Overview of Cell Membrane Structure and Function

Cell Membrane

Protective barrier separating cell interior from environment.

Homeostasis

Regulation of internal conditions for cellular stability.

Fluid Mosaic Model

Describes membrane structure with diverse components.

Phospholipids

Form bilayer with hydrophilic heads and hydrophobic tails.

Cholesterol

Stabilizes membrane fluidity at varying temperatures.

Peripheral Proteins

Located on membrane surfaces, not embedded in bilayer.

Integral Proteins

Span membrane; crucial for transport and communication.

Transmembrane Proteins

Integral proteins extending across both membrane layers.

Glycoproteins

Proteins with carbohydrate chains for cell recognition.

Glycolipids

Lipids with carbohydrate attachments aiding cell signaling.

Passive Transport

Movement across membrane without energy expenditure.

Diffusion

Movement of small molecules through lipid bilayer.

Facilitated Diffusion

Transport of larger molecules via specific proteins.

Osmosis

Diffusion of water across a selectively permeable membrane.

Concentration Gradient

Difference in particle concentration across a membrane.

Semipermeable Membrane

Allows selective passage of certain substances.

Cell Surface Area

Crucial for efficient nutrient absorption and function.

Metabolic Processes

Chemical reactions maintaining cellular functions.

Transport Mechanisms

Processes regulating substance movement in cells.

Cell Recognition

Identifying cells through glycoproteins and glycolipids.

Environmental Response

Cellular adaptation to changes in surroundings.

Nutrient Absorption

Process of taking in essential substances.

Waste Expulsion

Removal of byproducts from cellular metabolism.

Simple Diffusion

Nonpolar molecules pass through lipid bilayer directly.

Tonicity

Solution's effect on water movement in cells.

Hypotonic Solution

Lower solute concentration outside, causes cell swelling.

Hypertonic Solution

Higher solute concentration outside, leads to cell shrinkage.

Isotonic Solution

Equal solute concentration inside and outside cell.

Bacteria

Unicellular prokaryotic organisms without membrane-bound organelles.

Bacterial Size

Typically range from 0.5 to 5 micrometers.

Ribosomes

Cellular structures for protein synthesis in bacteria.

Coccus

Spherical shape of bacteria.

Bacillus

Rod-shaped bacteria.

Spirillum

Spiral-shaped bacteria.

Heterotrophs

Bacteria that consume organic material for energy.

Autotrophs

Bacteria that synthesize energy via photosynthesis.

Bacterial DNA

Double-stranded, circular DNA located in cytoplasm.

Plasmids

Small circular DNA molecules in bacteria for survival.

Beneficial Bacteria

Aid digestion and produce vitamins in humans.

Antibiotics

Substances that combat bacterial infections by targeting functions.

Zone of Inhibition

Area around antibiotic disc where bacteria cannot grow.

Gram Staining

Technique to classify bacteria by cell wall structure.

Gram-positive Bacteria

Appear purple due to thick peptidoglycan layer.

Gram-negative Bacteria

Appear pink due to thinner peptidoglycan layer.

Active Transport

Movement against concentration gradient requiring energy input.

Membrane Potential

Electrical difference across cell membrane, crucial for functions.

Primary Active Transport

Directly uses ATP to move molecules against gradients.

Sodium-Potassium Pump

Moves 3 sodium out, 2 potassium in per cycle.

ATP Hydrolysis

Process converting ATP to ADP, releasing energy.

Electrochemical Gradient

Difference in charge and concentration across membrane.

Cotransport

Simultaneous transport of two molecules across membrane.

Symport

Both molecules move in the same direction.

Antiport

Molecules move in opposite directions across membrane.

Sodium-Glucose Cotransporter

Uses sodium gradient to transport glucose into cells.

Endocytosis

Process of internalizing large molecules via membrane engulfing.

Phagocytosis

'Cell eating'; engulfs large particles or cells.

Pinocytosis

'Cell drinking'; uptakes small extracellular fluid amounts.

Receptor-Mediated Endocytosis

Selective uptake using receptor proteins for efficiency.

Exocytosis

Expels materials by fusing vesicles with membrane.

Vesicle

Membrane-bound sac transporting substances within cells.

Cellular Homeostasis

Maintenance of stable internal conditions in cells.

Nutrient Uptake

Process of absorbing essential substances into cells.

Waste Removal

Elimination of unwanted materials from cellular processes.

Conformational Change

Structural alteration of a protein during transport.

Cell Communication

Process of signaling between cells for coordination.