AP BiologyMolecules and Cells Unit Topic 3

Molecules and Cells

Cellular Energetics

Topical Understanding:

Cells require a continuous supply of chemical ATP energy to remain alive. The sum total of a cell’s chemical reactions is metabolism which uses energy from the transfer of electrons in coupled oxidation-reduction reactions.

All living organisms undergo cellular respiration to generate ATP molecules. The most efficient process of generating ATP energy from organic molecules is aerobic cellular respiration which occurs in three main stages: glycolysis, Krebs cycle and the electron transport chain. Fermentation is an anaerobic alternative to aerobic respiration.

The organic molecules that are broken down in cellular respiration ultimately are generated through the process of photosynthesis. Photosynthesis occurs in two stages that are linked by ATP and NADPH: the light reactions and the Calvin-Benson cycle. Different photosynthetic adaptations have evolved in response to different environmental conditions.

Essential/Probing Questions:

  • What is the role of ATP in coupling the cell’s anabolic and catabolic processes?
  • How does chemiosmosis function in bioenergetics?
  • How are organic molecules broken down by catabolic pathways?
  • What is the role of oxygen in energy-yielding pathways?
  • How do cells generate ATP in the absence of oxygen?
  • How does photosynthesis convert light energy into chemical energy?
  • How are the chemical products of the light-trapping reactions coupled to the synthesis of carbohydrates?
  • What kinds of photosynthetic adaptations have evolved in response to different environmental conditions?
  • What interactions exist between photosynthesis and cellular respiration?

Areas of Focus:

  • Coupled Reactions
  • Fermentation and Cellular Respiration
  • Photosynthesis

Knowledge:

How cells make ATP

  • substrate level phosphorylation
  • chemiosmotic synthesis of ATP

Redox reactions in metabolism

  • respiration as a redox reaction
  • NAD+ and the oxidation of glucose

Aerobic and anerobic catabolism

Glycolysis

  • fermentation

Citric Acid Cycle

  • formation of Acetyl CoA

Electron Transport Chain and oxidative phosphorylation

  • electron transport
  • generation of the proton gradient
  • proton-motive force and ATP synthesis
  • ATP ledger for respiration

Catabolism of other molecules

Biosynthesis

Control of respiration

Chloroplast structure

Photosynthesis

  • splitting of water
  • photosynthesis as a redox process
  • two stages of photosynthesis

Light Reactions

  • nature of sunlight
  • photosynthetic pigments
  • photooxidation of chlorophyll
  • two photosystems
  • cyclic electron flow
  • noncyclic electron flow
  • comparison of chemiosmosis in chloroplasts and mitochondria

Dark Reactions

  • Calvin-Benson Cycle
  • photorespiration
  • C4 pathway
  • CAM plants

Skills:

Separate pigments and calculate their Rf values

Describe a technique to determine photosynthetic rates

Compare photosynthetic rates at different temperatures, different light intensities, and different wavelengths of light in a controlled experiment

Explain why the rate of photosynthesis vary under different environmental conditions

Test the effects of temperature on the rate of cell respiration in ungerminated versus germinated seeds in a controlled experiment

Calculate the rate of cell respiration from experimental data

Relate gas production to respiration rate

C. Gay Revised 6/19/07Steamboat Springs High School