Energy and Metabolism Flashcards
Explain the terms spontaneous and non-spontaneous as applied to biochemical reactions.
Spontaneous reactions occur naturally and proceed without the need for external energy input, while non-spontaneous reactions require energy input to occur.
Describe potential reactions in terms of the changes in energy involved; and define exothermic and endothermic reactions.
Exothermic reactions release energy to the surroundings, resulting in a net decrease in energy, while endothermic reactions absorb energy from the surroundings, resulting in a net increase in energy.
Describe how enzymes catalyze cellular reactions and what factors affect enzyme activity.
Enzymes lower the activation energy required for a reaction to occur, thus increasing the rate of the reaction. Factors affecting enzyme activity include temperature, pH, substrate concentration, and enzyme concentration.
Describe equilibrium in relation to biochemical reactions (Le Chatelier’s Principle).
Equilibrium in biochemical reactions occurs when the rate of the forward reaction equals the rate of the reverse reaction. Le Chatelier’s Principle states that if a system at equilibrium is disturbed, it will shift to counteract the disturbance and restore equilibrium.
Define the terms: metabolism, catabolism, and anabolism. Explain what is meant by the term metabolic pathway.
Metabolism refers to all the chemical reactions occurring within an organism. Catabolism involves the breakdown of complex molecules into simpler ones with the release of energy, while anabolism involves the synthesis of complex molecules from simpler ones using energy. A metabolic pathway is a series of interconnected biochemical reactions that lead from a starting molecule to an end product.
Describe the process of cellular respiration.
Cellular respiration is the process by which cells break down glucose and other organic molecules to produce ATP, which is used as energy. It involves three main stages: glycolysis, the Krebs cycle (also known as the citric acid cycle or TCA cycle), and oxidative phosphorylation (which includes the electron transport chain).
Explain the role of adenosine triphosphate (ATP) in the cell.
ATP serves as the primary energy currency in cells. It stores and releases energy during cellular processes, such as muscle contraction, active transport, and biosynthesis, by undergoing hydrolysis to adenosine diphosphate (ADP) and inorganic phosphate (Pi).
Locate the following on a diagram of the cell and describe the main steps in cellular respiration:
a. Glycolysis
b. Krebs cycle (also called citric acid or tricarboxylic acid cycle - TCA)
c. Oxidative phosphorylation (includes the electron transport chain).
Compare provision of energy for cells in terms of metabolism of carbohydrates, fats, and proteins.
Carbohydrates, fats, and proteins serve as energy sources for cells, but they are metabolized differently. Carbohydrates are readily broken down into glucose, which enters glycolysis to produce ATP. Fats are broken down into fatty acids and glycerol, which enter beta-oxidation and the Krebs cycle, respectively, to generate ATP. Proteins are hydrolyzed into amino acids, which can be converted to intermediates of glycolysis or the Krebs cycle for ATP production.
Inter-relate carbohydrate, lipid, and protein metabolism and glycolysis as inputs to the TCA cycle and electron transport chain.
Carbohydrate, lipid, and protein metabolism are interconnected processes that ultimately provide substrates for the TCA cycle and electron transport chain (ETC) to generate ATP. In glycolysis, glucose is converted into pyruvate, which can then enter the TCA cycle as acetyl-CoA. Lipids are broken down into fatty acids and glycerol, with fatty acids undergoing beta-oxidation to produce acetyl-CoA for the TCA cycle. Proteins are hydrolyzed into amino acids, some of which can be converted to intermediates of the TCA cycle. The NADH and FADH2 generated from these processes feed electrons into the ETC, leading to ATP production through oxidative phosphorylation.
True or False: Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur.
True
True or False: ATP (adenosine triphosphate) is the primary energy currency of cells and is used to power cellular processes such as muscle contraction, active transport, and biosynthesis.
True
