Tag: chemiosmotic hypothesis

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Questions Related to chemiosmotic hypothesis

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP synthetase of chloroplasts is similar to that of

  1. Mitochondria

  2. Peroxisomes

  3. Golgi bodies

  4. Microsomes.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mitochondria and chloroplast both have:

  • A double membrane surrounding the organelles.
  • Purportedly prokaryotic origins according to the endosymbiotic theory which suggests that mitochondria and chloroplast were once prokaryotic bacteria engulfed by endocytosis in early eukaryotes.
  • Their own circular DNA which codes for certain enzymes required for the chemical reactions that take place in these organelles.
  • Their own 70S ribosomes made up of 50S and 30S subunits to translate proteins
  • The enzyme ATP synthase which utilizes the energy released from the movement of protons across it (proton-motive force) to phosphorylate ADP to ATP. (Thus, another similarity would be that they both produce ATP)
  • Electron transport chains, which are embedded in the inner mitochondrial membrane and thylakoid membrane in mitochondria and chloroplasts respectively.
So, the correct option is 'Mitochondria'.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP formation in chloroplast and mitochondrion is explained by

  1. Cholodny-Went model

  2. Chemi-osmotic theory of Mitchell

  3. Munch's mass flow theory

  4. Relay pump theory of Godlewski
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A theory postulated by the biochemist Peter Mitchell in 1961 to describe ATP synthesis by way of a proton electrochemical coupling.
it is based on the proton gradient and transfer of an electron from the mitochondrial matrix in respiration or in the stroma with the photophosphorylation of photosystems forms ATP.
So the correct option is 'Chemi-osmotic theory of Mitchell'.
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Chemiosmosis was first described by

  1. Boyer

  2. Walker

  3. Mitchell

  4. Meischer
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The chemiosmotic hypothesis of ATP synthesis in chloroplasts is based on proton gradient. The chemiosmotic hypothesis was explained by P. Mitchell in 1961. He recieved noble prize for it in 1978. ATP synthesis is linked to the development of a proton gradient across the membrane of the thylakoid of chloroplast and proton accumulation is towards the inside of the membrane i.e. in the lumen. 

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

When cell converts light energy into chemical energy, which of the following reaction would take place?

  1. ADP + iP = ATP

  2. ATP - iP = ADP

  3. AMP + iP = ADP

  4. GDP + iP = GTP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cells convert light energy is converted into chemical energy. During this process, a phosphate is added to adenosine diphosphate molecule to cause the formation of ATP.

So the correct option is 'ADP + iP = ATP'.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Oxidative phosphorylation refers to

  1. Anaerobic production of ATP

  2. The citric acid cycle production of ATP

  3. Production of ATP by chemiosmosis

  4. Alcoholic fermentation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxidative phosphorylation is the process where ATP is formed as a result of the transfer of electrons from NADH or FADH2 to O2 by a series of electron carriers, coupled with chemiosmosis.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP synthesis in cell requires

  1. $H^+$ gradient across the membrane
  2. $K^+$ gradient across the membrane
  3. $PO^{3-} _4$ gradient across the membrane
  4. $Ca^{2+}$ gradient across the membrane
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
A) A ${ H }^{ + }$ gradient or proton pump is developed in the lumen of the thylakoid which helps in ATP synthesis.
B) ${ K }^{ + }$ does not play a role in ATP synthesis.
C) ${ PO } _{ 4 }^{ 3- }$ does not play a role in ATP synthesis.
D) ${ Ca }^{ 2+ }$ is involved in the photolysis of water.
So the correct answer is '${ H }^{ + }$ gradient across the membrane'.
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

The chemiosmotic coupling hypothesis of oxidative phospohorylation proposes that adenosine triphosphate is formed because

  1. A Proton gradient forms across the inner membrane

  2. There is a change in the permeability of the inner mitochondria membrane toward adenosine diphosphate

  3. High energy bonds are formed in mitochondrial proteins

  4. ADP is pumped out of the matrix into the intermembrane space
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The chemiosmotic hypothesis states that the energy stored in a proton gradient across the inner mitochondrial membrane drives the synthesis of ATP by ATP synthase.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Chemiosmotic mechanism of ATP synthesis was proposed by 

  1. Warburg

  2. Dickens

  3. Krebs

  4. P. Mitchell
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis. Peter D. Mitchell proposed the chemisomotic hypothesis in 1961. The theory suggests essentially that most ATP synthesis in respiring cells  comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy of $NADH _2$ and $FADH _2$ formed from the breaking down of energy-rich molecules such as glucose.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Chemiosmotic theory of ATP synthesis in the chloroplasts and mitochondria is based on

  1. Membrane potential

  2. Accumulation of K ions

  3. Proton gradient

  4. Accumulation of Na ions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The chemiosmotic theory, proposed by Peter Mitchell, explains that ATP synthesis in both chloroplasts and mitochondria is driven by the electrochemical gradient of protons across the membrane.