1/22: Cell Membrane, Membrane Transport, and Membrane Potential II Flashcards
What is the function of transport proteins?
Move hydrophilic substances across the plasma membrane of cell
What are the three types of transport proteins?
- Channels
- Carriers
- Active transporters
What are channels?
Transmembrane proteins with a 3D shape that forms a tiny fluid filled pore connecting ECF and cytoplasm
What are two functions of channels?
- Facilitated diffusion of ions into and out of cell (passive; does not require energy)
- Can be somewhat specific (Ca+ channel Cl- channel, cation channel, etc)
Are channels saturable?
No
What are two types of channels?
Open channels
Gated channels
What are open channels?
Always open and ions freely flow through via facilitated diffusion
What do open channels create?
“Leak currents” - currents happening all the time
Where do gated chanels spend most of their time?
In the closed state
When do gated channels open?
When stimulated
What are the three types of gated channels?
a. Chemically gated
b. Mechanically gated
c. Voltage gated
What are four types of ion channel gating mechanisms?
A. ligand-gated
B. phosphorylation-gated
C. Voltage gaated
D. stretch or pressure gated
What two things are used for covalent modulation?
- Kinases
- Phosphatases
What are the functions of kinases and phosphatases
Kinase - attach covalent modulator
Phosphatase - remove covalent modulator
What are carriers?
Transmembrane proteins that move hydrophilic building blocks across the plasma membrane
What kind of transport do carriers use?
Facilitated diffusion (passive; doesn’t require energy)
What are properties of carriers?
- Specificity
- Saturation
- competition
What are active transporters?
Transmembrane proteins that move ions and hydrophilic building blocks across the plasma membrane via active transport (Active; requires energy)
What kind of transport do active transporters use?
Active transport; requires energy
What are properties of active transporters?
- Specificity
- Saturation
- Competition
What are structural proteins?
Form cell to cell attachments that hold adjacent epithelial cells together
What are the three types of attachments (cell to cell junctions) that are held together by structural proteins?
- Tight junctions
- Desmosomes
- Gap junctions
What are tight junctions?
Prevents intercellular movement of fluid and dissolved substances
What do desmosomes provide?
Structural support
What are the functions of gap junctions?
Cell to cell communication via ions
What are types of enzyme classifications?
Integral membrane proteins
Transmembrane proteins
Peripheral membrane proteins
What are the functions of enzymes?
Catalyzing specific chemical reactions either on the extracellular surface of cell or inside cell
What are properties of enzymes?
- Specificity
- Saturation
- Competition
How long does it take to synthesize proteins?
approx. 2 hours
How are proteins synthesized and stored?
Synthesized in advanced; stored in an inactive form, activated when needed
What does proteins storage provide a means for?
Immediate protein regulation
Interaction between substance and protein binding site follows the ________
Mass action model
Where are carbohydrates attached?
To the EC surface of membrane lipids and proteins (glycocalyx)
What do carbohydrates play an important role in?
Enabling cells to identify and interact with eachother
Because of the selectively permeable membrane, what do we find?
Concentrations of various extracellular and intracellular components vary
What is higher in the extracellular fluid?
Na
Ca
Cl
HCO3-
Glucose
What is higher in the intracellular fluid?
K+
Mg+
Phosphates
Amino acids
pH
Proteins
