Cellular Level of Organizatoin Flashcards
what is the cells flexible outer surface?
plasma membrane
aka Plasmalemma
what is the function of the plasma membrane?
4 functions
- acts as a barrier
- controls flow of substances
- helps identify cell to other cells
- participates in intracellular signaling
Cytoplasm
has two components
Consists of all the cellular contents between the plasma membrane & nucleus
Intracellular fluid
What is Cytosol
the fluid portion of the cytoplasm
contains water, dissolved solutes & suspended particles
the Nucleus
what is it’s function?
houses most of a cell’s DNA
structure of the plasma membrane
What is the lipid bilayer?
What are the 3 types of lipid molecules?
basic framework of the plasma membrane
phospholipids (~75%), cholesterol (~20%) & glycolipids (~5%)
this bilayer arrangement occurs because lipids are amphipathic
What are the functions of membrane proteins
- Ion channel
- Carrier
- Receptor
- enzyme (integral & peripheral)
- Linker
- Cell identity marker (glycoprotein)
Concentration gradient
difference in the concentration of a chemical inside vs outside a cell
ex. more Na+ outside cell than inside
more K+ inside cell than outside
Diffusion
a PASSIVE process where particles mix because of kinetic energy
Osmosis
What factors influence diffusion rate?
- steepness of concentration gradient
- temperature
- mass of diffusing substane
- surface area
- diffusion distance
explain
Simple diffusion
- passive process
- from high concentration to low
- nonpolar, hydrophobic molecules move across lipid bilayer this way
ex. oxygen, CO2, N+ gases, fatty acids, steroids & fat-soluble vitamins. Small uncharged particles such as water, urea, etc.
explain
Facilitated diffusion
- integral membrane proteins assist with transport across the membrane
- moves solutes that are too polar or highly charged
- form a channel or fuction as carrier
