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ENERGY AND
RESPIRATION
12a Bilegdemberel.M
Mitochondrial structure and
function




Mitochondria are rod-shaped or filamentous
organelles about 0.5-1.0 mm in diame...
Mitochondrion structure
Mitochondrion structure




Mitochondrion is surrounded by an envelope
of two phospholipid membranes. The outer
membrane...
Mitochondrion structure and
function


The inner membrane is more complex in structure
than the outer membrane as it cont...
Mitochondrion structure and
function






The matrix of the mitochondrion is the site of
the lonk reaction and Krebs c...
Anaerobic respiration


If oxygen is unavailable the Krebs cycle and
electron transfer chain cannot operate. This
is beca...
Anaerobic respiration




1). In yeast, pyruvate is decarboxylated to
produce ethenal. Ethenal then accepts the
hydrogen...
Respiratory Substrates.


Although glucose is the essential respiratory
substrate for some cells, such as neurones in
the...
Respiratory substrate
Respiratory substrate

Energy density (kJ/g)

Carbohydrate

15.8

Lipid

39.4

Protein

17.0

The gr...
Respiratory quotient


The respiratory quotient (RQ) is defined as the
ratio of carbon dioxide produced to oxygen
consume...


Thank you !
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Energy and respiration

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Energy and respiration

  1. 1. ENERGY AND RESPIRATION 12a Bilegdemberel.M
  2. 2. Mitochondrial structure and function   Mitochondria are rod-shaped or filamentous organelles about 0.5-1.0 mm in diameter. Number of mitochondria in a cell depends on its activity. Mammalian liver cells contain between 1000 and 2000 mitochondria, occupying 20% of the cell volume.
  3. 3. Mitochondrion structure
  4. 4. Mitochondrion structure   Mitochondrion is surrounded by an envelope of two phospholipid membranes. The outer membrane is smooth, but the inner is much folded inwards to form cristae. These give the inner membrane a large total surface area The two membranes have different composition and properties. The outer membrane is relatively permeable to small molecules, whilst the inner membrane is less permeable.
  5. 5. Mitochondrion structure and function  The inner membrane is more complex in structure than the outer membrane as it contains the complexes of the electron transport chain and the ATP synthetase complex. It is permeable only to oxygen, carbon dioxide and water. It is made up of a large number of proteins that play an important role in producing ATP, and also helps in regulating transfer of metabolites across the membrane. The inner membrane has infoldings called the cristae that increase the surface area for the complexes and proteins that aid in the production of ATP, the energy rich molecules.
  6. 6. Mitochondrion structure and function    The matrix of the mitochondrion is the site of the lonk reaction and Krebs cycle, and contains the enzymes needed for reactions. It also contains ribosomes and several identical copies of looped mitochondrial DNA. ATP is formed in the matrix by the activity of ATP synthase on the cristae. The energy for the production of ATP comes from the hydrogen ion gradient between the intermembrane space and the matrix.
  7. 7. Anaerobic respiration  If oxygen is unavailable the Krebs cycle and electron transfer chain cannot operate. This is because without oxygen there would be no way of disposing of the hydrogen at, for example, the end of the electron transfer chain. However, even in anaerobic conditions, glycolysis occurs so reduced NAD still forms. If glycolysis is to continue, the reduced NAD must be reoxidized, that is, the hydrogen must be removed and disposed of. Anaerobic organisms have developed two ways of doing this.
  8. 8. Anaerobic respiration   1). In yeast, pyruvate is decarboxylated to produce ethenal. Ethenal then accepts the hydrogen from NAD and forms ethanol. This releases the NAD to be reused in glycolysis. The conversion of pyruvic acid to ethanol with the release of carbon dioxide is called alcoholic fermentation. 2). In mammals, the pyruvate accepts the hydrogen from NAD and is reduced to lactate. The NAD is then available for further use in glycolysis. If oxygen later becomes available, the lactate is reoxidised.
  9. 9. Respiratory Substrates.  Although glucose is the essential respiratory substrate for some cells, such as neurones in the brain, red blood cells and lymphocytes, other cells can oxidise lipids and amino acids. When lipids are respired, carbon atoms are removed in pairs, as acetyl CoA, from the fatty acid chains and fed into the Krebs cycle. The carbon-hydrogen skeletons of amino acids are converted into pyruvate or into acetyl CoA.
  10. 10. Respiratory substrate Respiratory substrate Energy density (kJ/g) Carbohydrate 15.8 Lipid 39.4 Protein 17.0 The greater the number of hydrogens in the structure of the substrate molecule, the greater the energy value. The energy value of a substrate is determined by burning a known mass of the substance in oxygen in a calorimeter.
  11. 11. Respiratory quotient  The respiratory quotient (RQ) is defined as the ratio of carbon dioxide produced to oxygen consumed per unit time by an organism. Oxygen uptake during respiration can be measured using a respirometer.
  12. 12.  Thank you !

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