A/P CH. 3 - Cells Flashcards
Function of the plasma membrane
Forms the cells flexible outer surface, selective barrier that regulates flow of materials in and out of the cell, plays a key role in communicating with other cells.
Function of the cytoplasm
Consists of all the cellular contents between the plasma membrane and nucleus. Has two components, cytosol and organelles. Cytosol is the fluid portion, contains water, dissolved solutes, and suspended particles. Organelles have specific characteristics and functions.
Function of the nucleus
Large organelle that houses most of the cells DNA. Within the nucleus each chromosome, a single molecule of DNA associated with several proteins, contains thousands of hereditary units called genes.
Fluid mosaic model
Molecular arrangement of the plasma membrane resembles a continually moving sea of fluid lipids that contains a mosaic of many different proteins.
What is the basic structural framework of the plasma membrane?
The lipid bilayer.
What makes up the lipid bilayer?
Two back to back layers made up of three types of lipid molecules. Phospholipids 75%, cholesterol 20%, glycolipids 5%.
Amphipathic molecules in bilayer
molecules in bilayer have polar and non-polar parts, resulting in a specific arrangement. Head = hydrophilic, polar. Tail = hydrophobic, non-polar.
Integral proteins
Extend into or through the lipid bilayer and are firmly embedded. Most integral proteins are transmembrane proteins, meaning they span the entire lipid bilayer.
Peripheral proteins
Not as firmly embedded in the membrane. Attached to the polar heads of the membrane lipids or to integral proteins at the inner or outer membrane surface.
Glycoproteins
Proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid.
Glycocalyx
Carbohydrate portions of glycolipids and glycoproteins form an extensive sugary coat. Acts as a unique signature / identifier.
Ion channels
Selective channels formed by integral proteins only specific ions can pass through.
Carriers
Integral proteins that selectively move a polar substance or ion across cellular membrane. AKA transporters.
Receptors
Cellular recognition sites that bind to a specific molecule. A specific molecule that binds to a receptor is called a ligand.
Linkers
Integral proteins that anchor proteins in the plasma membrane to other cells.
Cell identity markers
Glycoproteins and glycolipids that enable a cell to recognize other cells or respond to dangerous foreign cells.
Selective permeability
Lipid bilayer is highly permeable to non-polar molecules such as O2 and CO2, moderately permeable to small, uncharged polar molecules such as water and urea, and impermeable to ions and large, uncharged polar molecules, such as glucose.
Facilitated diffusion
Integral membrane proteins assist specific substances across the membrane. Can be a membrane channel or a carrier.
Channel-mediated facilitated diffusion
Solute moves down its concentration gradient across the lipid bilayer through a membrane channel.
Carrier-mediated facilitated diffusion
Carrier moves a solute down its concentration gradient across the plasma membrane.
Tonicity
Measure of the solutions ability to change the volume of cells by altering their water content.
Isotonic solution
Equal concentration inside / outside of the cell.
Hypotonic solution
Lower concentration of solutes than the cytosol inside the cell.
Hypertonic solution
Higher concentration of solutes than the cytosol inside of the cell.