Tag: living organisms and energy production

According to the chemiosmotic theory of Peter Mitchell, a proton gradient created by the ETS across the membrane leads to the passive movement of protons from the intermembrane space into the matrix or the stroma, through ATP synthase present on the inner membrane. The passive energy released by the protons is used for the synthesis of ATP from ADP. If a proton gradient breaksdown there will be no synthesis of ATP and no movement of protons across the membrane.

Chromosome number in meiocyte $(2n)$ of onion cell is $32$, while chromosome number in gamete $(n)$ is $16$.

NADH and FADH$ _{2}$ transfer their electrons to molecules near the beginning of the transport chain. As electrons are passed down the chain, they move from a higher to a lower energy level, releasing energy. Some of the energy is used to pump H$^{+}$ ions, moving them out of the matrix and into the intermembrane space. The energy released in these reactions is captured as a proton gradient, which is then used to make ATP in a process called chemiosmosis. Together, the electron transport chain and chemiosmosis make up oxidative phosphorylation. 

The chemiosmotic theory explains how ATP is generated from mitochondria by electron transport chain. The chemiosmotic theory was developed by the British biochemist, Peter Mitchell, to explain the mechanism of oxidative phosphorylation in mitochondria (and photophosphorylation in chloroplasts). 

ATP is not a protein, it is a nucleotide. Proteins are made up of amino acids. While ATP is a nucleotide consisting of an adenine base attached to a ribose sugar, which is attached to three phosphate groups. 

The Hill reaction is defined as the photoreduction of an electron acceptor by the hydrogens of water, with the evolution of oxygen. In vivo, or in the organism the final electron acceptor is NADP⁺. We can measure the rate of the Hill reaction in isolated chloroplasts. first demonstrated by Robert Hill in 1939, in which illuminated chloroplasts evolve oxygen when incubated in the presence of an artificial electron acceptor (e.g. Ferricyanide). The reaction is a property of photosystem II. 

The synthesis of ATP is called phosphorylation. If it occurs in the presence of light, it is called photophosphorylation, that occurs during photosynthesis in the chloroplast. Mitochondria perform oxidative and substrate level phosphorylation.