Exam 4 (Topic 19) Flashcards
Lipid-bilayers are impermeable to…
MOST molecules
Regulate what the cell gets rid of and takes in
Transporters and Channels
Very high in K+
Inside of the cell
Very high in Na+
Outside of the cell
Required to maintain difference of K+ and Na+
Membrane transport proteins
Create a barrier to the passage of most molecules
The lipid bilayer
The rate of passage varies depending on
Size and solubility (polarity or charge)
Readily diffuse across the bilayer
Small nonpolar molecules (O2, CO2)
Diffuse rapidly if the are small enough
Uncharged polar (H2O, Ethanol)
Very impermeable to diffusion across the lipid bilayer
Larger uncharged polar and Ions
Two classes of membrane transport proteins
- Channels
2. Transporters
Allow molecules of certain size or charge
Channel (if open, molecule can pass through)
Allow passage to those molecules that fit into its binding site
Transporters (bind with high specificity like enzymes)
Bind with high specificity like enzymes
Transporters
Membrane transport proteins are
Multipass transmembrane proteins
Solutes cross membranes by
Passive or Active Transport
Molecules move from a region of high concentration to a region of low concentration
Passive Transport
Molecules move down a concentration gradient
Passive Transport
Does not require any energy
Passive Transport
Sometimes called Facilitated Diffusion
Passive Transport
Another name for Passive Transport
Facilitated Diffusion
Molecules move from a region of low concentration to a region of high concentration
Active Transport
Molecules move up a concentration gradient
Active Transport
Requires energy
Active Transport
Must be couple to some other process that releases energy
Active Transport
Many active transport proteins are called
Pumps
The plasma membrane has transporters for
Nucleotide
Sugar (Glucose)
Amino Acids
Ions
The_________ uses transporters for H+ to keep the pH very low
Lysosome
Lysosome uses transporters for
H+ to keep the pH very low
The ___________ uses transporters for Pyruvate and ATP
Mitochondria
The mitochondria uses transporters for
Pyruvate and ATP
Glucose Transporter
(Glucose Uniporter) Found in the plasma membrane of many animal cells
Moves glucose down a concentration gradient
Passive Transport
Can switch reversibly between two different conformations
Protein
Once glucose binds, the protein
switches conformations and carries the glucose molecules inside the cell
Starvation
Low glucose outside the cell
Glucose is made in the cell through
gluconeogenesis
Glucose is transported out of the cell into the
Bloodstream down its concentration gradient
Does a glucose transporter require energy
No