Chapter 3 Biology

who developed the cell theory?

Matthias Schleiden; Theodor Schwann; Rudolf Virchow

cell theory

all organism made of cells; all cells are produced by preexisting cells; the cell is the most basic unit of life

Matthias Schleiden

all plants are made of cells

Theodor Schwann

all animals are made of cells; wrong about spontaneous forming cells

Rudolf Virchow

all cells came from preexisting cells


contains nucleus and membrane-bound organelles; multicellular or single cellular


no nucleus or membrane-bound organelles; single cellular; floating DNA


discovered cells

Van Leeuwenhoek

first to observe living cells; named organelles "animalcules

are viruses considered cells?

No, they are nonliving


infectious particle only made of a strand of DNA or RNA surrounded by a protein coat

cell membrane aka

plasma membrane; lipid bilayer




to love


to fear

phospholipid bilayer

forms membranes in cell; composed of 2 layers of phospholipids


composed of hydrophilic head region and hydrophobic tail

channel protein

embedded in the cell membrane; allows molecules to move into and out of the cell

marker protein

identifies the cell

carbohydrate polymer

(attached to marker protein) identifying part "name tag" of the marker protein

receptor protein

receives signals, often causing a change inside the cell

non-polar region

hydrophobic tail - repels water and molecules with a charge

polar region

hydrophilic head - attracted to water and molecules with a charge

the cell membrane is _________ permeable.


diffusion always causes particles to move from a region of _____ concentration to a region of _____ concentration.

high; low

______ requires energy (ATP) to transport molecules against a concentration gradient.

active transport


amount of substance in a certain place


movement of small molecules from a high concentration to a low concentration to reach an equilibrium


diffusion of water molecules through a membrane in the direction towards a high solute concentration

selectively permeable membrane

allows some substances to pass through

cell membrane

forms boundary between a cell and external environment; controls passage of substances into and out of cell

what does a phospholipid contain?

charged phosphate group; glycerol; 2 fatty acid chains

fluid mosaic model

describes the arrangement of the molecules that make up a cell membrane


protein that detects a signal molecule and performs an action in response

intracellular receptor

receptor within a cell; binds with certain molecules in certain cells

membrane receptor

receptor within cell membrane; binds with molecule that cannot cross the membrane

cellular transport

movement into and out of a cell


concentration of a solute into and out of a cell is equal

concentration gradient

difference in the concentration of a solute across a cell membrane (high to low)

passive transport

movement of substance through cell membrane without using energy

facilitated diffusion

diffusion of molecules through membrane by channel protein (move high to low)

isotonic solution

solute concentration outside the cell is equal to inside concentration; homeostasis

hypertonic solution

solute concentration in environment is higher than inside; water moves out of cell

hypotonic solution

solute concentration outside cell is lower than inside; water moves into cell

osmotic pressure

increased water pressure that results from osmosis; plants withstand osmotic pressure

dynamic equilibrium

molecules travel from a high concentration to a low concentration and spread evenly throughout the solution

active transport

movement of particle through a membrane against a concentration gradient with the use of energy from ATP


similar to facilitated diffusion except the solute moves toward higher concentration; against concentration gradient; needs energy


adenosine triphosphate


process of taking material into cell; energy required to transport material in vesicles


process of expelling material from the cell


to drink


to drink


cell membrane engulfs large solid particles


cell membrane engulfs liquid substances