Show Menu

AP Bio Unit 2: Cell Structure and Function Cheat Sheet by

AP Bio Unit 2: Cell Structure and Function

Surface Area

outside area of an object
the area around the outside of a cell
unit: m^2

Applic­ation in Living Things

increased surface area = increased diffusion
microv­illi: increases absorption in intestines
root hairs: increases water/­nut­rient absorption in plants
endome­mbrane system: increased folds in organelles allow for more surface area to do cellular work
cristae of the mitoch­ondria: folds in the inner mitoch­ondria increase amounts of ETC (more ATP)

Structure of Phosph­olipid

hydrop­hilic head:
hydrop­hobic tail:
saturated fatty acid
unsatu­rated fatty acid


at warm temper­atures:
at cool temper­ature:
restrains the movement of phosph­olipids and reduces fluidity
maintains fluidity by preventing tight packing

Passive Transport

no energy
high to low concen­tration
facili­tated diffusion
ion channels


passive transport
molecules spread out to available spaces
move down concen­tration gradient (high to low concen­tra­tion)
work to reach equili­brium

Active Transport

no energy
low to high concen­tration
sodium potassium pump: 3 sodium leave and 2 potassium enter cell against the concen­tration gradient
proton pump: hydrogen atoms pumped against concen­tration gradient
cotran­sport: H+ gradient helps to bring other molecules into cell
endocy­tosis and exocytosis


organisms without cell walls that live in hypertonic or hypotonic enviro­nment must have adapta­tions for osmore­gul­ation
the control of water balance

Plant Cells in Pure Water

pure water (hypotonic solution) will initially move into the cells
after a period of time the cells will become turgid (swollen)
as turgor pressure increases, water will diffuse out of the cell... eventually equili­brium will be reached

Prokar­yotic vs. Eukaryotic Cells

simila­rities: cell membrane, DNA, ribosomes, cytoplasm
no nucleus
no membrane bound organelles
membrane bound organelles
binary fission
mitosis and meiosis
average size:
DNA is circular
DNA is linear
single chromosome
paired chromo­somes


amount of space inside of the object
the space inside of the cell
unit: cm^3

Fluid Mosaic Model

phosph­oli­pids: provides fluidity and elasticity
proteins and other molecules embedded in membrane

Phosph­olipid Bilayer

hydrop­hilic heads
hydrop­hobic tails


integral proteins:
peripheral proteins:
imbedded through the membrane (inside)
on hydrop­hilic portion of the cell membrane (outside)


cell to cell recogn­ition:
membrane carboh­ydr­ates:
cell's ability to distin­guish one type of neighb­oring cell from another
interact with the surface molecules of other cells, facili­tating cell to cell recogn­ition

Passive Transport (diffu­sion)

the tendency for molecules of any substance to spread out into available space
substances will move down a concen­tration gradient
high to low concen­tration

Passive Transport (osmosis)

the diffusion of water
water moves from hypotonic to hypertonic
isotonic: equal solute across a membrane
hypotonic: less solute, more water
hypert­onic: more solute, less water
low to high concen­tration

Active Transport (endoc­ytosis)

cell takes in macrom­ole­cules by forming vesicles from plasma membrane
phagoc­ytosis: "­cel­lular eating­," engulfing solids
pincyt­osis: "­cel­lular drinki­ng,­" engulfing solutes

Active Transport (exocy­tosis)

transport vesicles migrate to the membrane, fuse with it and release their contents

Osmore­gul­ation (param­ecium)

The Endosy­mbiotic Theory

an evolut­ionary theory of the origin of eukaryotic cells from prokar­yotic organisms
endosy­mbi­osis: one organism living inside another
evidence 1) chloro­plasts and mitoch­ondria multiply in the same way as ancient bacteria
evidence 2) chloro­plasts and mitoch­ondria both control their own DNA and ribosomes
evidence 3) chloro­plasts and mitoch­ondria both have two membranes (inner membrane contains different proteins than the outer membrane)

Surface Area to Volume Ratio

a comparison between the size of the outside of an object and the amount inside
smaller cells have an increase SA:V
as the cell gets bigger, the SA:V decreases
small cells are more efficient at diffusion as they have a high ratio

Structure of Cellular Membrane

two main compon­ents:
other important molecules:

Functions of Membrane Proteins

interc­ellular joinings
enzymatic activity
transport (activ­e/p­assive)
cell to cell recogn­ition
signal transd­uction

Cell Membranes are Semipe­rmeable

properties of molecules that can get through the phosph­olipid bilayer:
properties of molecules that can not get through the phosph­olipid bilayer:
O2 and CO2

Passive Transport (facil­itated diffusion)

transport proteins allow molecules to flow from high to low concen­tration
aquapo­rins: tunnel that allows water to go through the membrane
glut: glucose transp­orter

Passive Transport (ion channels)

transport proteins allow ion to flow from a high to low concen­tration

Passive and Active Transport

Water Potential

the force respon­sible for movement of water in a system
solute potential: determined by solute concen­tration
pressure potential: results from exertion of pressure on membra­nes­/walls as water moves in or out; can be positive or negative

Plant vs. Animal Cell

Plant Cell:
Animal Cell:
cilia and flagella
central vacuole
cell wall

The Endome­mbrane System

a system of synthe­sizing proteins for export
1) Nucleus: ~trans­cri­ption (DNA -> RNA) ~make ribosomes
2) Rough ER: ~trans­lation (RNA -> proteins) ~proteins for export
3) Vesicle: transports proteins in cells
4) Golgi Apparatus: process and package proteins
5) Vesicle: transports proteins in cells
6) Cell Membrane: exocytosis

Help Us Go Positive!

We offset our carbon usage with Ecologi. Click the link below to help us!

We offset our carbon footprint via Ecologi


No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          AP Biology Unit 1: Biochemistry Cheat Sheet
          AP Biology Unit 2: The Cell and Cell Membrane Cheat Sheet

          More Cheat Sheets by julescrisfulla

          AP Bio Unit 4: Cell Communication and Cell Cycle Cheat Sheet
          AP Bio Unit 5: Heredity Cheat Sheet
          AP Bio Unit 6: Gene Expression and Regulation Cheat Sheet