The Dynamic Cell: Energy and Transport
What is Energy?
Energy is the capacity __________________________.
Our biosphere gets its energy from the _____________.
Chloroplasts __________ and transform _____________ energy into _____________ energy
Mitochondria _____________ chemical energy for use by a cell.
The flow of energy
Two Processes create a flow of energy:
Photosynthesis
 solar energy used to convert water and carbon dioxide into ______________________
Cellular respiration
 carbohydrates broken down and energy used to build _____________
 Useful energy is __________________ with each transformation.
 Living things dependent on constant in/out of solar energy
ATP: Energy for Cells
• Adenosine triphosphate
• Cells use ATP to carry out nearly all
activities.
• One nucleotide along with 3 phosphates.
• Easily _________ a phosphate group to
become __________ (adenosine diphosphate)
• Continual cycle of breakdown and regeneration stores and
releases energy
ATP cycle
• ATP _______________ energy quickly.
• Amount of energy released is usually just enough for a
biological purpose
• Breakdown can be easily coupled to an energy-requiring
reaction.
• ADP is produced.
• ADP can be then be used to make another ATP
Metabolic Pathways
•
•
•
•
Metabolic pathway—___________________ of linked reactions
______________ of a previous reaction _______________ the ___________ of the next
reaction
The letters A–G indicate substrates.
The letters E1–E6 represent enzymes.
 Protein molecules that function as organic catalysts speed up reactions.
Cellular Aerobic Respiration
• Chemical pathway that ________________________________ molecules
• Requires ________________________, produces ___________________________ as wastes
• Also uses _____________________ NAD+ and FAD+ to transfer electrons
Four phases of Aerobic Respiration
• Glycolysis occurs outside the mitochondria in the cytoplasm.
• The preparatory reaction, citric acid cycle and electron transport chain occur inside the
mitochondria.
Outside the Mitochondria: Glycolysis
• In eukaryotes, takes place in the ________________
• Glucose is broken down into two molecules of
________________________ (3 carbons)
• Two phases…
– Energy-investment steps
– Energy-harvesting steps
Energy-investment steps
________ ATP molecules are used to make the first break and
activate the reactions
Energy-harvesting steps
ATP synthesis produces _________ATP
• Net gain of ________ATP
2 NADH made from NAD+
Two 3-carbon molecules of ___________________ are formed
Outside the Mitochondria: Fermentation
• Fermentation—_________________ breakdown of glucose
• Occurs if _________________________________ available
– no more ATP will be produced – only the two from glycolysis
• Lactic Acid Fermentation
– Animal and bacteria cells – __________________ formed (muscle cells)
• Alcohol Fermentation
– Microorganisms – bacteria and yeast
– ________________ and ____________________________ produced
• Yeast—carbon dioxide makes bread rise, ethanol made in wine and beer
Inside the Mitochondria
Other 3 phases take place inside the mitochondria only _________________________________
Inside the Mitochondria: Matrix
Preparatory Reaction
• prepares ________________ molecules for the citric acid cycle
• Each pyruvate is broken into carbon dioxide and a 2-carbon acetyl molecule
• The acetyl molecule is attached to a coenzyme A molecule
• NADH is produced from NAD+
Citric Acid Cycle
• __________________ the breakdown of the original glucose molecule
• Acetyl group is oxidized to carbon dioxide
• NAD+ → NADH and FAD → FADH2
• ________ ATP produced
Inside the Mitochondria: Cristae
Electron Transport Chain
Located in _______________ (inner folded membrane) of mitochondria
NADH and FADH2 ___________________________ from previous reactions
Series of carriers pass electrons along the membrane from one to the other
Energy is _____________ and
_________________________________
__________________ ATP produced
Final acceptor of electron is oxygen, forming water
A total of _________________ molecules are made from one
glucose molecule
C6H12O6 + 6O2 + ADP
6CO2 + 6H2O + ATP
Using other foods for energy
Cells use other energy sources
Fatty acids have longer carbon chains—________________ ATP
Intermediates can also be used to make other products
Extra food made into fat for ____________________
Cell Transport
Plasma membrane ___________________ traffic in and out of cell
Selectively ____________________—some substances pass freely, some transported, some prohibited
Three ways to enter:
Passive transport—substances move from _______________________________ concentration,
____________________________________________ required
Active transport—substances move from ________________________________ concentration,
additional energy ___________________________
Bulk transport—movement ___________________________________, additional energy
required
Passive Transport - Includes diffusion, Facilitated diffusion and Osmosis
Diffusion
Molecules move from higher to lower concentrations (_______________ their concentration
gradient) until equilibrium is reached.
__________energy required
Cell does not expend additional energy because molecules already in motion
________________, __________________________ molecules (carbon dioxide, methane,
oxygen, water, small lipids) can slip between membrane phospholipids.
Large or charged molecules cannot diffuse through the membrane
Facilitated diffusion
____________________ proteins in the cell membrane are used to transport some molecules
____________________ protein is specific to one molecule
 Water uses _____________________—explains faster than expected transport rate
 Glucose has several transport proteins
Osmosis
 Diffusion of ___________ across a selectively permeable ________________
 Can be simple diffusion or facilitated diffusion
 If solutes cannot diffuse through the membrane, water moves to equalize the concentrations
 Net movement of water is from beaker with the ______________________ concentration to
the tube with the _____________________________ concentration (with gradient)
Effect of osmosis on cells
 ____________________ solution
Cell neither gains nor loses water
_____________________________________________ on both sides of the membrane
0.9% saline isotonic to red blood cells

_____________________ solution
Concentration _____________________________________________ than inside cell
Cell _____________ water
Animal cells may lyse or burst
Plant cells use this to remain turgid

_____________________ solution
• Concentration of ____________________________________ than inside cell
• Cell ___________ water
• Animal cells shrink
• Plant cells undergo plasmolysis and may wilt
Active Transport
 Movement of molecules _________________________________ gradient (from low to high)
 Cells expend __________________
 Requires ________________ protein
 _____________________________________ important in maintaining gradient of ions used
in nerve impulse conduction
Bulk Transport
 Movement of _______________________ too large to be moved by transport proteins.
 Vesicle formation takes them in or out of cell.
 Exocytosis—movement ______________ of cell

Endocytosis—movement ________________ cell
Phagocytosis—cell surrounds, ________________, and digests particle
Pinocytosis—vesicle forms around __________________________________ particles
Receptor-mediated endocytosis—___________________ for particular substances found
in coated pit—selective and more ___________________