Cell Membrane and Cellular Transport (VOCAB)

A set of vocabulary flashcards covering the cell membrane structure, key organelles, and major transport mechanisms discussed in the lecture.

Plasma membrane

The phospholipid bilayer that encloses the cell, containing lipids, proteins, and carbohydrates; selectively permeable.

Phospholipid bilayer

Double-layer of phospholipids with hydrophilic heads facing water and hydrophobic tails away; forms the membrane's basic structure.

Hydrophilic

Water-loving; polar heads of phospholipids that interact with aqueous environments.

Hydrophobic

Water-fearing; nonpolar tails of phospholipids that avoid water.

Membrane proteins

Proteins embedded in the plasma membrane that function as receptors or channels for signaling and transport.

Receptors

Membrane proteins that bind signaling molecules (e.g., neurotransmitters, hormones) to trigger cellular responses.

Channel proteins

Proteins forming pores that allow specific ions or molecules to cross the membrane.

Carbohydrates (on membrane)

Carbohydrate chains that act as signals for self-recognition, helping the immune system distinguish self from non-self.

Cytoplasm

The inside of the cell excluding the nucleus; includes cytosol and organelles.

Cytosol

The watery fluid inside the cell (mostly water) where many metabolic processes occur.

Organelles

Membrane-bound structures within the cell that perform specialized functions (e.g., mitochondria, ER, Golgi, lysosomes, nucleus, ribosomes).

Nucleus

The control center that houses DNA; enclosed by the nuclear membrane.

Nuclear membrane

The envelope surrounding the nucleus (also called the nuclear envelope).

Mitochondria

Powerhouses of the cell; generate ATP through cellular respiration.

Endoplasmic reticulum (ER)

A network of membranes; rough ER has ribosomes and synthesizes proteins; smooth ER synthesizes lipids.

Rough endoplasmic reticulum

ER studded with ribosomes; site of protein synthesis destined for export or membranes.

Smooth endoplasmic reticulum

ER lacking ribosomes; site of lipid synthesis and detoxification.

Ribosomes

Molecular machines that synthesize proteins; can be free or attached to rough ER.

Golgi apparatus

Stacks of membranes that modify, package, and ship proteins in vesicles to their destinations.

Peroxisomes

Organelles involved in detoxification and lipid metabolism; break down reactive substances.

Lysosomes

Digestive organelles that recycle cellular waste and macromolecules.

ATP

Adenosine triphosphate; the cell’s energy currency used to power active processes.

Passive transport

Transport across the membrane that does not require ATP; includes diffusion and osmosis.

Simple diffusion

Movement of small, lipid-soluble molecules directly through the lipid bilayer without energy.

Facilitated diffusion

Passive transport via membrane proteins; includes carrier-mediated and channel-mediated diffusion.

Carrier-mediated diffusion

Facilitated diffusion using a specific transporter protein that moves a substrate across.

Channel-mediated diffusion

Facilitated diffusion through ion channels based on size/charge.

Osmosis

Diffusion of water across a membrane; often via aquaporin channels.

Aquaporins

Water channel proteins in the membrane that facilitate osmosis.

Isotonic

Solute concentration similar inside and outside the cell; no net water movement.

Hypotonic

Lower solute outside the cell than inside; water enters the cell, causing swelling.

Hypertonic

Higher solute outside the cell than inside; water leaves the cell, causing shrinkage.

Lysis

Bursting of a cell due to excessive swelling in a hypotonic solution.

Crenation

Shriveling of a cell due to water loss in a hypertonic solution.

Sodium-potassium ATPase (pump)

Primary active transporter that uses ATP to move Na+ out and K+ in, maintaining gradients.

Primary active transport

Active transport that directly uses ATP to move substances against their gradients.

Secondary active transport

Active transport that uses energy from the gradient created by primary transport to drive other substances.

Sodium-glucose cotransporter

Sodium-dependent transporter that co-transports glucose into the cell using the Na+ gradient.

Endocytosis

Process of taking in material by folding the membrane to form vesicles.

Pinocytosis

Cell drinking; uptake of extracellular fluid via endocytosis.

Phagocytosis

Cell eating; engulfment of large particles or microbes by phagocytes.

Exocytosis

Secretion of substances from the cell via vesicle fusion with the plasma membrane.

Vesicle

Small membrane-bound sac that transports substances within or outside the cell.