1. Biology 107 - Cell I September 24, 2003

3. Cell I Student Objectives:As a result of this lecture and the assigned reading, you should understand the following: 1.The basic structural and functional unit of life is the cell. 2.Cells may be classified as prokaryotic or eukaryotic, depending upon their internal organization. 3.Prokaryotic cells are typically smaller than eukaryotic cells, while eukaryotic cells generally are structurally and functionally more complex than prokaryotic cells.

4. Cell I 4.A eukaryote ("true nucleus") has a membrane-bounded nucleus, and possesses membranous organelles, each of which has a particular function in the cell. 5.Organelles are structures essential for the functioning of a cell. Not all organelles are membranous. Examples of non- membranous organelles are microtubules and ribosomes. 6.The advantages of membranous organelles (compartments) include: 1) metabolic processes in the cell that require different specific chemical conditions may occur simultaneous and 2) an increase in the cell's total surface area.

5. Cell I 7.Organization of Cells - Common Structures and Functions a.Cells are microscopic is size because of the surface area to volume relationships b.Membranes enclose and delimit cells c.Cells have a “genetic control center” containing DNA d.Cells have cytoplasm. The cytoplasm includes the organelles (membranous and non-membranous) and the fluids and dissolved substances; it excludes the nucleus of eukaryotic cells.

6. Cell I 8.The DNA genetic material in prokaryotes is concentrated in a region called the nucleoid region. In eukaryotes the DNA is enclosed in the nucleus. 9.Most of the DNA is attached to proteins, forming chromatin. The proteins associated with DNA assist in either the structural organization of the genetic material and/or the regulation of the use of the DNA.

7. Cell I 10.The eukaryotic nucleus: a.The nuclear material is enclosed by the nuclear envelope, a double membrane structure with pores that allows the passage of material into and out of the nucleus. Through the pores travel mRNA, ribosomes, and various proteins used in gene regulation and DNA maintenance. b.Contains is a mass of fibers and granules called the nucleolus. The nucleolus is a combination of DNA, RNA and proteins, and it is where ribosomal subunits are assembled.

8. Prokaryotic Cell

9. Eukaryotic Cell - Animal

10. Eukaryotic Cell - Plant

11. Surface area to Volume Relationship

12. Relationship Between Surface Area and Volume

13. Eukaryotic Nuclei Nucleus

14. Chromatin

15. Chromatin – DNA + Proteins

16. Eukaryotic Nucleus Nuclear Envelope – Double-membrane structure with pores Nucleolus