Heterotrophs – organisms that cannot make their own food.
6.1 ENERGY
| Energy – is the ability to do work. |
| Heterotrophs – organisms that cannot make their own food. |
6.2 ATP and Energy Transfer
| ATP – adenosine triphosphate – energy storage molecule used by most organisms. |
| Three major parts of ATP – ribose, adenine, and phosphate. |
| Energy is released when ATPase (enzyme) breaks the end phosphate off the ATP molecule. |
| During photosynthesis, energy is exchanged when chemical reactions called reduction reactions add electrons to carbon dioxide molecules. |
| Oxidation
– loss of an electron from atom or ion. |
| Redox
reactions are common in living systems. |
6.3 Photosynthesis
| Photosynthesis – process by which autotrophs convert sunlight to a usable form of energy. |
| Pigment – molecule that absorbs certain wavelengths of light and reflects or transmits other. |
| Thylakoids – disk-shaped structure that contain photosynthetic pigments. |
| Stroma – thylakoids surrounded by gel-like
matrix. |
| Photosynthesis has two reactions. |
| Light-dependent reaction – converts
light energy to chemical energy. |
| Carbon-fixing reaction – uses products of light-dependent to convert carbon dioxide and
water to sugars. |
| C3 plants
– use only the Calvin cycle for photosynthesis. |
| CAM plants – fixes carbon dioxide only
at night. |
6.4 Glycolysis and Aerobic Respiration
| Glycolysis – process where glucose is converted to pyruvate and energy is released. |
| Aerobic respiration(AR)– breakdown of pyruvate in the presence of oxygen. |
| 1st step of AR – yruvate binds to a molecule of coenzyme A (CoA).p |
| 2nd step
of AR – Krebs cycle- series of oxidation reactions. |
| In every completion of Krebs cycle, a molecule of acetyl-CoA generates one molecule of ATP and frees 8 electrons. |
| Pyruvate is converted to acetyl-CoA . |
| Acetyl-CoA is converted to a
series of intermediate molecules. |
| Some energy is lost as heat. |
6.5 Anaerobic Respiration
| Anaerobic respiration – chemical reactions that release energy food molecules in the absence of oxygen. |
| Alcoholic fermentation – anaerobic respiration that converts pyruvate to carbon dioxide and ethanol. |