Cell Membranes and Signaling CH5 Flashcards
Fluid Mosaic Model
Phospholipid bilayer contains proteins which can move
Membrane Protein Functions…
- Move materials through the membrane
2. Receive chemical signals from the cell’s external environment
Membrane Fluidity is affected by…
- Lipid Composition - cholesterol/long chain fatty acids make membranes less fluid - decreases cell activity
- Temperature
Peripheral Membrane Proteins
Lack exposed hydrophobic groupos and are not embedded in the bilayer
Have polar/charged regions that interact w/ exposed parts of integral membane proteins or w/ polar heads of phospholipids
Integral Membrane Proteins
At least partly embedded in the phos. bilayer
Have both hydrophilic and hydrophobic regions
Anchored Membrane Proteins
Hydrophobic lipid components anchor them in phos. bilayer
Transmembrane Protein
An integral membrane protein that extends all the way through the phos. bilayer and protrudes on both sides
Glycolipid
Carbohydrate covalently bonded to a lipid
Extend outside the cell surface, serve as recognition signal for interactions between cells
Glycoprotein
Carb covalently bonded to protein
Function as signaling sites (like glycolipids)
Can cause cells to adhere to eachother (cell-cell adhesion)
Passive Transport
Does not require direct input of metabolic energy
Moves WITH concentration gradient
1. Simple Diffusion
2. Facilitated diffusion
Active Transport
Requires input of metabolic (chemical) energy from an outside source
Moves AGAINST concentration gradient
1. Primary Active Transport
2. Secondary Active Transport
Hypertonic
More solute outside of the cell, water moves out of the cell
Hypotonic
More solute inside the cell, water moves into the cell
Channel Proteins
- An integral membrane protein that allows certain substances to pass (water/AA’s/ sugars/ions)
- Speed up diffusion through phos. bilayer
- Form of facilitated diffusion
Gated Channels
Open when a stimulus causes a change in the 3D shape of a channel
Ligand
Stimulus for the opening of gated channels –> Ligand Gated Channels
Voltage Gated Channels
Opening of channel is stimulated by a change in the voltage across the membrane
Aquaporins
Allow large amounts of water to move along its concentration gradient
Primary Active Transport
Involves the direct hydrolysis of ATP which provides the energy required for transport
Secondary Active Transport
Does not use ATP directly
Energy is supplied by an ion concentration gradient or an electrical gradient established by primary active transport
Autocrine
signals bind to receptors on the same cell that secretes them
Paracrine
signals bind to receptors on nearby cells
Signal Transduction pathway
A sequence of molecular events and chemical reactions that lead to a cell’s response to a signal
Hormones
Signals sent to distant cells that travel through the circulatory system
