Cellular Respiration
Chemical energy and food
 Calorie- the amount of energy need to raise the
temperature of 1 gram of water 1 degree Celsius.


Ex: 1 g of glucose releases 3811 calories of heat energy
Kilocalorie (used on food labels)
 Cells gradually release the energy from glucose and
other food sources

Begins with glycolysis
Overview of cellular respiration
 6O2 + C6H12O6  6CO2 + 6H2O + ENERGY
 Glycolysis, the Krebs cycle, and the electron
transport chain make up cellular respiration!
 Main goal= make energy (in the form of ATP)
Glycolysis
http://www.youtube.com/watch?v=3GTjQTqUuOw
Glycolysis
 The process in which one molecule of glucose (a 6
carbon compound) is broken is half, producing 2
molecules of pyruvate (a 3 carbon compound)
 If there is oxygen (aerobic) followed by the
Krebs cycle and electron transport chain
 If there isn’t oxygen (anaerobic) followed by
fermentation
Glycolysis
 Overall, ENERGY PRODUCING process
 HOWEVER, it needs to put IN energy to get things going
 2 molecules of ATP are used up

Analogy: Like an investment earning interest!
 4 molecules of ATP are produced!
What is the net gain of ATP?
Glycolysis
 After using energy to get things started and break 1
glucose into 2 pyruvate  glycolysis makes 4 ATP
and removes 4 high energy electrons
 Passes these electrons to electron carrier NAD+
 Similar to NADP+ in Photosynthesis
 NAD+  NADH (can hold 2 high-energy e-)
 NADH takes those electrons to the Electron
transport chain to make MORE energy (ATP)
Glycolysis
SO…
Glycolysis produces
 2 molecules of ATP
 2 molecules of NADH
PER molecule of glucose broken down
Glycolysis
 Energy yield from glycolysis is small but FAST!
 Cells can produce thousands of ATP molecules in a
few milliseconds
 Glycolysis itself does not need oxygen so it can
supply chemical energy to the cells when oxygen is
not present
Anaerobic
 If no oxygen is present (anaerobic followed
by fermentation
Yeast Lab
Yeast lab reflection
 What are the products of fermentation?
 Is there evidence for each product?
 How can we determine in this lab whether this was
aerobic or anaerobic?
 How is anaerobic different from aerobic respiration?
Yeast lab Explanation
 Yeast is a facultative anaerobe, meaning that it can
participate in aerobic respiration when possible, but
when this is impossible, it respires anaerobically.
 When using yeast in making dough, the yeast will use the
initial oxygen up very quickly and then start to respire
anaerobically.
 ATP will then be made via glycolysis, which requires no
oxygen.

To regenerate the NAD+, the yeast will undergo alcoholic
fermentation, which converts pyruvic acid into CO2
Fermentation
 Fermentation- releases energy from food molecules
by producing ATP in the absence of oxygen
 Cells convert NADH into NAD+ by passing high-
energy electrons BACK to pyruvic acid more ATP
production
 ANAEROBIC meaning “not in air”
Fermentation
 Two main types:
1.
2.
Alcoholic fermentation
Lactic acid fermentation
Alcoholic fermentation
 Yeast uses alcoholic fermentation, forming (ethyl)
alcohol and CO2 as waste
 Causes bread dough to rise
 When yeast in the dough runs out of oxygen, it begins to
ferment, giving off bubbles of CO2 (forms the air spaces you
see in bread)
 The small amount of alcohol evaporates when the
bread is baked.
Alcoholic Fermentation
Pyruvate + NADH  Alcohol + CO2 + NAD+
Lactic Acid fermentation
 Converts pyruvate into lactic acid
 Lactic acid is what builds up in your muscles when
you exercise to make you sore!
Why??
Lactic Acid fermentation
 Converts pyruvate into lactic acid
 Lactic acid is what builds up in your muscles when our exercise to make
you sore!
Why??
 Not enough oxygen
 Without oxygen, your body cannot produce all of the
ATP required
 No ATP= No Glycolysis!
Lactic acid fermentation
 Cells convert NADH into NAD+ by passing high-
energy electrons BACK to pyruvic acid more ATP
production
Lactic acid fermentation
Pyruvate + NADH  Lactic acid + NAD+
Aerobic Respiration
In the presence of oxygen (aerobic) followed by
the Krebs cycle and electron transport chain
Krebs Cycle
 The process in which pyruvate is transported to the
mitochondrial matrix and is converted into CO2
 Also known as the “citric acid cycle” or “TCA cycle”
Krebs cycle
How many molecules of pyruvate are formed during
glycolysis?
Krebs cycle
 2!
 Resulting
in two “turns” of the Krebs cycle for
each glucose molecule
Krebs cycle
 Net yield
 6 CO2 molecules
 2 ATP
 8 NADH
 2 FADH2
Krebs Cycle
Every time you exhale, you release CO2 from the Krebs
cycle!
Krebs cycle
http://www.youtube.com/watch?v=emLl7oibl8Q
Electron Transport Chain
 Final step!
 The point where most of the ATP is produced!
 High-energy electrons and H+ ions from electron
carriers (NAPDH) are used to convert ADP to ATP
Electron Transport Chain
Electron Transport Chain
 Electrons move down the mitochondrial membrane
from one protein to another
 As NADH and FADH2 release electrons, the energy
carriers are converted back to NAD+ and FAD
 The energy used to transport electrons down the
chain is used to transport H+ ions across the
membrane
Electron Transport Chain
 H+ ions diffuse down their concentration gradient
through ATP synthase  produce ATP
 At the end of the ETC is an enzyme that combines
these electrons with hydrogen ions
 Last carrier= Oxygen
 Protons and electrons are transferred to oxygen to form water
Electron Transport Chain
 Overall, produces
32
ATP
How do glucose and ATP differ in the amount of
energy they store?
Electron Transport Chain
 Overall, produces
 32 ATP
How do glucose and ATP differ in the amount of
energy they store?
Glucose stores more energy
(yields ATP)
Electron Transport Chain
http://www.youtube.com/watch?v=Ak17BWJ3bLg