Chapter 8 An Introduction to Metabolism Flashcards
Sugars can be converted to amino acids that are linked together into
proteins
when food is digested, proteins are dismantled into amino acids that can be converted to
sugars
drives this cellular economy by extracting the energy stored in sugars and other fuels. Cells apply this energy to perform various types of work, such as the transport of solutes across the plasma membrane,
cellular respiration
the ocean waves are brightly illuminated from within by free-floating, single-celled marine organisms called
dinoflagellates.
dinoflagellates convert the energy stored in certain organic molecules to light, a process called
bioluminescence
bioluminescent organisms are found in the oceans, but some exist on land, such as the
bioluminescent firefly
Bioluminescence and other metabolic activities carried out by a cell are precisely
coordinated and controlled
is an emergent property of life that arises from orderly interactions between molecules.
Metabolism
We can picture a cell’s metabolism as an elaborate road map of the thousands of chemical reactions that occur in a cell, arranged as .
intersecting metabolic pathways
begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product
metabolic pathway
Each step of the pathway is catalyzed by a
specific enzyme
Metabolism as a whole manages the
material and energy resources of the cell.
Some metabolic pathways release energy by breaking down complex molecules to simpler compounds. These degradative processes are called
catabolic pathways, or breakdown pathways
A major pathway of catabolism is
cellular respiration, in which the sugar glucose and other organic fuels are broken down in the presence of oxygen to carbon dioxide and water.
Pathways can have more than one starting
molecule and/or product
consume energy to build complicated molecules from simpler ones;
Anabolic pathways, sometimes called biosynthetic pathways
Examples of anabolism are the
synthesis of an amino acid from simpler molecules and the synthesis of a protein from amino acids.
Catabolic and anabolic pathways are the
“downhill” and “uphill” avenues of the metabolic landscape.
Energy released from the downhill reactions of catabolic pathways can be stored and then used to drive the uphill reactions of
anabolic pathways.
the study of how energy flows through living organisms.
bioenergetics
is the capacity to cause change
Energy
energy is the ability to rearrange a
collection of matter
Energy can be associated with the relative motion of objects; this energy is called
kinetic energy
is kinetic energy associated with the random movement of atoms or molecules;
Thermal energy
thermal energy in transfer from one object to another is called
heat
is also a type of energy that can be harnessed to perform work, such as powering photosynthesis in green plants.
Light
it is energy that matter possesses because of its location or structure
potential energy
possess energy because of the arrangement of electrons in the bonds between their atoms
Molecules
is a term used by biologists to refer to the potential energy available for release in a chemical reaction
Chemical energy
release energy by breaking down complex molecules
catabolic pathways
During a catabolic reaction, some bonds are broken and others are formed, releasing
energy and resulting in lower-energy breakdown products.
transformation also occurs in the engine of a car when the hydrocarbons of gasoline react explosively with oxygen, releasing the
energy that pushes the pistons and producing exhaust
a similar reaction of food molecules with oxygen provides chemical energy in biological systems, producing
carbon dioxide and water as waste products
woman climbing the ladder to the diving platform is releasing
chemical energy from the food she ate for lunch and using some of that energy to perform the work of climbing
The____________________ of muscle movement is thus being transformed into potential energy due to her increasing height above the water.
kinetic energy
man diving is converting his ________________________________which is then transferred to the water as he enters it, resulting in splashing, noise, and increased movement of _______________.
potential energy to kinetic energy, water molecules
small amount of energy is lost as heat due to
friction.
it the energy associated with motion
kinetic energy
energy that is not kinetic is called ___________, and is energy that matter possesses because of its location or structure
potential energy
is neither created nor destroyed but converted from one form to another
energy
this property is called the
conservation of energy
the bow and arrow start out with low
potential energy
as the archer’s arm pulls back the string ______________, from the arm’s motion is converted to ____________________ in the tense bowstring and arrow
kinetic energy, potential energy
when the bowstring is released, the stored potential energy is converted into the _______________ of the moving arrow
kinetic energy
when the arrow hits the target, is motion
ceases
when energy is converted from potential energy to kinetic energy some of the energy can be used to do
work
some energy ends up as _________, a type of _________________.
heat, kinetic energy
heat is the random motion of
atoms and molecules
as the arrow flies through the air, heat is generated by ___________ between the arrow and air molecules
friction
when the arrow strikes the target all the _______ becomes __________________.
energy, heat energy
the _______________ is rapidly transferred into the air and spreads out
heat energy
heat energy is a very disordered kind of __________
energy
heat energy has the highest amount of __________, or disorder, of any kind of energy
entropy
our bodies use the __________________ from food to perform work.
chemical energy
chemical energy is a form of
potential energy
when your body breaks down food molecules, the stored potential energy from food can be converted to
kinetic energy
the stored chemical energy in food is released in your ______________________ during the process of ___________________________
muscle cells, cellular respiration
using ___________, cellular respiration converts chemical energy from food to another form of chemical energy called ____
oxygen, ATP
water(H2O) and carbon dioxide (CO20) are by=products of
cellular respiration
the potential energy of _____ can be converted to _______________
ATP, kinetic energy
some of the _______________ is used to do useful work, such as pulling back a bowstring, but the _______________ that is generated cannot be used to do work.
kinetic energy, heat energy
The study of the energy transformations that occur in a collection of matter is called
thermodynamics
Scientists use the word ___________ to denote the matter under study; they refer to the rest of the universe—everything outside the system—as the ______________.
system, surroundings
An ____________________, such as that approximated by liquid in a thermos bottle, is unable to exchange either energy or matter with its surroundings outside the thermos
isolated system
an ________________, energy and matter can be transferred between the system and its surroundings.
open system
Organisms are
open systems
They _______________—for instance, light energy or chemical energy in the form of organic molecules—and release ______________________________, such as carbon dioxide, to the surroundings
absorb energy, heat and metabolic waste products
_______________ of thermodynamics govern energy transformations in organisms and all other collections of matter.
Two laws
the energy of the universe is constant: Energy can be transferred and transformed, but it cannot be created or destroyed.
first law of thermodynamics
The first law is also known as the
principle of conservation of energy
By converting sunlight to __________________, a plant acts as an ____________________, not an energy producer.
chemical energy, energy transformer
during every energy transfer or transformation, some energy becomes _______________ to do work.
unavailable
In the process of carrying out chemical reactions that perform various kinds of work, ________________ unavoidably convert other forms of energy to heat
living cells
A system can put this energy to work only when there is a ___________________________ that results in thermal energy flowing as heat from a warmer location to a ________________.
temperature difference, cooler one
If temperature is uniform, as it is in a living cell, then the heat generated during a chemical reaction will simply___________________, such as the organism.
warm a body of matter
used by scientists, has a specific molecular definition related to how dispersed the energy is in a system, and how many different energy levels are present
disorder
as a measure of molecular disorder, or randomness.
entropy
Every energy transfer or transformation increases the entropy of the universe.
second law of thermodynamics
entropy of the universe is more abstract, however, because it takes the form of
increasing amounts of heat and less ordered forms of matter.
by itself, leads to an increase in entropy, that process can proceed without requiring an input of energy
spontaneous process
when you read the formal term “spontaneous,” the word favored by chemists.
“energetically favorable”
A process that, on its own, leads to a decrease in entropy is said to be
nonspontaneous
Living systems increase the entropy of their surroundings, as predicted by
thermodynamic law
simpler molecules are ordered into the more complex structure of an amino acid, and amino acids are ordered into
polypeptide chains.
energy flows into most ecosystems in the form of _________ and exits in the form of _______
light, heat
we can trace the ancestry of the plant kingdom from much simpler organisms called
green algae to more complex flowering plants.
