Download Review sheet – Chapter 5

Review sheet – Chapter 5

Understand that the cell membrane is made up of a phospholipid bilayer and regulates what
moves into and out of the cell

Understand that a diverse collection of proteins are embedded in the phospholipid bilayer;
these proteins include:
o
Integrins – provide strength and support for the cell membrane
o
Glycoproteins – a protein bonded to a carbohydrate; act as identification tags, involved
in cell-to-cell recognition
o
Enzymes – catalyze reactions
o
Receptor proteins – receive and modify messenger molecules for entrance into the cell
o
Transporter proteins – transport molecules across the cell membrane (into and/or out
of the cell); uses passive or active transport

Understand that the infusion of proteins into a fluid membrane results in the cell membrane
being referred to as a “fluid mosaic”

Know that the cell membrane consists of phospholipids, proteins and steroids (lipids)

Understand that diffusion is the movement of particles/molecules from an area of high to an
area of low concentration (down its concentration gradient)

Know that small, nonpolar molecules (such as O2 and CO2) can diffuse across the membrane
with ease (through the spaces created by the fatty acid tails)

Know that diffusion across the membrane is considered to be passive transport (no work/energy
required)

Know that nonpolar molecules can dissolve through the cell membrane passively

Know that large, polar molecules and ions cannot diffuse across the membrane without
assistance; their movement across the membrane is known as facilitated diffusion and is
accomplished by transporter proteins

Know that facilitated diffusion is passive because the movement of molecules follows along its
concentration gradient (from high to low); no work is performed to move the molecules, but the
protein is needed to create a channel enabling the molecules to flow through

Know that osmosis is the transport of water across a selectively (“semi-“) permeable membrane,
such as a cell membrane

Understand that osmosis occurs along a concentration gradient (from high to low); water will
only flow out of the cell if there is more water on the inside of the cell than on the outside,
likewise, water will only move into the cell if there is more water on the outside of the cell than
the inside

Know the definitions of hypertonic, isotonic and hypotonic

Understand what happens when you place a cell into one of these solutions; where would the
solutes move (into or out of the cell)? Where would the water move (into or out of the cell)?
Remember that water will always move in the opposite direction of the solutes; if there are
more solutes outside of the cell, solutes will move inside the cell, but water will move outside of
the cell

Understand that active transport uses energy to move molecules against their concentration
gradient
Understand that active transport requires ATP
Know that ATP is the currency for work; it has chemical energy which is released when it
transfers one of its phosphate groups
Remember that ATP stands for adenosine triphosphate and consists of 3 phosphate groups;
when ATP transfers one of its phosphate groups releasing energy, it becomes ADP and consists
of 2 phosphate groups
Understand that active transport allows cells or organelles to maintain concentrations of
molecules that are different than their surroundings
Know that pinocytosis and phagocytosis are two forms of endocytosis; a way to transport
molecules against their concentration gradients involving an engulfing of fluid (pino) or solid
(phago) by the cell (and into the cell)
Know that exocytosis is the removal of molecules from the cell (the reverse of endocytosis)
Understand that kinetic energy is energy in motion, and potential energy is stored energy
Understand that potential energy can be converted into kinetic energy
Understand that chemical energy refers to potential energy stored in the bonds of chemical
compounds, such as sugars and lipids
Understand that energy cannot be created or destroyed, only transferred or transformed
Understand that energy conversions are never 100% efficient and some of this energy is lost as
heat
Understand that cells convert ~40% of the chemical energy stored in foods to energy for cellular
work, the remaining 60% is lost as heat
Understand that the sum/total of an organism’s chemical reactions is called its metabolism
Understand that the 3 phosphate groups of an ATP molecule are each negatively charged, but
crowded together in the ATP molecule; when a phosphate group is transferred, it releases
energy
Understand that ATP is reusable; ADP can regain its phosphate group becoming ATP



















Know that the energy of activation is the energy required to weaken the chemical bonds of
molecules; once this energy is reached, the reaction can begin
Know that enzymes speed up reactions by lowering this energy of activation; in this way they
are catalysts because they increase the rate of the reaction without being consumed by the
reaction in the process
Understand that enzymes are proteins with specific 3-D shapes; the shape of the protein
determines which chemical reaction the enzyme will catalyze
Understand that cofactors are non-protein enzyme helpers; cofactors include metal ions; organic
cofactors such as vitamins are considered coenzymes