2.8 Cellular Respiration

• series of metabolic reactions that convert biochemical energy from organic molecules into adenosine triphosphate (ATP), and then release waste products

• carbohydrate glucose • lipids and proteins can also be used if glucose is not readily available to the cell

ATP can be used throughout the cell to: - power active transport - synthesize polymers - move structures within the cell

• energy is released when a phosphate group is removed from ATP in a hydrolysis reaction • reverse reaction (what happens in cellular respiration) regenerates ATP and requires energy input

• ATP can not be stored for later use • ATP can not be transferred from cell to cell • Heat energy is released when ATP is used in cells. This heat energy can not be reused and will be lost to the environment

type of cellular respiration that does not use oxygen

1) when cellular oxygen is depleted since it anaerobic respiration can act as a backup e.g. when muscle cells use up oxygen faster than it can be replenished, the cells start to perform anaerobic respiration in order to keep muscles moving 2) when ATP is needed quickly since anaerobic respiration is more rapid than aerobic respiration 3) Anaerobic metabolism allows microbes to inhabit low-oxygen or oxygen-free environments which allows them to exploit an otherwise empty habitat

• both start with glycolysis where glucose is broken down into pyruvate and NADH and ATP are created • NADH is recycled into NAD+ • both reactions net 2 molecules of ATP [difference] - yeast: alcohol fermentation, pyruvate is converted to ethanol, CO2 is released - humans: lactic acid fermentation, pyruvate is converted into lactic acid

• anaerobic respiration: produces a net of 2 ATPs per molecule of glucose • aerobic respiration: produces up to 38 ATPs per molecule of glucose

• mitochondria

bubbles of carbon dioxide gas, one of the products of anaerobic respiration, expand the dough and help the bread rise

ethanol is one of the products of anaerobic respiration.

• when exercising at high intensity, cell demand will exceed available supplies of O2 -> Muscle cells will start breaking down glucose anaerobically to supply ATP rapidly for a short period of time • Red blood cells do not have mitochondria, so anaerobic respiration always happens

• in lactic acid fermentation, NADH produced in glycolysis transfers its electrons directly to pyruvate, generating lactate as a byproduct

• living specimen is enclosed in a sealed container • oxygen use or carbon dioxide production can be measured directly with a data logger • alternatively, changes in pressure can be measured. the change in pressure can be measured with a data logger or U-tube manometer

1) purpose of the experiment must have some benefit 2) overall use of animals should be minimized. Alternative methods should be used if available 3) Pain and distress must be minimized

1) purpose of the experiment must have some benefit 2) overall use of animals should be minimized. Alternative methods should be used if available 3) Pain and distress must be minimized