T4- Cell Membrane and Transport (diagrams & illustrations & common p1 & p2 misconceptions)
7 views 0 purchase
Course
Cambridge AS Biology
Institution
-AS Biology Cambridge Topic 2 full notes covering all points of the sylabus as you go on. contact us on:
-contact us about any help you need FOR FREE
-Includes diagrams & illustration for further understanding
-includes handwritten worked examples for common Paper 1 misconceptions.
-Most pa...
If phospholipids are mixed with water they form:
1. Micelles → ball like structures→ hydrophilic heads face outwards
2. Bilayers → sheet-like structures
Role of cell membrane:
1. Controls exchange of materials → nutrients & waste products between cell
& environment
2. Cell signaling
The fluid-mosaic model of membrane structure:
Fluid: The phospholipids and proteins can move around via diffusion mainly
sideways, within their own layers.
Mosaic: the scattered protein pattern within the phospholipid bilayer.
Describe the structure of phospholipid.
● Hydrophilic (polar) Phospholipid heads point outwards into the aqueous
solution that surrounds the membranes forming, stabilizing the
membrane by forming hydrogen bonds with water.
● Hydrophobic (non polar) phospholipid tails point inward facing each other
forming a hydrophobic core which acts as a barrier to hydrophilic
molecules & ions
Factors which impact membrane fluidity:
1. Increased percentage of ● Unsaturated fatty acids have C=C double bonds which causes kinks
unsaturated fatty acids (bending) in fatty acids → they fit together more loosely
present INCREASES
membrane fluidity
2. Tail length → The ● The longer the tail, the more bond interactions between fatty acids, holding
longer the tail the less them closer, so fluidity decreases
fluid the membrane
3. Temperature ● As temperature increases fluidity increases due to phospholipid molecules
having a greater kinetic energy.
4. Cholesterol (more detail ● Fits between phospholipid molecules
soon) ● At low temperatures, cholesterol increases the membrane fluidity →
cholesterol prevents phospholipids from packing close together
● At high temperatures, cholesterol decreases the membrane fluidity.
2
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 or Stuvia-credit 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 rodaynaelnaggar. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.48. You're not tied to anything after your purchase.
