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Bio Ch 5
microscopy, membranes etc.
86
Biology
Undergraduate 2
03/07/2010

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Term
endomembrane system
Definition
Network of membranes enclosing the nucleus, ER, golgi apparatus, lysosomes, and vacuoles.
Term
vesicle
Definition
small membrane-enclosed spheres which transfer materials between members of the endomembrane system
Term
nuclear envelope
Definition
double membrane structure enclosing the nucleus
Term
nuclear pores
Definition
provide a passageway for molecules/macromolecules to move in and out of the nucleus; formed when inner and outer membrane make contact with one another.
Term
nuclear matrix
Definition
filamentous network of proteins inside the nucleus
Term
chromatin
Definition
the complex formed by DNA and the proteins that pack it together.
Term
nucleolus
Definition
assembles ribosomes in nondividing cells.
Term
chromosome territory
Definition
distinct, non-overlapping area designated for a specific chromosome within the nucleus.
Term
endoplasmic reticulum (ER)
Definition
a convoluted (nice word) network of membranes that form flattened fluid-filled tubules
Term
cisternae
Definition
tubules of the ER
Term
lumen
Definition
internal space of an organelle
Term
rough ER
Definition
plays a key role in the initial synthesis and sorting of proteins. attaches carbohydrates to proteins and lipids.
Term
glycosylation
Definition
the process of attaching carbohydrates to lipids and proteins
Term
smooth ER
Definition
functions in diverse metabolic processes including detoxification, carbohydrate metabolism, calcium ion accumulation, and synthesis/modification of lipids.
Term
Golgi apparatus
Definition
stack of flattened membranes, each enclosing a single compartment. performs 3 overlapping functions: secretion, processing, sorting proteins.
Term
cis/trans/medial Golgi
Definition
cis - located nearest to ER
trans - nearest to plasma membrane
medial - in the middle!
Term
proteolysis
Definition
process of cutting proteins into smaller polypeptides
Term
proteases
Definition
the enzymes which cut proteins in proteolysis
Term
lysosomes
Definition
small organelles in animal cells which can lyse (disintegrate?) macromolecules.
Term
acid hydrolases
Definition
hydrolytic enzymes found in lysosomes which use a molecule of water to break a covalent bond.
Term
autophagy
Definition
(eating of one's self) process by which cellular materiel (ie an old organelle) is enclosed in a double membrane and disposed of.
Term
autophagosome
Definition
formed when a double membrane encloses an old organelle in the process of autophagy. bonds with a lysosome and the lysosome digests the contents.
Term
vacuole
Definition
(literally, empty space!) but they're not actually empty, they contain fluids and sometimes solids. varied functions include molecule storage, space-filling, metabolism in some protists.
Term
tonoplast
Definition
membrane of a central vacuole
Term
contractile vacuole
Definition
found in fresh water organisms, they expand as water enters the cell and expel that water outside the cell.
Term
phagocytic vacuole/food vacuole
Definition
some protists engulf their food into this digestive enzyme-containing vacuole
Term
membrane transport
Definition
process of moving things into and outside a plasma membrane
Term
cell signaling
Definition
all cell plasma membranes contain receptors that receive signaling molecules from the environment or other cells. once a receptor receives a signal, it begins a system of responses known as a signal cascade.
Term
cell adhesion
Definition
proteins allow adjacent cells to bind to one another.
Term
semiautonomous organelle
Definition
can grow and divide to reproduce, but depend on other parts of the cell for internal components.
Term
mitochondrion
Definition
primary function is to produce ATP, but also produce/modify/break down several types of cellular molecules.
Term
cristae
Definition
folded projections of the inner mitochondrial membrane
Term
mitochondrial matrix
Definition
area inside the inner membrane of a mitochondrion
Term
thylakoid membrane
Definition
forms many flattened, fluid filled tubules that enclose a single convoluted compartment.
Term
granum
Definition
a stack of thylakoids
Term
stroma
Definition
compartment of a chloroplast that is inside the inner membrane but outside the thylakoid membrane
Term
plastid
Definition
plant organelles including chloroplasts. weird description on the top of page 82.
Term
proplastids
Definition
ungeneralized, that which plastids are derived from.
Term
peroxisome
Definition
function is to catalyze various chemical reactions which break down molecules by removing H or adding O. peroxisomes are semiautonomous.
Term
catalase
Definition
an enzyme contained in peroxisomes which breaks down hydrogen peroxide into water and oxygen gas.
Term
glyoxysome
Definition
similar to peroxisomes. found in plant seeds and convert fats to sugars.
Term
phospholipid bilayer
Definition
framework of plasma membrane; 2 layers of amphipathic phospholipids
Term
amphipathic
Definition
hydrophobic and hydrophilic regions
Term
fluid-mosaic model
Definition
the model of a plasma membrane, which has fluid properties and has proteins embedded within the phospholipid framework
Term
leaflet
Definition
half of a phospholipid bilayer
Term
transmembrane protein
Definition
have one or more regions htat are physically embedded in the membrane; such a region is known as a transmembrane segment and its nonpolar amino acids interact well with the hydrophobic region.
Term
Brad from Jacque-imos says hi!
Definition
Term
lipid anchor
Definition
the covalent attachment of a lipid to an amino acid side chain within a protein.
Term
integral membrane proteins
Definition
cannot be released from the membrane without damage to the integrity of the membrane. include transmembrane and lipid anchor proteins.
Term
peripheral membrane proteins
Definition
proteins noncovalently bonded to regions of integral membrane proteins that project out from the membrane or to polar heads of phospholipids.
Term
semifluid
Definition
ability of a membrane's phospholipids to move in 2 different dimensions relative to each other, isn't it?
Term
unsaturated (phospholipid)
Definition
phospholipid tail has a double bond which makes the tail kinked and the bilayer more fluid
Term
glycosylation
Definition
the process of covalently bonding a carbohydrate to a lipid or protein. forms a glycolipid or glycoprotein
Term
cell coat/glycocalyx
Definition
carbohydrate-rich zone on a cell's surface that shields it from mechanical and physical damage
Term
transport proteins
Definition
allow membranes to be selectively permeable by providing a passageway for the movement of some but not all substances across the membrane
Term
diffusion; passive diffusion
Definition
solute moves from area of high concentration to area of low concentration. passive diffusion occurs w/o the help of a transport protein
Term
transmembrane gradient
Definition
concentration of a solute is higher on one side of membrane than the other
Term
ion electrochemical gradient
Definition
dual gradient that has both and electrical gradient and chemical gradient
Term
passive transport
Definition
refers to the diffusion of a solute across a membrane in a process taht is energetically favorable and does not require an input of energy
Term
facilitated diffusion
Definition
passive diffusion with the aid of transport proteins
Term
crenation
Definition
what happens to an animal cell in a hypertonic solution. fluid rushes out and cell shrinks
Term
osmotic pressure
Definition
the hydrostatic pressure required to stop the net flow of water across a membrane due to osmosis
Term
turgor pressure
Definition
osmotic pressure in plant cells
Term
aquaporin
Definition
protein that facilitates the diffusion of water into and out of a cell (aqua pours in!)
Term
channels
Definition
transmembrane proteins that form an open passageway for facilitated diffusion of ions or molecules across the membrane
Term
gated channel
Definition
can open to allow diffusion or close to prevent it (most channels are of this sort)
Term
ligand-gated channels
Definition
channels controlled by the noncovalent bonding of small molecules called ligands (hormones or neurotransmitters)
Term
voltage gated channels
Definition
opens and closes in response to changes in the amount of electrical charge across the membrane
Term
mechanosensitive channels
Definition
respond to changes in membrane tension
Term
transporters/carriers
Definition
bind their solutes in a hydrophilic pocket and undergo a conformational change that switches the exposure of the pocket to the other side of the membrane. much slower than channels
Term
uniporters
Definition
bind a single molecule or ion and transport it across the membrane
Term
symporters/cotransporters
Definition
bind 2 or more molecules or ions and move them in the same direction
Term
antiporters
Definition
bind 2 or more ions or molecules and move them in opposite directions
Term
pump
Definition
transporter that directly couples its conformational changes to an energy source, such as ATP hydrolysis
Term
ATP-driven pumps
Definition
pumps driven by the hydrolysis of ATP. pumps solutes against a gradient
Term
active transport
Definition
movement of a solute against its gradient
Term
primary active transport
Definition
involves pumps that directly use energy to transport a solute against a gradient
Term
secondary active transport
Definition
involves utilization of a pre-existing gradient to drive the active transport of a solute (i.e. H+/sucrose symporter)
Term
electrogenic pump
Definition
generates an electron gradient. (ie Na+/K+-ATPase)
Term
Na+/K+-ATPase
Definition
hydrolyzes one atp and antiports 3Na+ out and 2K+ in
Term
reaction mechanism
Definition
steps that direct the pumping of ions across a membrane
Term
exocytosis
Definition
process by which material inside the cell is packaged into vesicles and excreted into the extracellular environment
Term
endocytosis
Definition
plasma membrane invaginates (folds inward) to form a vesicle that brings substances into the cell
Term
receptor-mediated endocytosis
Definition
a receptor is specific for a given cargo. when a receptor binds to the cargo, this stimulates the formation of a vesicle. protein coat forms around the vesicle and is shed once inside the cell.
Term
pinocytosis
Definition
involves the formation of a vesicle to internalize extracellular fluid
Term
phagocytosis
Definition
involves the formation of an enormous membrane vesicle called a phagosome that engulfs a large particle such as a bacterium.
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