Biology for Majors- Exam 2
Reactant
(left side) A substance or molecule that participates in a chemical reaction that results in a product
Product
(right side) A substance that results from a chemical reaction
Identify the form of energy of each: -serving of beans -campfire -hike -stream with waterfall -wood stump to be chopped
-potential energy -Kinteic energy -kinetic energy -kinetic energy -potential energy
How many ATP are produced by fermentation
0
products of photosynthesis
02 and glucose
A single turn of the Kreb Cycle will yield__________
1 ATP, 3 NADH, 1 FADH2
Number of NADH molecules produced in glycolysis
2
Number of pyruvate molecules are produced in glycolysis
2
Used to activate glucose in glycolysis
2 ATP
What is the net gain of ATp produced in glycolysis?
2 ATP
Net yield of ATP per glucose molecule
2 ATP from glycolysis, 2 ATP from Citric Acid Cycle, 32 ATP from ETC
The net result of a single round of glycolysis is the formation of___________?
2 NADH and 2 ATP
The initial reaction of the Krebs Cycle involves the addition of a ____________________
2 carbon molecule to a 4 carbon molecule
Chemical formula for photosynthesis
6CO2 + 6H2O +light energy -----> 6O2 + C6H12O6 (Carbon dioxide +water +sunlight) ---> Oxygen + glucose)
What is a metabolic pathway?
A metabolic pathway begins with a particular reactant, proceeds through several intermediates, and terminates with a particular end product.
If Enzyme 1 (E1) is inactive, which of the following compounds will accumulate? A-(E1)---->B- (E2)---->C
A only - substrate A gets converted to product B (by E1) and that product serves as the substrate for E2, which becomes product C. If E1 is inactive,product B will never be made. No matter how much substrate A is pushed into the system product B will never be made. Substrate A would accumulate.
An anaerobic process
A process without oxygen
Why is the formation of ATP by ATP synthase known as oxidative phosphorylation?
A proton gradient created by the redox reactions of the electron transport chain is used to drive the synthesis of ATP.
substrate level phosphorylation (ADP phosphorylation)
ADP +P ----> ATP (adding a phosphate to take from diphosphate to triphosphate)
What is a high energy compound that is used to drive metabolic reactions?
ATP
What is the enzyme used to synthesize ATP?
ATP Synthase
If the inner mitochondrial membrane was freely permeable to protons H+, what would be the most devastating result to the cell?
ATP would not be produced by oxidative phosphorylation
The products of light dependent reactions
ATP, NADPH, O2
Before entering the Krebs Cycle, pyruvate is converted to _______________?
AcetylCoA
What is an ATP molecule composed of?
Adenine, Ribose, and three phosphates
If E1 is inactive, which compound will become deficient ? A-(E1)---->B- (E2)---->C
B and C (If A is not converted to B, B will be deficient. If B is deficient, it cannot be converted to C, which will also become deficient)
Why is chlorophyll green?
Because it absorbs much of the reds and blues of white light from the spectrum and reflects the green.
How many turns will the Calvin cycle make to form sugars?
Because of the amounts of reactants, the cycle will make 6 turns
How do C4 plants solve the problem of photorespiration?
By fixing Carbon Dioxide to a C3 molecule
The formula for cellular respiration
C6H12O6 + 6O2 ---> 6CO2 + 6H2O + ATP (Glucose + Oxygen ---> Carbon dioxide + water + ATP)
Which plants fix carbon by different day and night cycles?
CAM plants- during the day stomata close for water conservation, and NADPH and ATP are available with c4 plants releasing CO2 to the Calvin cycle. At night, car on dioxide is fixed and stored in Vacuoles as C4 molecules.
The product when an organic molecule is oxidized
CO2
light independent
Calvin cycle
Products of light independent reactions
Carbohydrate
What happens in plants when light production is stopped?
Chlorophyll absorbs light energy and when production is stopped, leaves will shed.
Highest to lowest energy
Cytochrome C, Cytochrome C oxidase, Oxygen
When forests are destroyed, they do not easily regrow. What is one issue that could result from the destruction of these forests?
Decreased production of oxygen worldwide
Describe the Calvin cycle?
During the Calvin cycle (dark) reactions CO2 attaches attaches to an RuBP molecule to form a six carbon molecule. This six carbon molecule then splits into 3PG. 3PG then reduces to BPG which reduces to G3P.
How does H+ get across the thylakoid membrane?
Electrons in the thylakoid space yield energy from oxidation of water to pump H+ across the thylakoid membrane
What re proteins that function as catalysts?
Enzymes
How do plants respond to hot weather?
In plants, during hot weather stomata will close to avoid wilting
Where do the light independent (Calvin cycle) reactions occur?
In the stroma (fluid surrounding the Grana)
Where does light reaction occur? (light dependent)
In the thylakoid of the chloroplast
What is the model called that demonstrates how the active site changes as the enzyme and substrate complex come together?
Induced Fit Model
As the enzyme and substrate complex come together, what happens to the active site?
It changes shape in order to hold the substrate in the right position for the reaction to occur
When sucrase binds to sucrose, wat happens?
It goes through a conformational change (sucrase is the enzyme for sucrose. When they bind, sucrase changes shape to fit the sucrose)
What is the change in free energy of the cleavage of sucrose into glucose and fructose?
It is negative (it is spontaneous-does not need ATP) and the reaction is exergonic (has a negative change in free energy)
What is the sum of all cellular chemical reactions in a cell?
Metabolism
What does fermentation provide for glycolysis?
NAD+
Electrons are brought to the Electron Transport System by the oxidation of
NADH and FADH2
The final electron acceptor in the ETC
O2 (reduced to form H2O)
What happens in plants when the stomata closes?
O2 gas increases and CO2 gas decreases causing oxygen to combine with RuBP instead of CO2, which is called photorespiration.
Where is sucrase found in the human body?
On the microvilli of the small intestine
The cyclic pathway involves the _______
PS1
H20 (split to form H+ and O2 ions) replaces lost electrons in the __________________
PS11 (photosystem 2)
The Noncyclic pathway involves these two photosystems
PSII, PSI (photosystem 1 and photosystem 2)
What does photosynthesis capture and what does it do with it?
Photosynthesis captures solar energy and stores it as carbohydrate
contains chlorophyll a pigment
Photosystem 2
What collects solar energy in the photosystems ?
Pigment complex
What would be the immediate consequence of all the glyceraldehyde 3-phosphate made during the carbon fixation and reduction phases of the Calvin cycle were used to make glucose?
Plant cells would not be able to regenerate RuBP.
Describe potential vs Kinetic energy
Potential energy is stored ; kinetic energy is energy in motion
What is the role of a proton pump in energy conversion?
Proton pump converts the energy from a redox reaction into an electrochemical gradient
endergonic reaction
Reactions that absorb/use energy (Reactants have less free energy, products have more)
Exergonic Reactions
Reactions that give off energy (Reactants have more energy, products have less)
In photosynthesis, the Carbon in CO2 is initially fixed to what molecule?
RuBP
What molecule would be most directly affected of two CO2 molecules could be fixed at the same time?
RuBP RuBP is the starting molecule that accepts CO2 from the atmosphere.
What is the first law of thermodynamics?(aka law of conservation of energy) ?
States that energy cannot be created or destroyed
What is the second law of thermodynamics (aka law of entropy) ?
States that there is a loss of usable energy when energy is changed from one form to another
If a mutation occurs in the gene that encodes the enzyme sucrase, resulting in a single amino acid substitution in the active site of the enzyme and a polar amino acid changed to a nonpolar amino acid, what is probably the result of this mutation?
Sucrose would not be able to bind to sucrase in the active site. (The shape of the active site is highly specific. The substitution of a polar amino acid to nonpolar disrupts the active site and sucrose would not be able to bind to the different shape.)
Three factors that affect enzyme activity
Temperature, pH, substrate concentration
How is the ATP Synthase complex used to produce ATP?
The ATP synthase complex channels H+ through to drive ADP to combine with a phosphate to produce ATP
If a plant lacked all pigments, how would this affect the Calvin cycle?
The Calvin cycle would not run in the absence of pigments (ATP and NADPH generated by light reactions are directly used in the Calvin cycle. If there are no pigments the plant cannot absorb light energy and thus cannot generate ATP and NADPH needed by the Calvin cycle)
Not all plants are green in color. a Japanese Maple uses dark red leaves for photosynthesis. What can you infer about the light color used by a Japanese Maple for photosynthesis
The Japanese Maple transmits or reflects red light
If B is also the substrate of another reaction that is Catalyzed by E3 to form product D, how does the cell regulate production of C and D? A-(E1)---->B- (E2)---->C
The cell uses activators and inhibitors to regulate the activity of E2 and E3. (to move a molecule down one branch of a pathway you can inhibit the enzyme in the other branch)
Several processes that occur along the mitochondrial ETC are required to generate a proton gradient. Which process directly involves a proton pump?
The movement of H+ through cytochrome oxidase
If a drug existed that could make the thylakoid membrane permeable to protons, how would this affect the plants ability to make sugar?
This drug would decrease the ability of the plant to make sugar (It would disrupt th proton gradient. no gradient, no chemiosmosis. No chemiosmosis, no ATP. No ATP, no sugar production during the Calvin cycle. )
What happens if you consume more Vitamin B than is needed?
Vitamin B will increase in the urine
L-Arabinose is a non-competitive inhibitor of sucrase. If L-Arabinose is consumed, what will happen to the Vmax of the reaction and Km of the substrate?
Vmax will decrease but Km will not change. Non competitive just means it can't go as fast anymore (Vmax) but still needs the same amount (Km) to get there. (In competitive inhibition the enzyme will still get to its maximum velocity eventually, meaning Vmax will remain unchanged. In non-competitive inhibition, no matter how much of the substrate you add to the sucrase enzyme, it will never be able to achieve it's full velocity and Vmax will decrease. But the amount of substrate required to meet half of maximum velocity wont change)
What does sucrase use to cleave sucrose into two monosaccharides?
Water (water breaks the molecules apart)
What is produced by a proton pump?
a concentration gradient
The final electron acceptor in fermentation
an organic molecule
Catabolic reactions___________?
break down compounds
Anabolic reaction ________?
builds compounds
How do enzymes catalyze reactions?
by lowering the activation energy
How do electrons enter the Electron transport chain?
by the oxidation of NADH
How do tropical rainforests help decrease global warming?
by up taking CO2
PS11 (photosystem 2)
captures light and causes ATP production
PS1 (photosystem 1)
captures light energy and causes NADPH production
Method of producing ATP
chemiosmosis
Synthesis of ATP via a proton gradient is called _______________
chemiosmosis
What molecule/complex is NOT found in the stroma?
chlorophyll (the stroma contains DNA and ribosomes to make photosynthetic proteins and enzymes for the Calvin cycle. Chlorophyll molecules are found in the thylakoid membrane)
The Mesophyll plant tissue carries cells that contain _______________ that carry out photsynthesis
chloroplasts
Overall: C3 plants are adapted to:
cold temperatures and high rainfall
Describe the ETC
electrons are received from NADH and FADH2. 32 ATP are produced, H+ from NADH and FADH2 deliver energy to make ATP
What replaces the electrons excites by sunlight in photosystem 1?
electrons from photosystem 2.
What happens to the energy when food is consumed?
energy is converted to other forms of chemical and kinetic energy and some of the energy is lost as heat.
Free Energy
energy that is available to do work (energy to give)
Type of fermentation that occurs in yeast cells
ethyl alcohol (ethanol) formed from pyruvate when there is no oxygen available
Overall: CAM plants are adapted to:
extreme environments
Heterotrophs
get their energy by consuming other organisms
spontaneous chemical reactions
give off energy because the free energy level of the reactants is more than the free energy of the product. Thus the change is negative and excess energy is given off
occurs in the cytoplasm of the cell and does not require energy
glycolysis
nonspontaneous reactions
have a positive change in free energy and wont readily run without some help (adding energy and coupling)
Overall:C4 plants are adapted to:
high temperature and limited rainfall
Why are 2 ATP required in the first phase of glycolysis?
in order to create a high energy molecule that will spontaneously split into two 3-carbon molecules
Where is the electron transport chain located in bacteria?
in the cell membrane
The movement of protons through ATP synths occurs from the
intermembrane space to the matrix
Type of fermentation that occurs in animal cells
lactate (lactic acid) formed by pyruvate when there is no oxygen available
Under anaerobic conditions, the end product of glycolysis is converted to ___________?
lactic acid
How often can a sucrase molecule be used to hydrolyze sucrose?
many times (enzymes are never used up)
Cofactors
molecules required to activate an enzyme (non protein portion of enzyme)
two pathways of light reactions
noncyclic, cyclic
Consider the biochemical pathway below where A, B, and C are substrates and products and E1 and E2 are the enzymes that catalyze the reactions. Enzyme 1 (E1) can use ______________? A-(E1)---->B-(E2)----> C
only A as a substrate
In an oxidation-reduction reaction, the molecule that loses an electron is_____?
oxidized
During aerobic respiration, the last carrier protein transfers a pair of electrons to ___________
oxygen
contains chlorophyll b pigment
photosystem 1
Creation of a proton gradient by the electron transport chain represents
potential energy
Three factors that affect metabolic reactions
presence/absence of enzyme, concentration of enzyme, activation/deactivation of enzyme
Autotrophs
produce their own energy using the sun
Not associated with a redox reaction in the Kreb cycle
production of acetyl-CoA
Coenymes
protein portion of enzyme
What type of molecule are enzymes?
proteins
In glycolysis, what is glucose converted to?
pyruvate
In an oxidation-reduction reaction the molecule that gains an electron is______?
reduced
Why must the electron transport chain proteins and molecules be embedded in a membrane?
so that protons can be compartmentalized and form a concentraction gradient
What is the ultimate source of energy in the biosphere?
solar energy from the sun
Where does the Calvin cycle take place?
stroma
The component that binds most tightly to the active site of an enzyme
substrate
The product from a reaction serves as what for the next reaction?
substrate
competitive inhibition
substrate and the inhibitor are both able to bind to the active site
Reactants of an enzymatically accelerated reaction are _____________?
substrates
FAD is a coenzyme associated with succinate dehydrogenase enzyme complex in the respiratory citric acid cycle and electron transport chain. Succinate dehydrogenase becomes reduced due to the oxidation of succinate. what would occur if the FAD coenzyme were not associated with succinate dehydrogenase?
succinate dehydrogenase would not oxidize succinate. (If the cofactor (FAD) is missing, the enzyme will not function)
If sunlight is the source of energy for most organisms on earth, how are humans and other animals able to utilize this energy if they cannot photosynthesize? Trace the flow of energy in order from source to destination.
sun-plant-animal-human
Describe the Krebs Cycle
the beginning molecule is Acetyl group which joins with enzyme CoA to form Acetyl CoA to form citrate (6NADH, 2FADH2, 2 ATP)
Describe Prep Stage
the beginning molecule pyruvate is converted to coenzyme A to form Acetyl CoA, CO2 is released into the cytoplasm (CO2 is produced by carbons being released from organic compounds)
If the gene encoding a specific enzyme in the plastoquinone biosynthetic pathway were mutated in a particular cell such that it became completely nonfunctional, what immediate effect would that have on a cell?
the cell would be unable to use light energy to make ATP (plastoquinone is the primary electron acceptor for photosystem 2. If the pathway that generate plastoquinone is nonfunctional, it would no longer be made. Since it Is involved in actively pumping protons across the thylakoid membrane, if it is nonfunctional that means there wouldnt be a proton gradient and no ATP could be produced.)
NADPH is made as a result of______________
the electron transport chain that follows photosystem 1.
Feedback inhibition
the end product of a pathway inhibits the pathway's first enzyme and shots down the pathway
non competitive inhibition
the inhibitor binds not at the active site, but at the allosteric site
chemiosmosis
the movement of ions across a semipermeable membrane, down their electrochemical gradient. (generation of ATP by movement of H+ across the membrane during cellular respiration or photosynthesis)
NAD+ and FAD+
the oxidation-reduction enzymes in cellular respiration
Which stages occur in the mitochondria and require Oxygen?
the prep stage (Acetyl CoA), Krebs Cycle,and ETC
Dehydration
the process in which a substrate is broken apart into two product molecules
Synthesis
the process in which substrates are joined together and released as a single product molecule
What reacts with the active site of the enzyme substrate complex?
the substrate
The most critical stage in the enzymatic reaction
the transition state (after they bind, when substrate molecules can form products)
Why are plants green in color?
they contain a pigment that transmits and reflects green light
What function do many B vitamins serve in the production of energy?
they function as co-enzymes
Where does Carbon dioxide enter a plant leaf?
through the stomata
An enzyme can couple a no spontaneous reaction with a spontaneous reaction so that anabolic processes will occur....true or false
true
Cytochrome complexes
used by the ETC to carry electrons between PS1 ans PS2, and pump H+ from the stroma to the thylakoid
What is the function of the enzyme ATP Synthase?
utilize the energy of the proton motive force to convert ADP to ATP
