to offspring generations, but for them to skip several generations before they are eventually seen in the offspring. In other words, each parent has a pair of genes for a given trait, and which one will be passed down to each offspring is entirely random.
Today, we now know these particles to be genes, or alleles, which are portions of DNA molecules, but back in the 1880's no one understood the molecular nature of genetics so Mendel called the genes "particles". He had the right idea, though, and he established the concept of dominant "particles" (genes) and recessive "particles" (genes), recognizing that some traits would always prevent other traits from being expressed.
For example, he found that genes for tall pea plants were dominant over those for short pea plants or that genes for smooth pods were dominant over genes for wrinkled pods.
The second law is the Law of Independent Assortment
Mendel also realized that each parent would pass on a single particle, or gene, for a given trait independently from the other parent's genes. The offspring would inherit a gene from one parent and a gene from another, but which "particle" the offspring plant got from each parent was not influenced in any way by which "particle" the other parent gave for the same trait.
The first law is the Law of Segregation.
Mendel realized, by crossing many generations of pea plants with various physical characteristics, that every individual has a pair of what he called "particles" for a given trait, and that each of the two parents pass on only one of these 'particles' to the offspring, and they are randomly passed on to the offspring. There are mathematical probabilities, but that's all they are. It's possible for recessive traits, for example, to be passed along from one parent to offspring generations, but for them to skip several generations before they are eventually seen in the offspring. In other words, each parent has a pair of genes for a given trait, and which one will be passed down to each offspring is entirely random.
Today, we now know these particles to be genes, or alleles, which are portions of DNA molecules, but back in the 1880's no one understood the molecular nature of genetics so Mendel called the genes "particles". He had the right idea, though, and he established the concept of dominant "particles" (genes) and recessive "particles" (genes), recognizing that some traits would always prevent other traits from being expressed.
For example, he found that genes for tall pea plants were dominant over those for short pea plants or that genes for smooth pods were dominant over genes for wrinkled pods.
The second law is the Law of Independent Assortment
Mendel also realized that each parent would pass on a single particle, or gene, for a given trait independently from the other parent's genes. The offspring would inherit a gene from one parent and a gene from another, but which "particle" the offspring plant got from each parent was not influenced in any way by which "particle" the other parent gave for the same trait.
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