1. CELLS Cytology - the study of cells Cytology - the study of cells

2. Cells are the basic unit of life.

3. I. Cell organization Organization is similar in all cellsOrganization is similar in all cells All cells have: 1) DNA 2) a membrane to protect the cell 3) organelles with special functions

4. Limits to Cell Size  Small because of surface area and volume ratio: as size increases, ratio of volume to surface also increases.  Microvilli increase surface area.

5. II. History A) THE CELL THEORY - - proposed by Schleiden and Schwann 1. All organisms are made of cells. - Virchow later added… 2. All cells come from other cells. ……………Now, let’s see a video about the Cell Theory

6. II. History B) Microscopy Robert Hooke Robert Hooke  1 st person to call them “cells” (1665)  observed cork cells (he was observing dead cell walls)

7. Anton Van Leewenhoek  made superior microscopes ( c. 1670)  Observed “animicules” in water (they were Protists!)

8. III.Study Techniques include: A. Cell fractionation 1. chop up cells in a blender 2. “spin out” different types of organelles based on size and density in a centrifuge.

9. III. Microscopes A. Related terms: a)Magnification – how large the image appears compared to what it seen with the naked eye. b)Resolution (focus) – how clear the image appears c)Micrograph – a photo taken of a microscopic image

10. B) 3 kinds 1)Compound (light) microscope -magnification/resolution to 2,000x -advantage: can view live cells/processes

12. 2) Scanning electron microscope (SEM) - uses electron beam - views cell surfaces - views cell surfaces

13. 3) Transmission electron microscope (TEM) - views internal cell structures

14. A view of a cell with cilia compound microscope

15. A view of the cilia of a cell transmission electron microsope vs. scanning electron microscope TEM (inside) SEM (outside) TEM (inside) SEM (outside)

16. Practice: What microscope would be used to observe… 1. A cell that is engulfing large bits of food? 2. A cell that is dividing (reproducing)? 3. An external view of the cell wall of a plant cell? 4. The folds of the endoplasmic reticulum? 5. The inside of a chloroplast?