Unit 2.md.bak

# Cell Structure and Function
S1 Final Exam Percentage: 19%
AP Exam Score Percentage: 10-13%

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## Chapter 4
A tour of the Cell

### Prokaryotes v Eukaryotes
| Prokaryotes | Eukaryotes |
| ------ | ------ |
| No Nucleus | Nucleus |
| No Membrane-Bound Organelles | Membrane-Bound Organelles |
| Circular Chromosomes | Linear Chromosomes |
| Evolved BEFORE (Pro-) Eukaryotes | Evolved AFTER Prokaryotes WITH (Eu-) a Nucleus |
| Bacteria, Archea | Protists, Fungi, Animals, Protists |
| ONLY Ribosomes | Other Organelles |

### Cytosol
**Cytosol** is the liquid-like substance in the cell that holds all the organelles in place and allows for chemical reactions to take place.
- The term **Cytoplasm** includes both the Cytosol and the organelles.

### Chromatin v. Chromosomes
Chromatin is uncoiled and not visible.
Chromosome are coiled (condensed) and visible under a microscope.

### Plasma Membrane
The **Plasma Membrane** regulates what enters and exits the cell.
Made up of a **phospholipid bi-layer, proteins, and carbohydrates**.

### Ribosomes
Create Proteins.

#### Free Ribosomes
Not attached to rough E.R, Products released into the Cytosol.

#### Bound Ribosomes
Attached to rough E.R, Products released directly into E.R. to be shipped.

### Golgi Apparatus
Produces Vesicles.
Modifies cellular compounds.

### Lysosome
Membrane Sac that contains enzymes to break down cellular compounds.

### Mitochondria
Produces ATP

### Cytoskelton 
Made of micro-tubules
Under the cell membrane
Allows things to move around inside the cell
Supports the cell membrane

### Centrioles and Centrisomes
Centrisome holds Centrioles
Centrioles move the chromosomes around during meiosis and mitosis

### Movement

#### Flagellum
Whip-like tail

#### Cilia 
Small hair-like projections 


### ER
#### Rough ER
Has membrane-bound Ribosomes
Transports proteins around cell

#### Smooth ER
Detoxifies
Makes new cell membrane

### Vacuoles

#### Food Vacuole
Formed after endocytosis, contains food
#### Central Vacuole
Only in plant cells; holds water
#### Contractile Vacuole
Excretes Excess water

### Extracellular Matrix
Like Velcro between animal cells; holds them together.

### Inter-cellular Junctions

##### Connection
Plasmodesmata - Plants 
Gap Junctions - Animals

#### Hold Cells together
Desmasomes - Button-like
Tight Junctions - Stitch-like

### Surface Area to Volume Ratio
Surface Area grows 
Volume grows
High SAV is better
Larger cells have LOWER SAVs (WORSE)

### Endomembrane System
Includes the Nuclear Envelope, Endoplasmaic Reticulum, Golgi, Lysosome,s, Vacuoles, and the Cell Membrane (not really endo)
Doesn't include Chloroplast and Mitochondria since they formed first as separate prokaryotes (Both even have their own DNA!) (See endosymbiont Theory)

### Membrane Sidedness
New cell membrane is carried in vesicles with the receptors facing in
	In other words, cell membrane is made inside out.

### Plants v.  Animals
Plants contain plastids | Animals do not
- Chloroplast - Holds Chlorophyll for photosynthesis
- Ameoplast - Holds Starch
- Chromoplast - Holds other pigments 
Plants do **not** contain lysosomes | Animals do
Plants **have** a cell wall | Animals do not
Plants do not have an extracellular matrix | Animals do
Plants have a central vacuole for water storage | Animals do not

## Chapter  5

### Selective Permeability
The cell membrane is **selectively permeable**, meaning that it can let some things through without letting other things through

### Amphipathic molecules
A molecule with hydrophobic and hydrophilic regions
i.e. Phospholipids

### Cell Membrane Structure
Phospholipid Bi-layer
- Proteins
	- Integral/Trans-membrane proteins go all the way through the membrane
		- Transport, Signaling
	- Peripheral proteins are only on one side of the membrane (outside and inside)
		- Recognition, Receptor, Enzyme
- Cholesterol
	- Maintains fluidity of the cell by maintaining distance between phospholipids

### Cell Transport

#### Passive Transport
No Energy because it moves along the concentration gradient (High to Low)
- Diffusion
	- Non-polar, non-charged, Hydrophobic, Small molecules can pass **directly through the membrane**, this is called diffusion. 
- Osmosis
	- **Water**, moving through a special type of type of facilitated diffusion through special transport proteins called **aquaporin.**
- Facilitated Diffusion
	- Movement of a polar, charged, hydrophilic, usually larger molecule through a transport protein. 

#### Active Transport
Requires energy because it is moving against the concentration gradient (Low to High)
	Always uses a transport protein since it requires energy

##### Bulk Transport
Special type of Active Transport for moving large amounts of molecules or larger molecules.
- Endocytosis - Folding of membrane to take in a substance
	- Phagocytosis - For solids
	- Pinocytosis - For Liquids
	Can include the use of Receptors (Receptor-Mediated Endocytosis) that cause the cell membrane to fold when a separate ligand molecule is introduced (hopefully alongside the target molecule.) 

#### Co-transport
Describes the active transport of one molecule to allow the passive transport of the molecule back along with another molecule. 

### Membrane Potential
Electrochemical Gradients describe chemical gradients of charged molecules, giving a "electrical potential" to the cells.
	Called a potential because they store potential energy that can be used in the cell for energy.
Proton Motive force describes an Electrochemical Gradient created using Protons (AKA Hydrogen Ions)

### Tonicity
Hypotonic - **Less** Solute in comparison to surroundings 
Hypertonic - **More** Solute in comparison to surroundings - Good for plant cells to be (describing cell not environment) because it creates turgour pressure. - Causes an animal cell to lyse
Isotonic - Same Solute in comparison to surroundings - Best for Animal cells to be (describing cell not environment)

### Water Potential

-   The “desire” of water to move from one place to another
  2 Factors that affect water potential
1.  Solute concentration  
-   More solute = less water potential
2.  Pressure
-   More pressure = more water potential
-   Animal Cells are considered to have (effectively) “no pressure”
-   Plant Cells have water pressure due to the cell wall.

#### Water potential Formula
The Greek letter Psi (Ψ) is used to represent water potential.
$$\psi _{total}=\psi _{solute}+\psi _{pressure}$$
Most times, total will equal the solute potential because the effect of pressure is minimal
## Solute Potential Formula
$$\psi _{solute}=0-iCRT$$
$i=$ ionization  factor
How many pieces the solute dissolves into
$C=$ molar concentration
Given in proble
$R=$ pressure constant (0.0831) (given)
$T=temperature (in \degree K)$
$273+\degree C=\degree K$