What are Redox reactions?
shorthand for an oxidation-reduction reaction and is a chemical reaction in which one molecule loses electrons while another molecule gains electrons.
Contrast oxidation and reduction of organic molecules?
Oxidation is when electrons are lost and reduction is when electrons are gained.
What element is usually transferred between organic molecules during redox reactions?
electrons - hydrogen atoms
What is NADH? What is its function?
Its a coenzyme that acts as an electron carrier. It functions as an oxidizing agent during respiration.
How are NADH and ATP similar?
They are both electron carriers
What are electron transport chains?
The electron transport chain releases the energy stored within the reduced hydrogen carriers in order to synthesise ATP
How does the way we extract energy from bonds determine whether or not we explode when we eat a cheeseburger?
We do it in steps. Like all the energy of pyruvate isn't released at once, but its done stepwise in the Krebs Cycle. If we released all the energy at once we would explode.
electron
a stable subatomic particle with a charge of negative electricity
ETC
A group of compounds that pass electron from one to another via redox reactions coupled with the transfer of proton across a membrane to create a proton gradient that drives ATP synthesis.
hydrogen
a colorless, odorless, highly flammable gas, the chemical element of atomic number 1.
NAD+
Nicotinamide adenine dinucleotide (NAD) is a coenzyme found in all living cells.
NADH
oxidized and reduced form abbreviated as NAD+ and NADH respectively
redox
a process in which one substance or molecule is reduced and another oxidized; oxidation and reduction considered together as complimentary processes.
reduction
gains an electron
Where is "chemical energy" stored in molecules?
The ATP molecule can store energy in the form of a high energy phosphate bond joining the terminal phosphate group to the rest of the molecule.
Describe changes in carbon during the anabolic-catabolic cycle.
Carbon is trapped and fixed into an organic molecule.
What happens during light reactions?Why do we call them light reactions?
It is during these reactions that the energy from sunlight is absorbed by the pigment chlorophyll in the thylakoid membranes of the chloroplast. The energy is then temporarily transferred to two molecules, ATP and NADPH, which are used in the second stage
What happens during dark reactions? Why do we call them dark reactions?
Dark reactions make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy while NADPH provides the electrons required to fix the CO2 (carbon dio
Explain how photosynthesis works. What are the products?What are the reactants?Where in the plant cell do the various reactions occur?
Photosynthesis can happen in plants because they have chlorophyll. Chlorophyll is the pigment that makes plants green. Chlorophyll captures the Sun's energy and uses it to make sugars out of carbon dioxide from the air and water. The sugars fuel a plant's
When in photosynthesis is oxygen formed? How does this happen?
We now believe that all the oxygen released in photosynthesis comes from the water molecules and all oxygen atoms that form the carbohydrates come from the carbon dioxide molecules. So, in other words during the light-dependent reaction a water molecule i
Could you illustrate or label a diagram of the chloroplast?
Why are Photosystem II and Photosystem I found in a membrane? Why is it important that the light reactions occur in the membrane?
This energy fall is harnessed, (the whole process termed chemiosmosis), to transport hydrogen (H+) through the membrane, into the thylakoid lumen, to provide a potential energy difference between the thylakoid lumen space and the chloroplast stroma, which
Can you explain the movement of electrons in the membrane of the thylakoid during the light reactions?
the high energy and low energy electron carriers rely on the charge of the electron and proton motive force to get the electrons through the light reaction.
Can you briefly describe the three stages of the calvin cycle? What are the purposes of each stage?
Carbon fixation, reduction, and regeneration
The phase name indicates what type of reactions occurs during that phase.
During stage 1, Carbon Fixation, a carbon atom from CO2 is added to RuBP (a 5C molecule), forming a 6 carbon molecule.
The 6 Carbon mole
Where does the energy to power the calvin cycle come from?
ATP
Can you think why photosynthesis evolved before cellular respiration?
cellular respiration requires oxygen and photosynthesis requires sunlight and water which are more readily available. photosynthesis produces oxygen.
If NADPH carries electrons, where do the photosystems get new electrons to keep the light reactions going?
The first electron transport chain generates an H+ gradient across the thylakoid membrane, and the flow of H+ back across the membrane powers ATP synthase.
ATP synthase
an enzyme that creates the energy storage molecule adenosine triphosphate (ATP). ATP is the most commonly used "energy currency" of cells for most organisms.
Calvin cycle
the set of chemical reactions that take place in chloroplasts during photosynthesis. The cycle is light-independent because it takes place after the energy has been captured from sunlight.
Carbon Fixation
the conversion process of inorganic carbon (carbon dioxide) to organic compounds by living organisms.
Chlorophyll
a green pigment, present in all green plants and in cyanobacteria, responsible for the absorption of light to provide energy for photosynthesis.
Chloroplast
a plastid that contains chlorophyll and in which photosynthesis takes place.
dark reactions
the cycle of reactions (the Calvin cycle) that occurs in the second phase of photosynthesis and does not require the presence of light. It involves the fixation of carbon dioxide and its reduction to carbohydrate and the dissociation of water, using chemi
energy coupling
(1) Transfer of energy from catabolism to anabolism, or transfer of energy from exergonic process to endergonic process. (2) Free energy (from ATP hydrolysis) is coupled or functionally linked to the energy needs of another chemical reaction.
G3P
is a chemical compound that occurs as an intermediate in several central metabolic pathways of all organisms.
light independent reactions
The series of biochemical reactions in photosynthesis that do not require light to proceed, and ultimately produce organic molecules from carbon dioxide. The energy released from ATP (produced during the light reactions) drives this metabolic pathway.
light reactions
energy captured from light by chlorophyll and its accessory pigments drives the production of ATP, the source of energy that is later used to drive the production of carbohydrates.
NADP+
A coenzyme that occurs in many living cells and functions as an electron acceptor like NAD but reacts with different metabolites. NADP is similar in structure to NAD but has an extra phosphate group.
NADP+ reductase
he last enzyme in the transfer of electrons during photosynthesis from photosystem I to NADPH. The NADPH is then used as a reducing equivalent in the reactions of the Calvin cycle.
NADPH
a cofactor used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent. NADPH is the reduced form of NADP+.
Photolysis
The splitting or decomposition of a chemical compound by means of light energy or photons.
Photon
It is a discrete concentration of energy.
photophosphorylation
the synthesis of ATP from ADP and phosphate that occurs in a plant using radiant energy absorbed during photosynthesis.
photosystem
A multisubunit complex found mainly in the thylakoid membranes of plants and algae, and in the cytoplasmic membranes of photosynthetic bacteria. It is primarily involved in capturing light to cause a series of redox reactions.
rubisco
an enzyme involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is converted by plants and other photosynthetic organisms to energy-rich molecules such as glucose.
RuBP
an organic substance that is involved in photosynthesis. It is a colourless anion
starch
A polysaccharide carbohydrate (C6H10O5)n consisting of a large number of glucose monosaccharide units
stroma
The spongy, colorless matrix of a cell that functionally supports the cell.
thylakoid
A saclike membrane that contains the chlorophyll in cyanobacteria and in the chloroplasts of plant cells and green algae. In chloroplasts, thylakoids are arranged in stacks called grana.
What are the substrates and the products of glycolysis?Krebs cycle?
Glycolysis:
Substrate-2 ATP + 2 NAD+
Product-4 ATP (Net 2) + 2 NADH (+ 2 Pyruvate molecules)
Krebs Cycle:
Substrate-6 NAD+ + FAD+ + 2 ADP
Product-6 NADH + 2 FADH + 2 ATP
What is the point of the pathways of glycolysis, pyruvate oxidation and the Krebs cycle?
The pyruvate molecules produced during glycolysis contain a lot of energy in the bonds between their molecules. In order to use that energy, the cell must convert it into the form of ATP. To do so, pyruvate molecules are processed through the Krebs Cycle,
Where in the cell do the reactions of cellular respiration occur?
In the mitochondria
Can you draw an ETC in a mitochondrial membrane and explain the flow of electrons and hydrogen ions? Can you explain chemiosmosis and oxidative phosphorylation?
As protons move through ATP synthase, ADP is turned into ATP. The production of ATP using the process of chemiosmosis in mitochondria is called oxidative phosphorylation.
Explain why glycolysis is divided into an investment and a payout phase?
The cell needs to use energy in order to complete the first 5 endergonic reactions which allow the completion of the exergonic reactions that pay that energy back
What other substrates can be used for energy besides glucose? How?
Amino Acids through cellular respiration
Could you illustrate mitochondria? and indicate where important enzymes needed for cellular respiration are located?
Why is oxidative phosphorylation an example of a process driven by an indirect energy source?
The energy released by electrons flowing through this electron transport chain is used to transport protons across the inner mitochondrial membrane, in a process called electron transport. This generates potential energy in the form of a pH gradient and a
What does fermentation accomplish?
If NADH cannot be metabolized through aerobic respiration, another electron acceptor is used. Most organisms will use some form of fermentation to accomplish the regeneration of NAD+, ensuring the continuation of glycolysis.
Compare are contrast alcohol fermentation and lactic acid fermentation.
Lactic acid fermentation happens in our muscle cells when we are exercising feverishly, while alcoholic fermentation is used in yeast cells and is what leads to beer, bread, and wine.
Compare and contrast respiration and fermentation.
cellular respiration requires oxygen to allow for the continuous production of ATP, or energy.
When there is no oxygen available, fermentation happens, which is a way to allow glycolysis to continue. The way glycolysis is allowed to continue is by regener
Where does fermentation take place?
cytoplasm
What are the substrates and end products of alcohol and lactic acid fermentation?
Alcoholic: Pyruvate is reduced to ethanol
Lactic Acid:Pyruvate is reduced to lactate.
What is the function of fermentation
All cells are able to synthesize ATP via the process of glycolysis. In many cells, if oxygen is not present, pyruvate is metabolized in a process called fermentation. Fermentation complements glycolysis and makes it possible for ATP to be continually prod
What would happen to glycolysis without fermentation? Explain why
The purpose of the extra reactions in fermentation, then, is to regenerate the electron carrier
+
NAD
?+
?? N, A, D, start superscript, plus, end superscript from the
NADHN, A, D, H produced in glycolysis. The extra reactions accomplish this by letting
NA
What kind of molecule is the final electron acceptor for fermentation?
NADH
Which enzymes in the pathways are most tightly regulated. Why? How?
Phosphofructokinase: the most important control element in the mammalian glycolytic pathway. The activity of the enzyme increases when the ATP/AMP ratio is lowered. In other words, glycolysis is stimulated as the energy charge falls. A fall in pH also inh
Acetyl CoA
An organic compound in which an acetyl group is attached to CoA. A compound that functions as a coenzyme in many biological acetylation reactions and is formed as an intermediate in the oxidation of carbohydrates, fats, and proteins.
Antimycin A
an inhibitor of cellular respiration, specifically oxidative phosphorylation.
Aerobic respiration
he metabolic process of most living things in which food molecules or glucose are turned into usable energy for the cell, called ATP.
alcohol fermentation
the anaerobic pathway carried out by yeasts in which simple sugars are converted to ethanol and carbon dioxide. The process of alcohol fermentation allows yeasts to break down sugar in the absence of oxygen and results in byproducts that humans benefit fr
cellular respiration
a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products.
chemiosmosis
the movement of ions across a semipermeable membrane, down their electrochemical gradient. An example of this would be the generation of adenosine triphosphate (ATP) by the movement of hydrogen ions across a membrane during cellular respiration or photosy
cyanide
The radical -CN or ion (CN)-. The ion is extremely poisonous, forming hydrocyanic acid in water; inhibits respiratory proteins.
decarboxylation
a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain.
FAD+/FADH
a redox cofactor that is created during the Krebs cycle and utilized during the last part of respiration, the electron transport chain.
glycolosis
the breakdown of glucose by enzymes, releasing energy and pyruvic acid.
isocitrate dehydrogenase
either of two enzymes which catalyze the oxidation of isocitric acid to alpha-ketoglutaric acid (as in the Krebs cycle) and of which one uses NAD as an electron acceptor and the other NADP
krebs cycle
the sequence of reactions by which most living cells generate energy during the process of aerobic respiration. It takes place in the mitochondria, consuming oxygen, producing carbon dioxide and water as waste products, and converting ADP to energy-rich A
lactic acid fermentation
the process by which our muscle cells deal with pyruvate during anaerobic respiration. When our cells need energy, they break down simple molecules like glucose. The cells turn pyruvate, the products of glycolysis, into lactic acid
mitochondria
an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner layer being folded inward to form layers
Oligomycin
any of several antibiotic substances produced by an actinomycete of the genus Streptomyces (S. diastatochromogenes or a closely related species) and used especially in biochemical research to inhibit oxidative phosphorylation.
oxidation
losing an electron
phosphofructokinase
an enzyme that functions in carbohydrate metabolism and especially in glycolysis by catalyzing the transfer of a second phosphate (as from ATP) to fructose.
proton motive force
the force that promotes movement of protons across membranes downhill the electrochemical potential.
substrate level phosphorylation
a metabolic reaction that results in the formation of ATP or GTP by the direct transfer of a phosphoryl (PO3) group to ADP or GDP from another phosphorylated compound.
thermogenin
an uncoupling protein found in the mitochondria of brown adipose tissue