Cellular Respiration: Day 04
Process whereby cells breakdown glucose and
other food molecules to release energy.
Updates
• We will test on Cellular Respiration before
moving onto Photosynthesis
• Test will be next week sometime
– When? It depends on if we miss school for the
elections or not – check our WIKI!!
• Lab – Lets talk about that first!
Lets Review the Cellular
Respiration Cycle
• Lets begin with a Respiration Tutorial
– Take a look at the big picture!
• When you exercise:
– Muscles need
energy in order to
perform work.
– Enzymes in
muscle cells help
the cell convert
glucose and
oxygen into ATP
(usable energy).
• Terms we have discussed:
– Aerobic Metabolism
– Anaerobic Metabolism
– Autotrophs
– Heterotrophs
– Producers
– Consumers
Chemical Cycling Between
Photosynthesis and Cellular Respiration
• The ingredients for photosynthesis are carbon
dioxide and water.
– CO2 is obtained from the air by pores on a plant’s
leaves.
– H2O is absorbed from the damp soil by the roots.
– Veins transport the water from roots to leaves.
• Chloroplasts rearrange the atoms of these
ingredients to produce sugars (glucose) and other
organic molecules (key products = glucose and
oxygen).
– Oxygen gas is a by-product of photosynthesis
Photosynthesis
Respiration
CELLULAR RESPIRATION: AEROBIC
HARVEST OF FOOD ENERGY
• Cellular respiration:
– The main way that chemical energy is harvested
from food and converted to ATP
– This is an aerobic process—it requires
oxygen
A common fuel molecule for cellular respiration is glucose.
• This is the overall equation for what happens to
glucose during cellular respiration.
Glucose
Oxygen
Carbon
dioxide
Water
Energy
• Cellular respiration can produce up to 38 ATP
molecules for each glucose molecule consumed.
The Metabolic Pathway of Cellular Respiration
• Cellular respiration is an
example of a metabolic
pathway (a series of
chemical reaction in cells).
• All of the reactions involved in
cellular respiration can be
grouped into three main
stages:
1. Glycolysis
2. The Krebs cycle
3. Electron transport
• Why does electron
transfer to oxygen
release energy?
– When electrons move
from glucose to
oxygen, it is as
though they were
falling
– This “fall” of electrons
releases energy
during cellular
respiration
Figure 6.5
Release
of heat
energy
NADH and Electron Transport Chains
• The path
that
electrons
take on
their way
down from
glucose to
oxygen
involves
many stops
1/
2
(from food via NADH)
2 H
Energy for
synthesis
of
2 e
2 e
2 H
1/
2
Figure 6.6
A Road Map for Cellular Respiration
Cytosol
Mitochondrion
High-energy
electrons
carried
mainly by
NADH
High-energy
electrons
carried
by NADH
Glycolysis
Glucose
2
Pyruvic
acid
Krebs
Cycle
Electron
Transport
I. Glycolysis (click)
Process whereby one glucose molecule is broken in half
producing two pyruvate molecules.
• Takes place in cell’s
cytoplasm.
• Does not require O2
to take place.
• Occurs very rapidly,
however, low energy
yield (Net 2 ATP and
2 NADH produced)
Cell with Mitochondria (red spots)
Mitochondria
Site of Krebs cycle and Electron Transport Chain
II. Krebs Cyle (click)
Process whereby pyruvate is broken down into CO2 in a
series of energy releasing reactions.
• Only occurs if O2 is present
(aerobic respiration).
• Takes place within the
mitochondria of the cell.
• Each pyruvate that goes
through the cycle produces
1 ATP, 4 NADH, 1 FADH2
and 3 CO2 (2 X that amount
for each glucose molecule).
III. Electron Transport Chain (click)
Uses the high energy electrons from NADH and FADH2 to
convert ADP into ATP.
• Occurs in proteins that are
•
•
•
•
embedded within the inner
membrane of the mitochondria.
As high energy electrons from
NADH and FADH2 are passed
from protein to protein in the
“chain”, H+ ions are pumped
across the membrane.
H+ ions flow back through ATP
synthase which converts ADP
into ATP.
Final electron acceptor in the
“chain” is O2 forming a H2O
molecule.
10 NADH and 2 FADH2 make
a total of 34 ATPs.
Adding Up the ATP from Cellular
Respiration
Cytosol
Mitochondrion
Glycolysis
Glucose
2
Pyruvic
acid
2
AcetylCoA
Krebs
Cycle
Electron
Transport
Maximum
per
glucose:
by direct
synthesis
by
direct
synthesis
by
ATP
synthase
Figure 6.14
The Versatility of Cellular Respiration
• Cellular respiration can “burn” other kinds of
molecules besides glucose.
– Diverse types of carbohydrates
– Fats
– Proteins
FERMENTATION: ANAEROBIC
HARVEST OF FOOD ENERGY
• Some of your cells can actually work for short periods
without oxygen.
– For example, muscle cells can produce ATP under
anaerobic conditions.
• Fermentation
– The anaerobic harvest of food energy
Without Oxygen!!!
• We cannot enter the Krebs Cycle
• Must use Anaerobic Respiration
– Alcohol Fermentation
– Lactic Acid Fermentation
In order for Glycolysis to continue NAD+
must be present.
• Without O2 (anaerobic
respiration) the NADH
can not move onto the
Krebs cycle.
• Think of NADH as “full
moving trucks” which
must be unloaded for
the company to
survive.
Like our lab!!
2 ways to “unload” the NADH in
anaerobic environments
• Alcohol Fermentation
NADH passes electron
back to pyruvic acid
creating alcohol
molecules. Occurs in
yeast and other
microorganisms
• Lactic Acid Fermentation
NADH passes electron
back to pyruvic acid
creating lactic acid
molecules. Occurs with
our muscle cells and other
prokaryotes (helps make
yogurt, kimchi and
cheese!)
Fermentation in Human Muscle Cells
• Human muscle cells can make ATP with and
without oxygen
– They have enough ATP to support activities
such as quick sprinting for about 5 seconds
– A secondary supply of energy (creatine
phosphate) can keep muscle cells going for
another 10 seconds
– To keep running, your muscles must generate
ATP by the anaerobic process of fermentation
• Glycolysis is the metabolic pathway that
provides ATP during fermentation.
– Pyruvic acid is reduced by NADH, producing
NAD+, which keeps glycolysis going
– In human muscle cells, lactic acid is a byproduct
2 ADP+ 2
Glycolysis
2 NAD
2 NAD
Glucose
(a) Lactic acid fermentation
2 Pyruvic
acid
+ 2 H
2 Lactic
acid
Fermentation in Microorganisms
• Various types of microorganisms perform
fermentation.
– Yeast cells carry out a slightly different type of
fermentation pathway
– This pathway produces CO2 and ethyl alcohol
2 ADP+ 2
2 CO2 released
2 ATP
Glycolysis
2 NAD
2 NAD
Glucose
2 Pyruvic
acid
+ 2 H
2 Ethyl
alcohol
(b) Alcoholic fermentation
Figure 6.15b
• The food industry uses yeast to produce
various food products
Figure 6.16
• Respiration tutorial
– Both high and low oxygen settings
– Copy and paste the questions into your
onenote and answer there.
– Read the blurb at the beginning of each
section before pressing play.
Images Cited
http://www.mir.com.my/rb/photography/companies/canon/fdresources/fdlenses/vinpix/swimmer.jpg
http://www.maratonasant-antonio.com/upload/file_ima_8ce13b8605.jpg
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http://www.msu.edu/course/isb/202/ebertmay/images/Energy%20Proc%20PNG.png
http://www.kidsco.co.uk/Entertainer%20Images/Fire%20Eater.gif
http://www.chinadaily.com.cn/english/doc/2005-02/04/xin_530202021019679268915.jpg
http://www.topicsites.com/health-fitness/woman-eating-apple.jpg
http://www.nhnr.org/wcheal/images/Ingredients_Healthy_Food.jpg
http://www.stationnight.com/Homer-Sleep1.gif
http://dept.kent.edu/projects/cell/tly1.jpg
http://www.a3243g.com/a3243g_images/mitochondria.gif
http://kentsimmons.uwinnipeg.ca/cm1504/Image110.gif
http://staff.jccc.net/pdecell/bio122/glycolysis.gif
http://www.biologycorner.com/resources/fermentation.jpg
http://images.jupiterimages.com/common/detail/53/04/23360453.jpg
http://images.jupiterimages.com/common/detail/11/81/23268111.jpg
http://www.trifood.com/image/kimchi_image_final.JPG
http://www.thefinalsprint.com/images/2007/01/lactic-acid-training.jpg
http://faculty.ircc.edu/faculty/tfischer/images/Krebs%20overview.jpg
http://student.ccbcmd.edu/~gkaiser/biotutorials/energy/images/chemios_il.jpg
http://fig.cox.miami.edu/~cmallery/150/makeatp/c9x6cell-respiration.jpg