BIOB11- Lecture 1 Part 1
First of all, just a quick review: there is quite a bit of difference between the prokaryotic and eukaryotic cells. They have different internal structures. Eukaryotic cells have internal membrane structures like nucleus, ER, Golgi; whereas they do not exist in the prokaryotic cells. When you look at the genetic material, DNA, you can see that it’s just present in the cytoplasm of the prokaryotic cell while in the eukaryotic cells it is present in the nucleus. An overview of several important discoveries on the nature of gene: In the 1860’s Mendel discovered the discrete units of inheritance. 1880’s: discovery of chromosomes.
1903: discovery of homologous chromosomes.
1909-1911: discovery of crossing over.
1911: discovery that genes could be mapped in order along length of chromosomes. 1944-1952: discovery of DNA as genetic material.
1953: Watson and Crick discovered DNA structure.
When Mendel was experimenting on plants, he was using 7 different traits: height, seed color, seed shape, flower color, flower position, pod color, and pod shape. He was looking at differences in the trait. For example, you would have a tall plant and a dwarf plant, or pod color is either green or yellow or, pod shape is either inflated or constricted. He later figured out which ones are dominant alleles and recessive alleles. Genes as a unit of Inheritance:
Gregor Mendel experimented by cross breeding pea plants over a number of generations and observed/followed different plant characteristics. Any given characteristic of the plant is governed by distinct units of inheritance. These distinct units are called genes. Each individual has 2 copies of a gene, one from each parent (inheritance). These alternate forms of gene are called alleles. Homozygous: same copy. Example: both parents having brown eyes. Heterozygous: different copy. Example: one parent has brown eyes and another one has hazel eyes. Each reproductive cell (called gamete) contained...
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