Energy and metabolism.pdf

Energy and metabolism

1. Metabolism, Enzymes, and Cellular Respiration
Metabolism refers to the sum total of every chemical reaction
in every organism.
Cells use enzymes and metabolic pathways to conduct these
chemical reactions.
It is essential to understand the reactions that comprise
metabolism to learn how organisms acquire and use energy to
survive.
Since this process is quite complicated
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2. Energy and Thermodynamics
Energy flows through all living systems.
The chemical reactions that build and break down energy-
containing compounds are vital to all living organisms.
Biochemical pathways involve the building and breaking
down through anabolism and catabolism, respectively. Notice
that all of these pathways involve chemical reactions that
requireenzymes, which are the biological catalysts we will
discuss in the next section.
Remember that the laws of thermodynamics state that energy
is neither created nor destroyed, but transformed from one
form to another.
Biochemical reactions follow these same laws of
thermodynamics which predict whether reactions will occur
spontaneously, or without any energy required.
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3. Energy is the ability to do work. It exists in
many forms, including:
1.Mechanical energy: the energy of motion or
position (e.g., the kinetic energy of a car or
the potential energy of a lifted object).
2.Thermal energy: the energy associated with
the temperature of an object (heat).
3.Electrical energy: the energy associated with
the flow of electric charges.
4.Chemical energy: the energy stored in the
bonds of atoms and molecules.
5.Nuclear energy: the energy stored in the
nucleus of an atom.
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4. Energy can be transformed from
one form to another, but it cannot
be created or destroyed according
to the first law of thermodynamics.
Thermodynamics is the branch of
physics that studies the relationship
between heat, work, temperature,
and energy. It governs the energy
transfers and transformations that
take place in a system and its
surroundings
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5. Thermodynamics
is a branch of physics that studies the
relationship between heat, work, temperature,
and energy. It governs the energy transfers and
transformations that take place in a system and
its surroundings. The four laws of
thermodynamics form the foundation of this
field.
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6. key concepts in thermodynamics:
•Systems and surroundings: A system is the part of the universe that you are
interested in studying, while the surroundings are everything else. The system
can exchange energy and matter with the surroundings.
•State functions: These are properties of a system that depend only on its
current state, and not on how it reached that state. Examples of state functions
include temperature, pressure, and volume.
•Energy: Energy is the ability to do work. There are different forms of energy,
such as thermal energy, mechanical energy, electrical energy, chemical energy,
and nuclear energy.
•Heat: Heat is the transfer of thermal energy between objects at different
temperatures. It flows from a hotter object to a colder object.
•Work: Work is done when a force acts on an object and causes it to move a
certain distance. In thermodynamics, work is often associated with the
expansion or compression of a system.
•Entropy: Entropy is a measure of disorder in a system. It tends to increase
over time in a closed system (i.e., a system that does not exchange energy or
matter with the surroundings).
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7. The laws of thermodynamics are:
•The zeroth law of thermodynamics: If two systems are
each in thermal equilibrium with a third system, then they
are in thermal equilibrium with each other. This law defines
temperature.
1.The first law of thermodynamics: The total energy of
an isolated system (i.e., a system that does not exchange
energy or matter with the surroundings) remains
constant. This is the law of conservation of energy.
2.The second law of thermodynamics: In a closed
system, the entropy tends to increase over time. This
law sets limits on the efficiency of converting thermal
energy into other forms of energy.
3.The third law of thermodynamics: The entropy of a
system approaches a constant value as the temperature
approaches absolute zero.
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8. the metabolic process. It describes
the two major kinds of metabolic
pathways, linear and cyclical. Pay
attention to the descriptions for
catabolic and anabolic pathways in
cellular metabolism.
Note that catabolism breaks down
molecules (creates energy), while
anabolism assembles molecules
(requires energy). You should also
be able to define the components
of a metabolic pathway: reactants
(substrate molecules),
intermediates (intermediate
substrates), and the final products.
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9. Metabolism is essentially the life force
of your body on a cellular level.
It refers to all the complex chemical
reactions that happen within your cells
to keep you going.
the chemical processes by
which a plant or an animal
uses food, water, etc., to grow
and heal and to make energy
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10. What Is Metabolism?
Metabolism (meh-TAB-uh-liz-um) is the
chemical reactions in the body's cells that
change food into energy. Our bodies need
this energy to do everything from moving
to thinking to growing.
Specific proteins in the body control the
chemical reactions of metabolism.
Thousands of metabolic reactions happen
at the same time all regulated by the body
to keep our cells healthy and working.
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11. How Does Metabolism Work?
After we eat food, thedigestive systemuses
enzymes to:
1.break proteins down into amino acids
2.turn fats into fatty acids
3.turn carbohydrates into simple sugars (for
example, glucose)
4.The body can use sugar, amino acids, and
fatty acids as energy sources when needed.
These compounds are absorbed into the
blood, which carries them to the cells.
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12. •Process: Metabolism is a two-way
street, with two main parts:
Anabolism: This is the building up
process. It uses energy and raw
materials (from food) to create new
molecules and tissues, like
repairing muscles or building
bones.
•Catabolism: This is the breaking
down process. It breaks down
complex molecules from food and
releases energy the body can use
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13. After they enter the cells, other enzymes act to
speed up or regulate the chemical reactions
involved with "metabolizing" these
compounds. During these processes, the
energy from these compounds can be released
for use by the body or stored in body tissues,
especially the liver,muscles, and body fat.
Metabolism is a balancing act involving two
kinds of activities that go on at the same time:
•building up body tissues and energy stores
(called anabolism)
•breaking down body tissues and energy stores
to get more fuel for body functions (called
catabolism)
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14. •Regulation
•Many factors influence your metabolic rate,
which is the speed at which these reactions
occur. These factors include: Age: Generally,
metabolism slows down with age as muscle
mass decreases.
1.Sex: Men tend to have a faster metabolism
than women due to higher muscle mass.
2.Muscle mass: Muscle burns more calories
than fat, even at rest, so more muscle mass
leads to a higher metabolic rate.
3.Physical activity: Exercise increases your
metabolic rate, both during activity and for a
short time afterward
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15. Anabolism
(uh-NAB-uh-liz-um), or constructive metabolism, is
all about building and storing. It supports the
growth of new cells, the maintenance of body
tissues, and the storage of energy for future use. In
anabolism, small molecules change into larger,
more complex molecules of carbohydrates, protein,
and fat.
Catabolism
(kuh-TAB-uh-liz-um), or destructive metabolism, is
the process that produces the energy needed for all
activity in the cells. Cells break down large
molecules (mostly carbs and fats) to release energy.
This provides fuel for anabolism, heats the body, and
enables the muscles to contract and the body to
move.
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16. As complex chemical units
break down into more
simple substances, the body
releases the waste products
through the skin, kidneys,
lungs, and intestines.
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17. What Controls Metabolism?
Severalhormonesof theendocrine systemhelp control the
rate and direction of metabolism. Thyroxine, a hormone
made and released by the thyroid gland, plays a key role in
determining how fast or slow the chemical reactions of
metabolism go in a person's body.
Another gland, thepancreas, secretes hormones that help
determine whether the body's main metabolic activity at any
one time are anabolic (an-uh-BOL-ik) or catabolic (kat-uh-
BOL-ik). For example, more anabolic activity usually happens
after you eat a meal. That's because eating increases the
blood's level of glucose — the body's most important fuel.
The pancreas senses this increased glucose level and
releases the hormoneinsulin, which signals cells to increase
their anabolic activity
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18. Metabolism is a complicated chemical process. So it's
not surprising that many people think of it in its
simplest sense: as something that influences how
easily our bodies gain or lose weight. That's
wherecaloriescome in. A calorie is a unit that
measures how much energy a particular food
provides to the body. A chocolate bar has more
calories than an apple, so it provides the body with
more energy — and sometimes that can be too
much of a good thing. Just as a car stores gas in the
gas tank until it is needed to fuel the engine, the
body stores calories — primarily asfat. If you overfill a
car's gas tank, it spills over onto the pavement.
Likewise, if a person eats too many calories, they "spill
over" in the form of excess body fat.
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19. The number of calories someone burns in a day is
affected by how much that person exercises, the amount
of fat and muscle in his or her body, and the
person'sbasal metabolic rate (BMR).
BMR is a measure of the rate at which a person's body
"burns" energy, in the form of calories, while at rest.
The BMR can play a role in a person's tendency to gain
weight.
For example, someone with a low BMR (who therefore
burns fewer calories while at rest or sleeping) will tend to
gain more pounds of body fat over time than a similar-
sized person with an average BMR who eats the same
amount of food and gets the same amount of exercise.
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20. BMR can be affected by a
person's genesand by some health
problems
. It's also influenced by body
composition — people with more
muscle and less fat generally have
higher BMRs.
But people can change their BMR in
certain ways. For example, a person who
exercises more not only burns more
calories, but becomes more physically
fit, which increases his or her BMR.
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21. Metabolism 21