Exam #3 Flashcards
There’s no input of energy in ________ transport.
passive
What are the two modalities of passive transport?
Simple diffusion and facilitated diffusion
What is the difference between simple diffusion and facilitated diffusion?
Simple diffusion: from high to low directly across a lipid bilayer without the assistance of any other molecule.
Facilitated diffusion: from high to low with the assistance of a transport protein
Most of the substances we need to get into the cell are _____/and or _______
polar and or charged
What are the two types of transport proteins?
Channels and carriers
Ions, which you may know as electrolytes…move through _______ _______.
channel proteins
Does water diffuse across a pure lipid bilayer?
Not easily, it is partially blocked
What are the water channels called to help in water diffusion?
Aquaporins
Water moves to areas of ______ solute concentration
higher
Water moves to where the solutes are _____ in concentration
higher
Water balance, also called ____________, is a primary level of homeostasis that all life must maintain
osmoregulation
Protists maintain osmoregulation by expelling excess water using a ________ _______.
contractile vacuole
As water comes in, the ____ ______ protects the cell from bursting
cell wall
What’s the difference between a hypotonic and a hypertonic solution?
Hypotonic: low solute concentration, water flows into the cell
Hypertonic: high solute concentration, water flows out of the cell
Which of the three (hypotonic, hypertonic, isotonic) environments does a plant prefer?
HYPOTONIC
Channels are _____ protein completely spanning the membrane
integral
Channels have a ________ pore that recognizes ____ type of solute
hydrophilic, ONE
All proteins have an elaborate confirmation…but some proteins have the ability to…..
change confirmation
A ______ protein can change its confirmation, and in so doing, it allows a solute to pass through
carrier
Now, who MOVES into cells this way?
Sugars. Glucose….
Now, who MOVES into cells this way? Sugars. Glucose….through the ______ transporter…fructose through the ______ transporter
glucose, fructose
Do lipids need channels or carriers?
No, they go right through
If we have this way of bringing sugar into the cell, why do we need active transport?
If the sugar is not high in the environment, which won’t always be the case…in which case WE GOTTA FORCE!
WE NEED THAT GLUCOSE! WE NEED IT NOW!
Monosaccharides (sugars) and amino acids use _______
carriers
Carriers are ______ membrane protein…_____ and _____ molecules.
integral. polar and charged molecules
What are the two types of active transport?
Primary (1º) active transport
Secondary (2º) active transport
Primary (1º) active transport is the way we concentrate _____ through via ____ ______
ions via ion pumps
What is the energy that drives ion pumps?
ATP
Where do you find a concentration of sodium about the cell? Inside or outside the cell?
OUTSIDE
In your body, your cells have more ______ outside, than inside.
sodium
Where do you find a concentration of potassium about the cell?
INSIDE
______ out, ________ in
Sodium, potassium
The sodium/potassium pump moves sodium ____ of the cell and potassium ____ the cell
out, into
What source of energy? (Na/K pump)
ATP
ATP has three phosphates on it…by breaking off a phosphate, you liberate _______
energy
So ATP becomes ___ and a _____ _______ _______
ADP, free inorganic phosphate
The Na/K Pump is essential to maintaining ___________ in animal cells
osmoregulation
Secondary (2º) active transport involves the movement of ____ substances.
two
What are those two substances?
1) The MOLECULE you’re intending to transport
2) The ION that’s driving the transport
Since two substances are always transported by secondary active transport, sometimes it’s called “__________”, since you’re actually moving two substances across the membrane at the same time.
“co-transport”
How is the sodium providing energy for the glucose to come in? What’s so energetic about this sodium ion?
It is arranged in a GRADIENT. There’s more outside than inside, it wants to go down!
So how does the ion provide energy?
It’s in a gradient
Does secondary (2º) active transport require ATP?
NOOOOOO
Is primary (1º) active transport driven by ATP?
YESSSS
Source of energy….. (direct/indirect ATP use)
Primary (1º) active transport:
Secondary (2º) active transport:
Primary (1º) active transport: direct ATP use
Secondary (2º) active transport: indirect ATP use
Plant cells do it another way…they have primary active transport that pumps _______ outside of the cell.
protons
What fuels secondary active transport?
Proton gradient
It’s always an ____ _______ providing that energy.
ion gradient
Channels can be referred to as “_____.”
static
We have a way of forcing a substance up the concentration gradient. How does that work? Well, you provide ______,. Either the energy is ___, and that’s going to generally pump ______ across the membrane.
Or the second way it could work is _________ _______ ______ where we use an ____ gradient as a source of energy.
energy, ATP, ions, secondary active transport, ion
We can move stuff out of the cell, or bring stuff in. If we move stuff out, we call that ________. If we move stuff in, we call that _________.
exocytosis, endocytosis
Exocytosis is simply ________
secretion
_________ is an example of endocytosis. “Eating”
Phagocytosis
Phagocytosis is generally ___-______. A lot of substances can come into the cell by phagocytosis
non-specific
Receptor mediated endocytosis depends upon a ______ in the cell membrane.
receptor. What type of molecule is a receptor? It’s a PROTEIN.
So receptor mediated endocytosis is a very ______ mechanism of transport
specific
Energy that is available is called ______ _______.
free energy
What fuels metabolism?
Free energy
The building of biochemistry is what?
Anabolism
The breakdown of biochemistry is what?
Catabolism
Catabolism provides _______.
energy
_______ requires energy.
Anabolism
What is thermodynamics?
The study of energy transformation
A system that is capable of taking energy from the surroundings, or releasing energy into the surroundings is referred to as an _____ system.
open
What type is the cell?
Open system
What does the first law of thermodynamics say?
Energy cannot be created, it can only be transformed
What’s one word that can describe the first law of thermodynamics?
Transformations
What does the second law of thermodynamics say?
In all those transformations, the universe will increase in its disorder
Any transformation, the universe will increase in disorder, which is symbolized by the letter _ which is referred to as what?
S, entropy
G = ?
Free Energy
H = ?
Total Energy
T = ?
Temperature
S = ?
Entropy
What is the equation to calculate free energy?
G = H - TS
Free energy = Total Energy - Temperature*Entropy
If the energy of the product is less than the energy of the reactant, then the delta G value becomes ________, which means energy must have been _________.
negative, released.
If the energy of the product is greater than the energy of the reactant, then delta G becomes _________, which means energy must have been _________.
positive, absorbed
If Delta G is negative…
1) Endergonic or exergonic ?
2) H and S ( which increases, which decreases) ?
3) Stability
4) Favorable/Non favorable?
5) Spontaneous/Non spontaneous?
1) Exergonic
2) H decreases, S increases
3) More stable
4) Favorable
5) Spontaneous
If Delta G is positive…
1) Endergonic or exergonic ?
2) H and S ( which increases, which decreases) ?
3) Stability
4) Favorable/Non favorable?
5) Spontaneous/Non spontaneous?
1) Endergonic
2) H increases, S decreases
3) Less stable
4) Non favorable
5) Non spontaneous
If the system is at equilibrium… Delta G?
Delta G is 0, reached maximum stability and is no longer capable of doing work. Means death lol
If you breakdown starch…exergonic or endergonic?
Exergonic, release of energy
No process is perfect, we always lose some energy as _____.
heat
This is stated in the second law of thermodynamics, every process increases the S of the universe because…..?
you lose heat
What is an example of a catabolic process?
The hydrolysis of sucrose
Catabolism releases _______ energy in nutrients and provides that energy for _________.
chemical, anabolism
_______ fuels ________.
Catabolism fuels anabolism
Catabolism fuels anabolism but…it does not do so directly. You don’t dismantle glucose every time you need energy. This is not efficient.
**Catabolism provides energy to make ____. *** Which in turn serves as the immediate source of energy for anabolism.
ATP
ATP is a _________.
nucleotide
ATP, in particular, is one of the four nucleotides used to make ___. The one with a in it…which is ?
RNA, adenosine (adenine —> base)
What are the components of a nucleotide?
Base, sugar, phosphate
Three units of negative charge on the phosphates that are all in close proximity…what do they want to do?
Move apart. Like charges repel
They would like to repel and come apart, but they can’t…because the ________ bond holds these phosphates together. The only way to liberate a phosphate is if you _____ the covalent bond…________ ATP…that’s how the energy gets released.
covalent, break, hydrolyze
Adenosine refers to the base adenine plus the sugar ______.
ribose
ATP hydrolysis is endergonic/exergonic?
EXERGONIC, provides energy
What is Pi?
Inorganic phosphate
If you put energy on the product side, you show that this is ________. Delta G will be _______.
Exergonic, negative
___ kcal/mole is released when a mole of ATP is hydrolyzed
-7.3kcal/mole
How is the ATP used to do work?
ATP hydrolysis is coupled to endergonic reaction, allowing it to move forward
Delta G will be positive…endergonic…_____ kcal/mole
+3.4 kcal/mole
Would the hydrolysis of 1 mole of ATP provide enough energy?
YES. The absolute value of 7.3 is greater than 3.4, therefore there’s enough energy.
If you add -7.3 + 3.4, you get a negative value. A negative value means…?
you have enough energy
How does coupling work?
Glutamic acid + ATP…when they react, a phosphate comes off of the ATP, which becomes ADP, and sticks onto the Glutamic acid. When it does that, the glutamic acid now becomes reactive. It’s now easy to replace that phosphate with an amino group. And now you have glutamine
It works through phosphorylation of a reactant.*
What does phosphorylation do?
Adding a phosphate covalently makes that compound unstable, makes it reactive…whenever you have a phosphate, that means you have energy.
How does the Na/K pump function?
Through conformational change
The Na/K pump was _________ in order to drive the conformational change
phosphorylated
Using ATP means _________ it.
hydrolyzing
What do we hydrolyze ATP into?
ADP and inorganic phosphate
Energy from catabolism is…
Energy from anabolism is…
exergonic
endergonic
Using ATP means breaking it down into ____ and ______ _______ and then making it again which means…
ADP and inorganic phosphate
…putting ADP and inorganic phosphate back together
We make ATP through _________
catabolism
What is the most efficient form of catabolism?
Cellular respiration
What is a less efficient, effective way of catabolism?
Fermentation
What do all reactions have in effect?
An energy barrier
The energy barrier is the energy to ______ bonds.
breaks
The barrier makes reactions _______.
slow
An energy barrier must be _______ for every single reaction.
overcome
How do we increase the rate of a reaction?
Use a catalyst
What’s an example of a catalyst?
Heat
Why is it not a good idea to apply heat to cells?
1) denaturing proteins
2) no specificity
What is the biological solution/catalyst?
We accomplish catalysis with ENZYMES.
Enzymes do not damage cells. Moreover…they’re very specific for the reaction we desire.
T/F: There’s an enzyme for every biochemical reaction
TRUE
How do enzymes work?
They will reduce the activation energy, allowing reactants to go to products at the ambient temperature of the cell
____ __ is unaffected by enzyme.
Delta G
Delta G is the change in energy from the _______ to the ______.
reactant, product
Enzymes reduce Ea without altering _____ __.
Delta G
By recognizing that enzyme doesn’t alter delta G, we’re saying it doesn’t change the need for energy that _________ reactions have. Endergonic reactions where the reactant is here, and the product is here. This reaction has a delta G that is positive. Adding the enzyme doesn’t take you there.
endergonic
The enzyme doesn’t provide energy to a reaction that _______ it. If you’re endergonic, you need a source of energy, ATP…and you need an ______ so that it happens quickly. So these are two separate requirements…the need for energy in a non spontaneous process…and the need for catalysis, so it happens quickly.
requires, enzyme
Do enzymes provide energy?
No, they lower Ea.
Who couples the endergonic to the exergonic?
Enzymes.
Enzymes enable ________.
coupling
Enzymes are ________. It is a requirement of a true catalyst.
reusable
T/F: An enzyme can be turned on and off. It’s regulated.
TRUE
Enzymes are a type of _______.
Protein…typically…
What other alternative is there for an enzyme? Besides a protein…
Nucleic acids…can also serve as a catalyst. More specifically RNA
RNA can be an enzyme
The _______ is the reactant that binds to the enzyme.
substrate
Where it binds to the enzyme is called the _______ site.
active. It’s where the reaction is catalyzed.
Enzymes often end in -____.
-ase
Sucrase is the specific hydrolase that hydrolyzes _______.
sucrose
How does the substrate bind to the active site? It binds how?
binds by weak interactions, forming an enzyme-substrate complex
Once the products of glucose and fructose are released, the enzyme is _______.
reused/recycled
How do enzymes accomplish this reduction of the Ea? What is actually happening to do that? (3)
Depends on the Enzyme…
1) Some enzymes will orient substrates so that the reaction can happen
2) Stress covalent bonds so that they may be broken
- That’s what sucrase does to sucrose, the bond has been bent, which makes it easier to break the bond
3) Create a microenvironment
- You can get the electrons to begin to flow in the direction to allow the reaction to happen
T/F: Enzymes make endergonic reactions exergonic.
FLASE!!! Recall, if a reaction is endergonic, you need energy. You need fuel. You need another reaction that is exergonic so that it can be coupled. In addition to that, you need the enzyme which is what couples the reaction and makes it fast.
So the enzyme couples reactions, and speeds it up.
As the substrate concentration increases, the reaction rate _______.
increases. If there is more substrate, it will more often find and bind to the enzyme and convert to product more quickly
T/F: As long as you give more substrate, the reaction will always go faster.
FALSE! Once you’re at a concentration that you’ve filled every single active site, the rate of the reaction will no longer increase
When you effectively max out the capacity of the enzyme. We say that the enzyme is then __________.
saturated
Is there anything we can do once the enzyme is saturated to make it go faster?
Add more enzyme, which will provide more active sites for the substrates to bind to
As the concentration of enzyme increases, so the ________ rate.
reaction
As the temperature increases, the reaction rate ________.
Increases
Our _____ temperature is the maximum rate for enzymes.
body
After 37 degrees C (98.6 deg F), the reaction rate drops off quickly. Why?
Denaturation of protein. If the temperature goes too high, you will break the weak interactions and the protein will unfold. There’s no active site if the enzyme is denatured.
Every enzyme has an optimal _________.
Temperature. Every enzyme has an optimal temperature where they operate most efficiently
Enzyme function also depends on __.
pH. Important for enzyme conformation
The enzyme that functions in your stomach has an optimum pH of __.
- That’s where it’s most active
Why does the stomach become acidic during digestion?
It’s all about the digestion of protein. The stomach is for the digestion of protein. Which is typically in a globular form. A globular form is hard to digest. So you change the pH drastically so the enzyme denatures…and now the hydrolyses can now cut the protein because it’s vulnerable.
The situation when a molecule is blocking the active site is called _________ _________.
competitive inhibition
If a molecule binds to an allosteric site, it changes the shape of the enzyme, which…
turns the enzyme off. It changed the shaped. Structure determines function.
Competitive inhibition involves an _______ site.
active
Noncompetitive inhibition involves an _________ site.
allosteric, means “other shape”
Allosteric regulation can either work _______ OR _______.
positively or negatively
If it’s negative, we call that __________ __________.
noncompetitive inhibition
Which one may be countered by increasing substrate concentration? Competitive inhibition or noncompetitive inhibition?
Competitive inhibition. If the inhibition is working this way…adding more substrate can outcompete the inhibitor.
In biology, when we say “two molecules bind,”…they also _____ _____. Remember, weak interactions are ________. Bind, come apart, bind, come apart. Yes, the inhibitor is binding and blocking the active site, but a moment later it will come off. And if there’s more substrate, guess who’s going to bind next? Substate and not the inhibitor. It is possible to outcompete the inhibitor by adding more substrate.
come apart, reversible
Do all enzymes have active sites?
Every enzyme has an active site, it’s not an enzyme without an active site
Do all enzymes have allosteric sites?
NO, that’s going to depend on the enzyme.
What is the regulatory molecule?
You get a snake bite and the poison might be the inhibitor.
The inhibitor might be something that’s already in your body that’s blocking the active site.
Is it necessary to regulate all the enzymes of a pathway?
Lets say we have a pathway with 5 enzymes…if we want to shut this pathway off, must we inactivate all 5 enzymes? How could we do this in a more efficient way?
There’s a mechanism to shut off a pathway. An entire pathway…using the final product of the pathway. Shut off a pathway using the final product. This is referred to as FEEDBACK INHIBITION.
Isoleucine is made from threonine in __ steps.
5
It takes 5 steps to make isoleucine.
Enzyme #1 has an ________ site. The allosteric site is complementary to the shape of isoleucine. So isoleucine can bind to that enzyme, and inhibit it. What’s the effect on that binding inhibition?
allosteric. You turn off the enzyme.
What happens if you shut off enzyme one?
You no longer make your product.
So we’ve shut off an entire pathway through the _______ of that pathway, which ______ back either the first enzyme or a very early enzyme in the pathway. This is called _______ inhibition.
product, feeds, feedback
By turning off key enzymes, you can shut down entire _______.
pathways
Where an enzyme is ________ can affect the rate of an enzyme catalyzed reaction
located
Describe three ways that cells localize their enzymes for more efficient functioning in metabolic pathways
1) In organelles
2) As membrane proteins
3) In multi-enzyme complexes
ATP hydrolysis can be COUPLED to an endergonic reaction to make that reaction happen. For example, an unfavorable reaction with a delta G of ____ could be driven (or fueled) by a mole of ATP.
a) +5.5 kcal/mole
b) +8.0 kcal/mole
c) -14.6kcal/mole
d) -7.3 kcal/mole
e) 0 kcal/mole
+5.5 kcal/mole. The delta g of ATP hydrolysis - an exergonic reaction - is -7.3 kcal/mole. ATP hydrolysis can be used to fuel an endergonic reaction - one with a positive delta G - that requires LESS THAN 7.3 kcal/mole
During coupling, HOW is ATP actually used to make a reaction happen?
A phosphate is transferred from ATP to a reactant.
_________ is the basic mechanism by which ATP is used to do work.
Phosphorylation
Either a _______ or a ______ may be phosphorylated.
reactant or a protein
In steps _ and _ of glycolysis, phosphorylation is used to boost the energy of metabolic intermediates.
1 and 3
How exactly does ATP drive the sodium-potassium pump?
A phosphate is transferred from ATP to the pump
Does allosteric regulation STIUMULATE or INHIBIT an enzyme’s activity?
Either stimulates or inhibits
Isoleucine biosynthesis is regulated by FEEDBACK INHIBITION; an early step of its metabolic pathway is blocked at high concentrations of _________.
isoleucine
If the activity of threonine deaminase is completely inhibited, would you expect greater concentrations of threonine to increase activity?
No, greater concentrations of threonine would not be able to out-compete the inhibitor, so inhibition would continue. Competition between the substrate and the regulatory molecule occurs when both molecules are capable of binding to the active site; this is known as competitive inhibition
Threonine deaminase binds threonine through _____ interactions.
weak
How are lysosomal hydrolyses localized in a cell?
They are confined together within an organelle
