CH 3 - CELLS & PLASMA MEMBRANES

Cell

the smallest unit of life capable of carrying out all vital functions

Cell Theory

states that cells are the basic structural and functional units of life

Plasma Membrane

selectively permeable membrane that surrounds the cell and controls substance movement

Selective Permeability

ability of a membrane to allow some substances to pass while restricting others

Fluid Mosaic Model

model describing the membrane as a fluid phospholipid bilayer with embedded proteins

Phospholipid Bilayer

double layer of phospholipids forming membrane structure

Hydrophilic Head

polar phosphate portion of phospholipid attracted to water

Hydrophobic Tail

nonpolar fatty acid portion of phospholipid repelled by water

Cholesterol

lipid that stabilizes membrane and regulates fluidity

Integral Protein

protein embedded within the membrane, often spans entire bilayer

Peripheral Protein

protein attached to membrane surface without penetrating bilayer

Glycoprotein

membrane protein with carbohydrate chain used for cell recognition

Glycolipid

membrane lipid with attached carbohydrate chain for recognition

Membrane Receptor

protein that binds ligands to trigger cellular responses

Transport Protein

membrane protein assisting substance movement across membrane

Cell Junction

specialized connection between neighboring cells

Tight Junction

junction that prevents leakage of substances between cells

Desmosome

anchoring junction providing mechanical strength

Gap Junction

communication junction allowing ion and small molecule passage

Cytoplasm

material between plasma membrane and nucleus

Cytosol

fluid portion of cytoplasm where metabolism occurs

Cytoskeleton

protein network maintaining cell shape and movement

Microfilaments

actin filaments involved in movement and tension resistance

Intermediate Filaments

fibers providing tensile strength

Microtubules

hollow rods involved in transport and cell division

Centrosome

microtubule organizing center

Centriole

cylindrical structure involved in spindle formation

Nucleus

control center containing genetic material

Nuclear Envelope

double membrane surrounding nucleus

Nuclear Pores

openings allowing RNA and proteins to pass

Nucleolus

site of ribosome assembly

Ribosome

organelle responsible for protein synthesis

Free Ribosome

synthesizes proteins for cytosol

Bound Ribosome

synthesizes proteins for secretion or membranes

Rough Endoplasmic Reticulum

modifies and transports proteins

Smooth Endoplasmic Reticulum

lipid synthesis and calcium storage

Golgi Apparatus

modifies, sorts, and packages proteins

Cis Face

receiving side of Golgi

Trans Face

shipping side of Golgi

Secretory Vesicle

transports materials to plasma membrane

Lysosome

contains digestive enzymes for intracellular digestion

Autophagy

lysosomal digestion of worn-out organelles

Heterophagy

lysosomal digestion of external material

Peroxisome

detoxifies harmful substances and metabolizes fatty acids

Mitochondrion

site of cellular respiration and ATP production

Cristae

folds increasing mitochondrial surface area

Matrix

inner mitochondrial fluid containing enzymes

Cilia

short cellular projections moving substances

Flagella

long projections propelling the cell

Passive Transport

membrane transport requiring no ATP

Diffusion

movement from high to low concentration

Facilitated Diffusion

diffusion via carrier or channel proteins

Osmosis

diffusion of water across a selectively permeable membrane

Aquaporin

water channel protein

Tonicity

ability of solution to change cell volume

Isotonic Solution

solution with equal solute concentration causing no net water movement

Hypotonic Solution

solution with lower solute concentration causing cell swelling

Hypertonic Solution

solution with higher solute concentration causing cell shrinkage

Active Transport

transport requiring ATP

Primary Active Transport

transport using ATP directly

Secondary Active Transport

transport using ion gradients

Sodium-Potassium Pump

pumps 3 Na+ out and 2 K+ into cell using ATP

Vesicular Transport

movement of large substances via vesicles

Endocytosis

transport into cell via vesicles

Phagocytosis

engulfment of solid particles

Pinocytosis

uptake of extracellular fluid

Receptor-Mediated Endocytosis

selective uptake using receptors

Exocytosis

export of materials via vesicles

Resting Membrane Potential

electrical charge difference across membrane

Electrochemical Gradient

combined effect of electrical and concentration gradients