Biology 457 & 557 -  Week 1

Historical Perspectives of Biology

 Origin of cell and molecular biology gradually developed from 17th century

 Common to all scientific discoveries is:

Major findings and Scientists:

1)      (1665)  Hooke

2)     (late 1600s)  Leeuwenhoek

3)     (1839)  Schleiden &Schwann  “

            a)

            b)

4)     (1855)  Virchow

            c)

5)     (1865)  Mendel

6)     (1880s)  Strasburger & Weismann

7)     (1910-1920)  Wilson

                               Morgan

8)     (1953)  Watson & Crick

9)     (late 1970s)  “The Molecular Revolution”

 science is ever-changing

Basics of Cells and Structural Features

2 types of cells:

1)     Prokaryotes:

2)     Eukaryotes:

Generalized Eukaryotic Cell Structure

            cell with organelles

            plasma membrane and transport

The Molecules of Life

 the life of a cell is a complicated orchestration of many events

 small mistakes in these processes have serious ramifications

 cells in an adult organisms can be viewed as a steady-state system

 cells can change their their functions over time

 non-growing cells can begin to grow when stimulated properly

Nucleic Acids, the Genetic Code and Synthesis of Macromolecules

 there exists an intricate relationship in cells between the synthesis of the nucleic acids

    DNA and RNA and that of proteins

 known as the Central Dogma

 commonalities in the synthesis of DNA, RNA and protein

            1)

            2)

            3)

            4)

            2 nucleic (found in the nucleus) acids (has net negative charge) that represent the            informational molecules of all living organisms

1)      DNA:

                        2)     RNA:

both are made up of subunits known as nucleotides which contain:

            nucleotides are joined in chains (growth proceeds from 5’þ3’)

            genetic information is stored in the

            linear sequence of bases has a high coding capacity

            human genome (complete set of genes) consists of ~

            any change in the order or number of bases in a stretch of DNA can result in a

            mutation which may be quite harmful

                        ex: Huntington Disease which affects neurological system

                                 mutation increases the length of a CAG repeat in a stretch of DNA

                                 normal individuals have 10-29 repeats, > 40 and get this disease

                            DNA replication depends on base pairing

                        helix is unwound and each original strand can serve as a template

                        in eukaryotes, replication starts at numerous sites called origins of

                           replication

                        each region of DNA served by one origin is called a replicon

                        strand growth is in 1 direction: 5’þ3’

                        3 common features of replication origins from E. coli to eukaryotes

                                    1)

                                    2)

                                    3)

                        hydrogen bonds are broken between bases in adjacent strands by a

                        helicase enzyme and DNA polymerase catalyzes synthesis of DNA

                                    a multifunctional protein locally unwinds duplex DNA