Cells and Energy

Chemical Energy and ATP The chemical energy used for most cell processes is carried by ATP (adenosine triphosphate). ATP transfers energy for cell processes such as building new molecules and transporting materials.

Chemical Energy and ATP Organisms break down carbon-based molecules to produce ATP. Carbon based molecules include proteins, carbohydrates, and lipids

Photosynthesis Photosynthesis: process that produces sugars that store chemical energy Chlorophyll: a molecule in chloroplasts that absorbs some of the energy in visible light

Chloroplasts Located in leaf cells Grana – stacks of coin-shaped, membrane-enclosed compartments called thylakoids Thylakoids – contain the chlorophyll, other light-absorbing molecules, and proteins Stroma – the fluid that surrounds the grana

Light Dependent vs Independent Light dependent – chlorophyll absorbs energy from sun, H2O broken down, O2 released, energy is transferred to ATP Independent - CO2 is added to build larger molecules, energy from the light dependent reactions is used, sugar is formed

Cellular Respiration Process converts sugar into ATP using oxygen Respiration is like a mirror image of photosynthesis

Glycolysis and the Krebs Cycle Glycolysis – splits glucose into smaller molecules and produces ATP Takes place in the cytoplasm Anaerobic (no oxygen needed) Krebs cycle – second part of cell respiration that produces ATP and water Takes place in the mitochondria Four steps

Krebs Cycle Steps

Fermentation A process that breaks down sugars to produce ATP without oxygen Fermentation and its products are important in several ways (ex. alcohol, yogurt, cheese)