Yield of ATP in Glycolysis and Aerobic Respiration:

 

ATP Yield in Eucaryotes from Glycolysis, TCA cycle, and

electron transport:

 

Glycolytic Pathway:

SLP (ATP) 2 ATPs

OPL with 2 NADH 6 ATPs

 

2 pyruvates to 2 Acetyl CO-A

OP with 2 NADH 6 ATPs

 

TCA Cycle

SLP (GTP) 2 ATPs

OP with 6 NADH 18 ATPs

OP with 2 FADH2 4 ATPs

 

Total Aerobic Yield 38 ATPs

 

Aerobic Oxidation of glucose to 6 CO2 38 ATPS

 

Anaerobic Respiration:

      Energy yielding process where the final electron acceptor is different than oxygen:

      The major acceptors are nitrate, sulfate, and CO2 (NO3-, SO4-, CO2)

      Bacteria can nitrate to nitrite to produce ATP, but it is not the most effective way to produce ATP.

      Because Nitrite is toxic, Nitrate is usually reduced to Nitrogen gas, denitrification.

      Anaerobic respiration does not yield as much ATp as aerobic respiration because less energy is available.

      Yet Anaerobic Respiration is useful bc it is more efficient than fermentation and allows ATP synthesis by ET and OP in the absence of oxygen.

      Find Anaerobic Respiration in oxygen depleted soils and sediments.

 

Anaerobic Respiration

       respiration in which a terminal electron acceptor other than O2 is used,

       less energy than aerobic respiration, but allows organisms to live in environments lacking O2.

 

Photosynthesis

       Light energy is trapped and converted to chemical energy.

       Photosynthetic pathways use light, rather than chemical compounds as a source of energy, move it through Photosystems I and II to synthesize ATP and NADH or NADPH.

       One of the most significant metabolic pathways on earth bc all our energy is ultimately derived from solar energy.

       Provides photosynthetic organisms with ATP and NADPH to synthesize organic cmpd needed for growth.

       Replenishing O2 supply

       Carried out by both Pro and Euc

 

 


TWO parts to Photosynthesis:

1. Light Reactions: light is trapped and converted to

chemical energy.

2. Dark Reactions: Energy made during the light reaction is

used here to reduce or fix CO2 and synthesize cell constituents.

Chlorophyll

 

       Photosynthetic organisms use chlorophyll to trap sunlight and extract the energy to drive ATP synthesis.

 

       Chlorophyll has a chemical structure that is similar to heme, but it contains a magnesium ion instead of iron

 

       Light energy is channeled to a chlorophyll molecule contained within a pigment complex called a reaction center.

 

       Light hits the reaction center, and excites electrons

 

       The excited electron is then passed to a series of electron carriers, each one removing some of the energy, until the electron returns to its ground state where it is passed back to the reaction center complex.

 

       The energy derived from the excited electrons by the electron carrier molecules is used to synthesize ATP.

 

       This process of light driven ATP synthesis is called cyclic phosphorylation because electrons in a cyclic pathway and ATP is formed.

 

       Involving the activity of Photosystem I alone

 

 

Non cyclic phosphorylation:

 

       In order to reduce CO2 into more complex compounds, the cells require H atoms (or protons) and the reaction center complex does not have the strength required to strip H away from HOH

 

       Therefore the Photoautotroph increases the energy by coupling a second reaction center to the first one.

 

       Electrons are stripped from HOH and passed to RCII

which is in turn stimulated to an excited state, and passed to RCI

       Which is stimulated, as the electron is passed through the carrier systems, they are passed to NADP+ to generate NADPH + H+ which in turn is used to reduce CO2

 

       This light driven reduction of NADP+ to NADPH + H+ is called non cyclic phosphorylation

 

       Involves both photosystem I & II

 

        

Photosystems

       In higher plants and algae, reaction centers I and II are found in the chloroplast membranes,

       If the cyanobacteria, they are found in the cell membrane

 

       The purple and green photosynthetic bacteria do not have reaction center II complexes, only RCI

       Therefore they are incapable of using water as an electron donor and must use other compounds, such as H2S