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25 Cards in this Set
- Front
- Back
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Metabolism
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-All chemical reactions in organisms
-conversion of organic substances -employs enzymes (biocatalysts) |
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Energy
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-equivalent to work
-measured in Joules -includes heat, mechanical work, electricity, light -interchangeable |
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1st Law of Thermodynamics
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The total amount of energy is stable.
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2nd Law of Thermodynamics
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Orderliness spontaneously decreases (and entropy increases).
Highly ordered organisms have low entropy. |
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3rd Law of Thermodynamics
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Organisms need to invest energy to maintain high levels of order
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4th Law of Thermodynamics
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Organic compounds are energy rich, they store energy
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5th Law of Thermodynamics
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Autotrophs convert light into chemical energy. Heterotrophs take up organic compounds.
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Catabolism
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Energy stored in organic compounds can be retrieved by breaking them down into low energy compounds
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Oxidation
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Fire is oxidation.
Glucose+Oxygen -> Carbon Dioxide and Water Biological Oxidation: Respiration. Energy is saved as ATP (Adenosine Triphosphate) |
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Anabolism
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The synthesis of high energy organic compounds. These reactions require energy.
Example: synthesis of sugars from carbon dioxide and water during Photosynthesis |
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Carbohydrates
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-high energy organic compounds
-often ratio C H2 O -initially formed in photosynthesis -Sugars: mono- and disaccharides -polysaccharides |
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Lipids and Fats
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-high energy organic compounds
-chemically diverse -hydrophobic -triglycerides -phospholipids -steroids |
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Triglycerides
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3 fatty acid molecules attached to a glycerol
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Phospholipids
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2 fatty acid molecules attached to a glycerol plus a phosphate group
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Steroids
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-Interlocked molecule rings
-cholesterol, a component of biomembranes -testosterone, produced in testes and ovaries -estrogen |
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Respiration
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-biological oxidation
-controlled by enzymes -catabolic process -energy is harvested as ATP |
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ATP - Adenosine Triphosphate
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-Assembled by energy-yielding metabolic pathways
-"Used" to drive energy-consuming pathways -a nucleotide |
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Other nucleotide-based Compounds shuttle hydrogen
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-hydrogen atoms are shuttled from one place to another and from one compound to another
-change between oxidized and reduced state -play a central role in metabolism |
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How do organisms use energy?
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Cellular respiration:
-metabolic pathways in which cells harvest the energy from the metabolism of food molecules -occurs in 3 stages: glycolysis, krebs cycle, and electron transport chain |
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Glycolysis
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-occurs in the cytoplasm
-net reaction -two results: generation of high-energy molecules (ATP, NADH); production of pyruvate that enters Krebs cycle |
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When Oxygen is Limited...
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Two problems with anaerobic cellular respiration:
-2 ATPs / glucose molecule will not sustain activity for long periods -in the absence of oxygen, glycolysis converts all of the limited NAD+ to NADH (and with no more NAD+ glycolysis ceases) |
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Fermentation
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-occurs in the absence of oxygen
-results in incomplete catabolism -lactic acid or ethanol -NAD+ is replenished to sustain Glycolysis |
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With Oxygen Present...
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Transitional step before Krebs cycle:
-Accomplishes 3 things: 1) Hydrogen atoms removed from pyruvic acid and added to NAD+ to make NADH 2) Carbon atom is removed from pyruvic acid and lost as CO2 3) resulting two-carbon molecule is attached to carrier molecule (coenzyme A) forming acetyl-CoA -performed by large enzyme in the mitochondria |
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Citric acid cycle - Definition
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-occurs in the matrix (inner compartment) of the mitochondria
-a cyclic series of enzymatically controlled reactions |
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Citric acid cycle - Process
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1. Pyruvate (product of glycolysis) is imported from the cytoplasm.
2. Pyruvate (3 carbon compound) is converted into a 2 carbon compound that is linked to a carrier molecule: acetyl-CoA 3. 1st reaction: citric acid (6C) is formed from oxalacetate (4C) and the acetyl group (2C) of acetyl-CoA --->two carbon atoms are lost as CO2 4. Oxalacetate is regenerated 5. Main outcome (in addition to ATP) is energy-rich NADH, which feeds into electron transport chain |
