If you're studying a life science (e.g. - biomed, bioscience, physiology, sports science, sports physiology etc), then this detailed set of lecture notes on cell transport/osmosis will help you smash your first set of exams on cell/molecular biology!
A sound knowledge and understanding of the ce...
Plasma membrane and transport 18/11/19
Membrane = boundary between intra and extracellular environment and neighbouring cells
- Selective permeability
Phospholipid bilayer – creates stable boundary, fluid mosaic model
- Some proteins/lipids/glycoproteins and lipids within or outside or inside membrane
- Receptors = specific – identifies function of certain cells – important for signals
- Receptors expression = dynamic – important for homeostasis – can increase and decrease
- Several types of receptors
- Phospholipids and receptors move laterally
Damage to membrane = loss of cellular integrity
Simple diffusion = down conc. grad
- Only non-polar, small polar (e.g. H2O, ethanol) and gasses
Net diffusion occurs for any number of solutes until some sort of equilibrium = reached (ideal state)
Osmosis = diffusion of water – selectively permeable membrane
- In most cells water movement = inward
Water movement = dependent on what cell is in
- Often cell = in isotonic solution – no net movement of water across membrane [ions/solutes]
is equal
- If cell is in solution with greater [solute] than inside cell = hypertonic – cell loses water
- If cell is in solution with lower [solute] than inside cell = hypotonic – cell gains water
Facilitated diffusion = for large/very polar substances
- Uses transport proteins – again – down conc. grad
- Transport proteins – contain transmembrane segments
- Channel proteins – hydrophilic channels through membrane
- Carrier proteins – Bind, change shape, release
Channel proteins span membrane
- No stimuli needed
- E.g. = aquaporins – causes water to enter cell faster – useful in renal function
- Ion channels allow K+ an Na+ diffusion – maintains RMP (-80 mV)
- Most ion channels = gated – only allow diffusion with specific stimuli
- Ligand gated may be due to hormone – causes shape change
Carrier proteins – for large/very polar substances
- Undergo shape change – moves solute-binding site across membrane
- High to low conc.
- GLUT1 = transporter of glucose – across plasma membrane
- Present in muscle cells
- Regulates blood glucose levels
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller jaz2. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £6.99. You're not tied to anything after your purchase.
