Cell Biology and Energetics Vocabulary

Vocabulary flashcards covering cellular structure, organelle functions, bacterial/archaeal body plans, membrane dynamics, and metabolic energy principles.

Reactant

A molecule that enters a chemical reaction and is changed by participating in it.

Product

A molecule that is produced by a chemical reaction.

Free Energy

The amount of energy available to do work, which is contributed to by both bond energy and entropy.

Endergonic Reaction

A chemical reaction that requires a net input of free energy to proceed ("energy in").

Exergonic Reaction

A chemical reaction that ends with a net release of free energy ("energy out").

Activation Energy

The minimum amount of energy required to get a chemical reaction started.

Antoni van LEEuwenhoek

Microscopist who in the mid-1600s constructed a crude microscope and observed "animal cules" (microbes).

Cell Theory

Biological theory stating that each organism consists of one or more cells; the cell is the structural and functional unit of life; all living cells arise by division of preexisting cells; and cells contain hereditary material (DNA) passed to offspring.

Three Universal Cell Components

The three components present in all cells: plasma membrane, cytoplasm, and DNA.

Plasma Membrane

The outermost membrane of a cell that encloses the cytoplasm and regulates the crossing of substances into and out of the cell.

Cytoplasm

A jelly-like mixture enclosed by the plasma membrane in which specialized organelles are suspended.

Surface to Volume Ratio

The physical relationship limiting cell size, where volume increases with the cube of diameter while surface area increases with the square.

Cell Size Range

The size range of most cells, which are $1\text{--}100\text{ }\frac{}{\text{micrometers}}$ in diameter.

Fluid Mosaic Model

Model describing a cell membrane as a two-dimensional fluid of mixed composition, consisting of a lipid bilayer with embedded or attached cholesterol, proteins, glycoproteins, and glycolipids.

Adhesion Proteins

Membrane proteins that help cells stick together.

Recognition Proteins

Membrane proteins that identify self cells.

Receptor Proteins

Membrane proteins that trigger a change in cell activity.

Transport Proteins

Membrane proteins that assist the movement of ions or molecules across the membrane.

Archaea

Single-celled organisms formerly grouped with bacteria as prokaryotes, now belonging to their own domain and more closely related to eukaryotes than to bacteria.

Plasmids

Small circular DNA molecules contained within the cytoplasm of bacteria and archaea.

Nucleoid

The region in prokaryotes where cellular DNA is concentrated.

Pili

Protein filaments that project from the surface of bacterial cells.

Flagella

Long, slender structures used by cells for motion.

Bacterial Structure

The body plan of a microscopic prokaryotic unicellular organism, featuring components such as capsule/slime layer, cell wall, plasma membrane, cytoplasm, ribosomes, nucleoid, plasmid, inclusion body, pili, and flagellum.

Biofilm

A shared layer of secreted polysaccharides and proteins attached to a solid surface that may include bacteria, algae, fungi, protists, and/or archaea.

Nucleus

Membrane-bound organelle that protects DNA from cellular metabolic processes and controls access to it.

Endoplasmic Reticulum

Membrane-bound organelle that makes and modifies new polypeptides and lipids.

Golgi Body

Membrane-bound organelle that modifies and sorts polypeptides and lipids.

Vesicle

Membrane-bound organelle that transports, stores, or breaks down substances.

Mitochondrion

Membrane-bound organelle that makes ATP through glucose breakdown.

Chloroplast

Membrane-bound organelle that makes sugars in plants and protists.

Lysosome

Membrane-bound organelle responsible for intracellular digestion.

Peroxisome

Membrane-bound organelle that breaks down fatty acids, amino acids, and toxins.

Vacuole

Membrane-bound organelle that stores and breaks down substances.

Ribosome

Organelle without a membrane that assembles polypeptides.

Centriole

Organelle without a membrane that anchors the cytoskeleton.

Cytoskeleton

Cellular component that contributes to cell shape, internal organization, and movement.

Nuclear Envelope

The outer boundary of the nucleus that controls access to DNA.

Nucleoplasm

Viscous fluid enclosed by the nuclear envelope.

Nucleolus

Dense, irregularly shaped region within the nucleus where ribosomal subunits are assembled.

Endomembrane System

Series of interacting organelles between the nucleus and plasma membrane, consisting of the endoplasmic reticulum, Golgi bodies, and vesicles.