Cell respiration topic 2.8 Flashcards
Cell Respiration
Cell respiration is the controlled release of energy
from organic compounds to produce ATP
The main organic compounds used are
carbohydrates (i.e. glucose), but lipids or proteins may also be used
ATP
ATP (adenosine triphosphate) is a molecule that functions as an
immediate source of energy when hydrolysed (to form ADP)
Glycolysis
Cell respiration begins with the break down of glucose
via a process called glycolysis (occurs in the cytosol)
- Glucose is broken down into pyruvate (×2)
- There is a small ATP yield (net gain = 2 ATP)
- Requires the reduction of NAD+ (to form NADH)
Anaerobic Respiration
Occurs in the cytosol and does not require oxygen
* Results in a small energy yield (2 ATP from glycolysis)
* Forms lactic acid (animals) or ethanol and CO2 (plants / yeast)
* Also known as fermentation and is reversible
Aerobic Respiration
- Occurs in the mitochondria and requires oxygen
- Results in a large energy yield (~36 ATP per glucose)
- Forms carbon dioxide and water
- Uses hydrogen carriers to make ATP (oxidative phosphorylation)
Fermentation
Fermentation is a reversible anaerobic process that allows
ATP production to continue in the absence of oxygen
Fermentation in animals produces?
lactic acid, and is used
to maximize muscle contractions when oxygen is limited
* This reaction can be reversed when oxygen is restored
Fermentation in plants and yeast produces
ethanol and CO2 gas which can be used in baking (leavening dough)
* Also for the production of alcohol, yogurts and cheese
Respirometry
A respirometer determines an organism’s respiration rate by
measuring either carbon dioxide production or oxygen uptake
* Commonly used for invertebrates or germinating seeds
A simple respirometer may involve
The use of a manometer:
* An organism is sealed in a container with a CO2 absorbent
* Oxygen uptake creates a pressure change which displaces
the fluid in the manometer (allowing for quantitation)
