Transcript Physical activity & metabolism

Cellular Energy:
ATP & Enzymes
What is it? Where do we get it?
How do we use it?
Energy
• The capacity to perform work; ability to
rearrange matter
• Energy is required to drive reactions
• 2 forms:
– Potential Energy (PE): stored energy, due to
position of structure
– Kinetic Energy (KE): Energy of motion
• Heat is KE associated with the movement of
molecules/atoms within matter
Energy is just transformed
• Total amount of Energy in Universe is
constant (1st Law)
– Nothing created or destroyed, only
transformed
• One result of ALL energy transfers is
the production of heat (2nd Law)
– Heat = disordered, unharnessed KE. This KE
is LOST; cannot be used to perform work
Energy is lost during rxns
Chemical Reactions
• Endergonic (energy input): Store Energy –
products have higher energy than
reactants; Anabolic
• Exergonic (energy output): Release
Energy – products have lower energy;
Catabolic
Endergonic/Anabolic
• Photosynthesis:
– Reactants = CO2 &
H2O + light energy
– Products = sugar
molecules
Exergonic/Catabolic
• Bonfire
– Reactants: Cellulose
(glucose), O2
– Products: light, heat,
CO2, H2O
• Cellular respiration
“burns” glucose to
harness energy for
work
Anabolic and Catabolic Reactions
ANABOLIC REACTIONS
Glycogen
Uses
energy
Triglycerides
Uses
energy
Glucose
+
Glucose
Glycerol
Protein
Uses
energy
+
Fatty acids
Amino acids + Amino acids
CATABOLIC REACTIONS
Glycogen
Glucose
Yields
energy
Triglycerides
Glycerol
Yields
energy
Protein
Fatty acids
Yields
energy
Amino acids
Yields
energy
Cellular metabolism
• The sum of all cellular endergonic and
exergonic rxns.
• Energy coupling (transfer) = use of
released energy to run cellular processes
• ATP provides coupling mechanism
ATP
• High energy bonds join negatively charged
phosphate groups
– Energy in bonds + energy of magnetic repulsion
(high PE!)
• Hydrolysis rxn frees trapped energy
ATP
• Some freed energy is lost as heat
• The rest is transferred via the phosphate
group when it binds to another molecule
(phosphorylation)
ATP fuels ALL cellular work
ATP is continually regenerated
Enzymes are also required to
drive reactions
Enzymes lower Activation Energy
• Some energy (EA) must be applied to begin a rxn
– Sometimes the energy barrier is prohibitively large
– Enzymes reduce that barrier, allowing rxn to proceed
with LESS energy input
Enzyme cycle
1. Available enzyme
w/ active site
2. Substrate binds
3. Conversion to
products
4. Products
released
Enzymes possess:
• Ideal temperature regimes
• Ideal pH ranges
• Cofactors (inorganic molecules & ions)
and coenzymes (organic molecules)
What fuels our bodies?
1.
2.
3.
4.
Adenosine triphosphate (ATP)
Creatine Phosphate (CP)
Glucose
Fats
What fuels our bodies?
• Adenosine triphosphate (ATP) – THE
energy carrying molecule in the body
• Muscles store only enough ATP for 1 –
3 seconds of activity
– ATP must be generated continuously
• Usually via carbohydrate metabolism with or
without O2
ATP structure
Alternative Fuels
• After depleting ATP stores, muscles
turn to other sources:
– Creatine phosphate (CP) stores energy that
is used to make ATP
– Creatine phosphate stores enough energy
for 3 to 15 seconds of maximal physical
effort
CP transfers P to make ATP
Glucose
• After CP, Glucose is the next source of
energy for production of ATP
• Metabolism of glucose
– Anaerobic breakdown of glucose yields 2 ATP
molecules (no O2)
– Aerobic breakdown of glucose yields 36 – 38
molecules of ATP (with O2)
Glucose metabolism
In cytoplasm
In mitochondria
Fat as fuel
• Stored triglycerides can be metabolized
to generate ATP
– For low intensity exercise
– For exercise of long duration
• Ex: 10 hr. car-to-car approach + climb
– Abundant energy source.
– Provides 2x more energy per gram as
carbohydrate
Carbs. or Fats
• Use BOTH as energy sources for
production of ATP
– Carbohydrates - high intensity activity
– Fats - low intensity exercise
• Proteins (amino acids) rarely used as a
fuel source for exercise
Distribution
• Short duration, max. int. (0-3
sec)
• Short duration, high int. (1012 sec)
• Short-Mid duration, high int.
(4-6 min)
• Mid duration, moderate int.
(32-40 min)
• Long duration, moderate int.
(2.5-3 hr)
• Extended duration, low-mod
int. (5.5-7 hr)