First Exam; Practice Exam Flashcards
What hormones bind to intracellular receptors?
Steroids
List the events of cAMP in order
Alpha subunit binds to adenylyl cyclase, cAMP is produced, cAMP binds to protein kinase, phosphate groups are attached to enzymes, phosphodiesterase breaks down cAMP
Name four different second messengers
cAMP, DAG, IP3, and CGMP
When is a G protein active?
When GTP is bound to it
The cholera toxin doesn’t allow GTP to be hydrolyzed to GDP. What effects would you expect to see in the cell?
The activated G proteins would remain locked in the “on” position, transmitting signal even in the absence of a signaling molecule
What converts ATP to cyclic AMP?
Adenylate Cyclase
What event would activate a G protein?
The replacement of GDP with GTP
Cholera develops when the bacterial toxin _______________
prevents G-protein inactivation, which leads to the continuous production of cAMP
During the transduction of a signal, one molecule or ion may be closely associated or interact with the activity of another. What are 4 examples of correctly combined molecules?
Calcium-IP3, cAMP-adenylyl cyclase, cAMP-protein kinase A, and DAG-IP3
What’s the difference between the mechanisms of cAMP and Ca2+ in signal transduction?
cAMP is synthesized by an enzyme in response to a signal, and Ca2+ is released from intracellular stores
What is IP3 produced as a result of?
IP3 is produced as a result of protein kinase A activation
What does IP3 do?
It opens CA2+ channels
What is the general name for an enzyme that transfers phosphate groups from ATP to a protein?
Protein kinase
What do G protein coupled receptors rely on? Examples?
G protein coupled receptors rely on second messengers such as Ca2+, cAMP, phosphatidylinositol, and cGMP to activate or inactivate a variety of pathways within the cell.
In an endothermic reaction, is the chemical potential energy lower in the reactants than in the products?
Yes
What is true of an endergonic reaction?
The reaction isn’t spontaneous and is accompanied by an increase in Gibb’s free energy (🔺G > 0), and the value of 🔺G provides a measure of the amount of free energy needed to drive the reaction
Define work
When energy is transferred from one body place to another
What is bond energy measured in? What two things is it equal to?
Bond energy is measured in kJ, and is equal to the minimum energy required to break one of the bonds between two types of atoms. It’s also equal to the amount of energy released when a bond is formed
Name 5 ways in which entropy can increase during a chemical reaction
- Liquid reactants become gaseous products, 2. Solutes move from an area of high concentration to an area of low concentration until they’re uniformly distributed in the volume 3. complex molecules react to form simpler molecules, 4. fewer molecules of reactant molecules form a greater number of moles of product molecules, and 5. solid reactants become liquid or gaseous products
Most of the reactions of metabolism are a series of chain reactions in which the product of one reaction is the reactant of another reaction. What happens to the final product of the chain?
It’s released into the external environment
What does the second law of thermodynamics state?
That the entropy of the universe increases with any change that occurs
True or false: Living things build up their bodies and the world around them. They do this at the expense of the entropy of the universe as a whole.
True
Define Gibbs free energy
Energy that can do useful work
True or false: The free energy release of ~54kJ/mol in a living cell ATP reaction makes it a relatively poor source of energy for driving endergonic processes in the cell
False
True or false: A cell whose reversible reactions have reached equilibrium is a living cell.
False
A diver jumps off a diving tower. When will the diver have the highest kinetic energy?
Just when the diver approaches the water
The substance that loses the electron is oxidized, and then the substance that takes the electron is called the ______ agent
Oxidizing
Adenosine triphosphate is the secondary source of free energy in living cells
False
Define a catabolic reaction
A reaction that results in the breakdown of complex substances
What does the first law of thermodynamics state?
That the total amount of energy in the universe is constant, and that if an object/process gains an amount of energy it does so at the expense of a loss in energy somewhere else in the universe
True or false: nature does provide energy in a readily usable form
False
Define a transition state
A temporary condition in which the bonds within reactants are breaking and bonds between products are forming
When a reaction results in a net energy output, what is it called?
An exothermic reaction
True or false: A reaction that’s spontaneous in one direction is also spontaneous in the reverse direction
False
What are two factors that need to be taken into consideration when determining whether a given chemical or physical change will occur spontaneously?
Energy and reaction rate
Define phosphorylation
An increase in reactivity of phosphate groups
True or false: In an exothermic reaction, the chemical potential energy is higher in the reactants than in in the products
True
True or false: all of the energy that ever existed on earth will disappear when it experiences a heat death
True
True or false: since an electron moves to successively stronger electron acceptors, free energy is released in every step of the process
False
True or false: the value of delta H is negative in exothermic reactions, and positive in endothermic reactions
True
In exothermic reactions, is delta H positive or negative?
Negative
Josiah Willard Gibbs discovered the relationship between what?
The relationship between energy change, entropy change, and temperature of a reaction
True or false: living organisms obey the second law of thermodynamics
False
Define entropy
The amount of heat released by a chemical reaction
What does Adenosine triphosphate include/ what are its parts?
A pure nitrogenous base (adenine) attached to a five-carbon sugar (ribose) and three phosphate groups
Define cellular respiration
A series of biochemical reactions that use glucose to make ATP
Where in the cell does glycolysis occur?
The cytoplasm
During glycolysis, 6-carbon glucose is broken down into what?
2 molecules of 3-carbon pyruvic acid or pyruvate
How much net ATP does glycolysis produce?
2 ATP
When oxygen isn’t present, fermentation may be used to break pyruvate into what three things?
Ethanol, carbon dioxide, and lactic acid
When oxygen is present, pyruvate enters the Krebs cycle. Where in the eukaryotic cell does this occur?
The mitochondria
Oxidative decarboxylation links glycolysis to the Krebs cycle. Pyruvate is oxidized into what two things?
Carbon dioxide and acetyl-CoA
What links glycolysis to the Krebs cycle?
Oxidative decarboxylation
What does oxidative decarboxylation link?
It links glycolysis to the Krebs cycle
Where can the electron transport system be found in animal cells?
The mitochondria
Where can the electron transport system be found in plant cells?
Chloroplasts
Where can the electron transport system be found in bacteria?
The plasma membrane
Which is more effective, aerobic metabolism or anaerobic metabolism?
Aerobic
How many ATP molecules theoretically can be generated by the complete oxidation of glucose into carbon dioxide?
36-38
Which of the following is a product of the Calvin cycle: carbon dioxide, NADP+, oxygen, or FADH2?
NADP+ is a product of the Calvin cycle
Where do the light-dependent reactions take place?
Stroma
What are photosystems?
Functional pigment groups
Where are photosystems located?
On the membranes of the thylakoids
What happens in the fluids of the vacuoles?
The Calvin cycle begins
Where does the Calvin cycle begin?
In the fluids of vacuoles
What does oxygen bind to during photorespiration?
RuBP
What happens in the light-dependent reactions?
ATP and NADPH are formed
What is the green pigment in plants that absorbs the sun’s energy?
Chlorophyll
What are the light dependent reactions of photosynthesis associated with?
The thylakoids of the chloroplasts
What happens in the photosynthetic reaction center?
Electrons are energized
Where does the oxygen released during photosynthesis come from?
The splitting of water molecules
In a noncyclical electron flow, what happens to the electrons that leave the chlorophyll?
They’re used to turn NADP+ into NADPH
What are four things that happen during light-independent reactions?
NADPH is required, carbon dioxide is fixed in organic molecules, energy in the form of ATP is used, and glucose is formed
In the C3 cycle, what is carbon dioxide combined with?
RuBP
The C4 pathway occurs in plants that are adapted to what?
Conditions of low moisture and intense sunlight
What does ATP stand for?
Adenosine triphosphate
