CH3 Flashcards
(67 cards)
Cell
The basic living thing, structural and functional unit of the body
Cell Biology
Or Cytology: study of cell structure
Parts of a cell
1) Plasma membrane
2) Cytoplasm
- Cytosol
- Organelles (except nucleus)
3) Nucleus
- Chromosomes
- Genes
Plasma Membrane
- Flexible, sturdy phospholipid bilayer barrier that surrounds and contains the cytoplasm. Seperates internal from external environment
- Selectively permeable
- Made up of:
+ Phospholipids - non-polar tails, polar heads, Cholesterol - helps to stabilize membrane and Proteins
Polar
Head, hydrophilic
Nonpolar
Tail, hydrophoboic. Points towards center of bilayer
Integral Proteins
Extend into or across entire lipid bilayer
- Transmembrane proteins
Peripheral Proteins
Found at the inner or outer surface of membrane
- Can be stripped away without damaging membrane
Concentration Gradient
Difference in concentration of a chemical b/w one side of plasma membrane and the other
Electrical Gradient
Difference in concentration of ions b/w one side and the other
Concentration + Electrical gradients
Make up electrochemical gradient
- O2 and NaCl are concentrated outside the cell
- Carbon dioxide and potassium ions are concentrated inside the cell
+ Inner surface negatively charged, outer surface positively charge
Diffusion
Net movement of molecules from an area of high concentration to low concentrations, like osmosis
Factors that affect rate of diffusion
Steepness of concentration gradient, temperature, mass, surface area, and distance of diffusion
Steepness
Diffusion will continue until the gradient is equalized and the concentrations are equal
Temperature
Higher temp will diffuse faster
Mass
Heavier will move slower, lighter moves faster
Surface Area
Surface area of membrane increases, the rate of diffusion also increases as there is more space for molecules to diffuse across the membrane
Diffusion distance
Diffusion is rapid over very short distances, and slow over longer distances
3 types of passive processes
1) Simple diffusion
2) Facilitated diffusion
3) Osmosis
Simple Diffusion
Nonpolar, hydrophobic molecules (O2, CO2, lipids)
- atoms, or ions move from a higher concentration to a lower concentration without the help of transport proteins
Facilitated diffusion
needs help with transportation due to high polarization
- Integral proteins: membrane channel or carrier and can be used to act as a bridge across plasma membrane
Membrane channel
protein embedded within a cell membrane, allowing specific ions or molecules to passively move across the membrane down their concentration gradient
Carrier
Solute binds to specific transporter, transporter changes shape
- Includes glucose, fructose and galactose
Osmosis
Diffusion of water molecules down their concentration gradient across a selectively permeable membrane