Cell biology II - USABO

osmolarity

relative concentration of solutes in an environment

facilitated diffusion

transport using transport proteins

cotransport/symport

when two molecules move in the same direction

countertransport/antiport/exchange

when two molecules move in opposite directions

microtubules

hollow rods made from alpha-tubulin and beta-tubulin

cilia/flagella microtubule arrangement

9+2

cilia/flagella microtubule arrangement at cell membrane

9+0 doublet

centriole microtubule arrangement

9+0 triple

kinesin

moves cells to plasma membrane end of the microtubule

dynein

does transport to minus (nucleus) end (retrograde)

intermediate filaments

permanent structures; used for support and strength in keratin

Microfilaments

Thin solid rods; AKA actin filaments; bears tension against forces

Microfilament function

Forms shape of the cell; function in psuedopodia for movement; work with myosin in muscle; bind to integrin proteins

Myosin

Anterograde motor protein; moves muscles, closes contractile ring in cytokinesis; transports cargo

plasmodesmata

Junctions only found in plant cells; allow direct cytoplasmic exchange

Gap junctions

Connect animal cells using connexin proteins

Tight junctions

Create a watertight seal between cells

Desmosomes

Connects two cells together using intermediate filaments

Adherens junctions

Connect two cells together using actin microfilaments and cadherin proteins

porin channels

transmembrane proteins which create water-filled channels to allow hydrophilic molecules to cross; passive diffusion

beta-barrels

Proteins made of beta-sheets; make up porins

Aquaporins

Transmembrane proteins of 6 alpha helices

Flippases

Uses ATP to translocate amino phospholipids to cytosolic side to prevent apoptosis

floppases

Moves cytosolic phospholipids to extracellular side and uses ATP

scramblases

moves phospholipids down their concentration gradient; uses no ATP; activity increases with cytosolic Ca2+

ligand

molecule that binds to a receptor on a cell

G-protein Coupled Receptor

Created by 7 alpha helices

Receptor Tyrosine Kinases

receptors embedded into the plasma membrane

Gated ion channel

receptor embedded into the membrane which acts as a valve

phosphorylation cascade

a chain of enzymes where each enzyme activates the next

protein kinases

adds a phosphate to proteins (activates)

protein phosphatases

removes a phosphate from proteins (deactivates)

scaffolding proteins

Holds together multiple kinases; improve efficiency

second messengers

have low intracellular concentration; amplifies signal by diffusion through cell

cAMP pathway

GPCR activates adenylyl cyclase, which converts ATP to cAMP, which is a second messenger

Ca2+ pathway

GPCR activates phospholipase C, which cleaves PIP2 into DAG/IP3