Pathways that release energy by
breaking down complex molecules
into simpler compounds
Catabolic
pathways that consume energy to
build larger, more complicated
molecules from simpler ones
Anabolic
Chemical reactions in the body that change food into energy.
Metabolism
Metabolic Pathways
Energy is stored in the bonds between phosphate gorups of the ATP molecule.
When ATP is broken down to ADP, energy is released.
When ADP and phosphate are joined to form ATP, energy is stored again.
ATP(adenosine triphosphate) is an organic compound that provides energy to support many processes in cells.
Receptor Mediated Endocytosis
Specialized pinocytosis that allows the
cell to acquire bulk amounts of specific substances
Endocytosis
Pinocytosis
The cell takes in extracellular
fluid from the outside through vesicles
Phagocytosis
The cell engulfs large
food particles/other cells by
extending part of the membrane
Exocytosis
Sucrose being transported against
the concentration gradients uses energy created from the movement of H+ ions down the concentration gradient
Cotransport
When the active transport of a solute
drives the transport of other substances.
Na+/K+ Pumps
&
Proton Pumps
Electrogenic Pump
Proteins or pumps that create
a voltage difference across membranes. The energy harvested can be used for cellular work
Active Transport
Needs energy to transport molecules
from low to high concentration
Bulk Transport
Large molecules like polysaccharides
and proteins cross the membrane
through vesicles
Ungated
Always Open
Carrier Protein
Undergo a change in shape that
moves the solute across. Typically triggered by the binding and release of the molecule.
Channel Proteins
Provide channels that allow a
specific molecule to cross
Stretch-gated
When the membrane
is deformed
Voltage-gated
Open and close in response
to changes in membrane potential
Ligand-gated
Open and close when
a neurotransmitter binds
to the channel
Aquaporin transports water across the
membrane. The amino acids with polar R goups make up the interior of the protein while the exterior part of the protein is made up of amino acids with non polar R groups.
Facilitated Diffusion
Passive transport but
aided by proteins
*Plant cells are best in a
hypotonic environment (turgid)
*Animal cells are best in an
isotonic environment
Hypotonic
Solute concentration is greater
on the inside of the cell.
Hypertonic
Solute concentration is greater
on the outside of the cell.
Isotonic
Solute concentration is the same
inside and outside of the cell.
Tonicity
Ability of a solution to cause a cell to
lose or gain water
Osmosis
Diffusion of water across a membrane from a lower solute concentration to a higher solute concentration until it's equal on both sides.
Diffusion
The tendency for molecules to spread out,
moving from areas of high concentration to low concentration.
Signal
Molecule
Binding
Intracellular
Receptor
Step 1: Signal
molecule passes
through membrane
A signaling molecule that is released by a different cell goes through the membrane. The membrane, phospholipid bilayer only allows nonpolar/hydrophobic molecules to go through.
Signal molecule is
nonpolar/hydrophobic
Step 2: Signal
molecule binds
to receptor protein
Once the signal molecule goes through the membrane, it binds to the receptor protein and activates it. When it is activated, the protein changes shape.
Step 3: Signal-Receptor
complex enters the
nucleus
Once the signaling molecule binds to the receptor protein, the protein enters the nucleus and starts to activate the genes that control water and sodium flow.
Step 4: Protein prompts
transcription of gene
into mRNA
The protein that is bound to DNA starts the transcription of a specific gene into mRNA.
Step 5: mRNA is
translate into a
specific protein
The mRNA is transcribed and a gene is expressed to create a protein.
Membrane
Receptor
Step 1: Reception
Reception is the process in which a signal molecule is received. A signal molecule binds to a receptor protein which causes it to change shape. Polar signal molecules are the ones that bind to membrane receptors.
Step 2: Transduction
Protein
Kinase 1
Activated
Kinase 1
Activates
Kinase 2
Kinase 2
Phosphorylates
a protein
Protein
Phosphatase
removes
Phosphate group
from Kinases
Step 3: Response
Passive Transport
Diffusion of a substance across
a membrane with no energy investment
Types of Transport
Polarity and size determines whether it can cross rapidly, slowly, or not even at all.
Hydrophobic molecules can easily cross
the membrane while polar molecules do not
Plasma Membranes are
selectively permeable
Signaling Molecule
Enzyme
G Protein
G protein couple receptor
Transmembrane Protein
Fully inserted and spans the entire membrane with parts inside and outside of the cell. N-terminus (amino) & C-terminus (carboxyl terminus)
Integral Proteins
Partially or Fully Inserted
Peripheral Proteins
Anchored to the membrane
Proteins
Some anchored, some
move and drift
Cholesterol
Presence between phospholipids around 37°C, movement is reduced. At low temperatures, packing is prevented.
Temperature
Above a temperature, the lipid is fluid.
Below, the lipid is in a gel phase and rigid.
Saturated Fatty Acid Tail
Lipids are tightly packed
and cannot move
Unsaturated Fatty Acid Tail
Lipids are not tightly packed
and can move in the membrane
Phospholipid Bilayer
Each phospholipid has a hydrophobic fatty acid tail and a hydrophilic head (due to the presence of a phosphate group). They are amphipathic molecules.
Biology Concept
Map #2
Cell Membranes
cellular respiration
Step 1: Glycolysis
breaks down glucose into
2 molecules of pyruvate
hexokinase transfers phosphate
group from ATP to glucose to form glucose-6 phosphate
phosphofructokinase transfers a phosphate group from ATP to the opposite end of the sugar, forming fructose 1,6-biphosphate
input: glucose, 2 ATP
output: 4 ATP, 2 NADH, 2 pyruvate
occurs in the cytoplasm,
outside of the mitochondria
Step 2: Pyruvate Oxidation
and Citric Acid Cycle
citric acid cycle
acetyl CoA adds its 2-carbon group
to oxaloacetate to form citrate;
highly exergonic reaction
isocitrate is oxidized and NAD+ is
reduced (redox reaction) to form
a-ketoglutarate
input: 2 acetyl CoA
output: 2 ATP, 6 NADH, 2 FADH
pyruvate is oxidized;
forms acetyl CoA
input: 2 pyruvate
output: 2 acetyl CoA, 2 NADH
Step 3: Oxidative Phosphorylation
electron transport chain
energy is released as electrons
move down the chain
energy pumps H+ against
the concentration gradient into
the intermembrane space
output: 26-28 molecules of ATP
chemiosmosis
H+ goes back down the
concentration gradient through
a membrane transfer protein
energy associated with the gradient is
used to add Pi to ADP to form ATP
Cell
Communication/signaling
Releasing
a signal
Cells that are not close enough to touch each other, can communicate with signaling molecules (ligands). The signaling molecule then binds to a receptor protein.
Synaptic
Signaling
1) An action potential
arrives, and depolarizes
the presynaptic membrane
2) Voltage-Gated
channels open and
Ca ions enter the cell
3) The high Ca
concentration cause
neurotransmitters to
be released into the
synaptic cleft
4) The neurotransmitter
binds to ion channels. This
may allow Na and K ions to
diffuse through
Hormonal
Signaling
Paracrine
Signaling
Physical
contact
Eukaryotic cells can communicate through physical contact. Animal and Plant cells have junctions that connect them to neighboring cells. Animal cells have gap junctions while Plant cells have plasmodesmata. Molecules are able to move through these junctions from one cell to the other.
Junctions
Energy Transfer
Thermodynamics
Laws of Thermodynamics
Every energy transfer or transformation increases the entropy of the universe
A consequence of a loss of heat creates disorder in the universe. It is possible for order to increase locally, but the universe as a whole tends to disorder.
Entropy - a measure of disorder
in the universe
Energy can be transferred and
transformed, but it cannot be
created or destroyed
This law is also known as the principle of conservation of energy. The energy of the universe is constant. Organisms can’t recycle their energy because, during energy transformation, some energy is converted to thermal energy and is lost to the surroundings as heat and not available to do work.
Enzymes
Regulation of enzyme function
Competitive Inhibitor
Noncompetitive inhibitor
Cycle
