biology
Big Idea 2
Biological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis.
Living systems require both free energy and matter to maintain order, grow and reproduce. Organisms employ various strategies to capture, use and store free energy and other vital resources. Energy deficiencies are not only detrimental to individual organisms; they also can cause disruptions at the population and ecosystem levels.
Biological systems must both capture free energy and then transform the energy into usable forms. Autotrophic cells capture free energy through photosynthesis and chemosynthesis. Photosynthesis traps free energy present in sunlight that, in turn, is used to produce carbohydrates from carbon dioxide. Chemosynthesis captures energy present in inorganic chemicals. Cellular respiration and fermentation harvest free energy from sugars to produce free energy carriers, including ATP. The free energy available in sugars drives metabolic pathways in cells. Photosynthesis and respiration are interdependent processes.
Cells and organisms exchange matter with the environment. For example, water and nutrients are used in the synthesis of new molecules; carbon moves from the environment to organisms where it is incorporated into carbohydrates, proteins, nucleic acids or fats; and oxygen is necessary for more efficient free energy use in cellular respiration. These processes release matter to the environment as waste products. For example, cellular respiration will release carbon dioxide. In addition, programmed cell death (apoptosis) plays a role in normal development and differentiation (e.g., morphogenesis). Differences in surface-to-volume ratios affect the capacity of a biological system to obtain resources and eliminate wastes.
Membranes allow cells to create and maintain internal environments that differ from external environments. The structure of cell membranes results in selective permeability
Biological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis.
Living systems require both free energy and matter to maintain order, grow and reproduce. Organisms employ various strategies to capture, use and store free energy and other vital resources. Energy deficiencies are not only detrimental to individual organisms; they also can cause disruptions at the population and ecosystem levels.
Biological systems must both capture free energy and then transform the energy into usable forms. Autotrophic cells capture free energy through photosynthesis and chemosynthesis. Photosynthesis traps free energy present in sunlight that, in turn, is used to produce carbohydrates from carbon dioxide. Chemosynthesis captures energy present in inorganic chemicals. Cellular respiration and fermentation harvest free energy from sugars to produce free energy carriers, including ATP. The free energy available in sugars drives metabolic pathways in cells. Photosynthesis and respiration are interdependent processes.
Cells and organisms exchange matter with the environment. For example, water and nutrients are used in the synthesis of new molecules; carbon moves from the environment to organisms where it is incorporated into carbohydrates, proteins, nucleic acids or fats; and oxygen is necessary for more efficient free energy use in cellular respiration. These processes release matter to the environment as waste products. For example, cellular respiration will release carbon dioxide. In addition, programmed cell death (apoptosis) plays a role in normal development and differentiation (e.g., morphogenesis). Differences in surface-to-volume ratios affect the capacity of a biological system to obtain resources and eliminate wastes.
Membranes allow cells to create and maintain internal environments that differ from external environments. The structure of cell membranes results in selective permeability