1. CELLS!

2. Cytology= the study of cells
Microscopes opened up the world of cells
The 1st cytologist–
Robert Hooke (1665)
Viewed a slice of cork and thought the tiny boxes looked like the rooms that monks lived in… so he named them “cells”.

3. Microscopes Light microscopy
- magnification ~ ratio of image size to real size
- resolution ~ measure of clarity
Electron microscopy
- TEM~ (transmitting) electron beam to study cell ultrastructure
- SEM~ (scanning) electron beam to study cell surfaces

4. An electron microscope
Images:
Grasshopper Spider

5. Isolating Organelles Cell fractionation
separate organelles from others in the cell
variable density of organelles (heaviest fall out first)
ultracentrifuge

6. Cell Theory All organisms are made up of cells
The cell is the basic living unit of organization for all organisms
All cells come from pre-existing cells

7. What makes a cell a cell? All cells: surrounded by a plasma membrane
have cytosol (semi-fluid substance within the membrane)
cytoplasm = cytosol + organelles
contain chromosomes (have genes in the form of DNA)
have ribosomes (tiny “organelles” that make proteins using instructions contained in genes)

8. Prokaryotic Cells pro- before karyon- kernel (nucleus)
Nucleoid region: DNA concentration
No membrane-bound organelles
Bacteria cells

9. Eukaryotic Cells eu- true karyon- kernel (nucleus)
Larger than prokaryotes
Membrane-bound organelles
Plant and animal cells

10. Cell Size
As cell size increases, the surface area to volume ratio decreases
Rates of chemical exchange may then be inadequate for cell size
Cell size, therefore, remains small

11. Cell Size Limits Lower limit smallest bacteria, mycoplasmas
0.1 to 1.0 micron (μm = micrometer)
most bacteria
1-10 microns
Upper limit
eukaryotic cells
microns
micron = micrometer = 1/1,000,000 meter
diameter of human hair = ~200 microns

12. Nucleus Genetic material... Nucleolus: rRNA; ribosome synthesis
chromatin (proteins and DNA)
chromosomes (units of DNA– humans have 46)
Nucleolus: rRNA; ribosome synthesis
Nuclear envelope: double membrane with pores and nuclear lamina (protein filaments for structure)
Directs protein synthesis (mRNA)

13. Ribosomes Protein manufacturing
Free- cytosol; protein function in cell
Bound- endoplasmic reticulum; membranes, organelles, and export

14. Endomembrane System
Synthesis of proteins, transport within and outside of cell
Parts involved:
Nuclear envelope
Endoplasmic Reticulum
Golgi apparatus
Lysosomes
Transport vesicles
Plasma membrane

15. Endoplasmic Reticulum
Continuous with nuclear envelope
Smooth ER
no ribosomes
synthesis of lipids
metabolism of carbohydrates
detoxification of drugs and poisons
Rough ER
with ribosomes
synthesis of secretory proteins (glycoproteins), membrane production

16. Golgi Apparatus ER products are modified, stored, and then shipped
Cisternae: flattened membranous sacs
Opposite sides have different thickness and polarity
cis face (receiving) & trans face (shipping)
Transport vesicles move modified materials to other parts of the cell

17. Lysosomes Sac of hydrolytic enzymes in animal cells
Digestion of macromolecules
Phagocytosis- cell eating
Autophagy: recycle cell’s own organic material (damaged organelles, etc.)
Tay-Sachs disease~ lipid-digestion disorder

18. Vacuoles
Membrane-bound sacs (larger than vesicles) for storage and hydrolysis
May contain proteins, ions, pigments, sap, toxins, etc.
Special types
Food (created in phagocytosis)
Contractile (pump excess water in protists)
Central (storage in plants); surrounded by tonoplast membrane