Energy Flow in Cells - 1
Thousands of chemical reactions occur in our cells and tissues to keep us alive
(and hopefully healthy).
We have discussed some of the molecules of living
organisms (carbohydrates, lipids, proteins, etc.) in the context of the functions
they perform in cells and tissues.
These coordinated, controlled and orderly
activities of cells collectively comprise the
of living organisms.
of metabolism involves energy transfer so it is helpful to have a common
knowledge base about energy.
The energy used in metabolism is
, the energy of electrons.
This energy is used to build and maintain our
cells and tissues, to move materials into and out of our cells, to process fuel
- to do the work of the cell.
We will briefly look at the physical laws that govern energy flow, how energy flow
relates to chemical reactions and how living organisms control the chemical
reactions that occur in their cells and tissues.
chemical reactions it's important to take a look at enzyme activity, too.
Energy is often defined as the capacity to do work. The two fundamental types of
(energy at work, or the movement of energy) and
(stored energy waiting to do work, such as the energy in the bonds of chemicals).
is energy that matter has because of its structure or location.
The water stored behind a dam has potential energy because of its location.
Chemical bonds have potential energy because of their structure.
flowing through the turbines of a dam has
Both kinetic and potential energy can be found in many forms, such as
light, chemical, heat, and mechanical.
Under the right conditions, energy can be
transformed from one type to another and from one form to another.
This is a
good thing, since different kinds of work require different kinds of energy, and as
it applies to living organisms, it is often thought of as energy flow.
flow, we would have no life on earth.
To make sense of this we have to understand both the
quantity of energy
available and the
usefulness of that energy
to do work, which is the study of
, the field that studies energy transformations.
There are two
laws: one addresses the quantity of available energy and the second addresses the
usefulness or availability of energy to do work.
In addition, thermodynamics
a system and its surroundings
The matter being studied is the
system, and everything outside of the system is the surroundings.