Lecture 9 Flashcards
Example of changes in volume driven by osmosis
Hypotonic environment
Hypertonic environment
Isotonic environment
Hypo, hyper, iso
Mean what
Less
More
Same
Hypotonic environment what happens to cell
H2O only. Cell swells
Hypertonic environment what happens to cell
Too salty, sucks the water out of the cell, cell shrinks
Isotonic environment what happens to cell
Same saltiness as cell, cell stays the same size
Primary Active transport example
Sodium potassium pump
Moves sodium ions out of cell and potassium ion into cell
Both ions are moved AGAINST their concentration gradients so ATP is needed
The transporter uses ATP to do this
Secondary active transport
Uses ion gradients (electrochemical) for energy
Energy released as an ion moves with its concentration gradient is used to drive movement of another molecule against its concentration gradient
Analogy for energy released by passive movement of a molecule across a membrane
Dam closed - concentration gradient
Dam open - movement of molecule across membrane
Energy released turns turbines
Secondary active transporters
symport (transported molecule and driving ion both going same direction)
Antiport (transported molecule and driving ion going opposite direction)
Secondary active transport examples
Sodium glucose coteansporter
It’s like a revolving door. Sodium falls (downhill) down which pushes the glucose (uphill)
Endocytosis types
1- receptor-mediated (ex. LDL cholesterol)
2- bulk-phase (pinocytosis) (pino = drink)
3- Phagocytosis (Phago=eat)
Exocytosis process. Simple
Vesicle joins plasma membrane and releases contents
Bulk phase endocytosis / pinocytosis
Solute molecules are outside the membrane>
Membrane pockets inward, enclosing solute molecules and water molecules >
Pocket pinches off as endocytic vesicle (ball of stuff it’s trying to take in)
Receptor mediated endocytosis simple
Substances attach to membrane receptors
Membrane pockets inward
Pocket pinches off as endocytic vesicles
(Same as the bulk phase. Just attaches instead of being consumed with the water)
Phagocytosis simple
Lobes surround prey
Lobes close around prey
Prey is enclosed in endocytic vesicle that sinks into cytoplasm
“When amoeba eat”
Membrane component responsible for transport
1-Simple diffusion
2-Facilitated diffusion
3-Active transport
1-Lipids
2-Proteins
3-Protein
Binding of transported substance
Simple diffusion
Facilitated diffusion
Active transport
No
Yes
Yes
Energy source for
Simple diffusion
Facilitated diffusion
Active transport
Concentration gradients
Concentration gradients
ATP hydrolysis or concentration gradients
Direction of transport
Simple diffusion
Facilitated diffusion
Active transport
With gradient of transported substance
With gradient of transported substance
Against gradient of transported substance
Specificity for molecules or molecular classes?
Simple diffusion
Facilitated diffusion
Active transport
Nonspecific
Specific
Specific
Saturation at high concentrations of transported molecules?
Simple diffusion
Facilitated diffusion
Active transport
No
Yes
Yes
Signal transduction simple
Reception> transduction> response
Signal transduction more in depth
1- reception:
Binding of a signalling molecule with a specific receptor of target cells
2- transduction:
Signal is changed into form for eliciting the cellular response. Typically involves a signalling cascade (a sequence of reactions that include several different molecules)
3- response:
Transduced signal causes a specific cellular response that depends on the signalling molecule and the receptors of the target cell
Kinase
Enzyme that phosphorylation other proteins things using ATP
Phosphorylation cascade
Inactive 1 + ATP = active 1
When active 1 then inactive 2 becomes active, starts a chain reaction
How to sense a faint signal
Amplify it
In the phosphorylation cascade, every step multiply by 100 for example
