6.2 Metabolic Reactions and Energy Transformations
The fate of all solar energy is randomized in the universe as heat.
A living cell can function because it serves as a temporary repository of order, purchased at the cost of a constant flow of energy.
The first and second laws of thermodynamics are related to cells.
Examine how cells use energy.
The structure and function of living organisms are maintained through chemical reactions.
Substances that form as a result of a reaction are called reactants.
The products are C and D. It depends on how much energy is left after the reaction.
If the universe has more disorder, a reaction occurs spontaneously.
We are less concerned about the entire universe in cell biology.
The concept of free energy is used by cell biologists.
The change in free energy is determined by subtracting the free energy content of the reactants from the products.
A negative result means that the products have less free energy than the reactants.
If C and D have less free energy than A and B, the reaction occurs without additional input of energy.
Spontaneous reactions and energy-requiring reactions are included in metabolism.
Exergonic reactions release energy, while endergonic reactions need an input of energy to occur.
Many reactions in the body are endergonic.
The nonspontaneous reactions must be coupled with exergonic reactions in order for a net reaction to occur.
Between exergonic and endergonic reactions, ATP is used as an energy carrier.
A human, a flying bat, and an oak tree need a lot of ATP.
The cells don't keep a large amount of the molecule on hand.
They use ADP and P to regenerate ATP.
The cycle is called the ATP.
This cycle is powered by the breakdown of biomolecules.
The process is not very efficient according to the second law.
Only 39% of the free energy stored in the chemical bonds of a glucose molecule is transformed to an energy source.
Energy is carried between exergonic reactions and endergonic reactions in cells.
The appropriate amount of energy is released when aphosphate group is removed.
There are many advantages to using the energy carrier ATP in living systems.
It is possible to use a common and universal energy currency in many different reactions.
The amount of energy released is sufficient to power most biological functions.
Energy loss can be mitigated by the combination of endergonic reactions and ATP breakdown.
The base adenine and the 5-carbon sugar ribose are found in the nucleus of the nucleotide.
The three phosphates repel each other, creating instability and potential energy.
The molecule is called a high-energy molecule because it can be easily removed.
A mole is equal to the weight of the molecule expressed in grams.
The energy needed to synthesise macromolecules that make up the cell is supplied by ATP.
The energy needed to pump substances is supplied by the ATP.
The energy needed to allow muscles to contract, cilia and flagella to beat, and chromosomes to move is supplied by ATP.
Most of the time, the source of energy for these processes is ATP.
The energyreleasing reaction is usually the hydrolysis of ATP.
The net reaction is exergonic because the amount of energy released is more than the amount consumed.
The reaction tells you that there is a relationship, but it doesn't show how it is achieved.
When a polar ion moves across a cell, it requires a carrier.
In order to make the carrierProtein assume a shape that is compatible with the ion, theATP is hydrolyzed and thephosphate group is attached to it.
The negatively charged phosphate causes a change in the shape of the molecule that allows it to interact with the ion.
When a polypeptide is made at a ribosome, it is a coupled reaction.
The energy needed to overcome the energy cost associated with bonding one amino acid to another is supplied by the transfer of a group ofphosphates from one group to another.
The high degree of order and structure is essential for life because of the unfavorable processes that must occur.
If life is to continue, macromolecules must be made and organized to form cells and tissues, the internal composition of the cell and the organisms must be maintained, and the movement of cellular organelles and the organisms must occur.
The example in Figure 6.4 shows how Page 105 is coupled to the muscle contraction process.
During muscle contraction, myosin and actin are pulled to the center of the cell.
The myosin head combines with the three green triangles to form a resting shape.
There are two green triangles and one green triangle.
The change in shape allows myosin to attach.
The actin filament is pulled on by the myosin head after the release of ADP and P. The cycle continues.
The chemical energy has been transformed into mechanical energy.