A little bit of 9th grade biology

A bit of biology / genetics

Chapter nine is about the fundamentals of genetics.Genetics is how characteristics are transmitted from parents to their offspring. Gregor Mendel is a geneticist. Gregor Mendel first discovered genetics while he was in Brunn, Austria. Gregor Mendel decided to record the genetics of pea plants. Mendel kept track of seven different characteristics of his pea plants. The characteristics included everything from plant height to stem height to flower position and color of the pod including the seeds. At the end of the year Gregor Mendel collected the seeds from all of his special plants. Then he planted them the following year. Mendel discovered that some of the seeds that came from the white plants had changed to purple and that some of the stems that were supposed to be short were tall and some of the seeds that were supposed to be purple were white and some of the stems that were supposed to be tall were short. Mendel was confused and tried to find the answer to why the plants are changing and why the plants are not staying the same. He collected and then replanted his seeds the following year so he would be able to answer his question. After a couple of years doing this Gregor Mendel discovered the dominant and recessive factor or allele. The dominant factor masks the recessive factor, thus you will get the dominant trait or factor.

When you get two alleles that are alike the organism is called homozygous. When you get two alleles that are different you get heterozygous.

Ex. Pp= heterozygous PP= homozygous

If you want to find the probability of what an offspring of two parents could be you can use a punnett square. A punnett square is where you cross the genetics to find out what offspring will be like. You can use a monohybrid cross or a dihybrid cross. A monohybrid cross involves one pair of organisms. A dihybrid cross involves two pairs of organisms. When looking at the organisms BB and Bb, you can tell that all of the offspring will have black fur (B= Black fur dominant) (b= brown fur recessive). If the organisms show to be homozygous or heterozygous you still look at the dominant and recessive factors that influence the offspring (usually in capital letters)

Ex. Bb B= dominant b= recessive