Cell Biology and Cytology (Video Notes)

Vocabulary flashcards covering key terms from the lecture on cells, cytology, and tonicity.

cytology

The study of cells.

cell theory

Principles that all organisms are made of cells, cells arise from pre-existing cells, and the cell is the basic unit of life.

cell

The basic unit of life; the smallest unit that carries all properties of living organisms.

plasma membrane

The cell boundary; a lipid-protein barrier that controls entry and exit of substances. Also called the cell membrane.

cytoplasm

The intracellular, gel-like fluid inside a cell that contains cytosol, organelles, and inclusions.

nucleus

Organelle that houses the cell's DNA and serves as the genetic blueprint.

extracellular fluid

Fluid outside the cell, including interstitial fluid, blood plasma, lymph, and CSF.

intracellular fluid

Fluid located inside the cell.

phospholipid bilayer

Two-layer arrangement of phospholipids that forms the core of the plasma membrane; hydrophilic heads face water, hydrophobic tails face inward.

phospholipid

A lipid with a hydrophilic head and hydrophobic tails; major component of cell membranes.

glycocalyx

Carbohydrate-rich coating on the cell surface formed by glycolipids and glycoproteins; aids in cell recognition.

glycolipid

Lipid with attached carbohydrate; contributes to the glycocalyx.

glycoprotein

Protein with carbohydrate attached; contributes to the glycocalyx and cell identification.

transmembrane protein

Protein that spans the entire lipid bilayer, enabling transport or signaling across the membrane.

peripheral protein

Membrane protein located on one surface of the membrane; often anchored to the cytoskeleton.

receptor

Membrane protein that binds a chemical signal and triggers a cellular response (possibly via second messengers).

membrane enzyme

Membrane protein that lowers activation energy to speed a chemical reaction.

channel protein

Protein forming a pore that allows specific solutes and water to cross the membrane.

leak channel

An always-open channel that allows continuous diffusion.

ligand-gated channel

Channel that opens in response to binding of a chemical messenger (ligand).

voltage-gated channel

Channel that opens in response to a change in membrane potential (voltage).

carrier protein

Protein that binds a solute and moves it across the membrane; may require energy.

cell identity markers

Glycoproteins that label a cell type to the immune system.

cell adhesion molecules

Membrane proteins that help cells stick to each other or to the extracellular matrix.

immune self/non-self recognition

Glycocalyx and membrane components help identify self from non-self to guide immune responses.

microvilli

Extensions of the plasma membrane that greatly increase surface area for absorption (up to ~40x).

brush border

Dense array of microvilli on the apical surface, resembling a brush.

cilia

Hair-like projections that beat to move mucus, fluid, or other substances along the cell surface.

microtubules

Cytoskeletal filaments that form the backbone of cilia and flagella (nine plus two arrangement).

sperm flagellum

Long whip-like structure that propels the sperm cell; a type of flagellum.

pseudopod

False foot; temporary projection of cytoplasm used for locomotion and phagocytosis.

endocytosis

Process by which cells engulf external material by forming vesicles.

filtration

Passive transport driven by pressure differences; typically from high to low pressure.

diffusion

Movement of molecules from high to low concentration; may require a permeable membrane.

osmosis

Diffusion of water across a selectively permeable membrane toward higher solute concentration; sped by aquaporins.

isotonic

Solution with equal solute concentration inside and outside the cell; no net water movement.

hypotonic

Solution with lower solute concentration outside the cell; water enters the cell (possible lysis).

hypertonic

Solution with higher solute concentration outside the cell; water exits the cell (cell shrinks, crenation).

osmolarity

Osmotic concentration; number of osmotically active particles per liter of solution.

tonicity

The ability of a solution to affect cell volume by osmosis; depends on non-permeating solute concentration.

isotonic saline

0.9% sodium chloride; isotonic to blood; used in IV fluids.

crenation

Shrinking of a cell due to water leaving in a hypertonic solution.