Lesson 1 Flashcards
Bioenergetics
flow and exchange of energy in a system
What are the types of biological work in the body?
mechanical; muscle action
chemical; molecule synthesis
transport; active concentration, active movement across membrane of substances
define metabolism
the chemical processes and reactions that result in breakdown of molecules (catabolic) or synthesis of molecules (anabolic)
which processes use and produce ATP?
catabolic produce
anabolic use
Explain ATP
- PE in this molecule powers all of a cells energy requiring processes
- contains 2 high-energy phosphate bonds that easily transfer energy when hydrolyzed
- cells contain only small amounts of ATP so various metabolic processes must maintain a steady supply of ATP so living cells can grow, reproduce, and respond to stress caused by exercise, starvtion and injury
- ATP often restored by transferring energy from food to ADP and P to form ATP
what is an oxidation reaction ?
electron removed from atom or molecule
what is a reduction reaction?
electron added to atom or molecule
Give some important examples of oxidation and reduction
- in metabolic reactions, electron transfer often involves H
- 2 important electron carriers are NAD+ and FADH
Explain NAD+
nicotinamide adenine dinucleotide
- derived from the vitamin niacin (Vit B3)
- NAD+= oxidized form, NADH + H+= reduced form
Explain FADH
flavin adenine dinucleotide
- derived from vit riboflavin (Vit B2)
- FAD= oxidized form, FADH= reduced form
Define hydrolysis
breakdown of a molecule through the addition of the components of H20
Define condensation
synthesis of a molecule resulitng in additional production of H20, sometimes called dehydration synthesis
Give an important example of hydrolysis
ATP releases energy to be used in biological work when hydrolyzed
- ATP + H20= ADP+ P+ energy
- under control of ATPase
What are the 3 primary pathways that cells resynthesize ATP?
- PCr system
- Substrate level phosphorylation
- oxidative phosphorylation
PCr system
PCr+ ADP= ATP + Cr
- controlled by creatine kinase
- occurs very rapidly, limited supply of PCr in muscle
- resynthesis requries ATP and only occurs @ rest
- short term, high intensity (5-10 sec)
Substrate level phos.
- free phosphate transferred directly from intermediate molecule in metabolic pathways
- occurs during glycolysis
- fast, but not as fast as PCr
Oxidative phos.
- occurs in mitochondria
- substrate oxidized, NAD+ and FAD reduced
- energy used to drive ETC
- slowest, but high supply
- provides majority of ATP for sustained exercise
Define glycogen
polysaccaride composed of hundreds of thousands of glucose molecules. stored in liver and skeletal muscle
define glycogensis
synthesis of glycogen
define glycogenolysis
breakdown of glycogen to yield glucose
define glycolysis
breakdown of glucose to pyruvate. produces ATP
- splits glucose (6 carbon chain) into 2 molecules pyruvic acid (3 carbon chain)
- transfers energy from chemical bonds in glucose to join Pi and ADP to produce ATP
- ANAEROBIC
explain the stages of glycolysis
Energy investment stage:
-2 stored ATP used (convereted to ADP + Pi) to rearrange and phosphorylate (add Pi to) plasma glucose to form which is then split into two molecules
Energy generation stage:
- 2 molecules oxidized (H removed) and phosphorylated, and NAD+ reduced to NADH
- 2 NADH produced, NAD+ must be available for this to happen
- 2 phosphates on each molecule are used to generate ATP as the moleucle is convered to pyruvate, via substrate level phosphyration
- 4 ATP produced
Where does aerobic metabolism occur?
mitochondria
which two pathways are involved in aerobic metabolism?
ETC
Citric acid cycle (krebs)
Explain the Citric Acid Cycle
- requires Acetyl-coA
- pyruvate irreversilby oxidized to acetyl-coA in mitochondria
- produces 1NADH and 1 CO2
- Acetyl-coA enters cycle and combines w oxaloacetic acid, where it undergoes several oxidative reactions, which ultimately regenerate oxaloacetic acid to reinitiate the cycle w more Acetyl-coA
- For each molecule of acetyl-coA that enters the cycle, the following are produced: 3 NADH, 1 FADH2, 1 ATP, 2 CO2
Explain the ETC (oxidative phosphorlyation)
- occurs in mitochondiral membrane, via 3 protein pumps on membrane
- requires NADH/FADH and oxygen
- 1st pump: NADH oxidized to NAD+, H+ pumped from mitochondiral matrix to intermembrane space….electron obtained from oxidation of NADH passed within membrane, activating 2nd and 3rd pumps, moving additional H from matrix to intermembrane space
- FADH initiates the chain at 2nd pump…more H moved through the oxidation of NADH and FADH
- NONE OF THE PUMPS WILL OPERATE IF OXYGEN NOT PRESENT TO ACCEPT ELECTRON AT 3RD PUMP
- oxygen combines with H to form H20
- process creates large concentration of H in the intermembrane space relative to matrix, large H+ gradient
- H wants to move down gradient but can only move through specific protein channels
-H re-renters matrix by traveling through the protein channel ATP synthase, ATP synthase uses energy of H movement fo syntehsis ATP
Explain ATP production for ETC
each molecule NADH oxidized= 2.5 ATP produced
each molecule FADH oxidized= 1.5 ATP produced
Define chemiosmotic hypothesis
process of ETC creating an H+ gradient to drive ATP production
What is the ATP Tally for 1 molecule of glucose and other fuel sources TOTAL?
32 ATP per 1 molecule glucose
What are alternative fuel sources for aerobic metabolism?
- Fatty acids= can be converted to acetyl-coA via beta oxidation
- amino acids= only provide 2-15% energy during exercise, diff amino acids can be converted to glucose, pyruvate, acetyl-CoA and enter metabolism pathways at various points
What are the only fuel sources for anerobic metabolism?
PCr and glucose
When is lactate produced?
-some always produced by body, even during rest, used quickly as fuel
- begins to accumulate during periods of increased reliance on anerobic metabolism
- allows exercise to continiue in prescence of not enough oxygen, or when aerobic metabolism does not produce ATP fast enough for the current exercise (high intensity)
How and why is lactate produced?
If the aerobic metabolism is functioning slower than the current energy demand requires….
- there is an acculumation of pyruvate
- depletion of NAD+ avail for glycolysis
- occurences limit rate of glycolysis
- pyruvate convered to lactate via oxidation of NADH
- allows glycolysis to continue at a high rate, reducing excess pyruvate and replenishing NAD+
What happens to lactate?
- lactate= valuable source of chem energy
- lactate shuttle= diffuses into adjacent fibers where it is converted back to pyruvate and used as fuel
diffusion into bloodstream:
used as fuel in inactive muscles and the heart
cori cycle; used by liver to synthesis glucose (gluconeogensis)
Explain lactate and acidosis
though a complete understanding of lactate is unclear, it appears that an acculumation of lactate contributes to an overall lowering of pH during high intensity exercise
