Respiration + ATP Flashcards
What is the structure of ATP?
ATP is an energy-carrying nucleic acid made up of a phosphorylated nucleotide. It consists of an adenine base, ribose sugar, and three phosphate groups.
How is ATP synthesized?
ATP is synthesized by combining ADP with a phosphate group through the enzyme ATP synthase, which requires energy in a condensation reaction.
What is the function of ATP and how is it adapted for this function?
ATP transfers energy released from respiration and provides a short-term energy store. It is stable at cellular pH levels and releases just the right amount of energy to control cell actions.
How does ATP hydrolysis work?
ATP is hydrolyzed to adenosine diphosphate (ADP) and a phosphate molecule by the enzyme ATPase. This process is coupled with energy-requiring reactions, as there is a free energy release. The released phosphate groups can phosphorylate other molecules to make them more reactive. It is a reversible process.
What are the needs for respiration?
Respiration is needed for movement, anabolic reactions, active transport, and maintaining body temperature.
Where does glycolysis occur and what are the steps?
Glycolysis occurs in the cytoplasm and includes the following steps:
- Phosphorylation: Glucose (6C) + 2 ATP (to make glucose more reactive) → fructose biphosphate (6C).
- Lysis: Fructose biphosphate → 2 triose phosphate (3C).
- Oxidation: Hydrogen is removed from triose phosphate, reducing NAD (2NAD + 4H → 2NADH + 2H+).
- Dephosphorylation: Phosphates from intermediates undergo substrate-linked phosphorylation (4Pi + 4ADP → 4ATP).
- 2 Triose phosphate → 2 pyruvate.
What happens during the link reaction in aerobic respiration? Where does it occur?
Pyruvate moves across the membrane by active transport and is oxidized to acetate (2C), requiring the reduction of NAD. The acetate combines with coenzyme A to produce acetyl-CoA. It is a process of dehydrogenation and decarboxylation. It occurs in the mitochondrial matrix.
What is the role of coenzymes in respiration?
Coenzymes are molecules used to help enzymes carry out their functions but are not used up in the reaction. Coenzyme A, for example, carries the acetyl group to the Krebs cycle.
What happens during the Krebs cycle?
In the Krebs cycle:
- Acetyl-CoA combines with oxaloacetate which accepts an acetyl group to form citrate. CoA released in reaction.
- Citrate undergoes decarboxylation, releasing 2 CO2.
- Citrate undergoes dehydrogenation, reducing NAD and FAD.
- Substrate-linked phosphorylation forms 1 ATP.
Where does oxidative phosphorylation occur?
Oxidative phosphorylation occurs in the cristae of the mitochondria by chemiosmotic theory.
How do electrons and protons contribute to ATP synthesis in oxidative phosphorylation?
Hydrogen atoms donated by reduced NAD and FAD split into protons (H+ ions) and electrons. The high-energy electrons enter the electron transport chain, releasing energy as they move through, which is used to transport protons across the inner mitochondrial membrane into the inter-membrane space which creates a conc gradient of protons between the inter membrane space and the matrix. Causing protons to return to the matrix via facilitated diffusion through ATP synthase (channel protein). Movement of proteins down concentration gradients provided energy for ATP synthesis
What is the role of oxygen in oxidative phosphorylation?
Oxygen acts as the ‘final electron acceptor’ in the electron transport chain, combining with protons and electrons to form water.
What is the role of the electron transport chain in respiration?
The electron transport chain is a series of membrane proteins close together. These proteins are impermeable to H+ ions, so electron carriers pump protons across the membrane to create a concentration gradient.
What happens during anaerobic respiration when oxygen is unavailable?
In the absence of oxygen:
- There is no final electron acceptor.
- Reduced NAD and FAD cannot be oxidized.
- The Krebs cycle stops.
- Lactate fermentation occurs, where reduced NAD transfers hydrogen to pyruvate, forming lactate via lactate dehydrogenase.
What is lactate fermentation and what are its consequences?
Lactate fermentation is when reduced NAD transfers hydrogen to pyruvate, forming lactate. The lactate can either be oxidized back to pyruvate (requiring large amounts of oxygen, creating an oxygen debt) or stored as glycogen in the liver. Glucose is only partially oxidized, so only a small amount of its chemical energy is harnessed.
