Exam 3
In order for glycolysis to continue in the absence of cellular respiration with oxygen, which product must be regenerated?
NAD+
Under anaerobic conditions, glycolysis slows due to the depletion of:
NAD+
When a muscle is working strenuously and becomes anaerobic, pyruvate from glycolysis is reduced to lactate to allow the oxidation of ______ to ______
NADH to NAD+
anabolic/biosynthetic reaction
a chemical reaction in which small molecules are used to synthesize larger molecules
Bacteriorhodopsin
a light driven H+ pump found in archaea
ATP synthase functions like what?
a rotary machine; it spins
hydrolysis of ATP
a water molecule is added to ATP resulting in its breakdown to ADP and inorganic phosphate
electronegativity
ability to attract electrons in a chemical bond
Many of the proteins of the electron transport chain contain prosthetic groups. These prosthetic groups commonly contain iron, which can easily:
accept or release an electron
Ethanol production by yeast results when NADH donates its electrons to...
acetaldehyde
Krebs Cycle reactants
acetyl CoA and oxaloacetate
ATP
adenosine triphosphate; common energy source of cells; all cells use ATP to carry and release energy cyclically
anaerobic
an environment without oxygen
During strenuous exercise, what type of condition may develop in cells when the rate of oxygen delivery cannot keep up with the rate of oxygen demand?
anaerobic
What mechanisms have evolved to allow the metabolism of organic molecules in the absence of oxygen?
anaerobic respiration and fermentation
kinetic energy
associated with movement
The oxidation of NADH initially leads to a high concentration of protons in the:
intermembrane space
Glycolysis
involves the breakdown of one molecule of glucose into two molecules of pyruvate
what are the two general forms in which energy exists?
kinetic energy and potential energy
oxidation
loss of electrons
anaerobic respiration
metabolizes organic molecules in the absence of oxygen by using a substance other than O2 as the final electron acceptor of an electron transport chain
The matrix has a (blank) charge compared to the intermembrane space because positively charged protons are constantly pumped from the matrix to the intermembrane space
negative
chemical reaction
one or more substances are changed or converted into other substances
The final electron acceptor in the electron transport chain is:
oxygen
Some species of bacteria that live in anaerobic conditions have evolved specialized enzymes that work like cytochrome c to...
pass electrons to molecules other than O2
The purpose of the energy investment phase of glycolysis is to:
prime glucose for the exergonic reactions to follow
fermentation
produces ATP by substrate-level phosphorylation without any net oxidation of organic molecules
The energy released during the transfer of electrons in the electron transport chain is used to:
pump protons across the inner mitochondrial membrane
substrate
reactant of an enzyme-catalyzed reaction
The electron transport chain involves a series of
redox reactions
The final step in fermentation, leading to the production of lactate or ethanol, results from pyruvate or acetaldehyde being (blank) by NADH.
reduced
Muscle cells overcome the buildup of NADH and decrease of NAD+ under anaerobic conditions by...
reducing pyruvate to lactate
endergonic reaction
requires an input of energy; products have higher free energy that reactants; not spontaneous; have a positive change in free energy
potential energy
stored energy; associated with the position of an object
biochemistry
study of the chemistry of living things
Fermentation produces less ATP than aerobic respiration because during fermentation:
the NADH that is made during glycolysis is not used to make ATP by chemiosmosis
energy
the ability to promote change or do work
The second event in oxidative phosphorylation is the production of ATP by...
the enzyme ATP synthase
In E. coli, under anaerobic conditions, the production of a proton gradient is coupled to:
the reduction of nitrate to nitrite
During oxidative phosphorylation, ATP synthesis is coupled to:
the removal of high-energy electrons from NADH and FADH2
all the steps of glycolysis can be grouped into...
three phases
Enthalpy (H)
total energy of a system
spontaneous reaction
type of reaction or process that occurs without needing an input of energy
what form of energy can be used to drive cellular processes such as muscle contraction and cellular movements?
usable energy
When would E. coli use nitrate rather than oxygen as a final electron acceptor?
when oxygen is absent
chemical equilibrium
when the rate of formation of products equals the rate of formation of reactants
How do anaerobic conditions develop in cells?
when the rate of oxygen delivery cannot keep up with the rate of oxygen demand
exergonic reaction
will proceed without the input of energy; releases energy during product formation; spontaneous
glycolysis can take place...
with or without oxygen
energy investment phase
During this phase, two ATP molecules are used as reactants. ATP is hydrolyzed so that the phosphate groups can be added to glucose
Krebs Cycle products
- 1 GTP - 3 NADH - 1 FADH2 - 2 CO2 - regenerated oxaloacetate
What describes the three conformations of the β subunit of ATP synthase?
- ATP is released - ATP is bound - ADP and Pi are bound
Why does fermentation produce less ATP than aerobic respiration?
- Electrons in the NADH produced during glycolysis are not used to make ATP by chemiosmosis - The pyruvate produced during glycolysis is not oxidized to produce additional ATP
What problem results from the buildup of NADH and decrease of NAD+ under anaerobic conditions?
- High concentrations of NADH can lead to the release of free radicals, which can damage DNA and proteins -
What happens during the fermentation reactions that occur in muscle cells?
- Pyruvate is reduced to lactate - NADH is oxidized to NAD+
Aerobic respiration yields ______ ATP molecules per glucose, while fermentation typically yields ______ ATP molecules per glucose
34-38 ; 2
What is true regarding the generation of an electrochemical gradient during the conversion of nitrate to nitrite when nitrate serves as a final electron acceptor?
- Ubiquinone picks up H+ in the cytoplasm and carries it to the other side of the membrane - NADH dehydrogenase pumps H+ out of the cytoplasm - The reduction of nitrate to nitrite consumes H+ in the cytoplasm
metabolic pathway
- a coordinated series of chemical reactions in which each step is catalyzed by a specific enzyme - can result in the synthesis of larger molecules from smaller molecules - a different enzyme catalyzes each step - can result in the breakdown of large molecules - the product of one reaction becomes the substrate for the next reaction - categorized according to whether the sequence of coordinated chemical reactions leads to the breakdown or synthesis of substances
redox reaction
- an oxidation reaction paired with a reduction reaction - reduction= gain of electrons, reduction in charge (-) - oxidation= loss of electrons, gain in charge (+)
three levels of regulation of catabolic and anabolic pathways
- genetic - cellular - biochemical
What do I need to know about glycolysis?
- occurs in the cytoplasm - series of reactions that convert glucose (6-C) into 2 pyruvates (3-C) - 2 ATPs are initially expended to phosphorylate sugars - A net of 2 ADPs are eventually converted to ATP - 2 NAD+ are reduced to 2 NADH - steps are all catalyzed by enzymes - (do not need to know intermediates or enzymes that catalyze reactions)
Intermediate Step between glycolysis and Krebs Cycle
- pyruvate is transferred to mitochondrial matrix - pyruvate is oxidized by pyruvate dehydrogenase - pyruvate is left as an acetyl group, produces CO2 and NADH
the following can occur during a chemical reaction?
- rearrangement of atoms within molecules - molecules are broken apart - molecules attach to each other to form larger molecules - electrons are transferred between atoms
two main functions of catabolic pathways
- recycle components of macromolecules - produce energy intermediates, such as ATP, which are directly used to drive endergonic reactions in cells
The structural components of the electron transport chain include:
- small organic molecules - protein complexes
three energy intermediates for cellular respiration
ATP, NADH, FADH2
4 steps of cellular respiration
1. Glycolysis 2. Pyruvate processing 3. Citric acid cycle 4. Oxidative phosphorylation
Arrange the steps that occur when ATP synthase produces ATP in the correct order
1. Hydrogen ions flow through a channel in the membrane-bound subunits of ATP synthase 2. the y subunit of ATP synthase rotates in a clockwise direction 3. the β subunits of ATP synthase change confirmation 4. ATP is synthesized
cellular respiration order of processes
1. glycolysis 2. Intermediate step 3. Krebs (citric acid) Cycle 4. Oxidative Phosphorylation
electron transport chain (ETC)
A group of protein complexes and small organic molecules within the inner membranes of mitochondria and chloroplasts and the plasma membrane of prokaryotes; the components accept and donate electrons to each other in a linear manner and produce a H+ electrochemical gradient
Which of the following statements is true about all forms of anaerobic respiration?
A molecule other than O2 is used as the final electron acceptor
oxidative phosphorylation
A process during which NADH and FADH2 are oxidized to make more ATP via the phosphorylation of ADP
cleavage phase
A six-carbon molecule is converted to two three-carbon molecules
In different conformations, ATP synthase may be bound to (blank) and Pi, bound to ATP, or not bound to a nucleotide.
ADP
energy-liberation phase
ATP and NADH are synthesized; produces 4 ATP, 2 NADH, and two pyruvate molecules
ATP synthase
An enzyme that utilizes the energy stored in a H+ electrochemical gradient for the synthesis of ATP via chemiosmosis
As a result of the reactions of the citric acid cycle, the carbons from acetyl CoA are released as:
CO2
Fermentation that occurs in yeast cells is represented by the equation:
Glucose -----> 2 ethanol + 2 CO2 + 2 ATP
Which of the following equations represents the type of fermentation carried out in muscle cells?
Glucose -----> 2 lactate + 2 ATP
As electrons travel through the electron transport chain, (blank) ions are pumped across the cristae into the space between the inner and outer mitochondrial membranes, from a low concentration to a high concentration
H+
In aerobic respiration, O2 is reduced to what?
H2O
When electrons are transferred to oxygen in the final step of the electron transport chain, what molecule is produced
H2O
How is ATP produced during fermentation?
Substrate-level phosphorylation
Krebs (citric acid) Cycle
The citric acid cycle captures the energy stored in the chemical bonds of acetyl CoA (processed glucose) in a step-by-step process, trapping it in the form of high-energy intermediate molecules, then passes it on to oxidative phosphorylation
cellular respiration
The metabolic reactions that a cell uses to get energy from food molecules and release waste products
When will an endergonic and exergonic reaction that are coupled proceed spontaneously?
When the net free energy change for both reactions combined is negative (exergonic)
If an organism can use only O2 as a final electron acceptor, can it generate ATP under anaerobic conditions?
Yes, it can generate ATP through glycolysis
In yeast cells, fermentation regenerates NAD+ and produces which chemicals?
carbon dioxide and ethanol
products of cellular respiration
carbon dioxide, water, and ATP
cytochrome oxidase
catalyzes the transfer of electrons to O2 at the end of the electron transport chain
what bonds in glucose store large amounts of energy?
covalent bonds
what are the two main factors that determine the fate of a chemical reaction?
direction and rate
mitochondria
double-membraned organelle; Krebs Cycle occurs here
The flow of electrons through the electron transport chain is exergonic. Therefore...
electron flow occurs spontaneously and does NOT require an input of energy.
In the electron transport chain, electrons are transferred to molecules with increasingly higher:
electronegativity
free energy (G)
energy available to do work
three phases of glycolysis
energy investment, cleavage, energy liberation
The flow of electrons through the electron transport chain is:
exergonic
The breakdown of glucose to lactate or ethanol as a final end product is an example of what?
fermentation
The flow of protons through ATP synthase causes the ______ subunit to turn clockwise. This causes the three ______ subunits to change their conformations in a way that favors ATP synthesis and release.
γ ; β
