Cell structure/function 3 Membrane movement Flashcards
what do membranes consist of?
Fats (lipids - phospholipids
& cholesterol)
Proteins
Sugars - on lipids & proteins
on outside of membrane
why are membranes a phospholipid bilayer?
Phospholipids are amphipathic
molecules, allowing both hydrophobic and hydrophilic molecules through the membrane
can lipid soluble molecules get through the membrane?
yes
diffusion across membranes involves the energy of what? (Ions, molecules or atp)
The energy of
molecules. Gradients
across membranes create
the driving force
Is Diffusion slow? Is this a problem?
Yes, very slow. Not quick enough for body’s needs
Intrinsic proteins that form channels across a membrane help with what aspect of difussion? (Eg rate)
time. helps the process speed up
Carriers are membrane proteins that transport specific molecules and ions across
the
membrane
TRUE or FALSE: Receptors initiate reactions inside cell when ‘signal’
molecules bind to outside of membrane
TRUE
what is the point of membrane bound enzymes?
they help break down molecules- can be a protective measure or helps with absorption into cell.
Filamentous Meshwork Proteins act as anchor points for…? THINK Crenation
cytoskeleton of cell
under the membrane
passive diffusion is when molecules follow
their concentration gradient
there are 3 reasons why we know Carrier Mediated
Transporters Exist
1- Specificity: preference based on
molecular structure
2 Saturation: limited capacity
3 Competition: similar molecules
fight for binding at site
which type of diffusion involves membrane proteins
transporting ions & molecules normally into the cell - driven
by concentration gradients rather than ATP
Facilitated diffusion
Secondary Active Transport is a special type of facilitated diffusion that are
are membrane transporters that
transport ions & molecules. eg Sodium-Glucose Cotransporter
which type of diffusion across membranes uses ATP? eg sodium-potassium pump
Active transport
