Cell/Plasma Membrane Flashcards
Basic structural framework
Lipid bilayer
The lipid bilayer is made up of 3 layers from lipid molecules namely
Phospholipids
Cholesterol
Glycolipids
What percentage does each layers 3 layers of the lipid bilayers cover? and what are those made of?
Phospholipids: 75%; phosphorus
Cholesterol: 20%; steroid with hydroxyl group (OH)
Glycolipids: 5%; carbohdyrate group
What does amphipathic mean?
Amphipathic is having both sides of polar and nonpolar
Differentiate polar and nonpolar
Polar is the phosphate-containing head which is hdrophilic, while nonpolar is the 2 long fatty acid tails which are hydrophobic
Insterted among lipids in both layers of the membrane
Cholesterol molecule
Is the cholesterol molecule strongly or weakly amphipathic?
Weakly amphipathic because cholesteril molecule is made up of fat which is hydrophobic
This forms a polar head
glycolipid
Nonpolar tails in glycolipids
fattty acids
On which side do glycolipids appear?
On the side that faces the extracellular fluid
2 classifications of membrane proteins
Integral proteins
Peripheral proteins
Other term for integral proteins
Transmembrane protein
Embedded into the lipid bilayer
Intergral proteins
Span the entire lipid bilayer
Transmembrane protein
Proteins with carbohydrate that protrude to the extracellular fluid
Glycoproteins
Describe the composition of carbohydrate
Carbohydrates are oligosaccharides and chains of 2-60 monosaccharide
Extensive sugary coat that are hydrophilic and attracts fluid
Glycocalyx
Proteins that are not fully embedded in the membrane
Peripheral proteins
Where are peripheral proteins attched?
To the polar heads of membrane lipids/ integral proteins
Differentiate integral and peripheral proteins
Integral proteins are embedded into the lipid bilayer while peripheral proteins are not fully embedded in the membrane
Pores/ holes that function as passage of ions
Ion channel
Integral proteins that move polar substances from one side to another
Carriers/ Trasnportes
Integral proteins that serve as cellular recognition sites
Receptors
Receptors recognize and binds what specific types of molecules?
Ligands
Integral proteins that catalyze specific chemical reaction
Enzymes
These two often serve as cell-identity markers
Membrane glycoproteins and Glycolipids
Integral proteins which anchor proteins in the plasma membrane of neighboring cells to another
Linkers
These cell-identity markers enable cells to:
a. Recognize other cells (same kind) during (1)
b. Recognize and respond to (2) foreign cells
- tissue formation
- potentially dangerous
5 General Functions of Peripheral Proteins
a. (1)
b. Anchor (2)
c. Participate in mechanical activities (3)
d. Change (4) in dividing
e. Attach cell to one another
- Support
- integral proteins
- movement of materials
- cell shape
Allows the lipid bilayer to self-seal when punctured
Membrane fluidity
Membrane fluidity enables movement of membrane components responsible for —
cellular process
Permits passage of substances
Membrane permeability
Membrane permeability criteria
- permeable to non-polar
- impermeable to large uncharged particle (solid substances)
- slightly permeable to water,
urea, waste products (amino acid)
This is how easily proteins and lipids carry out their environment in the cell membrane
Membrane fluidity
Differentiate membrane fluidity and membrane permeability in terms of the entry of substances
Membrane fluidity: What goes in to the cell, comes out of the cell
Membrane permeablity: Only allows specific materials to enter and leave the cell
Processes that transort materials in and out of cells
Passice Process
Active Process
Movement of substance that do not require cellular energy (ATP)
Passive Process
Processes under passive process
Diffusion (Simple and Facilitated)
Osmosis
Movement of molecules/ions
due to the molecule’s kinetic energy
Diffusion
Where are the 2 classifications of membrne proteins (Integral & Peripheral) located?
Plasma
Passive movement of a
substance without the help of membrane transport protein
Simple diffusion
Passive movement of a
substance through the channels or carriers
Facilitated diffusion
Differentiate simple and facilitated diffusion
Simplke diffusion is the passive movement of a
substance without the help of membrane transport protein, while facilitated diffusion is the passive movement of a
substance through the channels or carriers
Passive movement of water molecules from lower concentration to higher
concentration
Osmosis
Types of active processes
Active transport
Transport in vesicles (Endocytosis, Exocytosis, Transcytosis)
Cell expands energy; carriers
Active transport
Differentiate primary from secondary active transport
Primary active transport is when energy comes from hydrolysis of ATP while secondary active transport is when energy is supplied by Sodium or Hydrogen concentration gradient
Breakdown of water to produce ATP / energy
hydrolysis
3 processes in the transport of vesicles
Endocytosis
Exocytosis
Transcytosis
Movement of substance into a cell in vesicle
Endocytosis
Types of endocytosis
Bulk-phase endocytosis
Phagocytosis
Receptor-mediated endocytosis
Ligand-receptors triggers infolding of a clathrin-coated pit that forms a vesicle containing ligands
Receptor-mediated endocytosis
“Cell eating”; engulfing of
pseudopods
Phagocytosis
Example of a pseudopod
White blood cells
“Cell drinking”; movement of extracellular fluid
Bulk-phase endocytosis
Movement of substance out of the cell in secretory vesicles that fuse with the plasma membrane
Exocytosis
Movement of substance as a result of endocytosis on one side and exocytosis on the
opposite side
Transcytosis
