Ch. 7.4: Cellular Respiration
Vocabulary
Aerobic
Electron transport chain
Objectives:
1. Relate breathing and cellular respiration.
2. Summarize the cellular respiration equation.
3. Tell how “falling” electrons are a source of
energy.
4. Explain the role of electron transport chains.
Ch. 7.4: Breathing & Respiration
Cellular respiration converts the energy stored in
food to energy stored in ATP.
Physical processes of
moving O2 & CO2
Gases exchanged b/w blood
& outside air via lungs.
Chemical rxn involving the
oxidation of glucose to H2O&
CO2
Gases exchanged b/w cells &
surroundings (blood or
lymph)
Ch. 7.4: Cellular Respiration Equation
Respiration occurs in a SERIES of reactions (not 1 rxn).
Goal: Generate ATP for cellular work.
7.4: Where does energy for ATP come from?
Moving to a lower
energy level is like
moving downhill.
Moving to an outer
energy level is like
climbing uphill … it
costs energy.
Falling Electrons = Energy Source for ATP
“Falling Electrons” release energy; Excited --> ground state
Why?: Negative electrons are attracted to positive nucleus.
Moving farther fr. nucleus requires energy; falling to nucleus
releases energy.
7.4: Reacting with Oxygen; Oxidation
Respiration
Oxygen is an excellent “electrongrabber”; electrons are pulled to O
(electro-negative).
(O is much better than N or H @ attracting
electrons)
Oxidation
+ ATP ENERGY
In respiration, C-H bonds of
glucose are re-arranged into C-O
and H-O bonds of carbon dioxide
and water. These bonds store less
energy. The energy difference is
stored in ATP.
If glucose is BURNED in a combustion rxn; energy is released as heat and
light all at once.
7.4: Electron Transport Chains (E.T.C.)
•Energy from glucose is
released in small steps.
•Electrons from glucose are
passed from one molecule to
another in an E.T.C.
•Each transfer releases energy
to make ATP. Electrons are “falling
downhill”.
•O2 is ultimate electrongrabber @ end of ETC. O2
grabs electrons and combines
w/ H+ions to form H2O.
7.5: Making ATP
Vocab:
Metabolism
Krebs Cycle
Glycolysis
ATP synthase
Objectives:
1. Describe the structure of the mitochondrion.
2. Summarize the 3 stages of cellular respiration and identify
where ATP is made.
7.5: Mitochondia
Found in almost all
eukaryotic cells.
2 membranes (inner &
outer)
Inner membrane highly folded w/
enzymes (ATP
synthase) built in.
Thick fluid in matrix.
Structure & Function go together: Folds of inner membrane
increases surface area for enzymes and sites for reactions …
MORE ATP gets made (more surface area = more ATP
synthase)!
7.5: Steps of Cellular Respiration
Metabolism: all of a cell’s combined chemical reactions.
Respiration is a series of rxns … a metabolic pathway.
Step 1: Glycolysis
•Break down glucose molecule into (2) 3 carbon-molecules called PYRUVATES.
•Outside mitochondria, in cytoplasm (cystol)
•Requires 2 ATPs to break glucose; Electrons & H+ ions transfer to NAD -->
NADH and make 4 ATP
Summary: Glucose breaks down into 2 Pyruvates (3 C) and 2
ATPs!
7.5: Step 2: Krebs Cycle
•Pyruvic acid (3C) --> Acetyl CoA (2C) --> CO2; Energy Released
and stored in ATP, NADH, and FADH2 (Electron acceptors)
•Where: Enzymes in fluid matrix inside inner membrane.
Summary: 2 Pyruvate (3C) break down to CO2 & 2ATP, NADH,
FADH2
7.5: Step 3: Electron Transport Chain and
ATP Synthase Action
•Electrons (fr. Glucose)
carried by NADH move
thru. E.T.C. (getting pulled
by stronger electronattractor molecules)
•Oxygen grabs electrons @
end; combines w/ H+ to
make H2O.
•Energy from ETC used to PUMP H+
(fr. NADH) across membrane
AGAINST GRADIENT. H+ ions then
move down gradient thru. channel
proteins called ATP synthase.
ATP synthase: enzyme that
catazlyzes ADP + P --> ATP
Electron Transport Chain & ATP Synthase
Summary: Use moving electrons to make ATP!
Makes BULK
of ATP (~34
ATP)
7.5: Cellular Respiration
Energy stored in bonds of glucose --> ~ 38 ATP molecules
Most ATP production occurs after glycolysis and REQUIRES
OXYGEN.
7.5: Cellular Respiration
7.6: Anaerobic Respiration (Fermentation)
Vocab.:
Fermentation
Anaerobic
Objectives:
1. Explain how
fermentation in
muscle cells is
different from cellular
respiration.
2. Give examples of
products that depend
on fermentation in
microorganisms.
7.6: Fermentation
What: Making ATP w/out O2 (using glycolysis)
Context: Working muscles need an ongoing ATP supply;
faster than O2 can be supplied for respiration.
Yield: 2 ATPs for each glucose (but regular respiration is
occuring @ same time too).
Waste Product: Lactic Acid
2 Lactic acid
7.6: Fermentation in Humans
After rigorous exercise,
fermentation leads to a build
up of lactic acid -->
MUSCLE FATIGUE &
SORENESS As your body
converts lactic acid -->
pyruvic acid you NEED
OXYGEN and breathe
heavily.
7.6: Fermentation in Microorganisms
Yeast (fungi) cells can ferment sugar in anaerobic
Environments (No O2 ).
Product of yeast fermentation is ETHANOL, an alcohol (not
lactic acid) and CO2 .
7.6: Application of Fermentation
Production of:
•
Breads (CO2 makes break
rise)
•
Alcoholic beverages
•
Yogurts and cheeses from
milk (Fungi & bacteria that
make lactic acid)
•
Soy sauce (fr. Soybeans)
•
Sauerkraut (fr. Cabbage)