Plasma Membrane Flashcards
What does compartmentalizations accomplish?
Specialized activities to proceed without external interference
Enables cellular activities to be regulated independently of one another
What does scaffold and barrier do for the plasma membrane? (4)
- allow for fixed location of proteins
- reduced dependence on random collision
- barrier can choose which molecules enter/leave the cell
- specific cellular responses
What about gradients?
Transporters allow solutes passage in different ways
What works w/gradients?
Passive transport
What works against and makes gradients?
Active transport
What are the 3 types of amphipathic membrane lipids?
- Phosphoglcerides
- Sphingolipids
- Cholesterol
O blood group
Basic oligo no additions
A blood group
Addition of N-acetylgalactoseamine GalNAc
B blood group
Addition of galactose
AB blood group
Addition of both N-acetlgalactoseamine GalNAc and galactose
What are the 3 types of membrane proteins?
- Integral
- Peripheral
- Lipid-anchored
Integral Proteins
Transmembrane domain
20 mostly polar amino acids
Peripheral proteins
Entirely outside
Associate via noncovalent bonds
Lipid-anchored
Covalently linked to a lipid
Apical plasma membrane functions
- regulation of nutrition and water intake
- regulated secretion
- protection
Lateral plasma membrane functions:
- cell contact and adhesion
- cell communication
Basal membrane functions:
- cell-substratum contact
- generation of ion gradients
What are the 4 basic types of transport?
- Passive
- Nonmediated (diffusion, pore)
- Transporter
- Active Transport
What are the requirements for passive diffusion?
Materials must be
- very small
- not charged (polar is fine)
- move down the concentration gradient
Define Osmosis?
Water moves from lower solute to higher solute
Define Hypotonic
Water move net inward the cell swells
Less solute
Define Hypertonic
Water moves net outward the cell shrinks
More solutes
Define Isotonic
No net movement
What are the 3 types of ion transporters?
- Voltage-gated
- Ligand-gated
- Mechano-gated
Voltage-gated
Allow diffusion in response to electrical changes
Ligand-gated:
Allow diffusion in response to binding of a particular molecule
Mechano-gated:
Allow diffusion in response to changes in shape due to physical stress
I.E. Hair cells of the inner ear responding to physical sound wave impacts
Facilitated diffusion:
- energy comes from concentration gradient
- allows direct transfer across membrane
- works for larger molecules
- rate increases
Active Transport:
-required to move materials agains concentration gradients
-ATP for energ
I.E. Na+/K+ Transporter (moves 3 sodium a and 2 potassiums agains their gradients)
Co-transport:
Form of active transport but energy comes from a gradient rather than ATP hydrolysis
Could be antiport/symport
Ion flows down a concentration gradient
Molecule of interest flows against the concentration gradient
Antiport means
Opposite directions
Symport means
Same direction
Cystic Fibrosis is what?
A failure of ion transfer that results in the lungs not maintaining proper hydration which allows bacteria to establish on lung epithelium which leads to chronic infections.
Na+/Glucose symport:
Sodium transported down gradient
Glucose co-transported against gradient
What distinguishes sphingolipids from phosphoglycerides?
The absence of glycerol
What is true of cholesterol?
It is important for human life
It changes the fluidity of the plasma membrane
This protein is non-covalently associated w/the plasma membrane and/or other membrane proteins. What membrane protein am I?
Peripheral membrane protein
The enzyme desaturase increases activity on the fatty acids in the lipid bilateral. What is the expected result in fluidity?
Fluidity will increase due to loss of packing due to loss of kings from the actions of the desaturase
A red blood cell is place in a hypertonic solution. What is the expected result?
Water will exit the red blood cell and the cell will shrink
What type of transporter contributes to hearing due to the impact of sound waves?
Mechano-gated
What contributes to the infection in a CF patient?
CFTR fails to transport Cl- out of the epithelial cells in the lung, therefore water does not diffuse out of the cell allowing the lung surface to dehydrate. Pathogenic bacteria are able to for a biofilm.
What is meant by the plasma membrane being a scaffold?
Allows for fixed position of proteins
A membrane fatty acid that lacks double bonds is considered __________.
Saturated
Aquatic plants living in freshwater are surrounded by a hypotonic environment. Water flows into the cells, creating a __________ pressure. If the plant is placed in a hypertonic solution, such as seawater, the cell loses water, and the plasma membrane pulls away from the cell wall, causing plants to wilt. This process is known as _________.
Turgor; plasmolysis
In 1957, an ATP-hydrolyzing enzyme in the nerve cells of a crab was discovered to be the same enzyme responsible for the active transport of two ions in the human body. Which ions?
Na+/K+ ATPase
Careful examination of a synapse reveal that two cells do not make direct contact but are separated from each other by a narrow gap (synaptic cleft) of about ____________.
20 to 50nm
Qualification must be met before a molecule can diffuse possible across a plasma membrane. What are these qualifications?
Material must be small
Material must be hydrophobic
Protein conduits in the membrane that are permeable to specific ions are known as __________.
Ion channels
What is true of cystic fibrosis?
70% do alleles responsible for CF contain the same genetic alteration. (DeltaF508)
CF heterozygous may be protected from cholera and typhoid fever
Most common ion channel disorder
Gene responsible for CF was isolated in 1989
Which property of the plasma membrane plays a critical roles in signal transduction?
Response to stimuli
What prevents digestive enzymes from digesting anything and everything in the cell?
Compartmentalization
This protein was discovered when it was shown that certain membrane proteins could be related to phospholipase that specifically recognized and cleaned inositol containing phospholipids. A rare type of anemia, paroxysmal nocturnal hemoglobinuria, results from deficiency of this protein and makes red blood cells susceptible to lysis. What protein is it?
GPI-anchored
Looking at blood groups, the basic oligo w/only galactose added will yield which blood type?
B
Using a freeze fracture technique, the picture viewed under the electron microscopes revealed a specific transmembrane domain w/20 nonpolar amino acid peptide sequences. What are we looking at?
An integral membrane protein
In the lumen of your small intestine, the Na+/glucose symport moves sodium and glucose in the same direction working to get energy w/Na+/K+ active pump. What specific method of transport is used?
Co-transport
An ___________ at one site on the membrane depolarizers an adjacent region of the membrane, triggering this agains a second site. It can flow in the forward direction because the portion of the membrane remains in a refractory period.
Action potential
Smokers bodies become accustomed to high levels of nicotine, and they experience symptoms of withdrawal when they stop smoking because the postsynaptic neurons that possess ___________ are no longer stimulated at their usual level. The drug Chantix, acts by binding to the most common version of this receptor. Once bound, Chantix molecules partially stimulate the receptor while preventing binding of nicotine.
nAChRs receptor
Without ________, plasma membranes would be too fluid, not firm enough, and to permeable to some molecules.
Cholesterol
What are the 7 functions of the plasma membrane?
- Compartmentalizations
- Biochemical event scaffold
- Selectively permeable barrier
- Substance transport
- Response to stimuli
- Intercellular communication
- Energy transduction
