week 3 Flashcards
define a redox reaction
any chemical reaction where electrons are transferred
- e- donor gets oxidized
- e- acceptor gets reduced
what does the electron donor do
it gets oxidized
it does the reducing
it is the reducing agent
what does the electron acceptor do
it does the oxidizing
it is the oxidizing agent
it gets reduced
what are the 8 key events in glycolysis
- oxidation of glucose to pyruvate
- generation of glycolytic intermediates
- investment of ATP
- ATP resynthesis
- production of H+
- conversion of NAD+ to NADH (reduction)
- conversion of NADH to NAD+ (oxidation)
- conversion of pyruvate to lactate (reduction)
what is NAD+ replenished by
aerobic respiration
when is lactate produced
lactate is produced during high intensity exercise
what is exercise-induced acidosis caused by
H+ production during conversion of glucose to pyruvate
where does lactate go?
it accumulates in the blood according to the amount of
- production in the cytoplasm
- efflux into the blood
- clearance (elimination) by various mechanisms
- w/ no shuttle
- stays in cytoplasm where it was produced
- converted to glycogen - aka stored as future fuel - w/ intracellular lactate shuttle
- stays within the same cell
- travels from cytoplasm to mitochondria for oxidation to pyruvate
- La- becomes a fuel substrate
- pyruvate and NADH can enter aerobic respiration the same as if they came “direct” from glucose - w/ extracellular lactate shuttles
- moved to various other places via blood
- oxidized to pyruvate (used as fuel)- in other muscle cells
- in the heart
- converted to glucose (liver, future fuel)
- converted to amino acids (muscle cells, future fuel/building blocks)
- excreted in sweat (very small proportion of what is produced, waste)
why is lactate a good thing
- its production allows for faster rates of glycolysis / ATP resynthesis
- it has nothing to do w/ acidosis
- accumulation isn’t rly a problem because it can be so readily moved around and eliminated in various ways
- it is a useful fuel source
why is acidosis a bad thing
in muscle, acidosis leads to:
- decreased activity of PFK and glycogen phosphorylase (slows glycolysis)
- decreased activity of various ATPases (enzymes that cleave ATP in order to release energy needed for biological work)
- Na2+/K+ ATPase -> decreased membrane transport
- SR ATPase -> decreased Ca2+ regulation -> decreased contraction
- myosin ATPase -> decreased contraction
- inhibits Ca2+ binding at troponin
- decreased contraction
- pain
what is the resting pH of blood
7.40 - tightly regulated within 7.35-7.45
what blood pH is considered systemic acidosis and what are some reactions to this
systemic acidosis = blood pH < 7.35
- reduced blood flow to the brain - lightheadedness/fainting
- nausea/vomiting - attempt to rapidly dump acid from the body
what is the chemical equation for the bicarbonate buffering system
HCO3- + H+ —> H2CO3 —> CO2 + H2O
HCO3-: bicarbonate
H2CO3: carbonic acid
enzyme that converts carbonic acid to CO2 and H2O is carbonic anhydrase
which system requires oxygen and which does not
aerobic glycolysis: sufficient oxygen
anaerobic glycolysis: insufficient oxygen or when we need ATP fast
name and briefly describe the 4 stages of aerobic metabolism
stage 1: glycolysis
- convert glucose -> pyruvate
- make ATP (substrate-level phosphorylation), NADH, and H+
stage 2: prep phase
- convert pyruvate -> acetyl Co-A
- make NADH, H+, and CO2
stage 3: citric acid cycle
- make ATP (substrate-level phosphorylation), CO2, NADH, FADH2, and H+
stage 4: electron transport chain
- e- delivered to / transported along ETC
- convert O2 to H2O
- create proton gradient
- make ATP (oxidative phosphorylation)
