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Respiration. =the process by which chemical energy is released from a foodstuff by oxidation. Oxygen + glucose water + carbon dioxide + energy C6H12O6.

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Presentation on theme: "Respiration. =the process by which chemical energy is released from a foodstuff by oxidation. Oxygen + glucose water + carbon dioxide + energy C6H12O6."— Presentation transcript:

1 Respiration

2 =the process by which chemical energy is released from a foodstuff by oxidation. Oxygen + glucose water + carbon dioxide + energy C6H12O6 + 6O2 -----> 6CO2 + 6H20 + energy (heat and ATP)

3 Chemistry of Respiration

4 We can split the process of respiration into 3 distinct stages, each occurring in a specific part of the cell. Glycolysis- cytoplasm of cell Krebs cycle- central matrix of mitochondrion Cytochrome system- cristae of mitochondrion


6 Glycolysis

7 Glycolysis = glucose splitting 2 molecules of ATP are required to trigger glycolysis. 4 molecules of ATP are formed during the process, giving a net gain of 2 ATP. During glycolysis released hydrogen becomes temporarily bound to a hydrogen carrier (NAD NADH 2 ). Oxygen is not required for glycolysis.

8 Krebs cycle

9 Krebs cycle (= Citric acid or Tricarboxylic acid cycle) During this aerobic stage of respiration, citric acid is broken down to 5 and 4 carbon intermediates. At each step hydrogen is released and binds to NAD. At the first two steps carbon is released to form CO 2. The enzymes controlling carbon release are termed decarboxylases. Enzymes controlling the release of hydrogen are called dehydrogenases.

10 Cytochrome system / Hydrogen Transfer system

11 Cytochrome System During glycolysis and the Krebs cycle, there are 6 points where hydrogen is released to bind with NAD. The cytochrome system is a chain of hydrogen carriers that releases energy when hydrogen passes along it. Each hydrogen passing along the chain releases sufficient energy for the formation of 3 ATP. The complete oxidation of one glucose molecule generates 38 ATP.


13 Multiple choice test Cell variety in relation to function Absorption and secretion of materials, ATP and energy release.

14 1. Which of the following statements about a cell wall is true? AIt is living. BIt is composed mainly of cellulose. CIt is composed mainly of protein. DIt is selectively permeable. 2.Which of the following processes requires infolding of the cell membrane? ADiffusion BPhagocytosis CActive transport DOsmosis

15 3.Human red blood cells contain potassium ions at a concentration about 30 times greater than the concentration of potassium ions in the blood plasma. If red blood cells are cooled, potassium ions are lost to the surrounding plasma. If the cells are warmed again to body temperature, they regain their original concentration of potassium ions. These movements of potassium ions are explained by Outward movementInward movement ADiffusionActive transport BDiffusionOsmosis CActive transportDiffusion DOsmosisActive transport

16 4.The table below shows the concentration of three ions found in sea water and in the sap of cells of a seaweed. Which of the following statements is supported by the data in the table? APotassium and sodium ions are taken into the cells by active transport. BPotassium and chloride ions are removed from the cell by diffusion. CSodium ions are removed from the cell by active transport. DChloride and sodium ions are removed from the cell by diffusion. PotassiumSodiumChloride Sea water0.010.550.61 Cell sap0.570.040.60 Ion concentrations (mg l )

17 5.A piece of muscle was cut into three strips, X, Y and Z, and treated as described in the table. Their final lengths were then measured. Muscle strip Solution added to muscle Muscle length at start (mm) Muscle length after 10 minutes (mm) X1% glucose50 Y1% ATP5045 Z1% ATP boiled & cooled 5046 From the data it may be deduced that AATP is not an enzyme Bmuscles contain many mitochondria Cmuscles synthesise ATP in the absence of glucose Dmuscles do not use glucose as a source of energy

18 6.When a red blood cell is immersed in a hypertonic solution it will Ashrink Bbecome flaccid Cburst Dbecome turgid 7.Which of the following is a structural carbohydrate? AGlucose BStarch CGlycogen DCellulose

19 8.Which two substances are found to occur in cell membranes? ACellulose and protein BProtein and phospholipid CPhospholipid and carbohydrate DProtein and carbohydrate 9.Which of the following statements is false? APhagocytosis and pinocytosis are examples of exocytosis BEndocytosis involves the cell membrane folding inwards to form a pouch CA cell may aquire hormones by pinocytosis DMolecules of carbon dioxide move out of a respiring cell by diffusion

20 10.What compound is represented by the letters ATP? AAdenine triphosphate BAdenine trinucleotide phosphate CAdenosine tricarboxylic phosphate DAdenosine triphosphate

21 Chemistry of Respiration


23 Anaerobic respiration In the absence of oxygen the Krebs cycle and the cytochrome system are unable to occur. In this process, little energy is released from the partial breakdown of sugar. An alternative metabolic pathway takes place in the cells cytoplasm. This pathway varies depending on the type of organism involved.


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