Chapter 4 covers information about life's basic unit, the cell. Start by reading the chapter to
familiarize yourself with the material, then complete the SmartBook assignment and memorize
the bold terms. You will need to know the following for the quiz and the test:
The Cell Theory
Microscopes – types and what they are used to view
Prokaryotic (Bacteria & Archaea) vs. eukaryotic (Eukarya: Plantae, Animalia, Fungi, Protista):
remember, prokaryotes (smaller & simple) do not have a true nucleus or any internal
membranes; eukaryotes (larger & complex) do.
Prokaryotic cell – be able to label a picture (word bank provided) and know the functions of the
common features/organelles: nucleoid region/DNA, ribosomes, cell membrane, cell wall,
capsule, flagella, pili
Eukaryotic cell (plant & animal) – be able to label pictures (word bank provided) and know the
functions of the common features/organelles: nucleus, DNA/chromatin/chromosomes,
nucleolus, nuclear envelope & pores, smooth ER, rough ER, Golgi, ribosome, lysosome,
vesicle (transport/secretory), vacuole, peroxisome, mitochondria, cytoskeleton, cell
membrane, cilia, flagella, centrioles (centrosome)*, cell wall**, chloroplast**, central
vacuole**
*animals only, **plants only
Cell membrane – be able to label a picture (word bank provided) and know what it is made of &
the function of each: phospholipids in a bilayer, proteins (enzymes, receptors, structural,
transport, identification), cholesterol
Membrane transport – passive (no energy used), active (energy & pump required), & bulk
transport (also requires energy). All can be into or out of cell.
Passive transport – there must be a concentration gradient (unequal amounts of
substances on either side of the membrane). Substances move down/with the
gradient (from higher concentration to lower concentration) because they have
natural tendency to spread out evenly across the membrane. They move from the
crowded side to the less crowded side until equal on both sides.
Types of passive transport – simple diffusion (moves directly through the phospholipids;
only for very small & nonpolar substances), facilitated diffusion (moves through a
pored protein; for very small & polar substances), selective diffusion (moves
through pored protein that allows only certain substances to pass), osmosis
(selective diffusion of water through proteins called aquaporins; for water only).
Osmosis – water moves through aquaporins when concentration gradients exist because
there are substances that cannot cross the membrane. Water always moves
toward the more concentrated side (side with more solutes). This is the
hypertonic side. Think of water chasing the “hyper kids.”
Water will continue to move until (1) gravity or pressure stops it, (2) the cell
bursts or shrivels completely, or (3) the concentrations become equal, called
isotonic.
Hypotonic – the side with lower concentration, fewer molecules.
Osmotic pressure – caused by the flow of water in one direction due to osmosis.
Hemolysis – bursting of a blood cell (due to it being hypertonic inside & water
flowing in)
Crenation – shriveling of a cell (due to it being hypotonic inside & water flowing
out)
Active transport – requires energy; no concentration gradient required, but ultimately
occurs because membrane protein pumps move certain substances in one direction
only (to one side of the membrane) & up/against the concentration gradient.
Ex: sodium-potassium pump. Na+ is pumped out of the cell while K+ is pumped
in. One protein pump does both; sometimes called double pump.
Coupled transport – when one substance requires another to move across the membrane.
Ex: Na+ can sneak into cells by hitching a ride on sugars.
Bulk transport – movement of large substances or quantities across the membrane via the
membrane forming vesicles & vesicles merging with the membrane. Requires
energy.
Includes:
Exocytosis – vesicle merges with interior side of membrane and dumps
contents to the outside.
Endocytosis – membrane caves in and surrounds outside substance forming a
vesicle to the inside.
3 types:
Phagocytosis – when the substance is solid
Pinocytosis – when the substance is liquid
Receptor-mediated endocytosis – when receptor proteins are used to
capture very specific molecules (ex: cholesterol)