1. Chapter 7A
A Tour of the Cell

2. Cytology: science/study of cells
Light microscopy
Resolving power~ measure of clarity
Electron microscopy
TEM~ electron beam to study cell ultrastructure
SEM~ electron beam to study cell surfaces
Cell fractionation~ cell separation; organelle study
Ultracentrifuges~ cell fractionation; 130,000 rpm

3. Electron Micrograph

4. Cell Types: Prokaryotic
Nucleoid: DNA concentration, single circular chromosome
No organelles with membranes
Plasmids: extra-chromosomal rings of DNA
Ribosomes: protein synthesis(all cells)
Plasma membrane (all cells); semi-permeable
Pili: used for attachment and genetic transfer
Cytoplasm/cytosol (all cells)

6. 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

8. Nucleus Contains the Genetic material Chromatin (chromosomes)
Nucleolus: rRNA; ribosome synthesis
Double membrane envelope with pores
Protein synthesis/Transcription (mRNA copies DNA)

10. Ribosomes Protein manufacture
Free - cytosol; produce proteins that function in the cell
Bound – rough endoplasmic reticulum; found on surface membranes; manufacture proteins that are exported from the cell
Composed of 2 subunits (rRNA & protein)
Prokaryotic ribosomes are smaller

12. Endomembrane System, I Endoplasmic reticulum (ER)
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

14. Endomembrane System, II
Golgi apparatus - ER products are modified, stored, and then shipped
Cisternae: flattened membranous sacs making up Golgi
trans face (shipping) & cis face (receiving)
Transport vesicles pinch off of ends of Golgi

16. Endomembrane System, III
Lysosomes - sac of hydrolytic enzymes; digestion of macromolecules
Phagocytosis
Autophagy: recycle cell’s own organic material
Tay-Sachs disease~ lipid-digestion disorder

18. Endomembrane system, IV
Vacuoles -membrane-bound sacs (larger than vesicles)
Food Vacuole (phagocytosis)
Contractile (pump excess water)
Central (storage in plants) •tonoplast membrane