Cells Flashcards
polar head and a non polar hydrophobic tail region
phospholipids are made of
made up of a polar group (choline), phosphate functional group, 3 carbon glycerol
polar head
2 long fatty acid chains
non polar tail
nonpolar, repels large objects that attempt to pass through
interior of phospholipid bilayer
located in inner/outer layer, maintains membrane fluidity by limiting phospholipid packing, allows cell membrane to function at wide range of temperatures and rigidity
cholesterol molecules
speed up biochemical reactions in the cell
enzymes
only at surface of lipid bilayer, allow for cell to cell interactions
surface/peripheral proteins
span the entire lipid bilayer, allow for movement of molecules by passive or active transport, proteins for signal transduction which allows for identification of chemical messengers, proteins for cell adhesion which allow for intercellular joining
transmembrane/integral proteins
transport channels, carrier proteins, protein pumps & coupled channels
examples of transmembrane/integral proteins
contain chains of carbohydrates on outer layer of cell membrane that are attached to surface, allow for cell to cell recognition and communication, cell identity markers for self recognition, enables immune cells to process antibodies
glycoproteins/glycocalyx
attach to the cytoskeleton to provide anchorage and support
proteins attached to cytoskeleton
chains of carbohydrates that are attached to lipid molecules embedded in the lipid bilayer, cellular recognition, cell connections and tissue formation as well as immune response
exterior glycolipids
cell membranes are reinforced by a network of protein supporting fibres of cytoskeleton on inside of plasma membrane which are attached to transmembrane proteins in the lipid bilayer
network of supporting fibres
phospholipids & components of the cell membrane, including proteins are able to drift sideways laterally, due to fluid consistency of phospholipid bilayer
fluid mosaic model
moving from high to low concentration down the concentration gradient, no energy
passive transport
random movement of molecules down the concentration gradient
diffusion
cell membrane is a semi permeable membrane, small uncharged, hydrophobic molecules can move through
diffusion occurs bc
water can move across semi-permeable membrane, doesn’t allow large/charged molecules (sugar, salt, amino acids, ions)
osmosis happens bc
movement of water by diffusion across the phospholipid bilayer
osmosis
lower concentration of solute
hypotonic solution
equal concentration of solute and solvent
isotonic solution
greater concentration of solute
hypertonic solution
animal cell in hypotonic solution
lysed
plant cell in hypotonic solution
turgid
animal cell in hypertonic solution
shriveled
plant cell in hypertonic solution
flaccid
plant cell in an extremely hypertonic solution
plasmolysed
water pressure
osmotic pressure
help maintain cell structure, vacuole expands to hold excess water and cell wall maintains shape through rigidity and flexibility
cell wall + vacuole
transmembrane proteins can transport molecules e.g. ions, salt and glucose to cross semipermeable membrane, down the concentration gradient more quickly than regular diffusion
facilitated diffusion
transmembrane proteins, always open, tunnel for molecules to pass through
channel proteins
through hydrophobic interactions, hydrogen bonds, ionic bonds etc. transmembrane/integral proteins change shape when right molecule is met, allowing it to pass through
carrier proteins
transmembrane/integral proteins that are just for water allowing water to move more quickly than simple diffusion
aquaporins
movement of materials against concentration gradient, requires energy e.g. from low to high or movement between equilibrium reached liquids
active transport
when food is digested, carrier proteins must continue to absorb glucose even when glucose levels increase in intestinal cells
ex of active transport
materials (ions, sugars, amino acids) moved to be stockpiled, ions e.g. Na, K are used to ensure cell functioning
why active transport is used
ribose sugar attached to adenine base and three phosphates, bonds between phosphates are high energy bonds that are released when ATP is broken down into ADT (adenine triphosphate) and inorganic phosphate
ATP
low internal concentration of Na, high internal concentration of K. Pumps 3 Na ions out of cell, then 2 K into the cell. Protein changes shape as it pumps ion similar to active site change and when ions are released, it returns to original shape
sodium potassium pump
mitochondria and chloroplasts, 2 special transmembrane protein channels, 1st pumps protons outside of membrane, creating proton gradient higher on outside of membrane, protons move through second channel pump by diffusion, coupled with production of ATP
proton pump
two transmembrane work together, one transports largest molecule, other is usually sodium potassium pump or proton pump, creates concentration gradient that target molecule links to Na or H across cell membrane
coupled channels
kidney cell membrane contains sodium glucose that transports glucose accompanied by Na, concentration outside of kidney cell is high bc of sodium potassium pump, as Na diffused back into the cell through sodium glucose coupled channel bringing glucose w it
ex of coupled channels
movement of large molecules into the cell requiring energy, cell membrane wraps around and engulfs it in a endocytic vesicle
endocytosis
cell eating, particles/bacteria/viruses, engulfed and taken into cell in a vesicle
phagocytosis
cell drinking, extracellular water contains solutes is taken in the cell in a vesicle
pinocytosis
surface receptor proteins bind to specific molecules, collect into a pit coated with proteins called clathrin, pit forms a vesicle which enters the cell
receptor mediated endocytosis
movement of large molecules out of the cell requiring energy, secretory vesicles form around a molecule, combining w cell membrane to release contents outside of the cell
exocytosis
