What Is ATP? Flashcards
Describe ATP
Adenosine triphosphate. When the energy is released from glucose during cellular respiration, it is stored in ATP molecules to be used by the cell later. It is a nucleotide (sugar, phosphate, and base)
Describe the functions of ATP
Major energy carrier to provide energy to endothermic reactions, monomer for DNA and RNA, regulates many biochemical pathways
Show a diagram of ATP
By what process does ATP give us energy?
ATP - ADP cycle
Describe the ATP - ADP cycle
ATP stores energy in the bonds between phosphate groups. When the third phosphate’s bond is broken (high energy bond) by a hydrolysis reaction, ADP is formed and free energy is released for the cell to use. The equation will move in both directions depending on the needs of the cell (forward when the cell needs energy, reverse when cell stores energy)
What enzyme is present in the hydrolysis of ATP into ADP?
ATPase
Give the equation for the hydrolysis of ATP into ADP
A-P-P-P + H2O <-(ATPase)-> A-P-P + Pi + energy
What enzyme is present in the synthesis of ATP from ADP?
ATP synthase
How is ATP made?
By adding phosphate back to an ADP molecule, the cell can replace its energy molecules. This process requires an input of energy (which comes from the breaking down of glucose in cellular respiration and storage in its bond)
Give the equation for the synthesis of ATP from ADP
A-P-P + Pi + energy <-ATP synthase-> A-P-P-P + H2O
Where is ATP made?
In the cytoplasm by glycolysis, in mitochondria by cellular respiration, in chloroplasts by photosynthesis
Where is ATP consumed?
Assembly of amino acids into proteins, nucleotides into DNA and RNA, and polysaccharides; synthesis of fats; active transport; supplies energy for muscles, cilia, and flagella
By what processes do cells make ATP?
Substrate-level phosphorylation and oxidative phosphorylation (chemiosmosis)
What is the ultimate goal of cellular respiration?
To capture as much available free energy as possible in the ATP
Describe substrate-level phosphorylation
Enzyme-catalyzed anaerobic process which occurs in glycolysis and Kreb’s cycle. A phosphate-containing group (phosphoenol pyruvate) transfers a phosphate group directly to ADP to form ATP
Give the equation for substrate-level phosphorylation
PE-P + A-P-P <-enzymes-> pyruvate + A-P-P-P
The enzymes are phosphoglycerate kinase and pyruvate kinase
Describe oxidative phosphorylation (chemiosmosis)
Highly efficient aerobic process which occurs in the electron transport chain. It is the osmosis of protons
Give the first step of oxidative phosphorylation
NADH and FADH2 molecules are reduced from the glucose molecule from the first three stages of cellular respiration. They enter the electron transport chain where they are oxidized, transferring electrons to molecules near the beginning of the ETC
Give the second step of oxidative phosphorylation
The H ions on the inside of the membrane are moved to the outside of the membrane using a proton pump. A hydrogen ion gradient is formed where there is a high concentration of H+ in the ECF and a low concentration of H+ in the ICF
Give the third step of oxidative phosphorylation
This concentration gradient creates an electrochemical gradient (more positive on the outside) which creates a force that moves protons through special proton channels. As the protons move through the pump, ATP synthase uses this proton motive force to phosphorylate ADP to ATP
Give a simple three-step explanation of chemiosmosis
NADH is oxidated and the H+ ions are pumped into the ECF. Huge H+ gradient is used to drive the proton pumps. As H+ ions are sucked through the pump, it drives the production of ATP with the aid of ATP synthase
Read pages 141-145 of the textbook
