2. Cytology – the science of studying the cell, became possible with the invention of the compound/light microscope.

3. Cytology reached new levels with the invention and use of the Electron Microscope.

4. Scientists often measure in micrometers, there are 1000 micrometers in a single millimeter. Sometimes micrometers are too large, so scientists measure in nanometers. There are 1000 nanometers in a single micrometer.

6. Prokaryotic = “Before Nucleus” Much smaller cell (10-100 X smaller) No membrane bound organelles No true nucleus Use different ribosomes Only life forms that use this cell are bacteria Eukaryotic = “True Nucleus” Much larger size Various membrane-bound organelles A true membrane-bound Nucleus Much more metabolically efficient Used by all other life forms, Protists, Fungi, Plants and Animals.

8. This can be identified as being a Plant Cell in that it possesses the following: 1. Cell Wall 2. Large Central Vacuole 3. Chloroplasts

9. Fig. 3.2a

10. Consists primarily of a double layer of phospholipids. Acts as a gate-keeper to determine what will enter and exit the cell.

11. Passive transport Membranes are semi-permeable which means that they allow certain molecules through but not others. The molecules can move in and out through passive transport which is a method that does not require any input of outside energy. It can either be done by simple diffusion or facilitated diffusion. Molecules will go from a region of high concentration to a region of low concentration as they move randomly and eventually become evenly distributed within the system if they are permeable to the membrane. Simple diffusion involves the diffusion of molecules through the phospholipid bilayer while facilitated diffusion involves the use of channel proteins embedded in the membrane. The cell membrane is hydrophobic inside so hydrophobic (lipid soluble) molecules will pass through by simple diffusion whereas hydrophilic molecules and charged particles will use facilitated diffusion. Water moves through by osmosis which is also by passive transport. Osmosis involves the movement of water molecules from a region of low solute concentration, to a region of high solute concentration. So if the solute concentration is higher inside the cell than outside the cell, water will move in and vice versa.

12. Active Transport Active transport involves the movement of substances through the membrane using energy from ATP. The advantage of active transport is that substances can be moved against the concentration gradient, meaning from a region of low concentration to a region of high concentration. This is possible because the cell membrane has protein pumps embedded it which are used in active transport to move substances across by using ATP. Each protein pump only transports certain substances so the cell can control what comes in and what goes out.

13. Fig. 3.2b

14. Acts as the control center for the cell. Stores the DNA in the form of Chromatin. This DNA has all the blue prints to build all the crucial structural and functional proteins of the cell. These proteins build the cell and run the cell.

15. Recall that membrane consists of a double layer of phospholipids. The nucleus is enclosed with a double membrane (Nuclear Envelope). Nuclear pores tunnel through.

16. Branching out from the nuclear envelope is a series of membranous folds that form a network of channels (Endoplasmic Reticulum). These membranous channels act like roadways to transport materials.

17. Rough E.R. – Is studded with Ribosomes. These Ribosomes translate mRNA to make proteins which then enter the inside of the Rough E.R. Smooth E.R. – Lacks ribosomes. It is responsible for producing sterol lipid hormones (Ex. Testosterone) and for housing detoxifying enzymes.

18. ROUGH ER Function: To build and transport proteins.

19. SMOOTH ER Function: To help form Sterol Lipids as well as key Detoxifying Enzymes and then transport them.