Cellular Respiration and ATP

Study Notes

Food provides living things with energy and raw materials
Food is a source of energy and building blocks
ATP (adenosine triphosphate) is a principal chemical compound for storing and releasing energy in cells

The ATP molecule consists of an adenine group, a ribose sugar, and three phosphate groups.

ADP (adenosine diphosphate) resembles ATP but has two phosphate groups instead of three
Cells store energy by adding a third phosphate group to ADP to form ATP.
When the cell needs energy, the third phosphate is removed, releasing energy for cellular activities.

Energy flows into an ecosystem as sunlight and leaves as heat (a one-way flow).
Essential components such as the raw materials in photosynthesis will be recycled. Photosynthesis in the chloroplasts converts energy from the sun to carbohydrates.
Plants produce energy through photosynthesis, which other organisms then use as fuel through respiration.
Cellular respiration breaks down organic compounds into smaller compounds releasing stored energy.
Respiration produces carbon dioxide and water as waste products.
Photosynthesis produces carbohydrates and oxygen.

Cellular respiration is the process of converting biochemical energy into ATP.
The process converts larger molecules into smaller ones, releasing energy.
There are two main types of respiration: aerobic and anaerobic.
The process takes place in three main stages: glycolysis, the Krebs cycle, and the electron transport chain.
Glycolysis occurs in the cytoplasm; the Krebs cycle and electron transport chain occur in the mitochondria.

The energy of glucose is used to convert glucose into two pyruvic acid molecules.
Two molecules of PGAL will be oxidized to produce two molecules of pyruvic acid.
The oxidation of PGAL also results in the production of two molecules of NADH.
Pyruvic acid may enter the mitochondria or remain in the cytoplasm (for fermentation).

Cellular respiration is an energy process that requires a small energy input to begin
Glycolysis produces a gain of two ATP molecules.
NAD+ (nicotinamide adenine dinucleotide), similar to NADP in photosynthesis, accepts electrons and converts to NADH.
NADH carries electrons to other energy pathways within the cell enabling ATP synthesis
Disadvantages of using only glycolysis include inability to supply enough ATP to meet cells' needs. Glycolysis does not require oxygen and can supply a quick, short burst of ATP production.

Aerobic respiration has two major stages: the Krebs Cycle and the Electron Transport Chain
Pyruvic acid enters the Citric/Krebs Cycle.
Electron carriers like NADH and FADH2 carry energy to the electron transport chain for ATP production.

Electron transport chain uses electrons to generate a large amount of ATP
The high-energy electrons released from the electron transport chain are used to pump protons across the mitochondrial membrane creating a hydrogen gradient.
The hydrogen ions rush back across the membrane producing ATP.
The final electron acceptor in the electron transport chain is oxygen.

Fermentation is an anaerobic metabolic pathway.
Fermentation occurs in the absence of oxygen.
Fermentation yields a small amount of ATP compared to aerobic respiration.
Two main types of fermentation are lactic acid fermentation and alcohol fermentation.

Photosynthesis uses sunlight to convert carbon dioxide and water to glucose and oxygen.
Respiration breaks down glucose and oxygen to produce carbon dioxide, water, and ATP.
Photosynthesis occurs in chloroplasts, while respiration takes place in mitochondria.