Lecture 7 - Cell Membranes Flashcards
What does a Membrane Structure include ?
Lipids
Carbohydrates
Proteins
Proteins In Cell Membrane
The cell membrane contains various proteins, which are primarily involved in transport, cell recognition, and signaling.
Channel and Carrier Proteins
In Cell Membrane
These proteins facilitate the movement of ions and molecules across the membrane. Channel proteins create pores for specific ions to pass through, while carrier proteins change shape to move molecules across.
Receptor proteins In Cell Membrane
These bind to specific molecules outside the cell, triggering changes inside the cell (signal transduction).
Structural Proteins In Cell Membrane
These help anchor the cell membrane to the cytoskeleton, providing structural support and maintaining cell shape.
Glycoproteins In Cell Membrane
These are proteins with carbohydrate chains attached, contributing to cell recognition and immune responses.
Cell Recognition In Cell Membrane
Glycoproteins on the cell surface help cells recognize each other, which is crucial for immune responses, as the immune system can identify self from non-self cells.
Cell Signaling In Cell Membrane
Some glycoproteins act as receptors for hormones and neurotransmitters, facilitating cell communication.
Glycolipids In Cell Membrane
These are lipids with carbohydrate chains, mainly located on the outer layer of the cell membrane.
Cell Recognition and Communication In Cell Membrane
Similar to glycoproteins, glycolipids help in cell-to-cell recognition and communication, important for tissue formation and immune responses.
Protection and Stability in Cell Membrane
Glycolipids form a protective coat on the cell surface, helping to stabilize the membrane and protect it from harsh environmental conditions.
Movement across molecules
Hydrophobic molecules can easily pass through (steroids)
Hydrophilic (polar) water soluble molecules hard to pass through
Water can (very small)- slow
5 things Membranes contain
GlycoProteins
GlycoLipipds
PhosphoLipids
Protein Channels/Carriers
Cholesterol
Why do Phospholipid molecules make a barrier ?
Phospholipid molecules form a barrier to dissolved (water soluble ) substances
Why is the centre of bilayer is hydrophobic ?
so water- soluble substances can’t easily pass through
What does a Polar hydrophilic head do ?
Its attracted to water
What does a non-polar Hydrophobic tail do ?
Repels water
Describe how Phospholipid are arranged in plasma membrane
its a Bilayer
Hydrophobic tail on inside
Hydrophilic head on outside
Name me all the Movements across molecules
Simple Diffusion
Facilitated diffusion
Osmosis
Active transport
Co-transporters
Simple Diffusion
The net movement of particles from an area of high concentration to an area of lower concentration
Molecules move down the concentration gradient
Osmosis
Water potential if the potential (likelihood) of water molecules to diffuse out of or into a solution. Pure water has a potential of zero. Adding solutes lowers the water potential so water potential is always negative. The more negative a water potential the stronger the concentration of solutes in the solution
.
Isotonic = same water potential
Hypotonic = high water potential
Hypertonic = lower water potential
Facilitated diffusion
Larger molecules (amino acids and glucose) diffuse slowly
Charged particles (ions and polar molecules) because they are water soluble (centre of bilayer is hydrophobic) also would diffuse slowly
B- Channel proteins form pores – charged particles
C- Carrier proteins (large molecules)
Carrier proteins are used for ?
Large molecule attaches to carrier protein
Protein changes shape
Releases molecule on opposite side of membrane
Down the concentration gradient
Channel proteins are used for ?
Form pores in the membrane
Small Charged particles can diffuse through
Smaller ions and polar molecules
Down the concentration gradient
