VOCAB TEST 2 Flashcards
A collection of machines, cytoskeletal components, and organelles that together produce, process, and transport proteins, and lipids destined for organelles, the cell membrane, or outside the cell
endomembrane system
a series of amino acids at the start of a protein that allows that protein to enter the endomembrane system
signal sequence
a protein that functions in cell movement through shape changes caused by phosphorylation or dephosphorylation
motor proteins
the addition of a phosphate group to a protein or other molecule. In most cases, the prosphate group comes from ATP.
phosphorylation
proteins move between the cytosol and the nucleus
through nuclear pore complexes
gated transport
protein translocators directly transport specific
proteins across a membrane from the cytosol to a space that is topologically
distinct
transmembrane transport
membrane enclosed transport vesicles ferry proteins
from one compartment to another that is topologically equivalent
vesicular transport
What has these functions
protein folding
modifications
ER
Destination of some
newly synthesized
proteins
● Materials brought in by
endocytosis
● Usually targeted to
lysosome
● Materials released by
exocytosis
Endosome
Path of newly
synthesized digestive
enzymes
● Site of degradation
lysosome
Further modifications
(glycosylation)
● Sorted into compartments
golgi
Motor proteins (kinesin)
direct vesicle to destination
(ATP dependent)
● Soluble proteins released
● Integral proteins embedded
in plasma membrane
secretory vesicle
secretion that does not require no special targeting sequence beyong the ER insertion sequence required for cotranslation translocation.
Constitutive secretion
the amount of free energy required to move a sequence of amino acids from a nonpolar solvent to water
hydropathy
If the hydropathy plot is positive the sequence is _______
hydrophobic
If the hydropathy plot is negative the sequence is ______
hydrophilic
The protein containing the mitochondrial targeting sequence, known
as a __________, is synthesized entirely in the cytoplasm.
- The presequence is always located at the N-terminus of the protein
and contains roughly 15–50 amino acids. This sequence is quite
specific to make the correct shape once it is translated.
presequence
Protein targeting to the mitochondrial matrix requires _______
ENERGY
Once the protein is inside the matrix of the mitochondria, the
_______ is removed by a proteolytic enzyme known as the
mitochondrial processing peptidase, or MPP.
presequence
In the mitochondria, chaperones assist with keeping the protein ______
unfold
The chloroplast __________ is cleaved by a stromal
processing peptidase (SPP), releasing the protein into the stroma of
the chloroplast
targeting sequence
________: energy related to interactions among charged particles
electrical energy
the energy of motion in ions and molecules, measured as temperature
thermal energy
energy that is related to an object’s positions
potential energy
conversion of substances into other substances via breaking and forming chemical bonds
chemical reaction
the total energy available to do work– a combination of entropy and thermal and potential energy
free energy
a phosphorylation reaction that makes a nonspontaneous reaction spontaneous, (it raises free energy of the reactants)
energetic coupling
- They are each specific to one reaction
- they each contain an active site where reactants bind and where the bond-breaking and bond-making required for the reaction actually occur
3.speed up reactions by bringing reactants together in an orientation that allows them to interact and then lowers the free energy present in the transition state - it is the same molecule before the reaction starts and after it ends
- do not affect the amount of free energy in reactant or products
ENZYMES
one that results in an increas in free energy; another way of referring to a nonspontaneous reaction
endergonic
one that results in a decrease in free energy; spontaneous reaction
exergonic
the amount of energy required to get a chemical reaction through its transition state
activation energy
during a chemical reaction, an intermediate state where old bonds are being broken but new bonds have not yet formed
transition state
a protein that catalyzes a chemical reaction
enzyme
the place on a enzyme (or ribozyme) where a reaction is catalyzed
active site
energy is transferred in a biological ssytem to harness energy for work
bioenergetics
enzymes changes shape slightly as substrate binds
INDUCED FIT
a measure of velocity that is independent of enzyme concentration
Kcat
The concentration of the enzyme-substrate complex ES remains constant over time. This means that the rate of formation of the ES complex is equal to the rate of its breakdown.
Steady-state assumption:
The initial rate of the reaction is measured, meaning that the concentration of the substrate is much higher than the concentration of the product, and the concentration of the enzyme-substrate complex is approximately constant.
Initial velocity assumption:
The Michaelis-Menten model assumes that the enzyme-catalyzed reaction involves a single substrate interacting with the enzyme to form an enzyme-substrate complex.
Single-substrate assumption
The reverse reaction of the substrate dissociating from the enzyme-substrate complex to form the enzyme and substrate again is negligible under typical conditions.
Reversibility assumption
[S]»[E] such that [S] is effectively constant when measuring the instantaneous velecoity
Substrate concentration
The Michaelis-Menten equation is as follows:
V= Vmax (concentration S) / ( Km + concentration S)
the study of rates of enzyme-catalyzed reactions
Enzyme kinetics
the amount of product produced per unit time at the start of the reaction
initial velocity
maximum rate of a reaction that is characteristic of a particular enzyme at a particular concentration
maximal velocity
the Michaelis-Menten constant, defined as the amount of substrate necessary to allow an enzyme to function at half its maximal velocity.
Km
a state in which all available enzyme molecules are already tied up processing substrates
saturation
a phenomenon in which a substrate molecule is prevented from binding to the active site of an enzyme by a molecule that is very similar in structure to the substrate.
competitive inhibition
a specific type of enzyme inhibition characterized by an inhibitor binding to a site on the enzyme that is not the active site, resulting in a decreased maximal velocity of the enzyme.
noncompetitive inhibition
Chemical reactions involving the gain (reduction) or loss (oxidation) of an electron.
Redox reactions
A multi-step process that uses energy captured from carbon oxidation to power ATP production via an electron transport chain and ATP synthase.
cellular respiration
A series of machines that uses an electric current to pump protons across a membrane, establishing a proton gradient that is then used to generate ATP.
Electron Transport chain
The multi-protein machine that transforms the kinetic energy in a flow of protons to mechanical energy that catalyzes the addition of a phosphate group to ADP to form ATP.
ATP synthase
A sequence of ten enzyme-catalyzed reactions that begins with glucose and ends with pyruvate, producing 2 ATP and 2 NADH per molecule of glucose.
glycolysis
A series of enzyme-catalyzed reactions that begins with pyruvate as a substrate and produces acetyl-CoA and NADH.
Pyruvate processing
A sequence of nine enzyme-catalyzed reactions that begins with acetyl-CoA, completes the oxidation of glucose to CO2, and produces ATP, NADH, and FADH2.
Citric acid cycle
Molecules that function as electron carriers during cellular respiration, meaning that they transport electrons to or within the electron transport chain.
NADH, FADH2, Q
A pathway that transfers electrons from NADH to a carbon-based molecule to regenerate NAD+ and keep glycolysis running to produce small amounts of ATP.
Fermentation
Cellular respiration that uses O2 to accept electrons from the electron transport chain and produces water as a byproduct.
Aerobic respiration
Cellular respiration that uses any ion or molecule other than O2 to accept electrons from the electron transport chain.
Anaerobic respiration
involves the breakdown of complex molecules such as
carbohydrates, proteins, and fats into simpler substances
catabolism
involves the synthesis of complex molecules from
simpler substances.
- It requires energy input and is responsible for the production of
molecules such as proteins, nucleic acids, and carbohydrates needed
for cellular growth, repair, and maintenance.
anabolism
molecules that increase the activity of an enzyme
activators
molecules that decrease the activity of enzyme
inhibitors
any form of regulation where the regulatory molecules binds to an enzyme someplace other than the active site
allosteric regulation
the place where the regulator binds in allosteric regulation
allosteric site
the substrate itself can serve as an allosteric activator: when it binds to one active site, the activity of the other active site goes up
cooperavity
helper molecules that bind to enzymes
cofactors
a subset of cofactors that organic molecules
coenzymes
the end product of a metabolic pathway acts on the key enzyme regulating entry to that pathway, keeping more of the end product from being produced.
feedback inhibition
The movement of a metabolite through a pathway over time
metabolic flux
________ reactions are insensitive to changes in concentration and regulated by different mechanisms
irreversible
A process that transforms light energy into chemical energy — meaning the potential energy found in electrons that participate in covalent bonds, usually in sugars or other carbohydrates.
photosynthesis
A molecule that absorbs specific wavelengths of light.
Pigment
The primary photosynthetic pigment in land plants and most algae.
chlorophyll
A complex of molecular machines that acquire electrons by oxidizing water, use the energy in sunlight to excite those electrons to a high-energy state, and pass them on to an electron carrier that feeds the electron transport chain, leading to ATP production by ATP synthase.
PSII
A complex of molecular machines that receive low-energy electrons at the end of the electron transport chain, use the energy in sunlight to excite those electrons to a high-energy state, and pass them on to electron carriers that either feed the electron transport chain or an enzyme that catalyzes the reduction of NADP+ to NADPH.
PSI
A series of reactions that results in carbon from CO2 being “fixed,” or reduced, and used to synthesize sugars.
calvin cycle
the openings in the epidermis that are not covered in wax where CO2 and O2 can diffuse out.
stomata
The enzyme that catalyzes the reduction of CO2 and its incorporation into sugars.
Rubisco
the process by which ATP is synthesized using the movement of protons acoss a membrane, driven by a proton gradient
Chemiosmosis
What is the signal recognition particle?
a complex present in the cytosol or associated with the cytosolic side of the ER membrane
