This document provides an overview of cellular respiration by discussing its three main stages: glycolysis, the Krebs cycle, and the electron transport chain. It explains that cellular respiration occurs in the mitochondria and releases energy from glucose and other food molecules to produce ATP, the energy currency of cells. The document also compares aerobic and anaerobic respiration, and contrasts how photosynthetic and non-photosynthetic cells generate ATP through these metabolic pathways.

2. YEAST Demo
• Saccharomyces cerevisiae
• Observations
– Start:
– Middle:
– End:

3. Getting Energy for
Biological Work

4. Examine this photograph:

5. How does this organism get energy
to do biological work?

6. Examine this photograph:

7. How does this organism get energy
to do biological work?

8. Examine the photograph:

9. How does this organism get energy
to do biological work?

10.  Plants capture energy from the sun and
store it in carbohydrates
Done through photosynthesis
 Consumers acquire energy by either:
 Eating producers directly.
 Eating consumers that eat producers.
 All consumers depend on producers!
To Review:

11. What does a cell need energy for?
 Movement
 Digestion
 Reproduction
 Cellular transport
 Production of proteins
 Repair
 Growth

12. Matter, Energy, & Organization
 All living things are highly organized
 require an input of matter and energy to
maintain their organization.
 Cells (organisms) obtain energy by:
 breaking down carbohydrates
 other macromolecules may be used
 chemical pathways transfer energy from one
molecule to another.

13. Remember from Part 1:
 Plants convert energy from light (the sun)
into the form chemical energy:
Primary product = Glucose
 Further stored as other, larger carbohydrates:
Starch
Cellulose
 Most organisms use glucose as their
primary source of energy.
 Remember: Plants make their own!

14. Fo cus o f the rest o f this presentatio n:
 The process by which organisms convert
energy in carbohydrates into a form they
can use to drive cellular activities.
 This process is called…
…CELLULAR RESPIRATION

15. Cellular Respiration
 Takes place at the cellular level.
 When you eat, your food has to be broken
down small enough to be used by your
cells!
Then your cells break down molecules into
even smaller pieces!
Cells then build new materials with all of the
pieces.

16.  The stored energy of glucose (carbs) is
therefore:
released bit by bit and:
 used to form another type of chemical energy:
ATP!
The energy currency of cells!

17. So…
the GOAL of cellular respiration…
 …to make ATP for the cell.
 The food you eat provides the energy
needed for ATP production!

18. ATP = High-energy molecule
 Adenosine triphosphate
 Recall:
 ATP contains phosphate
(PO4
-
) groups that are
held together by high-
energy covalent bonds
 Remember: energy is
stored in …
 …BONDS!!

19. ATP, continued
 When bonds between
phosphates in ATP are
broken:
 energy is released.
 This energy is used by
the cell to drive all of the
chemical reactions that
allow the cell/organism
to function.
 (Remember: why do
organisms need energy?)

20. Cells constantly recycle ATP!

21. The Metabolic
Pathway of Cellular
Respiration

22. Metabolic Pathway
 Cellular respiration is part of metabolism.
Remember: metabolism is the general term
for ALL the chemical processes that occur in
cells.
 Metabolic pathway = biochemical pathway
 More than 2 dozen chemical reactions
comprise cellular respiration.
A specific enzymes catalyze each reaction.

23. Metabolic Pathway, con’t.
 All the chemical reactions of cellular
respiration can be grouped into three
main metabolic stages
1. Glycolysis
2. Krebs cycle
3. Electron transport chain

25. A look inside a
Mitochondrion
• Mitochondrion = The POWERHOUSE of the cell!

26. Cellular Respiration: Stage 1
 The first step of
respiration is always:
 Glycolysis
 Glyco = sugar/carb
 Lysis = split
 occurs in cytosol of
cells
 Cytosol = aqueous
solution of cytoplasm

27. Cellular Respiration:
Stages 2-3
• Take place inside the Mitochondria.

28. Cellular Respiration: Stage 2Cellular Respiration: Stage 2
 Called the Krebs CycleCalled the Krebs Cycle
 Completes the breakdown of sugar all theCompletes the breakdown of sugar all the
way to COway to CO22, a waste product of cellular, a waste product of cellular
respiration.respiration.
 Enzymes for the Krebs cycle are dissolvedEnzymes for the Krebs cycle are dissolved
in the fluid within the mitochondriain the fluid within the mitochondria
mitochondrial matrixmitochondrial matrix

29. Cellular Respiration: Stage 3Cellular Respiration: Stage 3
 Called the Electron Transport ChainCalled the Electron Transport Chain
 In an electron transport chain, electrons areIn an electron transport chain, electrons are
passed from one molecule to the next, to thepassed from one molecule to the next, to the
next, to the next, and so on.next, to the next, and so on.
 Electron transport in cellular respirationElectron transport in cellular respiration
occurs across the inneroccurs across the inner
membrane of mitochondria:membrane of mitochondria:
cristaecristae

30.  ElectronElectron
transporttransport
requiresrequires
oxygenoxygen..

31. Electron transport proteins are embedded withinElectron transport proteins are embedded within
the inner mitochondrial membrane (the inner mitochondrial membrane (cristaecristae).).

32. Oxygen is the terminal electron acceptor, combining
with electrons and H+
ions to produce water

33. Proton gradient is built up.

34. Protons (+) enter back into the mitochondrial matrix
through channels in ATP synthase.
This entry is coupled to ATP synthesis from ADP and
phosphate (Pi
)

35. EQUATION FOREQUATION FOR
RESPIRATIONRESPIRATION
CC66HH1212OO66 ++
GLUCOSEGLUCOSE
6O6O22
OXYGENOXYGEN
6CO6CO22 ++
CARBONCARBON
DIOXIDEDIOXIDE
6H6H22OO ++ ENERGYENERGY
WATERWATER
ATPATP

36. How Much ATP is Produced
Per Glucose Molecule?
Glycolysis 2 ATP
Krebs Cycle 2 ATP
Electron transport chain 34 ATP
TOTAL 38 ATP

37. How efficient is cellular respiration?
 In other words, how well do cells do at
“burning” glucose to get the energy?
 Let’s think back…

38.  Think back to the ecological pyramid
concept…
 …What was the rule to describe the
amount of energy and matter transferred
from one level up to the next?

39. 10% Rule
 The 10% Rule means
that out of all the
energy available in an
ecological level, only
10% is passed on to
the next level.
 Is 10% efficient?
 What happens to the
other 90%??
 It is LOST!
 HEAT is generated
 Some organisms don’t
get eaten
 Every bit of an
organism might not get
eaten
 Energy is used for life
functions

40. Glucose as a cellular fuel
 When cellular respiration occurs, this
means your cells are “burning” glucose…
Cellular respiration is a special type of
combustion…
 …combustion of the fuel GLUCOSE

41. An analogy can be drawn between our cells and a car. The mitochondria
are the engines of our cells where sugar is burned for fuel and the
exhaust is CO2
and H2
O. In a car that burns fuel perfectly, the only
exhaust should theoretically be CO2
and H2
O. Is this 100% efficient?
Glucose as a cellular fuel

42. How efficient is cellular
respiration?
• In other words, how well do
cells do at “burning” glucose to
get the energy?
• Calculating Energy…

43.  Respiration can be:
Aerobic = occurs in the presence of O2
Anaerobic = occurs in the absence of O2

44. The versatility of cellular respirationThe versatility of cellular respiration
 Most of the time, we concentrate onMost of the time, we concentrate on
glucoseglucose as the fuel that is broken down inas the fuel that is broken down in
cellular respiration.cellular respiration.
 But, respiration is a versatile metabolicBut, respiration is a versatile metabolic
“furnace” that can “burn” many other kinds“furnace” that can “burn” many other kinds
of food molecules.of food molecules.
Cellular respiration is calledCellular respiration is called intermediaryintermediary
metabolism.metabolism.

46. Here’s an Analogy:
 Think of cellular respiration like
exchanging money.
 You would have different kinds of currency
depending on what country you are in.
(ex: dollars, pounds, yen, lira, etc.)
 But, any of those can be exchanged to a
worldwide currency of gold!

47. Analogy, continued…
 So, no matter what type of food (money)
your cells take in,
 Energy containing food molecules are all
converted to a common energy currency:
ATP! (GOLD!)

48. Anaerobic Respiration
• Produce ATP in the absence of O2
• Ex: Used regularly by skeletal muscle
fibers and Red Blood Cells (RBC)
• Only two steps (in cytosol ONLY):
– Glycolysis
– Fermentation
• Lactic Acid Fermentation
• Alcoholic Fermentation

49. What happens when there is no oxygen?What happens when there is no oxygen?
Only the process of glycolysis is carried out and lactic
acid is produced in the muscles. The body cannot
tolerate much lactic acid and it must eventually be
converted in the liver to pyruvate.
results in muscle soreness
• Also essential to the
production of many
dairy products.
(cultured dairy
products)
• Microorganisms are
added to cause

50. Alcoholic FermentationAlcoholic Fermentation
• Some organisms carry out alcoholic fermentation.
• This was discovered by Louis Pasteur in his study of the
chemistry of wines.
• Yeasts break down the sugars in the juice by glycolysis,
then the byproducts are dismantled to yield:
CO2 and ETHANOL
the alcohol in
alcoholic beverage

51. Summary and OverviewSummary and Overview
Photosynthesis and CellularPhotosynthesis and Cellular
RespirationRespiration

52. Overview of photosynthesisOverview of photosynthesis
and respirationand respiration
PHOTOSYNTHESISPHOTOSYNTHESIS CELLCELL
ACTIVITIESACTIVITIES
CELLULARCELLULAR
RESPIRATIONRESPIRATION
SUNSUN
RADIANTRADIANT
ENERGYENERGY
GLUCOSEGLUCOSE ATPATP
(chemical energy)(chemical energy) (chemical energy)(chemical energy)

53. • 6CO2 + 6H2O C6H12O6 + 6O2
• C6H12O6 + 6O2 6CO2 + 6H2O

57. How does a photosynthetic cell
make ATP?
Glycolysis
Glucose from photosynthesis
Krebs Cycle,
Electron transport chainFermentation
No oxygen present
(anaerobic)
Oxygen present
(aerobic)

58. How does a non-photosynthetic cell
make ATP?
Glycolysis
Glucose from food
Krebs Cycle,
Electron transport chainFermentation
No oxygen present
(anaerobic)
Oxygen present
(aerobic)