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47 terms

BSCS Molecular Biology Chapter 3

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cytoplasm
entire contents of the cell, except the nucleus, bounded by the plasma membrane
transport proteins
special proteins embedded in the membrane that
selectively permeable
membranes regulate the exchange of materials in a very specific way
glycoproteins
proteins embedded in the membranes that have sugars attached to the heads
glycolipids
lipids embedded in the membranes that have sugars attached to the heads
diffusion
movement of a substance down its concentrated gradient from an area of higher concentration to an area of lower concentration; increases the entropy of the system
concentration gradient
difference in the concentration of a substance over a distance
osmosis
movement of water down its concentration gradient
turgor
outward pressure of a cell against its cell wall
passive transport
diffusion of a substance through a biological membrane
active transport
movement of a substance through a biological membrane against a concentration gradient
facilitated diffusion
spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients
endocytosis
cellular uptake of materials where the plasma membrane surround and engulfs extracellular materials
exocytosis
release of macromolecules from a cell by the fusion of vesicles with the plasma membrane
alveoli
air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place
cuticle
waxy outlayer covering the surfaces of mos land-dwelling plants, animals, fungi
stomates
openings between two guard els in the epidermis of a plant leaf through which gases are exchanged with the air
transpiration
the loss of water to the atmosphere by a plant through the stomates in its leaves
homeostasis
the balanced and controlled conditions in the internal environment of an organism
ammonia
toxic nitrogen compound (NH3) excreted by some aquatic organisms; though to have been present Earth's early atmosphere
kidneys
an organ that regulates water and salt levels, filters water and wastes from the lood, and excretes the end products
nephrons
functional unit of a kidney consisting of a glomerulus, its associated capsule, and tubule, surrounded by capillaries
urinary system
vertebrate organism the regulates levels of water and dissolved substances in the body, execreting wastes as urine
urine
the solution of wastes execreted from the kidney
ureter
carries urine from kidney to urinary bladder;
urinary bladder
an organ that stores urine before it is discharged from the body through the urethra
urethra
tube through which urine travels from the bladder to the outside of the body
glomerular capsule
the cup of a nephron, which filters blood
glomerulus
a ball of capillaries surrounded by a glomerular capsule in the nephron; the site of filtration in the kidneys
filtration
fluid from plasma passes into nephron; is filtered thru the glomerular capillaries
reabsorption
takes place in tubules of nephron; cells of tubule reabsorb substances needed by body into the capillaries
secretion
cells in tubule wall selectively remove from capillaries material left in blood after filtration or reabsorption and excrete it into filtrate; regulates hormones
aldosterone
a hormone secreted by the adrenal gland; helps regulate sodium and potassium concentrations and water balance
feedback regulation
the regulation of the activity of an enzyme by one of its products
antidiuretic hormone
hormone released from the posterior lobe of the pituitary; enhances conservation of water by the kidneys
urea
colorless crystalline compound that is the main nitrogenous breakdown product of protein metabolism in mammals and is excreted in urine
uric acid
insoluble in H20; requires virtually no H20 for excretion; nontoxic form of nitrogenous waste
contractile vacuole
pumps excess water outside of a cell (using a pore in the membrane)
equilibrium
a state of balance
pituitary
an endocrine gland in the brain
cell membrane
encloses the cell; composed of two thin layers of phospholipids and proteins
filtrate
the materials that cross from the capillaries to the glomerular capsule
capillary
microscopic blood vessel penetrating the tissues and consisting of single layer of cells that allows exchange between the blood and tissue fluids
cellular respiration
the series of chemical reactions by which a living cell breaks down carbohydrates and obtains energy from them
hypotonic
net movement of water is into the cell; a lower osmotic pressure
hypertonic
net movement of water is out of the cell; a higher osmotic pressure
nitrogen waste
toxic by-product of metabolism proteins and nucleic acids