BM - ATP Flashcards
What is ATP?
ATP (adenosine triphosphate) is a nucleotide that acts as an immediate source of energy for cellular processes. It consists of an adenine base, a ribose sugar, and three phosphate groups.
How is ATP produced in cells?
ATP is produced through processes like cellular respiration (including glycolysis, the Krebs cycle, and oxidative phosphorylation) and photosynthesis (in plants).
Why is ATP considered an energy currency?
ATP is considered an energy currency because it is used by cells to carry out work such as muscle contraction, protein synthesis, and active transport, and it can be easily regenerated.
How is energy released from ATP?
Energy is released from ATP when the terminal phosphate group is hydrolyzed (broken off) by the enzyme ATPase, forming ADP (adenosine diphosphate) and inorganic phosphate (Pi).
What is the difference between ATP and ADP?
ATP has three phosphate groups, while ADP has two. ATP can be hydrolyzed to ADP to release energy, whereas ADP can be rephosphorylated to form ATP during energy regeneration.
What is phosphorylation?
Phosphorylation is the process of adding a phosphate group to a molecule, such as ADP to form ATP, which stores energy for later use.
What is the role of ATP in active transport?
ATP provides the energy needed to move substances against their concentration gradient through membrane pumps, such as the sodium-potassium pump.
What is the significance of ATP in muscle contraction?
ATP provides the energy for muscle contraction by enabling the interaction between actin and myosin filaments, allowing for the sliding filament mechanism to occur.
What is the process of oxidative phosphorylation in ATP production?
Oxidative phosphorylation occurs in the mitochondria, where high-energy electrons from NADH and FADH2 are transferred through the electron transport chain, generating a proton gradient that drives ATP synthase to produce ATP.
How is ATP regenerated during cellular respiration?
ATP is regenerated through substrate-level phosphorylation in glycolysis and the Krebs cycle, and oxidative phosphorylation in the electron transport chain.
What is the structure of ATP?
ATP consists of an adenine base, a ribose sugar, and three phosphate groups, with the phosphate groups linked by high-energy bonds.
What happens to ATP when it is used in metabolic reactions?
ATP is hydrolyzed into ADP and inorganic phosphate (Pi), releasing energy that is used by the cell for various metabolic processes.
Why is ATP a better immediate energy source than glucose?
ATP is better because it can be quickly and easily broken down to release energy, while glucose requires multiple steps (like glycolysis and the Krebs cycle) to release energy, making ATP more efficient for immediate use.
How does ATP aid in protein synthesis?
ATP provides the energy required for the formation of peptide bonds between amino acids during protein synthesis on ribosomes.
What is chemiosmosis?
Chemiosmosis is the process where the energy from the electron transport chain is used to pump protons (H+) across the mitochondrial membrane, creating a proton gradient that drives ATP synthesis via ATP synthase.
Describe how an ATP molecule is formed from its component molecules.
- ATP is made from a condensation reaction between the nucleotide base adenine, a ribose sugar and three phosphate groups.
- ATP can be resynthesised in a condensation reaction between ADP and Pi and is catalysed by ATP synthase.
Water is used to hydrolyse ATP.
Name the two products of ATP hydrolysis
Adenosine diphosphate and (inorganic) phosphate;
ATP is an energy source used in many cell processes. Give two ways in
which ATP is a suitable energy source for cells to use.
5 marks
- Releases relatively small amount of energy
- Releases energy instantaneously/ energy is readily available
- Phosphorylates other compounds, making them more reactive;
- Can be rapidly re-synthesised;
- does not leave cells.
Describe how ATP is resynthesised in cells.
- From ADP and phosphate;
Accept - By ATP synthase;
- During respiration/photosynthesis;
Give two ways in which the hydrolysis of ATP is used in cells
- To provide energy for other reactions
- To add phosphate to other substances and make them more
reactive
Describe the roles of calcium ions and ATP in the contraction of a myofibril
7 marks
- Calcium ions diffuse into myofibrils from (sarcoplasmic) reticulum;
- (Calcium ions) cause movement of tropomyosin (on actin);
- (This movement causes) exposure of the binding sites on the actin;
- Myosin heads attach to binding sites on actin;
- Hydrolysis of ATP (on myosin heads) causes myosin heads to bend;
- (Bending) pulling actin molecules;
- Attachment of a new ATP molecule to each myosin head causes myosin
heads to detach (from actin sites).
Humans synthesise more than their body mass of ATP each day. Explain why it is
necessary for them to synthesise such a large amount of ATP.
- ATP cannot be stored / is an immediate source of energy;
- ATP only releases a small amount of energy at a time;
Describe the part played by the inner membrane of a mitochondrion in
producing ATP.
- Electrons transferred down electron transport chain
- This movement Provide energy to take H+ through membrane into matrix through ATPase;
- Energy used to combine ADP and phosphate / to produce ATP;
In anaerobic respiration, what is the net yield of ATP molecules per molecule
of glucose?
2 molecules
Mitochondria in muscle cells have more cristae than mitochondria in skin cells.
Explain the advantage of mitochondria in muscle cells having more cristae.
- more cristae means larger surface area for electron transport chain
- more enzymes for ATP production / oxidative phosphorylation;
muscle cells use more ATP (than skin cells
Substance X enters the mitochondrion from the cytoplasm. Each molecule of
substance X has three carbon atoms.
(i) Name substance X.
Pyruvate