Topic 2.8 - Cell respiration Flashcards
What is cell respiration ?
Cell respiration is the controlled release of energy
from organic compounds to produce ATP
What are the main organic compounds used ?
The main organic compounds used are carbohydrates
(i.e. glucose), but lipids or proteins may also be used.
Why do different organic compounds have varied ATP yields ?
Different organic compounds will have distinct
breakdown pathways and so have varied ATP yields
What is ATP ?
ATP (adenosine triphosphate) is a molecule that functions as an immediate source of energy when hydrolysed (to form ADP)
What is glycolysis ?
The break down of glucose (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)
How many pathways can pyruvate follow ?
Two pathways, aerobic and anaerobic respiration.
What is 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)
What is aerobic 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
What is fermentation ?
Fermentation is a reversible anaerobic process that allows ATP production to continue in the absence of oxygen
Why are NAD stocks important ?
To ensure a continued production of ATP
What does fermentation result in in animals ?
Fermentation in animals produces lactic acid, and is used to maximise muscle contractions when oxygen is limited
* This reaction can be reversed when oxygen is restored
What does fermentation result in in plants ?
Fermentation in plants and yeast produce ethanol and
CO2 gas which can be used in baking (leavening dough)
* Also for the production of alcohol, yogurts and cheese
What is a respirometer and why is it used ?
A respirometer determines an organism’s respiration rate by measuring either carbon dioxide production or oxygen uptake
* Commonly used for invertebrates or germinating seeds
