biology EXAM #3 pt.2 Flashcards
The living cell is a
Cellular respiration extracts
Cells apply this energy to
Some organisms even convert
miniature chemical factory where thousands of reactions occur
energy stored in sugars and other fuels
perform work
energy to light, as in bioluminescence
An organism’s metabolism transforms ¡
Metabolism
Is the totality of an
Arises from
matter and energy, subject to the laws of thermodynamics
organism’s chemical reactions
interactions between molecules
A metabolic pathway has many steps
That begin with a ___________ and end with a ________
That are each catalyzed by a
specific molecule; product
specific enzyme
Change of free energy ΔG => free energy indicates
-ΔG then = ___________ reaction
+ ΔG then = __________ reaction
the portion of the system’s energy that can perform work when To and pressure are uniform throughout the system.
exergonic
endergonic
Catabolic pathways:
-Break down
-Release
- example of a pathway of catabolism?
complex molecules into simpler compounds
energy
Cellular respiration
Anabolic pathways:
consume energy to
For example, the synthesis of
Bioenergetics is the study of
build complex molecules from simpler ones
protein from amino acids is an anabolic pathway
how energy flows through living organisms
Energy:
Is the
Exists in various forms, of which some can perform work
Kinetic energy is _____ energy: is the energy associated with ________
Potential energy is _______ energy: is stored in the…
Includes energy stored in
-capacity to cause change
-solar energy; associated with motion
-chemical energy, food: location of matter
molecular structure
Thermodynamics:
Is the study of
According to the first law of thermodynamics – the principle of
Energy can be
Energy cannot be
*hacer flashcards de los law of thermodynamics
energy transformations
conservation
-transferred and transformed
-created or destroyed
According to the second law of thermodynamics – every…
Spontaneous changes that do not require outside energy increase
There is loss of usable energy in the form of ____
energy transfer or transformation increases the entropy of the universe
the entropy, or disorder, of the universe.
heat
Living cells unavoidably convert
Spontaneous processes occur without ____ _____; they can happen :
For a process to occur spontaneously, it must:
Processes that decrease entropy are _____________; they will occur only if :
organized forms of energy to heat, a more disordered form of energy
energy input; they can happen quickly or slowly
increase the entropy of the universe
nonspontaneous; they will occur only if energy is provided
Organisms create ordered structures from
Organisms also replace…with…
For example, animals consume complex molecules in their food and release smaller, lower energy molecules and heat into the surroundings
less organized forms of energy and matter
ordered forms of matter and energy in their surroundings with less ordered forms
Living systems: increase the…
Use energy to :
ATP- energy for … (meaning of the abvr)
Generated from:
ATP structure:
“_____ ______” compound because :
Releases:
entropy of the universe
maintain order
cells; Adenosine triphosphate; ADP + P
Modified adenine, ribose,
and 3 phosphates
“high energy” compound because
the terminal phosphate group is
easily removed
7.3 kcal per mole
Advantages of ATP as energy carrier:
Provides a
Breakdown of ATP to ADP+P releases
ATP breakdown is coupled to
-common energy currency for many reactions
-sufficient energy for biological processes- little wasted
-endergonic reactions in such a way that it minimizes energy loss
The free-energy change of a reaction tells us whether
A living system’s free energy is energy that
The change in free energy, ∆G during a biological process is related directly to the
the reaction occurs spontaneously
can do work under cellular conditions, when temperature and pressure are uniform, as in a living cell
system’s enthalpy change or total energy (∆H) and the change in system’s entropy (∆S)
ΔG is negative for all ___________ ___________; processes with zero or positive ΔG are never __________
spontaneous processes; spontaneous
Spontaneous processes can be harnessed to
Organisms live at the expense of
During a spontaneous change free energy …
perform work
free energy
decreases and the stability of a system increases
Free energy is a measure of
During a spontaneous change, free energy
Equilibrium is a
A process is spontaneous and can perform work only when
a system’s instability, its tendency to change to a more stable state
decreases and the stability of a system increases
state of maximum stability
it is moving toward equilibrium
Reactions in a closed system eventually reach
The concept of free energy can be applied to
equilibrium which is considered maximum stability and can then do no work
the chemistry of life’s processes
Cells are not in __________; they are:
A defining feature of life is that
A catabolic pathway in a cell releases
equilibrium; they are open systems experiencing a constant flow of materials
metabolism is never at equilibrium
free energy in a series of reactions
An exergonic reaction :
An endergonic reaction is one that :
net release of free energy and is spontaneous
absorbs free energy from its surroundings and is nonspontaneous
Cells in our body experience a constant flow of….., preventing :
flow of materials in and out, preventing metabolic pathways from reaching equilibrium
ATP powers
A cell does three main kinds of work:
cellular work by coupling exergonic reactions to endergonic reactions
Mechanical —such as contraction of muscle cells
Chemical —pushing endergonic reactions
Transport —pumping substances against the direction of spontaneous movement
To do work, cells manage energy resources by
ATP drives _________ reactions by ____________, which is:
The recipient molecule is now called a
Most energy coupling in cells is mediated by
by energy coupling, the use of an exergonic rxn to drive an endergonic rxn
endergonic reactions by phosphorylation, which is transferring a phosphate to other molecules
phosphorylated intermediate
ATP
The three types of cellular work are powered by:
In the cell, the energy from the exergonic reaction of
Overall, the coupled reactions are
the hydrolysis of ATP
ATP hydrolysis can be used to drive an endergonic reaction
exergonic
ATP is a renewable resource that is
The energy to phosphorylate ADP comes from
The ATP cycle is a revolving door through which energy
Catabolic pathways drive the :
renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP)
catabolic reactions in the cell
passes during its transfer from catabolic to anabolic pathways
regeneration of ATP from ADP and phosphate
A catalyst is a
An enzyme is a
Enzymes do not affect the change in ___________; instead, they:
chemical agent that speeds up a reaction without being consumed by the reaction
catalytic protein that speed up metabolic reactions by lowering energy barriers without being consumed by the reaction
free energy (ΔG); instead, they hasten reactions that would occur eventually
Induced fit of a substrate
The active site is the region on the enzyme where
Brings chemical groups of the active site into __________ that :
the substrate binds
positions that enhance their ability to catalyze the chemical reaction
Every chemical reaction between molecules involves:
An example of a chemical reaction is the
both bond breaking and bond forming
hydrolysis of sucrose
The activation energy
Is the:
Is often supplied
An enzyme catalyzes reactions by
initial amount of energy needed to start a chemical reaction
in the form of thermal energy or heat that the reactant molecule absorbs from the surroundings in a system
lowering the EA barrier
The enzyme binds to __ ________, forming an ____________
The active site can lower an EA barrier by:
(4)
binds to its substrate, forming an enzyme-substrate complex
1)Orienting substrates correctly
2)Straining substrate bonds
3)Providing a favorable microenvironment
4)Covalently bonding to the substrate
In an enzymatic reaction, the substrate binds to the
Enzymes are extremely
Very small amounts of enzyme can have
active site of the enzyme
fast acting and emerge from reactions in their original form
huge metabolic effects because they are used repeatedly in catalytic cycles
The catalytic cycle of an enzyme
1) Substrates enter active site; enzyme
changes shape so its active site
embraces the substrates (induced fit).
2) Substrates held in
active site by weak
interactions, such as
hydrogen bonds and
ionic bonds.
3) Active site (and R groups of
its amino acids) can lower EA
and speed up a reaction
4) Substrates are
Converted into
Products.
5) Products are
Released.
6) Active site
Is available for
two new substrate
Mole.
The activity of an enzyme is affected by
Each enzyme has an
Has an optimal ____ in which it can function
general environmental factors
optimal temperature in which it can function
pH
Cofactors - molecule which
-Are…
-_____ such as zinc, iron and copper in ionic and vitamins
Organic nonprotein cofactors are called
helps enzyme function
-nonprotein enzyme helpers
-Inorganic
coenzymes
Factors affecting enzymatic rate
Enzyme inhibition occurs when:
Activity of cell enzymes is regulated by
Ex: when product is abundant it binds to the enzyme’s active site and blocks further production
When product is used up, it is removed from the active site
In a more complex type of inhibition,
enzyme cannot bind its substrate
feedback inhibition
product binds to a site other than the active site, which changes the shape of the active site
Competitive inhibitors bind to the
Noncompetitive inhibitors bind to…., causing:
Some examples of inhibitors are:
active site of an enzyme, competing with the substrate
another part of an enzyme, causing the enzyme to change shape and making the active site less effective
toxins, poisons, pesticides, and antibiotics
Competitive inhibitors like:
Bind to the
morphine
active site of an enzyme, competing with the substrate
Noncompetitive inhibitors bind to
A noncompetitive inhibitor binds to the
enzyme __________________, altering
the….. so that:
another part of an enzyme, changing the function
away from the active site; altering
the conformation of the enzyme so that its
active site no longer functions.
Inhibitors act as
DDT, parathion, nerve gas – inhibitors of enzymes of the nervous system
Antibiotics – inhibit specific enzyme´s active site that produce cell walls of bacteria.
regulators of enzyme activity
Enzymes are
Changes (mutations) in genes lead to
Altered amino acids, particularly at the active site, can result in
proteins encoded by genes
changes in amino acid composition of an enzyme
novel enzyme activity or altered substrate specificity
Under environmental conditions where the new function is beneficial, natural selection would favor the mutated allele
For example, repeated mutation and selection on the β-galactosidase enzyme in E. coli resulted in a change of sugar substrate under lab conditions
Regulation of enzyme activity helps
A cell’s metabolic pathways must be ________, for example with:
control metabolism
tightly regulated, allosteric regulation and feedback mechanisms
Allosteric regulation is the term used to describe
Many enzymes are
any case in which a protein’s function at one site is affected by binding of a regulatory molecule at another site
allosterically regulated
Most allosterically regulated enzymes are made from
The enzyme complex has
The binding of an activator stabilizes the
The binding of an inhibitor stabilizes the
They change shape when
polypeptide subunits, each with its own active site
active and inactive forms
active form of the enzyme
inactive form of the enzyme
regulatory molecules bind to specific sites, affecting function
Cooperativity is a form of
One substrate molecule primes
Cooperativity is allosteric because
allosteric regulation that can amplify enzyme activity
an enzyme to act on additional substrate molecules more readily
binding by a substrate to one active site affects catalysis in a different active site
In feedback inhibition :
The end product of a metabolic pathway:
Feedback inhibition prevents
shuts down the pathway
a cell from wasting chemical resources by synthesizing more product than is needed
Within the cell, enzymes may be: (3)
Grouped into complexes
Incorporated into membranes
Contained inside organelles
Enthalpy =
(the sum of the internal energy E) + ( pressure p x volume V). Using the symbol H for the enthalpy:
H = E + p * V
