Antibiotics

Chemicals that can slow or stop the growth of bacteria; often naturally produced by living organisms.

Cell Theory

All living things are made of cells, and every new cell comes from the division of a pre-existing cell.

Prokaryotic Cells

Cells that lack internal membrane-bound organelles, including a nucleus. Examples: Archaea & Bacteria.

Eukaryotic Cells

Cells that have membrane-bound organelles, including a nucleus.

Cell Membrane

A membrane of phospholipids and proteins enclosing all cells.

Cytoplasm

The gelatinous, aqueous interior of a cell.

Ribosomes

A complex of RNA and protein that carry out protein synthesis in all cells.

Peptidoglycan

A polymer made of sugars and amino acids that forms the cell wall of prokaryotic cells.

Osmosis

The diffusion of water across a semipermeable membrane.

Isotonic

When the concentration of water are equal inside and outside the cell and water flows in and out of the membrane at the same rate.

Gram-positive

Bacteria that retain the Gram stain due to peptidoglycan in their cell wall, and appear violet.

Gram-negative

Bacteria that do not retain the Gram stain due to a lipid outer layer in their cell wall, and appear red.

Phospholipids

The primary component of cell membranes, consisting of a hydrophilic head and hydrophobic tails arranged in a bilayer.

Simple Diffusion

The natural tendency of dissolved substances to move from an area of higher concentration to one of lower concentration, without requiring energy.

Facilitated Diffusion

The diffusion of large or hydrophilic solutes across a membrane with the help of transport proteins, without requiring energy input.

Active Transport

The movement of solutes across a membrane with the help of transport proteins, requiring energy input to pump solutes against their concentration gradient.

Nucleus

An organelle that encloses the cell’s DNA.

Endoplasmic Reticulum (ER)

A network of membrane-covered pipes where proteins and lipids are synthesized; can be rough or smooth.

Golgi Apparatus

Stacked membranous discs that receive proteins from the ER, package, and transport them.

Mitochondria

Organelles that extract energy from food and convert it into a usable form.

Chloroplasts

Organelles found in plants and algae that are the sites of photosynthesis.

Lysosomes

Organelles full of digestive enzymes that break down worn-out cell parts and food molecules.

Cytoskeleton

A network of protein fibers that provides cell support, cell movement, and movement of structures within cells.

Endosymbiosis Theory

The theory that mitochondria and chloroplasts originated from free-living prokaryotic cells that were engulfed by other cells.