2. Cell Biology

plasma membrane

• composed of double layer of phospholipids; proteins embedded

• controls passage of materials in and out of cell

integral proteins

span membrane

peripheral proteins

embedded in only one face of membrane

membrane proteins

provide structure, catalyze reactions, act as receptors, act as antigens

glycocalyx

glycoproteins & glycolipids on surface of cell membrane

passive trasnport

net movement of ions & molecules across membrane from area of higher to lower conc., no metabolic energy used

simple diffusion

molecules pass through membrane directly or through channels

facilitated diffusion

small, organic molecules binds to carrier pro., causing conformational change to release molecule onto other side

active transport

net movement of ions & molecules across membrane from area of lower to higher conc., using energy (ATP)

promary active

hydrolysis of ATP directly responsible for action of pump

secondary active (coupled transport)

cotransport or countertransport of Na+ is necessary for transport

ATP used indirectly

carrier-mediated transport

• facilitated diffusion: carrier protein in membrane binds to target and changes shape to allow target into cell; does not use ATP

• active transport: uses pump to transport molecules against their concentration gradient; use ATP

non-carrier-mediated transport

all types of simple diffusion (even if it uses a channel protein)

paracellular transport

transport through spaces between cells

junction complexes: intercellular junctions btwn epithelial cells

zona occludens

tight junctions - no space btwn cells, proteins span btwn cells & anchored in place, circumferential

zonula adherens

belt desmosomes - proteins anchored in either cell interact, circumferential

macula adherens

desmosomes - cells “buttoned” together by desmosomal proteins

gap junctions

connexons in cell membrane create “bridge” across cells, often allow ions through

cytoplasm

material inside the cell (exclusive of nucleus) - cytosol & organelles

cytoskeleton

Latticework of microfilaments & microtubules

• support, mvment, intracellular transport

lysosome

membranous sac that digests foreign molecules and damaged organelles

peroxisome

membranous vesicle that contains enzymes to detoxify harmful molecules and break down hydrogen peroxide

• endocytosis, exocytosis, autophagy

mitochondrai

provide cellular energy via ATP production (ETC); have own DNA

cristae

folds in the inner membrane that inc. surface area

ribosomes

composed of two subunits (30S & 50S), each comprised of protein & ribosomal RNA

smooth ER

lacks ribosomes, metabolizes nonpolar compounds, stores Ca2+ in striated muscle

rough ER

ribosomes, assists in protein synthesis & transport to Golgi

Golgi complex (apparatus)

processes (adds oligosaccharides & lipids) and packages macromolecules into vesicles

nucleus

center for genetically determined info in eukaryotic cells

nuclear envelope

inner membrane & outer membrane

chromatin

DNA in nucleus

heterochromatin

dense, tightly wound DNA

euchromatin

diffuse, transactionally active DNA

nucleolus

site of synthesis of ribosomal DNA

membrane potential

difference in charge btwn inside of cell & outside of cell