Tarek
8.1
The totality of an organism’s chemical reactions is called metabolism.
Metabolism is an emergent property of life that arises from interactions between molecules within the orderly environment of the cell.
a. The chemistry of life is organized into metabolic pathways
Metabolic pathways begin with a specific molecule, which is then altered in a series of defined steps to form a specific product.
A specific enzyme catalyzes each step of the pathway.
Catabolic pathways release energy by breaking down complex molecules to simpler compounds.
A major pathway of catabolism is cellular respiration, in which the sugar glucose is broken down in the presence of oxygen to carbon dioxide and water.
b. Organisms transform energy.
Energy is the capacity to do work.
Energy exists in various forms, and cells transform energy from one type into another.
Kinetic energy is the energy associated with the relative motion of objects.
Objects in motion can perform work by imparting motion to other matter.
Photons of light can be captured and their energy harnessed to power photosynthesis in green plants.
Heat or thermal energy is kinetic energy associated with the random movement of atoms or molecules.
c. The energy transformations of life are subject to two laws of thermodynamics.
Thermodynamics is the study of energy transformations.
In this field, the term system refers to the matter under study and the surroundings include everything outside the system.
A closed system, approximated by liquid in a thermos, is isolated from its surroundings.
In an open system, energy and matter can be transferred between the system and its surroundings.
Organisms are open systems.
They absorb energy—light or chemical energy in the form of organic molecules—and release heat and metabolic waste products such as urea or CO2 to their surroundings.
8.2
How can we determine which reactions occur spontaneously and which ones require an input of energy?
The
The totality of an organism’s chemical reactions is called metabolism.
Metabolism is an emergent property of life that arises from interactions between molecules within the orderly environment of the cell.
a. The chemistry of life is organized into metabolic pathways
Metabolic pathways begin with a specific molecule, which is then altered in a series of defined steps to form a specific product.
A specific enzyme catalyzes each step of the pathway.
Catabolic pathways release energy by breaking down complex molecules to simpler compounds.
A major pathway of catabolism is cellular respiration, in which the sugar glucose is broken down in the presence of oxygen to carbon dioxide and water.
b. Organisms transform energy.
Energy is the capacity to do work.
Energy exists in various forms, and cells transform energy from one type into another.
Kinetic energy is the energy associated with the relative motion of objects.
Objects in motion can perform work by imparting motion to other matter.
Photons of light can be captured and their energy harnessed to power photosynthesis in green plants.
Heat or thermal energy is kinetic energy associated with the random movement of atoms or molecules.
c. The energy transformations of life are subject to two laws of thermodynamics.
Thermodynamics is the study of energy transformations.
In this field, the term system refers to the matter under study and the surroundings include everything outside the system.
A closed system, approximated by liquid in a thermos, is isolated from its surroundings.
In an open system, energy and matter can be transferred between the system and its surroundings.
Organisms are open systems.
They absorb energy—light or chemical energy in the form of organic molecules—and release heat and metabolic waste products such as urea or CO2 to their surroundings.
8.2
How can we determine which reactions occur spontaneously and which ones require an input of energy?
The