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Cell Membrane Transport
Terms in this set (30)
What kind of molecules can diffuse across the phospholipid bilayer?
small hydrophobic or uncharged molecules
How do small hydrophobic molecules diffuse across the bilayer?
they go between adjacent phospholipids via simple diffusion
what kind of molecules can't diffuse across the phospholipid bilayer?
ions, larger uncharged molecules
how to molecules that can't diffuse across the bilayer get across?
What kinds of transport proteins are there?
carrier (transporter) proteins and channel proteins
what kinds of molecules do carrier proteins transport?
small organic molecules and inorganic molecules, nucleotides, amino acids, monosaccharides
how do carrier proteins transport molecules across the bilayer?
they change conformation, allowing the solute to cross the membrane
how to carrier proteins discriminate
have specific binding sites so depends on if the molecules can bind
what kind of molecules do channel proteins transport?
how do channel proteins transport ions across the bilayer?
they form tiny hydrophilic pores (alpha helixes with polar side chains facing inward) in the membrane through which solutes can pass by diffusion
how do channel proteins discriminate?
based on size and charge, they are usually gated and open in response to cellular conditions
what does the diffusion rate of ion in channel proteins depend on?
the electrochemical gradient
what is passive transport/facilitated diffusion?
proteins necessary for transport but via diffusion along concentration gradient (no input of energy is necessary)
what is active transport?
moving molecules against a concentration gradient, requires energy
what is coupled/cotransport?
the electrochemical gradient of one molecule drives the transport of another molecule against its concentration gradient
what is osmosis?
diffusion of water across a semi permeable membrane in response to a concentration gradient
what is a hypotonic solution?
the surrounding solution is less concentrated than the inside of the cell
what will happen to a cell in a hypotonic solution?
water will be absorbed into the cell, in animal can cause lysing, in plants vacuole absorbs water and the rigid cell walls dont rupture
what is a isotonic solution?
the surrounding solution is same concentration
what is a hypertonic solution?
the surrounding solution is more concentrated than the inside of the cells
what will happen to a cell in a hypertonic solution?
water will leave the cell and cells become crenated (animal cells), in plant cells, vacuole will shrink but still cell wall prevents overall shrinking
how are large molecules transported across the cell membrane?
endocytosis or exocytosis
what is exocytosis?
releasing large molecules out of the cell
what molecules does exocytosis involve?
occurs with newly synthesized proteins from the ER and golgi
what is endocytosis?
taking particles into the cell
what are the types of endocytosis?
phagocytosis, pinocytosis, receptor mediated
what is phagocytosis?
uptake of large particles
what is pinocytosis?
uptake of dissolved particles, result from invagination of the cell membrane, resulting vesicle (endosomes) will sort and transport contents to appropriate cellular locations
what is receptor mediated endocytosis?
receptors for uptake of specific molecules
how is cholesterol transported through the blood?
transported via lipoproteins
THIS SET IS OFTEN IN FOLDERS WITH...
Introduction to Cellular Biochemistry
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