Cell Membrane Flashcards
What is a symport?
Secundary transport that lets two molecules at the same time in the same direction
What are the levels of organisation of life?
Atom-molecule-macromolecule-organelle-cell-tissue-organ-organsystem-organism
What are the bodyfluid contents of a body?
60% of body weight, 2/3 intracellular fluid (ICF), 1/3 extracellular fluid (ECF)
What are the reasons for water output?
Insensible loss= lungs/breathing, evaporation from skin
Sensible loss= sweating, feces, urine
What are reasons for water input?
Drinking
Food
Metabolically produced water
What is membrane proteins?
Peripheral proteins- loosely bound to surface, cell surface identity markers (antigens)
Integral proteins- goes through the membrane (transmembrane), transport proteins (channels, pumps)
What is the main solute in ECF and thereby responsible for ECF osmolarity?
Na+
What is an antiport?
Secundary transport of molecules in different directions (one in-one out)
What are the major differences between ICF and ECF?
ICF-more protein, more K+ ions, less Na+ ions, more PO3-
ECF-no protein (except in plasma), less K+ ions, more Na+ ions, more Cl- ions
What are the concequence of isotonic ECF?
None
What is secondary active transport?
Uses the gradient of one ion to let another one through at the same time. No ATP needed
What is osmolarity?
The concentration of solute particles dissolved in the fluid
What makes the cell membrane semi-permiable?
Protein channels
Specific channels allow soecific material across
How does large molecules move through the cell membrane?
Through vesicles and vacuoles
What is the use of membrane carbohydrates?
Cell-cell recognition (ability to distinguish one cell from another)
Antigens
Immune system (basis for rejection of foreign cells)
What does diffusion mean?
Since the universe strives for entropy (disorder) diffusion is movement from high concentration to low concentration
What is the main solute in ICF, and thereby responsible for ICF osmolarity?
K+
What different kinds of endocytosis are there?
Phagocytosis-“cell eating”
Pinocytosis-“cell drinking”
Receptor medlares endocytosis-triggered by molecular signal
What is the Na+/K+ pump?
Active transport (requires ATP) and lets 3 Na+ into cell and 2 K+ out
What are the functions of membrane proteins?
Transporters Enzyme activity Cell surface receptors Cell surface identity markers Cell adhesion Attachment to cytoskeleton
What can move freely through a phospholipid bilayer?
Hydrophobic molecules (O2, CO2, N2, benzene) can move freely Small uncharged polar molecules (H2O, urea, glycerol) can move in some extent Large uncharged molecules (glucose, sucrose) can hardly move in
What is endocytosis?
The movement of large molecules into the cell via vesicles (phagocytosis or pinocytosis)
What is the meaning of the Fluid Mosaic Model?
It is not rigid, it is asymmetrical, comprised of different molecules
Consists of phospholipid bilayer, proteins and carbohydrates
What is facilitated diffusion?
Diffusion through protein channels, do not need ATP
Where can you find polar amino acids?
On outersurface of membranes since hydrophilic
How is fluid balance regulated?
ECF volume
ECF osmolarity
What are the concequence of hypertonic ECF?
Cells shrink due to water leaving the cell
What are the main composition of ions in ICF and ECF?
ICF mainly K+ and PO4—
ECF mainly Na+ and Cl-
What is active transport?
When molecules move AGAINST concentration gradient
Through “pumps” that changes shape while moving solute from one side to the other
Requires ATP
What is physiology?
The study of functions in living systems
What is needed to maintain stable water balance?
Water input must equal water output
What are the concequence of Hypotonic ECF?
Cell swells due to water entering the cell
What are the different transports through the cell membrane?
Passive transport (simple diffusion) needs no ATP Facilitated transport (through protein channel) needs no ATP Active transport (protein pump) against concentration gradient=needs ATP
What classes of amino acids are there?
Nonpolar=hydrophobic
Polar=hydrophilic
What is the osmolarity of ICF/ECF?
~300mOsm/L
What is Hypertonic, isotonic and hypotonic?
Hypertonic=more solute, less water
Isotonic-equal solute and water
Hypotonic=less solute, more water
Describe the phospholipid bilayer
Consists of two layers of phospholipids which each has a hydrophilic (polar) head and a hydrophobic tail (nonpolar)
The heads turn outwards and the tails inwards creating a double layer in membranes
Where can you find nonpolar amino acids?
Within membrane, since hydrophobic
What is plasma membrane?
A thin bi-layered phospholipid layer surrounding each cell
What is osmosis?
The diffusion of water from high concentration of water to low concentration of water (across semi-permiable membranes)
What can NOT move through phospholipid bilayers?
Ions
Polar molecules
Large molecules (starch, proteins)
What is exocytosis?
The movement of large molecules out through cell membrane via vesicles
