2.1.5 - Biological Membranes Flashcards
Phospholipid structure
A glycerol molecule
Two fatty acid tails (saturated and unsaturated)
Phosphate group
Properties of phospholipid
Phosphate group is polar —> hydrophilic
Fatty acid tails are non polar —> hydrophobic
(Amphipathic)
Why does soap dissolve the membrane easily
Membranes are made from lipids
What is selective permeability
When what goes in and out of the cell is regulated by only letting certain things in and out
Major molecules in cell membranes
Phospholipids
Proteins
Amphipathic
The molecule has dual nature (hydrophobic and hydrophilic)
What roles do proteins play in transport
Regulation
What kinds of cells have cell walls
Plant
Bacterial
Fungal
What are glycoproteins made from
Proteins
Sugars
Example of a glycoprotein
Antibodies - important in immune response
What are glycolipids made of
Fats
Sugars
Why can’t water pass through the phospholipids
The inside is non polar
How do proteins assist in transport
Allow big things and things that have a charge to move across the membrane
What is a plant cell wall made of
Cellulose
What is a bacteria cell wall made from
Peptidoglycan
What is a fungal cell wall made from
Chitin
Function of chlolesterol in cell membranes
Regulates fluidity of membrane by keeping phospholipids slightly apart or pulling them closer
Hydrophilic ends interact w/ heads and hydrophobic end interacts w/ tails; pulls them together
Prevent phospholipids from grouping together too closely and crytsallising
Function of glycoprotein in cell membrane
Cell adhesion - binding site for hormones and drugs
Cell signalling to coordinate activities of organisms
Antigens for the recognition of ‘self’
Acts as receptor
Function of glycolipid
Form cell markers/ antigens
Function of carbohydrates in cell membrane
Hydrophilic molecules that sit on the cell surface membrane and attracts water with dissolved solutes
Carrier protein
Changes shape to allow specific molecules in and out of the cell
Channel protein
These provide a hydrophilic channel that allows the passive movement of polar molecules down a concentration gradient
Water filled channel inside is lined with hydrophilic amino acids
Integral/ intrinsic proteins
Proteins that span the whole membrane
Either channel or carrier proteins
Protein receptor site
Acts as receptors to detect hormones and/or drugs
How do carrier proteins work
Molecule binds
Carrier protein changes shape
Releases molecules on the other side
When is diffusion rapid
Small
Non-polar molecules
Facilitated diffusion
Involves carrier and channel proteins within the cell membrane.
These help transport large, polar molecules e.g. glucose, across the membrane