effect of time on

-ATP-PC system

-glycolysis

-aerobic metabolism

glycolysis energy investment phase

(5 steps, need whiteboard)

first step is to phosphorylate the glucose molecule

[image]

formation of lactate allows aerobic glycolysis to continue

net ATP = 2

sufficient availability of NAD is required for anaerobic glycolysis to continue

[image]

continuation of glycolysis and NAD:

how is NAD reformed from reduced NADH in 2 ways?

1.) when sufficient O₂ is available NADH is shuttled into mitochondria where O₂ accepts the hydrogens at the end of the ETC forming H₂O

2.) if NADH production exceeds ability to be used in ETC, hydrogens can be accepted by pyruvic acid to form lactic acid

*why contiune anaerobic glycolysis?*

the rate of ATP production is 100x faster than aerobic mitochondrial ATP production

1.)generation of acetyl-CoA

2.)oxidation of acetyl-CoA in Krebs cycle

3.)oxidative phosphorylation in the ETC

[image]

Krebs cycle

(citric acid cycle)

-occurs within the mitochondria

-completes the oxidation of substrates and produces NADH and FADH to enter the ETC

-forms small amount of ATP (from GTP via substrate level phosphorylation)

-1 cycle yields: 1 ATP, 3 NADH, 1 FADH

ETC

(electron transport chain)

-oxidative phosphorylation

-e^- removed from NADH and FADH are passed along a series of carriers to produce ATP

-H⁺ from NADH and FADH are accepted by O₂ to form water

the process in which ATP is formed as a result of the transfer of e^- from NADH or FADH₂ to O₂ by a series of e^- carriers in the ETC

occurs in mitochondria

chemiosmosis is the movement of ions across a selectively-permeable membrane, down their electrochemical gradient

the movement of H⁺ across a mitochondrial membrane

Peter D. Mitchell

mechanisms of the chemiosmotic hypothesis of ATP formation

part 1

-the energy in NADH and FADH₂ is used in the ETC to form ATP

-the e^- from the hydrogens transported by NADH and FADH₂ to mitochondria are passed along the ETC by cytochromes

-as the e^- move along the ETC energy is released

-some energy is used to pump H⁺ ions across inner mitochondrial membrane into the intermembrane space

-H⁺ can only pass through special channels (ATP synthase) in the inner membrane

-results in INC [H⁺] within intermembrane space which creates an electrical gradient across the inner membrane, a form of PE

-H⁺ ions can only move through the inner membrane through special channels (ATP synthase). The movement of H⁺ through these channels activates ATP synthase

-as H⁺ pass through ATP synthase channels some of the PE can be captured to drive the r(x) to form ATP from ADP + Pi (oxidative phosphorylation)

-ATP synthase catalzes oxidative phosphorylation, thus converting PE into chemical energy in the form of ATP

theoretical yield: 38 ATPs

actual yield: 32 ATPs

-difference due to cost of transport of ATP across mitochondrial membrane into the cytoplasm

-actual costs calculated into tally by reducing the ATP yield from each NADH to 2.5 and from each FADH to 1.5

summary of aerobic metabolism

(need whiteboard)

1.) choose 1: glucose or glycogen (w/in cytoplasm)

glucose + 2 ADP + 2 PO₄ --> 2 pyruvate + 2 ATP + 2 NADH

glycogen + 2 ADP + 2 PO₄ --> 2 pyruvate + 3 ATP + 2 NADH

2.) inside mitochondria

2 pyruvate + 2 CoA -->  2 acetyl-CoA + 2 NADH             (2 cycles of Krebs)

3.) total ATP

An. glycolysis      2 ATP (3 ATP)

Krebs cycle         2 ATP

10 NADH            25 ATP  [10 x 2.5]

2 FADH₂             3 ATP  [2 x 1.5]

TOTAL              32 ATP (33 ATP)

[image]

overall efficiency of aerobic respiration is about 34%

about 66% of energy released as heat

-located in mitochondrial matrix

-degrades Fatty acyl-CoA to Acetyl-CoA's

-produces high-energy intermediates (NADH and FAHD₂) for ATP production in ETC

-does NOT produce ATP

1.) formation of fatty acyl-CoA molecule from fatty acid in the cytoplasm

2.) transport of fatty acyl-CoA to inside of mitochondria

3.) degradation of the fatty acyl-CoA via beta oxidation

4.) each cycle of beta oxidation yields 1 acetyl-CoA, 1 NADH, 1 FADH₂

beta oxidation ctnd. 

(need whiteboard)

-a reduced state of mitochondrial cofactors (NADH and FADH) will inhibit the dehydrogenases

-oxidized cofactors (NAD^- and  FAD) and low levels of acetyl-CoA will stimulate beta oxidation

-production of fatty acyl-CoA requires E_A = to 2 ATPs and occurs in cytoplasm

calculate ATP production from palmitic acid (16-C)

(need whiteboard)

[image]

[image]

• acetyl-CoA = # carbons/2 =  #cycles
• NADH = # cycles -1
• FADH = # cycles -1

-rate limiting enzymes

-an enzyme that regulates rate of a metabolic pathway

-levels of ATP and ADP+Pi

-high levels of ATP inhibit ATP production

-low levels of ATP and high levels of ADP and Pi stimulate ATP production

-calcium may stimulate aerobi ATP production