Ch. 2: Cells and Organelles

Cell membrane

Selectively permeable membrane that regulates the movement of substances in and out of the cell.

Phospholipid bilayer

Contains hydrophilic heads and hydrophobic tails.

Membrane proteins

Facilitate transport, used as receptors, and provide structural support.

Integral proteins

Embedded in the membrane.

Peripheral membrane proteins

On the membrane surface.

Carbohydrates

Attached to membranes surface and important for cell recognition, signaling, and adhesion.

Cholesterol

Steroid that helps stabilize membrane fluidity.

Transmembrane proteins

Specific type of integral protein that spans the entire membrane.

Agonists

Bind to receptors and activate a biological response.

Antagonists

Bind to receptors and prevent other molecules from binding, inhibiting a biological response.

Simple diffusion

Transport of small uncharged and lipid-soluble molecules across the cell membrane along the concentration gradient without energy.

Facilitated transport

Large or charged molecules travel across the cell membrane through channel proteins along the concentration gradient.

Active transport

Molecules travel against concentration gradient and requires energy.

Primary active transport

Membrane transport proteins pump molecules against the concentration gradient via ATP hydrolysis.

Secondary active transport

Uses energy from a molecule moving down the electrochemical gradient to drive the transport of another molecule against the concentration gradient.

Endocytosis

Cell membrane internalizes extracellular substances.

Phagocytosis

Cell eating.

Pinocytosis

Cell drinking.

Nucleus

Protects and stores DNA; DNA replication and transcription occur here.

Nuclear envelope

Encapsulates the nucleus; contains both an inner and outer phospholipid bilayer.

Nucleolus

Produces components of ribosomes (rRNA).

Ribosome

Produces proteins via translation.

Rough endoplasmic reticulum (rough ER)

Organelle attached to the outer membrane of the nuclear envelope with embedded ribosomes.

Smooth endoplasmic reticulum (smooth ER)

Synthesizes lipids, produces steroid hormones, and detoxifies cells.

Golgi apparatus

Stores, modifies, and exports proteins to be secreted from the cell.

Lysosomes

Membrane-bound organelles that break down cellular waste via hydrolytic enzymes.

Mitochondria

Powerhouse of the cell that produces ATP via cellular respiration.

Chloroplasts

Perform photosynthesis and contain thylakoids.

Centrosomes

Organelles only found in animal cells that contain a pair of centrioles.

Endomembrane system

Group of organelles and membranes that work together to modify, package, and transport proteins and lipids.

Rough ER

Endoplasmic reticulum with ribosomes, involved in protein synthesis.

Smooth ER

Endoplasmic reticulum without ribosomes, involved in lipid synthesis.

Vacuoles

Storage organelles that can hold various substances.

Vesicles

Small membrane-bound sacs that transport materials within the cell.

Cytoskeleton

Provides structural support within the cytoplasm.

Microfilaments

Smallest cytoskeletal filaments composed of actin.

Intermediate Filaments

Medium-sized cytoskeletal filaments used for structural support.

Microtubules

Largest cytoskeletal filaments that stabilize and shape the cell.

Cyclosis

Movement of cytoplasm facilitated by actin and myosin.

Myosin

Motor protein that binds to actin to generate muscle contraction.

Flagella

Long hair-like structures used for cell movement.

Cilia

Small hair-like structures that help transport substances.

Kinesin

Motor protein that walks down microtubules to transport substances.

Dynein

Motor protein that walks down microtubules in the opposite direction.

Centrioles

Hollow cylinders composed of microtubules found in animal cells.

Extracellular Matrix (ECM)

Provides support on the outside of the cell.

Proteoglycan

ECM glycoprotein with a lot of carbohydrates.

Collagen

Structural protein secreted by fibroblasts for tissue support.

Integrins

Transmembrane proteins that control ECM adhesion.

Fibronectin

Protein that helps with signal transduction in the ECM.

Laminin

Essential for cell differentiation, adhesion, and movement.

Cell walls

Carbohydrate-based structures providing support to certain cells.

Tonicity

Influences water movement across a cell membrane via osmosis.

Isotonic Solution

Solution with the same solute concentration as the cell.

Hypertonic Solution

Solution with a higher solute concentration than the cell.

Hypotonic Solution

Solution with a lower solute concentration than the cell.

Epithelial cells

Sheet of cells that line organs and body surfaces.

Connective Tissue

Tissue that provides structure, support, and protection.

Muscle tissue

Tissue that functions in locomotion and support of organ systems.

Nervous tissue

Tissue that processes and transmits information.

Neurons

Nerve cells that transmit signals in the body.

Glial cells

Non-neuronal cells that support and maintain the nervous system.