Cell Structure, Diffusion, and Microscopy – Vocabulary Flashcards

A set of vocabulary flashcards covering cell size, diffusion concepts, cell organelles, and microscopy topics discussed in the lecture notes.

Surface area to volume ratio

The relationship between a cell's surface area and its volume; smaller cells have a larger ratio, allowing faster diffusion to the interior.

Diffusion

Net movement of molecules from high concentration to low concentration; a passive transport mechanism.

Concentration gradient

A difference in the concentration of a substance across space that drives diffusion; represents potential energy.

Passive transport

Movement of substances across a membrane that does not require cellular energy.

Facilitated diffusion

Diffusion that requires a membrane protein channel or carrier to help substances cross the membrane while still moving down a concentration gradient.

Active transport

Movement of substances across a membrane that requires energy input (e.g., ATP).

Plasma membrane

The cell’s outer membrane that regulates entry and exit of substances; selectively permeable.

Selectively permeable

Property of the plasma membrane to allow some substances through while excluding others.

Phospholipid bilayer

Two-layer membrane with hydrophilic phosphate heads facing outward and hydrophobic fatty acid tails inward.

Cytoplasm

Semi-fluid interior of the cell that surrounds organelles and contains cytosol.

Cytosol

The aqueous component of cytoplasm; contributes to the cell’s viscosity and movement of internal parts.

Endomembrane system

A network of internal membranes derived from invaginations of the plasma membrane, forming organelles with distinct environments.

Nucleus

The organelle that houses DNA and acts as the cell’s control center.

Mitochondria

Powerhouse of the cell; site of cellular respiration and ATP production; contains its own DNA and originated via endosymbiosis.

Endosymbiosis

Theory that mitochondria and chloroplasts originated as free-living bacteria engulfed by a host cell and became integral organelles.

Chloroplast

Organelle in plant cells where photosynthesis occurs; arose from endosymbiotic photosynthetic bacteria.

Ribosome

RNA-protein complex that synthesizes proteins; present in prokaryotic and eukaryotic cells.

Prokaryotic cell

Cell type lacking a nucleus and membrane-bound organelles; DNA is in the cytosol and typically smaller.

Eukaryotic cell

Cell type with a nucleus and membrane-bound organelles; generally larger and more complex.

Fluid mosaic model

Model of the plasma membrane as a fluid phospholipid bilayer with embedded proteins that move within the membrane.

Extracellular matrix (ECM)

Network outside the plasma membrane that provides support, signaling, and interaction with the environment.

Aquaporin

Water channel proteins in the plasma membrane that regulate water movement into and out of the cell.

Light microscope

A microscope that uses visible light; example in notes shows 250x magnification of a blood vessel cross-section.

Transmission electron microscope

Electron microscope that provides high magnification (about 4,000x in notes) and a 2D image of internal structures.

Scanning electron microscope

Electron microscope that provides high magnification with a 3D-like view of surfaces and textures.

Diffusion rate factors

Factors affecting diffusion rate: distance, temperature (higher speeds diffusion), solvent characteristics, molecular mass, barrier properties, and membrane surface area/thickness.

Alveolar diffusion

Diffusion of oxygen from alveoli to blood and carbon dioxide from blood to alveoli, enabling respiration.