Cellular respiration occurs in three stages: glycolysis, the Krebs cycle, and the electron transport chain. Glycolysis breaks down glucose in the cytoplasm, producing two pyruvic acid molecules, two ATP molecules, and two NADH molecules. The pyruvic acid then enters the mitochondrion for the Krebs cycle and electron transport chain, where electrons are passed through electron carriers, releasing energy to produce more ATP. Cellular respiration requires oxygen and produces carbon dioxide and water, harnessing the energy from glucose to produce ATP for cellular work.

1. Energy and Cellular
Respiration
Chapter 7

2. Cellular Respiration vs.
Photosynthesis
• Formulas

5. Cellular Respiration vs.
Photosynthesis
• Organelles
• Mitochondria
• Eukaryotic cells
• Structure is key
− Two membranes
− Space between membranes
− Matrix makes up inner
membrane
– Lots of enzymes found
here for chemical
reactions
− Complex folding=many sites
for reactions to take place
– Maximizes ATP
production
• Chloroplast
• More about this one later…

8. Energy
• Heat (thermal)
• Light (solar)
• Chemical
• Ex.Glucose
• What carries energy?
• Electrons (little energy packets)
• Negatively charged particle
• Involved in making bonds between
atoms
• Electromagnetic spectrum

9. Why do cells need
energy?
• To Do Work!
• What kind of work?
• Transport
• Get things across the membranes
• Mechanical
• Moving things around the cell/moving
the cell itself
• Chemical
• Building up/breaking down molecules

11. How is Energy
Transferred?
• Think food chain!
• First Law of
Thermodynamics
aka the Law of
Conservation of
Energy
• E cannot be created
or destroyed, only
transferred
(converted)

12. Kinetic vs. Potential
• Stored energy due to
an objects position or
• Energy of arrangement
• Glucose is has LOTS of
motion potential energy…look at
all of its bonds
• Anything moving (electrons)
or in motion
• Ex.
• Climbing stairs
• Leg muscles
working
• As you climb up, you
are getting higher,
more gravitational pull,
increase potential E

13. Two Types of Kinetic
Energy
• Directed kinetic • Random kinetic
energy energy of molecular
• Ex. Your body as motion
it moves down • Thermal energy
slide • Ex. When your body
collides with water.
Air and water
molecules are forced
to move and collide
at random,
transferring energy

14. • Thermal Energy
• Created from Random molecular
motion
• “Heat” is thermal energy that is
transferred from warmer object to
cooler object

15. How do we get
Energy?....Eat food!
• Food is
composed of
organic
compounds
• Carbohydrates
• Fats
• Proteins
• All rich in E
• These organic compounds
contain a form of potential
energy we call
• CHEMICAL ENERGY

16. Organic compounds
• Potential to do work is
in the arrangement of • Structures of…
atoms in the molecules • Proteins
• Amount of potential • Carbohydrates
energy depends on the • Fats
structure of the
molecules
• When you break a bond,
you release E
• Energy now available for
muscles to do work

18. Cells and Cars use
Combustion
• Cells • Cars
• Glucose • Hydrocarbons (in
• Oxygen gasoline)
• Energy to do • Oxygen
work • Energy to do
• Transport, mechanical work
mechanical, • Releases carbon
chemical
dioxide and
• Releases carbon water
dioxide and
water

20. calorie
• Amount of energy required to raise
the temperature of 1 g of water 1*C
• Very tiny
• Not practical to measure energy in
food
• Express in kilocalories (kcal), or
Calories, what is on the nutrition
label
• KHDmdcm

21. Burning food…
• Changes chemical energy to
thermal energy (releases heat)
• Measure increase of water
temperature and definition of
calorie to find out how much
chemical energy is in food

22. Find the amount of calories in each food and
which provides the most energy
1 2 3

23. Energy From Electrons
• Atom nucleus
• Positive
• Attracts/pulls electrons
• Potential energy released when nucleus pulls electrons to it (makes
bond)
• Think of the atomic structure of the following atoms
• Oxygen (make up the oxygen molecule in cell resp)
• Hydrogen and Carbon (bonded to each other in glucose)
• Which has a stronger attraction for electrons?
• What happens in cell respiration?
• Oxygen molecule reacts with glucose
• Carbon and hydrogen leave each other and become bonded to
oxygen's, creating the carbon dioxide and water produced in cellular
respiration
• The electrons in hydrogen and carbon are pulled toward the
nucleus of the oxygen atoms, thus releasing potential energy
• Occurs when you burn sugar, lots of energy released almost
instantaneously
• In cellular respiration, occurs in controlled steps to prevent a
massive release of energy

25. Electron Transport
Chain (etc)
• Cell respiration releases E in small amounts in the
form of ATP molecules
• Several steps
• Oxygen is only involved in the end
• Electrons=energy
• Electrons are carried by electron carrier molecules
• Electron carrier is a molecule that can accept a pair of high-E
electrons and transfer them along with most of their energy to
another molecule
• Oxygen is the final electron acceptor that joins with
hydrogen ions to make water
• This transfer of electrons throughout cellular
respiration is called the electron transport chain (ETC)
• For every transfer of electrons between molecules in
the chain, a little E is released

28. Cellular Respiration
• A cellular process (part of metabolism)
• Metabolism
• Set of chem. rxns through which an
organism builds up or breaks down
materials as it carries out life’s
processes
• Catabolic Rxn  breaking molecules down
• Anabolic Rxn  building molecule/putting
things together
• C6H12O6 (aq) + 6O2 (g) → 6CO2 (g) + 6H2O (l)
• Glucose reacts with oxygen to produce
carbon dioxide and water
• REQUIRES OXYGEN
• Aerobic

29. Cellular Respiration: 3
parts
1. Glycolysis
 cytoplasm
2. Kreb’s Cycle
 Mitochondrian
matrix
3. Electron
Transport Chain
 Within the inner
mitochondrial
membrane

30. Mitochondrion
Electrons carried in NADH
Electrons
Pyruvic
carried in
acid
NADH and
Glucose FADH2 Electron
Krebs Transport
Glycolysis
Cycle Chain
Mitochondrion
Cytoplasm

31. Cellular Respiration
Carbon
Glucose
Dioxide
(C6H1206) Electron
Krebs (CO2)
+ Glycolysis Transport
Cycle +
Oxygen Chain
Water
(02)
(H2O)

32. Glycolysis summary
ENERGY INVESTMENT endergonic
invest some ATP
-2 ATP
G3P
ENERGY PAYOFF C-C-C-P exergonic
harvest a little
4 ATP
ATP & a little NADH
like $$
in the
bank
NET YIELD net yield
2 ATP
2 NADH

33. Glycolysis
• Greek word “glukus” sweet
• Latin word “lysis” loosening or decomposing
• Def: the process in which one molecule of glucose is
broken in half, producing two molecules of pyruvic
acid (a three-carbon compound)
• Takes place outside mitochondria, in cytoplasm of
cell
• Energy releasing process
• Does NOT require oxygen
• Requires an investment of 2 ATP molecules at
beginning to get it going
• These 2 atp’s are like an investment that pays back with
interest
• In order to earn money from a bank, you have to put $$
in
• 4 molecules of ATP produced at the end of Glycolysis
• What is the “net” gain?
• 2 ATPs

34. NADH production
• 4 high-E e- are removed and passed to two
electron carriers called NAD+
(nicotinamide adenine dinucleotide) (each
NAD+ carries 2 e-)
• Each NAD+ molecule accepts a pair of
high-E e-
• Once e- are accepted, NAD+ becomes
NADH, which will transfer e- to other
molecules
• NAD+ helps pass energy from glucose to
other pathways in the cell

36. Glycolysis
• Glucose, a six-carbon sugar, receives 2 phosphates from
the first 2 ATPs invested in Glycolysis
• Glucose now becomes fructose 1,6-biphosphate (highly
energized)
• Fructose 1,6-biphosphate splits to become two molecules
of CCC-P (glyceraldehyde 3-P)
• Each of these molecules transfers electrons and
hydrogen ions to NAD+ molecules that come in
• Accepting two e- and hydrogen ion changes NAD+ to
NADH, which carry electrons to the next part of
Glycolysis
• An inorganic phosphate is added to the CCC-P molecule
changing it to P-CCC-P (1,3-biphosphoglycerate)
• 2 ADP molecules will come in and snatch off the
phosphates from P-CCC-P and the molecule has now
become PYRUVATE or PYRUVIC ACID
• Pyruvate is then sent on to the next phase, the Kreb’s
Cycle

39. Reactants and Products of
Glycolysis
• In
• 1 glucose
• 2 ATP
• 2 NAD+
• Out
• 2 NADH (to ETC)
• 4 ATP
• 2 Pyruvates (to Kreb’s cycle)
• (Net ATPs 2)

40. Glucose 2 Pyruvic acid
To the electron
transport chain