Transcript Electron Transport Chain (ETC)

Dr. Rebekah S. Marsh
Kaplan University
Unit 7: Exercise paper
Four hours ago, I ate 3 oz of baked
chicken marinated in 1 tsp olive oil
and other spices, 1 cup rice and ½
cup beans, 2 cups salad (romaine
lettuce, carrots, onions and radishes)
with 2 tablespoons ranch dressing
and 1 cup of skim milk. Now, I am
going to run for 45 minutes and will
lift weights for another 30 minutes
1.
2.
3.
4.
5.
DUE: by EOD Tuesday
03/22/2011
Are these activities considered aerobic,
anaerobic or a combination of both? And
why do you believe so based on the
scenario above?
Based on the meal plan above, what foods
contain carbohydrates, proteins and fats?
How are carbohydrates, proteins and fats
digested and absorbed?
Which main pathway is utilized (glycolysis,
gluconeogenesis, beta oxidation) when first
starting to work out? What macronutrient
does this pathway use and what are the end
products?
Please explain beta oxidation and
gluconeogenesis: what macronutrients they
are utilizing, what the end products are
and why they are needed while working
out?
Key Terms
 Anabolism:
Assembly of complex
organic molecules
 Catabolism:
molecules
Degradation of complex
 Heterotrophs:
Synthesize their organic
metabolites only from other organic
compounds, which they consume
Key Terms
 Intermediary
Metabolism: All reactions
concerned with storing and generating
metabolic energy and with using that
energy in biosynthesis of low molecular
weight compounds
 Energy
Metabolism: Pathways that store
or generate metabolic energy
Overview of Metabolism
Three Stages of Metabolism
ncbi.nlm.nih.gov
The Major Metabolic Pathways
http://staff.jccc.net/PDECELL/cellresp/simpleover.gif
Biosynthesis & Degradative Pathways
Key Terms
 Glycolysis:
central pathway for the catabolism
of carbohydrates; occurs in most organs
 Glyconeogenesis:
Biosynthesis of new glucose;
occurs mainly in liver
 Glycogenesis:
group of enzymatic reactions
leading to the formation of glycogen
 Glycogenolysis:
group of enzymatic reactions
that use stored glycogen to form glucose
Key Terms (continued)
 Pyruvate:
final 3 carbon molecule of
glycolysis, involved in the Krebs cycle
which facilitates energy production
 Adenosine
diphosphate (ADP) /Adenosine
triphosphate (ATP): energy storing molecule
used by an organism on a daily basis
 Aerobic:
in the presence of oxygen
 Anaerobic:
no presence of oxygen
Glycolysis Animation
Please review the website for an animated description of
glycolysis pathway and we will discuss it in 5 minutes
http://www.youtube.com/watch?v=x-stLxqPt6E
Other good sites to review Glycolysis:
1.
2.
http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Introductio
n-to-Glycolysis.topicArticleId-24998,articleId-24980.html
http://www.dnatube.com/video/2338/Glycolysis
Glycolysis
http://www.accessexcellence.org/RC/VL/GG/ecb/ecb_images/13_01Glycolysis-Steps_1-5.jpg
Fates of Pyruvate
Under aerobic conditions
In most aerobic organisms,
pyruvate continues in the
formation of Acetyl CoA and
NADH that follows into the Krebs
cycle and ETC
Under anaerobic conditions
Under anaerobic conditions, such as
during exercise or in red blood cells
(no mitochondria), pyruvate is
reduced to lactate by lactate
dehydrogenase producing NAD for
glycolysis
Gluconeogenesis
http://themedicalbiochemistrypage.org/images/gluconeogenesis.jpg
Gluconeogenesis
 Synthesis of glucose from 3-4 carbon precursors is a
reversal of glycolysis
 3 reactions in glycolysis are essentially irreversible, thus
they are bypassed in gluconeogenesis:
 Hexokinase (1)
 Phosphofructokinase (3)
 Pyruvate Kinase (10)
 Share 7 of the 10 steps in glycolysis
2 pyruvate + 2 NADH + 4 ATP + 2 GTP
glucose + 2 NAD+ + 4 ADP + 2 GDP + 6 Pi
Glycolysis vs Gluconeogenesis
Fed state
Fasting state
•Cytoplasm
• Cytoplasm
•All cells
• Liver mostly, but
also kidney
Definitions



Krebs cycle - series of enzymatic reactions in aerobic
organisms involving oxidative metabolism of acetyl units
and producing high-energy phosphate compounds, which
serve as the main source of cellular energy
Electron Transport Chain (ETC) - Composed of
mitochondrial enzymes that transfers electrons from one
transport to another, resulting in the driving force for the
formation of ATP
Oxidative phosphorylation - Process occurring in the cell,
which produce energy and synthesizes ATP
Definitions
 NAD/NADPH:
Reducing agent in several
anabolic reactions such as lipid and
nucleic acid
 FAD/FADH:
Reducing agent in several
anabolic reactions such as lipid
Krebs Cycle
 Also known as the citric acid cycle or tricarboxylic acid
(TCA) cycle
 Under aerobic conditions pyruvate enters the mitochondria
MATRIX and is oxidized to Acetyl CoA which enters the
Krebs cycle
 Krebs cycle can occur after glycolysis, after Beta oxidation
or protein degradation to provide energy for cellular
respiration
 Equation for Krebs cycle with the beginning products and
the ending. 8 steps involved
2 pyruvate + 2 GDP + 2 H3PO4 + 4 H2O + 2 FAD + 8 NAD+
6 CO2 + 2 GTP + 2 FADH2 + 8 NADH
Krebs Cycle
 Please go to: http://highered.mcgraw-
hill.com/sites/0072507470/student_view0/chapte
r25/animation__how_the_krebs_cycle_works__q
uiz_1_.html and we will discuss the krebs cycle
after the animated movie.
 Other sites for the Krebs Cycle:
1. http://www.dnatube.com/video/2354/Electron-
Transport-Chain
2. http://www.elmhurst.edu/~chm/vchembook/596
electransport.html
Krebs Cycle (TCA)
http://image.tutorvista.com/content/respiration/krebs-cycle.jpeg
Summary TCA
 Occurs in the mitochondrial matrix
 Uses acetyl CoA to produce:
 3 NADH, 1 FADH, 1 GTP, 2Co2
 Produce intermediates for biosynthetic pathways
such as amino acid synthesis, gluconeogenesis,
pyrimidine synthesis, phorphyrin synthesis, fatty
acid synthesis, isoprenoid synthesis.
Electron Transport Chain (ETC)
 Final pathway by which electrons generated from
oxidation of carbs, protein and fatty acids, are
ultimately transferred to O2 to produce H2O
 Located in the inner mitochondrial membrane
 Electrons travel down the chain, pumping protons into
the intermembrane space creating the driving force to
produce ATP in a process called oxidative
phosphorylation
 There are 4 complexes that comprise the ETC
Electron Transport Chain
 Please go to:
http://www.brookscole.com/chemistry_d/template
s/student_resources/shared_resources/animations
/oxidative/oxidativephosphorylation.html
and we will discuss about the ETC after the
animated film.
Other help link to explain the ETC:
1.
2.
http://www.stolaf.edu/people/giannini/flashanimat/metaboli
sm/mido%20e%20transport.swf
http://vcell.ndsu.edu/animations/etc/movie.htm
Electron Transport Chain
http://vcell.ndsu.nodak.edu/animations/etc/Stills/0917.jpg
Summary ETC
 Reduced electron carriers NADH & FADH2 reduce O2 to H2O
via the ETC. The energy released creates a proton gradient
across the inner mitochondrial membrane. The protons flow
down this concentration gradient back across the inner
mitochondrial membrane through the ATP Synthase. The
driving force makes this enzyme rotate and this conformation
generates enough energy to produce ATP.
 Oxidation of NADH to NAD+ pumps 3 protons which charges
the electrochemical gradient with enough potential to
generate 3 ATPs.
 Oxidation of FADH2 to FAD+ pumps 2 protons which charges
the electrochemical gradient with enough potential to
generate 2 ATPs.
Oxidative Phosphorylation
http://stevebambas.com/images/AP%20220%20ox%20phosph.jpg
References
Introduction to Carbohydrate Metabolism

Mathews C & Van Holde K. (1990). Biochemistry. Redwood City: The Benjamin/Cummings
Carbohydrate Metabolism

King, M (2010). Digestion of Dietary Carbohydrates. Retrieved on May 13, 2010 from
http://themedicalbiochemistrypage.org/glycolysis.html

Hardy, J (2003). Gluconeogenesis. Retrieved on May 13, 2010 from
http://www.elmhurst.edu/~chm/vchembook/604glycogenesis.html

Campbell, Neil A. (2005) AP Edition Biology. 7th. San Francisco, CA: Pearson Benjamin
Cummings
Carbohydrate Metabolism: Krebs Cycle and Electron Transport Chain

Phases of the Krebs Cycle (N.D.) Retrieved on May 13, 2010 from
http://incolor.inebraska.com/mcanaday/Krebs%20Phases.htm

Electron Transport Chain (N.D.) Retrieved on May 13, 2010 from
http://vcell.ndsu.edu/animations/etc/movie.htm

Campbell, Neil A. (2005) AP Edition Biology. 7th. San Francisco, CA: Pearson Benjamin
Cummings