Module 2 (BIOLOGY) Flashcards
What are the key differences between prokaryotes and eukaryotes?
Nucleus: Absent in prokaryotes (nucleoid region), present in eukaryotes
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Transcription location: Cytoplasm in prokaryotes, nucleus in eukaryotes
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Translation location: Cytoplasm in both
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Cell membrane additions: Hopanoids in prokaryotes, sterols (cholesterol) in eukaryotes
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Size: Smaller in prokaryotes (1−2 micrometers), larger in eukaryotes (10−20 micrometers)
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Ratio of surface area to volume: High in prokaryotes, low in eukaryotes
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Internal organization: No organelles in prokaryotes (some contain plasmids), organelles present in eukaryotes
: What is the cell theory?
All organisms are made up of cells.
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The cell is the fundamental unit of life.
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Cells come from preexisting cells
Front: What are cell membranes composed of?
Lipids, proteins, and carbohydrates
What is the endomembrane system?
An interconnected system of membranes that includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and plasma membrane
What is the role of mitochondria and chloroplasts?
They are organelles involved in harnessing energy and likely evolved from free-living prokaryotes.
What are phospholipids?
Amphipathic molecules with a hydrophilic head and hydrophobic tails that spontaneously form bilayers.
What are liposomes?
Enclosed bilayers spontaneously formed by phospholipids
What is the function of cholesterol in animal cell membranes?
It acts as a buffer to lessen the impact of temperature changes.
What are the three main types of proteins in the membrane and their functions?
Receptors: Allow the cell to receive signals from the environment.
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Enzymes: Catalyze chemical reactions.
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Transporters: Move ions or molecules across the membrane
What is the difference between integral and peripheral membrane proteins?
Integral membrane proteins: Permanently associated with cell membranes.
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Peripheral membrane proteins: Temporarily associated with the lipid bilayer or integral membrane proteins through weak noncovalent interactions
What is passive transport?
The simplest movement into and out of cells, which does not require energy
hat is the difference between simple diffusion and facilitated diffusion?
Simple diffusion is the movement of molecules across a membrane from an area of high concentration to an area of low concentration. Facilitated diffusion is similar, but the molecules move through a transport protein.
What is osmosis?
The diffusion of water across a semi-permeable membrane from a region of higher water concentration to a region of lower water concentration
What is turgor pressure?
The force exerted by water pressing against an object
What is the difference between passive and active transport?
Passive Transport: Movement of molecules across a membrane that does not require energy.
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Active Transport: Movement of molecules across a membrane that requires energy.
What is secondary active transport?
A type of active transport that uses the energy from the movement of one molecule down its concentration gradient to drive the movement of another molecule against its concentration gradient.
What is an example of primary active transport?
The sodium/potassium pump, which moves sodium and potassium ions in opposite directions across the cell membrane.
What are exocytosis and endocytosis?
Exocytosis: A vesicle fuses with the plasma membrane to deliver its contents outside the cell.
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Endocytosis: Material from outside the cell is brought into a vesicle
What are the functions of the Golgi apparatus?
Further modifies proteins and lipids produced in the ER.
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Sorts proteins and lipids as they move to their final destinations.
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Synthesizes the cell’s carbohydrates.
What is the function of lysosomes?
They degrade proteins, nucleic acids, lipids, and complex carbohydrates
What are the two main types of metabolism?
Catabolism: The breakdown of complex molecules into simpler ones, releasing energy.
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Anabolism: The synthesis of complex molecules from simpler ones, requiring energy.
What is an enzyme?
A biological catalyst that speeds up the rate of a chemical reaction without being consumed in the process.
What is cellular respiration?
The process by which cells convert glucose and oxygen into ATP, the cell’s primary energy currency.
What is photosynthesis?
The process by which plants and other organisms use sunlight to synthesize glucose from carbon dioxide and water.
What are the main phases of the cell cycle?
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Interphase: The cell grows and replicates its DNA.
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Mitosis (M phase): The replicated chromosomes are separated and the cell divides into two daughter cells.
Flashcard 27
What are some key characteristics of fungal cells?
Eukaryotic cells
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Have a cell wall made of chitin
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Heterotrophic - they obtain nutrients by absorbing organic matter from their environment
Front: What is metabolism?
Back: Metabolism is the set of biochemical reactions that transform biomolecules and transfers energy.
Front: What are the first and second laws of thermodynamics?
Back:
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The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed.
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The second law of thermodynamics states that the entropy of a closed system always increases over time.
What is entropy?
Back: Entropy is a measure of disorder or randomness.
Front: What is ATP?
Back: ATP (adenosine triphosphate) is a molecule that stores and releases energy for cellular processes.
Front: Why is ATP called the “currency of energy”?
Back: The chemical energy of ATP is held in the bonds connecting the phosphate groups. Breaking these bonds releases energy that can be used by the cell.
Front: What is chemical energy?
Back: Chemical energy is a form of potential energy held in the chemical bonds between pairs of atoms in a molecule.
Front: What are the requirements of a cell?
Back:
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A membrane to separate the inside of the cell from the outside
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A way to encode and transmit information
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Energy
Front: What is the microbiome?
Back: The microbiome is a collection of microbes that are both helpful and potentially harmful. It consists of mutualists, commensals, and pathogens
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Front: Where does the energy come from to support human activities?
Back: The energy to support human activities comes from the food we eat. This includes glucose, fructose, proteins, lipids, sucrose, and polysaccharides. These molecules are broken down by the body to release energy.
Front: What is catabolism?
Back: Catabolism is the breakdown of complex molecules into simpler ones, releasing energy.
Front: What is anabolism?
Back: Anabolism is the synthesis of complex molecules from simpler ones, requiring energy.
Front: What is the main difference between catabolism and anabolism?
Back: Catabolism involves the breakdown of complex molecules into simpler ones, releasing energy, while anabolism refers to the synthesis of complex molecules from simpler ones, requiring energy.4
Front: List the key biomolecules that contribute to energy production for human activities.
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Glucose78
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Fructose78
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Proteins78
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Lipids78
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Sucrose8
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Polysaccharides8
Front: Identify the primary source of energy for human activities.
Back: The food we consume provides the primary source of energy for human activities.78
Front: What type of microbes are present in smaller numbers within the human microbiome and what is their effect?
Back: Pathogens, microbes that can promote diseases, are present in smaller numbers within the human microbiome.7
Front: Characterize the majority of microbes within the human microbiome.
Back: Most microbes within the human microbiome exist as either mutualists, providing benefits to both the host and themselves, or commensals, neither harming nor benefiting the host.7
Front: Describe the cellular composition of the microbiome associated with the human body.
Back: The microbiome associated with the human body contains a greater number of microbial cells than the total number of human cells.7
Front: What is the composition of the microbiome?
Back: The microbiome comprises microbes that can be both beneficial and potentially detrimental to the host.7
Front: Define entropy.
Back: Entropy serves as a measure of disorder or randomness within a system. A system with high entropy exhibits greater disorder than a system with low entropy.67
Front: What is the focus of the second law of thermodynamics?
Back: The second law of thermodynamics deals with energy transformation and asserts that the entropy of a closed system inevitably increases over time.6
Front: Explain the first law of thermodynamics.
Back: The first law of thermodynamics centers on the principle of energy conservation, stating that energy cannot be created or destroyed, but only transferred or transformed.6
Front: Where is the chemical energy of ATP stored?
Back: The chemical energy of ATP is stored within the bonds connecting the phosphate groups.5
Front: How do cells manage the energy they possess?
Back: Instead of utilizing all their energy at once, cells package energy into a readily accessible chemical form, primarily ATP.5
Front: Explain the relationship between strong bonds and potential energy in molecules.
Back: Strong bonds possess less potential energy compared to weak bonds.5
Front: Define metabolism.
Back: Metabolism encompasses all the biochemical reactions that occur within an organism to transform biomolecules and transfer energy.34
Front: Provide two examples of how ATP is utilized in cellular activities.
Back:
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The sodium/potassium pump, an example of an antiporter.2
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Muscle contraction.2
Front: Where is the highest energy bond located in Adenosine Triphosphate (ATP)?
Back: The highest energy bond is located at the outer layer, linking the phosphate group.2
Front: Besides a phospholipid bilayer and associated proteins, what else can be found in the plasma membranes of human liver cells?
Back: Cholesterol. Cholesterol is a component of animal cell membranes.1
Front: What is Gibbs free energy?
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Back: Gibbs free energy (ΔG) is the amount of energy in a system available to do work.
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Front: Define endergonic reactions.
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Back: Endergonic reactions have a positive ΔG, require an input of energy, and are non-spontaneous.
Front: What is the formula for Gibbs free energy?
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Back: ΔG = ΔH − TΔS, where ΔH is the enthalpy change, T is the absolute temperature, and ΔS is the entropy change.
Front: Define exergonic reactions.
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Back: Exergonic reactions have a negative ΔG, release energy, and are spontaneous.
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Front: Describe energetic coupling.
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Back: Energetic coupling is a process where a spontaneous reaction (negative ΔG) drives a non-spontaneous reaction (positive ΔG
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Front: What is ATP’s role in energetic coupling?
Back: ATP acts as the energy provider in energetic coupling.
Front: What is activation energy (EA)?
Back: Activation energy is the minimum amount of energy required to start a chemical reaction.
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Front: How do enzymes affect the rate of a reaction?
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Back: Enzymes are protein catalysts that increase the rate of biochemical reactions by lowering the activation energy.
Front: What is the enzyme-substrate complex?
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Back: The enzyme-substrate complex (ES) is formed when a substrate (S) binds to the active site of an enzyme (E).
Card 10
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Front: What happens at the enzyme’s active site?
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Back: The active site binds to the substrate and facilitates its conversion into the product, lowering the activation energy.
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Front: How is enzyme shape related to its function?
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Back: The specific shape of the enzyme’s active site determines which substrates it can bind and the reaction it catalyzes.
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Front: Explain enzyme specificity.
Back: Enzyme specificity refers to the selective binding of an enzyme to a particular substrate due to the complementary shapes of the active site and the substrate
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Front: What are enzyme inhibitors?
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Back: Enzyme inhibitors are molecules that bind to enzymes and decrease their activity
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Front: Differentiate between reversible and irreversible enzyme inhibitors.
Back: Reversible inhibitors bind to the enzyme through weak bonds and can dissociate, while irreversible inhibitors form covalent bonds and permanently inactivate the enzyme
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Front: What are allosteric enzymes?
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Back: Allosteric enzymes are enzymes that are activated or inhibited when a molecule binds to a site other than the active site, changing the enzyme’s shape.
Front: What are the core concepts of chemical reactions?
1.
Chemical reactions involve the breaking and forming of bonds.
2.
Energetic coupling: Spontaneous reactions drive non-spontaneous reactions.
3.
Enzymes are protein catalysts that can increase the rate of biochemical reactions.
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Allosteric enzymes are activated or inhibited when binding to another molecule changes their shape.
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Front: What are free radicals?
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Back: Free radicals are unstable molecules due to the loss of electrons and contribute to the aging process.
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Front: What are anabolic pathways?
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Back: Anabolic pathways build larger molecules from smaller units, consuming energy (endergonic).
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Front: What are catabolic pathways?
Back: Catabolic pathways break down molecules into smaller units, releasing energy (exergonic) and producing ATP.
Front: How do glycolysis and the citric acid cycle function?
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Back: These pathways break down glucose into smaller molecules, releasing energy. They are catabolic pathways and take place in both animal and plant cells.
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Front: What is the function of RNA polymerase II?
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Back: RNA polymerase II is a vital enzyme in the synthesis of messenger RNA (mRNA), microRNA, and small nuclear RNA (snRNA).
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Front: What is α-Amanitin?
Back: α-Amanitin is a selective inhibitor of RNA polymerase II, found in some toxic mushrooms.
Front: Why are some mushrooms toxic to humans?
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Back: Some mushrooms, like Amanita phalloides, contain toxins such as amatoxins that inhibit RNA polymerase II, disrupting vital cellular processes.
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Front: What are mycotoxins?
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Back: Mycotoxins are toxic secondary metabolites produced by fungi. Examples include aflatoxins, amatoxins, citrinin, and ergot alkaloids
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Front: Name some fungi that produce mycotoxins.
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Back: Examples include Aspergillus, Penicillium, Amanita, Lepiota, Galerina, and Fusarium species.
Front: What are the health effects of mycotoxins?
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Back: Mycotoxins can have various adverse effects on human and animal health, including liver damage, cancer, and immune suppression. (This information is not explicitly stated in the provided source but is a general understanding of mycotoxins.)
Front: What is the role of the mediator complex in transcription?
Back: The mediator complex acts as a bridge between transcription factors bound to enhancer sequences and RNA polymerase II at the promoter, facilitating transcription initiation.
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Front: What is the promoter region in DNA?
Back: The promoter region is a specific DNA sequence that signals the start site for transcription, where RNA polymerase II binds to initiate mRNA synthesis
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Front: What are the different types of RNA produced by RNA polymerase II?
Back: RNA polymerase II synthesizes messenger RNA (mRNA), microRNA, and small nuclear RNA (snRNA).
Front: What is phylogenetic analysis of RNA polymerase II?
Back: Phylogenetic analysis of RNA polymerase II can be used to study the evolutionary relationships among different species based on the similarities and differences in their RNA polymerase II genes.
1.
Describe the starting molecule and the ending molecule of glycolysis.
Glycolysis begins with a molecule of glucose and ends with two molecules of pyruvate.12
What are the net products of glycolysis per glucose molecule?
The net products of glycolysis are 2 ATP, 2 NADH, and 2 pyruvate molecules.2
How does the cell trap glucose inside the cytoplasm for glycolysis?
The cell traps glucose inside the cytoplasm by phosphorylating it. This means that a phosphate group is added to the glucose molecule. This phosphorylation is done by an enzyme called hexokinase.2
Why is glucose destabilized before entering the second phase of glycolysis?
Glucose is destabilized before entering the second phase of glycolysis to prepare it for cleavage. The addition of the phosphate group in the first phase makes the glucose molecule more reactive and less stable, allowing it to be broken down into two three-carbon molecules.2
Describe the structure of the mitochondria, including its membranes and compartments.
Mitochondria are double-membraned organelles with an outer membrane and an inner membrane that folds inward to form cristae. The space between the outer and inner membranes is called the intermembrane space, and the space enclosed by the inner membrane is called the mitochondrial matrix.3
How does pyruvate enter the mitochondria from the cytoplasm?
Pyruvate enters the mitochondria from the cytoplasm through transport proteins located in the mitochondrial membranes.3
What three key events happen during the conversion of pyruvate to acetyl-CoA?
he three key events that happen during the conversion of pyruvate to acetyl-CoA are:
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Decarboxylation: A carboxyl group is removed from pyruvate as CO2.3
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Oxidation: Pyruvate is oxidized, and the electrons are transferred to NAD+, reducing it to NADH.3
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Coenzyme A attachment: Coenzyme A (CoA) is attached to the remaining two-carbon molecule, forming acetyl-CoA.3
List all the products generated from one molecule of pyruvate in pyruvate oxidation.
For each molecule of pyruvate, the products of pyruvate oxidation are one molecule of acetyl-CoA, one molecule of NADH, and one molecule of CO2.3
Explain the role of oxaloacetate in the citric acid cycle.
Oxaloacetate is a four-carbon molecule that combines with acetyl-CoA (a two-carbon molecule) at the beginning of the citric acid cycle to form citrate, a six-carbon molecule. At the end of the cycle, oxaloacetate is regenerated, allowing the cycle to continue.4
How many molecules of CO2 are produced per one turn of the citric acid cycle?
Two molecules of CO2 are produced per one turn of the citric acid cycle.4
Why is the citric acid cycle considered a cycle, and what is regenerated at the end of each cycle?
The citric acid cycle is considered a cycle because the starting molecule, oxaloacetate, is regenerated at the end of the cycle. This allows the cycle to continue, processing more acetyl-CoA molecules.4
What are the total products generated from two molecules of acetyl-CoA in the citric acid cycle?
The total products from two molecules of acetyl-CoA in the citric acid cycle are 2 ATP, 6 NADH, 2 FADH2, and 4 CO2.4
Which electron carriers feed electrons into the electron transport chain?
The electron carriers that feed electrons into the electron transport chain are NADH and FADH2.5
Explain which complex in the ETC accepts electrons from NADH and which accepts electrons from FADH2.
Complex I of the ETC accepts electrons from NADH, while Complex II accepts electrons from FADH2.5
How does the movement of electrons through the ETC power the pumping of protons across the inner mitochondrial membrane?
As electrons move through the ETC, they release energy, which is used to pump protons from the mitochondrial matrix to the intermembrane space. This pumping is carried out by protein complexes within the ETC.56
Describe the chemical gradient and the electrical gradient that comprise the proton gradient.
The chemical gradient is created by the higher concentration of protons in the intermembrane space compared to the matrix. The electrical gradient is created by the positive charge of the protons in the intermembrane space compared to the more negative matrix.6
Explain the process of chemiosmosis and its role in ATP synthesis.
Chemiosmosis is the process by which the potential energy stored in the proton gradient is used to drive ATP synthesis. Protons flow back down their gradient, from the intermembrane space to the matrix, through a protein complex called ATP synthase.6
How does ATP synthase use the proton gradient to generate ATP?
ATP synthase acts as a molecular turbine. The flow of protons through the F0 subunit causes it to rotate. This rotation is transmitted to the F1 subunit, which catalyzes the synthesis of ATP from ADP and inorganic phosphate (Pi).6
19.
Describe the rotation of the F0 and F1 subunits of ATP synthase and how this leads to ATP synthesis.
The F0 subunit is embedded in the inner mitochondrial membrane and rotates as protons flow through it. This rotation causes the F1 subunit, which extends into the matrix, to rotate as well. The rotation of the F1 subunit induces conformational changes that allow it to bind ADP and Pi, and catalyze the formation of ATP.6
What is the final destination of the electrons passing through the electron transport chain?
The final destination of the electrons passing through the electron transport chain is oxygen (O2), which acts as the final electron acceptor.6
What happens to the oxygen molecule when it accepts electrons at the end of the ETC?
When oxygen accepts electrons at the end of the ETC, it combines with protons (H+) to form water (H2O).6
What are the three main types of fuel molecules that can be broken down in cellular respiration?
The three main types of fuel molecules that can be broken down in cellular respiration are carbohydrates, lipids, and proteins.1
Explain the difference between a catabolic reaction and an anabolic reaction.
A catabolic reaction breaks down larger molecules into smaller molecules, releasing energy. Cellular respiration is an example of a catabolic pathway. An anabolic reaction builds larger molecules from smaller molecules, requiring energy. Photosynthesis is an example of an anabolic pathway.17
Why is ATP considered the energy currency of the cell?
ATP is considered the energy currency of the cell because it is the primary molecule used to store and transfer energy within cells. ATP can be hydrolyzed (broken down) to release energy that can be used to power various cellular processes.17
Differentiate between substrate-level phosphorylation and oxidative phosphorylation.
Provide examples of where each process occurs in cellular respiration. Substrate-level phosphorylation is the direct transfer of a phosphate group from a substrate molecule to ADP, forming ATP. This process occurs in glycolysis and the citric acid cycle. Oxidative phosphorylation is the production of ATP using the energy released by the electron transport chain and the proton gradient. This process occurs in the inner mitochondrial membrane during the final stage of cellular respiration.158
In redox reactions, explain the role of the electron donor and the electron acceptor.
In redox reactions (oxidation-reduction reactions), the electron donor loses electrons and is oxidized. The electron acceptor gains electrons and is reduced.8
How can you identify the oxidizing agent and the reducing agent in a redox reaction?
The oxidizing agent is the substance that causes the oxidation of another substance by accepting electrons. The reducing agent is the substance that causes the reduction of another substance by donating electrons.8
Front: What is the significance of the rising levels of atmospheric oxygen in the evolution of life?
Back: The rising levels of atmospheric oxygen allowed for the evolution of aerobic respiration, which is much more efficient at ATP production than fermentation. This paved the way for the evolution of larger, more complex organisms.6
Front: How is cellular respiration regulated?
Back: Cellular respiration is regulated by a complex interplay of enzymes, substrates, and regulatory molecules that respond to the energy needs of the cell.10
Front: What is the approximate total ATP yield from aerobic respiration?
Back: Aerobic respiration can yield approximately 32 ATP molecules per glucose molecule.12
Front: What is metabolic integration?
Back: Metabolic integration refers to the interconnectedness and regulation of various metabolic pathways, which allows cells to control their energy levels and respond to changing conditions.57
Front: What is the likely evolutionary origin of mitochondria in eukaryotic cells?
Back: It is thought that all known eukaryotes likely diverged after the symbiotic development of mitochondria, originating from an ancestral prokaryotic cell.9
Front: What are hydrogenosomes, and in what organisms are they found?
Back: Hydrogenosomes are H2-producing mitochondrial homologs found in some anaerobic microbial eukaryotes, including certain anaerobic fungi.9
Front: Describe the appearance of hydrogenosomes.
Back: Hydrogenosomes (H) are small (~0.5 um diameter), spherical, or variously elongate organelles.10
Front: What is the energy source for the electron transport chain?
Back: High-energy electrons from NADH and FADH2 provide the energy for the electron transport chain.11
Front: What is formed as a result of the energy transformation in the electron transport chain?
Back: A proton gradient is formed across the inner mitochondrial membrane as a result of the energy transformation in the electron transport chain.11
Front: What is the final electron acceptor in aerobic respiration?
Back: Oxygen (O2) is the final electron acceptor in aerobic respiration, and it is reduced to form water (H2O).211
Front: What happens to pyruvate in the presence of oxygen?
Back: In the presence of oxygen, pyruvate is oxidized to acetyl-CoA, which enters the citric acid cycle.5
Front: What is the net ATP yield from glycolysis?
Back: Glycolysis produces a net yield of 2 ATP molecules per glucose molecule.34
Front: Give two examples of anaerobic fungi that assist ruminants in digestion.
Back:
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Neocallimastix sp.
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Anaeromyces sp.8
Front: How do ruminants digest plant material?
Back: Ruminants rely on symbiotic microbes to digest plant material, particularly the cellulose component.8
Front: What is the primary difference between aerobic and anaerobic respiration?
Back: Aerobic respiration uses oxygen as the final electron acceptor in the electron transport chain, while anaerobic respiration (fermentation) uses an organic molecule.12
Front: Describe the process of fermentation.
Back: Fermentation extracts energy from fuel molecules without oxygen or an electron transport chain by using an organic molecule as an electron acceptor. This process produces a modest amount of ATP.12
Front: What are the two main types of fermentation?
Back: The two main types are lactic acid fermentation and ethanol fermentation.34
Front: What is the product of lactic acid fermentation?
Back: Lactic acid fermentation produces lactic acid. This process is utilized by anaerobic bacteria, such as Lactobacillus and Streptococcus, often found in milk.3
Front: What are the products of ethanol fermentation?
Back: Ethanol fermentation produces ethanol and carbon dioxide. Yeast utilizes this process in the production of alcoholic beverages.4
Front: How is NAD+ regenerated during fermentation?
Back: During fermentation, NADH, produced during glycolysis, donates its electrons to an organic molecule (either pyruvate or a derivative of pyruvate), regenerating NAD+. This NAD+ can then be used in glycolysis to continue ATP production.34
Front: What are the four stages of cellular respiration?
Back:
1.
Glycolysis (cytoplasm)
2.
Pyruvate oxidation (mitochondria)
3.
Citric acid cycle (mitochondria)
4.
Oxidative phosphorylation (mitochondria)5
Front: Where does glycolysis occur?
Back: Glycolysis takes place in the cytoplasm of the cell.5
Front: Where do pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation occur?
Back: Pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation all occur in the mitochondria.5
Front: What are the two ways energy is released during cellular respiration?
Back:
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Substrate-level phosphorylation.
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Transfer to electron carriers NADH and FADH2.5
Front: How is the energy from electron carriers used to generate ATP?
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Back: The energy of the electron carriers is transformed into energy stored in a proton electrochemical gradient across the inner mitochondrial membrane.5
Front: What is the role of ATP synthase in cellular respiration?
Back: ATP synthase converts the energy of the proton gradient into rotational energy, which drives the synthesis of ATP.2
Front: Before atmospheric oxygen was present, how did early organisms likely generate ATP?
Back: Early organisms likely used fermentation pathways to generate ATP before the presence of atmospheric oxygen.6
Front: What are two advantages of fermentation compared to aerobic respiration?
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Fermentation can provide a quick burst of ATP.
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Fermentation can have higher efficiency in certain environments.7
Front: What is glycogen, and where is it stored?
Back: Glycogen is a branched polymer of glucose and serves as a storage form of glucose. It is stored primarily in muscle cells and liver cells.7
Front: How is glycogen utilized in glycolysis?
Back: Glucose molecules at the end of glycogen chains are cleaved one at a time in the form of glucose 1-phosphate, which is then converted into glucose 6-phosphate, an intermediate in glycolysis.7
Question 1: What is the primary function of photosynthesis?
Answer: Photosynthesis is the main process by which energy from sunlight and carbon from carbon dioxide are converted into carbohydrates.12
Question 2: Describe the Calvin cycle’s role in photosynthesis.
Answer: The Calvin cycle is a three-step process that uses carbon dioxide (CO2) to synthesize carbohydrates. It’s a crucial part of photosynthesis, responsible for converting inorganic carbon into organic forms.13
Question 3: What is the role of light-harvesting reactions in photosynthesis?
Answer: Light-harvesting reactions capture sunlight energy and convert it into chemical energy in the form of ATP and NADPH. These molecules are then used in the Calvin cycle to synthesize carbohydrates.1
Question 4: How do desert crusts demonstrate the survival of photosynthetic organisms in harsh environments?
Answer: In deserts, photosynthetic bacteria and unicellular algae form a delicate layer on the surface called desert crust. This adaptation allows these organisms to survive in the arid conditions by efficiently capturing limited water and sunlight.2
Question 5: What are some examples of “uncommon photosynthetic players,” and where can they be found?
Answer: Examples include Nostoc sp. and Geosiphon pyriforme. These organisms might be found in diverse environments, highlighting the adaptability of photosynthesis.4 Additionally, lichen thalli, consisting of Cyphobasidiales yeasts, Lecanoromycete, and algal chlorophyll A, showcase a symbiotic relationship for photosynthesis.4
Question 6: Explain the redox reaction involved in photosynthesis.
Answer: Photosynthesis is a redox reaction where water is oxidized, losing electrons, while carbon dioxide is reduced, gaining electrons. This electron transfer occurs through a series of reactions in the photosynthetic electron transport chain, ultimately leading to carbohydrate synthesis.4
Question 7: Describe the structure and function of photosystems in photosynthesis.
Answer: Photosystems are protein-pigment complexes that absorb light energy. They use this energy to drive redox reactions, moving electrons through a chain that ultimately generates ATP and NADPH for the Calvin cycle.5
Question 8: What is the significance of thylakoid membranes in photosynthesis?
Answer: Thylakoid membranes form flattened sacs called grana within chloroplasts. These membranes house the photosystems and electron transport chains necessary for the light-dependent reactions of photosynthesis.6
Question 9: Compare and contrast the ATP requirements of cellular respiration and photosynthesis.
Answer: While both processes involve ATP, their roles are different. Cellular respiration uses glucose to generate ATP, while photosynthesis uses light energy to produce ATP, which is then used to synthesize glucose.6
Question 10: Describe the carboxylation step of the Calvin cycle.
Answer: In carboxylation, CO2 is added to a 5-carbon molecule called RuBP. This 6-carbon molecule is then split into two 3-carbon molecules of 3-PGA. This step is the initial incorporation of inorganic carbon into an organic molecule.6
Question 11: What is the role of NADPH in the Calvin cycle?
Answer: NADPH is the reducing agent in the Calvin cycle. It provides the electrons needed to reduce 3-PGA to G3P, a precursor to glucose.6
Question 12: Explain the regeneration step of the Calvin cycle.
Answer: The regeneration step ensures the continuous operation of the Calvin cycle. Some G3P molecules are used to regenerate RuBP, the initial CO2 acceptor, enabling the cycle to continue.6
Question 13: Describe the appearance of starch granules within a chloroplast.
Answer: Starch granules, the storage form of glucose produced in photosynthesis, appear as grey structures within chloroplasts when viewed under a scanning electron microscope. They accumulate in the stroma, the fluid-filled space surrounding the thylakoid membranes.7
Question 14: Define light and its relationship to the electromagnetic spectrum.
Answer: Light is a form of electromagnetic radiation. Visible light is the portion of this spectrum that humans can see, encompassing a range of wavelengths that correspond to different colors.7
Question 15: Explain the role of pigments in the absorption of light.
Answer: Pigments are molecules that absorb specific wavelengths of visible light. The wavelengths they don’t absorb are reflected, giving them their characteristic color. In photosynthesis, pigments like chlorophyll capture light energy for the process.78
Question 16: Why does chlorophyll appear green?
Answer: Chlorophyll appears green because it absorbs wavelengths in the red and blue regions of the visible spectrum but reflects green wavelengths. This reflected light is what we perceive as the green color of plants.8
Question 17: How are chlorophyll molecules structured and positioned within the thylakoid membrane?
Answer: Chlorophyll molecules are bound by their tail region to integral membrane proteins within the thylakoid membrane. This arrangement positions the chlorophyll molecules to effectively capture light energy.8
Question 18: What are accessory pigments, and what is their function in photosynthesis?
Answer: Accessory pigments, such as carotenoids, absorb light wavelengths that chlorophyll doesn’t capture efficiently. They broaden the range of light energy that can be used for photosynthesis.8
Question 19: Explain the concept of a reaction center in photosynthesis.
Answer: The reaction center is a specialized chlorophyll molecule within a photosystem. It’s where light energy is converted into chemical energy by initiating electron transfer reactions.9
Question 20: How is the energy captured by chlorophyll used in the light-harvesting reactions?
Answer: The energy absorbed by chlorophyll in the light-harvesting reactions is used to produce ATP and NADPH, the energy carriers needed to power the Calvin cycle.9
Question 21: What is oxidative phosphorylation?
Answer: Oxidative phosphorylation is the process where the majority of ATP is produced during cellular respiration.3
Question 22: What is the general equation for photosynthesis?
Answer: The general equation represents the overall process of photosynthesis: Carbon Dioxide + Water + Light Energy → Glucose + Oxygen.4
Question 23: What is the function of photosystem II in photosynthesis?
Answer: Photosystem II absorbs light energy and uses it to split water molecules, releasing oxygen, electrons, and protons.5
Question 24: What is the function of Photosystem I in photosynthesis?
Answer: Photosystem I absorbs light energy and uses it to energize electrons, which are then used to reduce NADP+ to NADPH.5
Question 25: What is the relationship between the light-harvesting reactions and the Calvin cycle?
Answer: The light-harvesting reactions provide the ATP and NADPH necessary for the Calvin cycle to fix carbon dioxide and synthesize sugars.19
Question 26: What is the role of enzymes in photosynthesis?
Answer: Enzymes catalyze (speed up) the various biochemical reactions involved in photosynthesis, ensuring the process occurs efficiently.10
Question 27: How does the cell cycle relate to photosynthesis?
Answer: While not directly involved in photosynthesis, the cell cycle is essential for plant growth and development. New cells produced through the cell cycle can differentiate into specialized photosynthetic tissues, increasing overall photosynthetic capacity.10
Question 28: How do fungal cells differ from plant cells in terms of photosynthesis?
Answer: Fungi are heterotrophic organisms, meaning they obtain nutrients from other organisms. Unlike plant cells, fungal cells lack chloroplasts and cannot perform photosynthesis.10
Question 29: What is the importance of the regulation of the cell cycle in plants?
Answer: Regulation ensures that plant cells divide and differentiate properly, contributing to the organized growth of tissues and organs, including those involved in photosynthesis.10
Question 30: What is the connection between cancer and the regulation of the cell cycle?
Answer: Cancer can arise from dysregulation of the cell cycle, leading to uncontrolled cell division. While not directly related to photosynthesis, understanding cell cycle regulation is crucial for addressing plant diseases and improving crop yields
Question: What are two major challenges to the efficiency of photosynthesis?
Answer: Two major challenges to the efficiency of photosynthesis are excess light energy and the oxygenase activity of rubisco.1
Question: What happens when light density is too high for a plant?
Answer: When the light density is too high, the high-energy electrons produced during photosynthesis lack a safe destination. This increases the likelihood of Reactive Oxygen Species (ROS) formation, which can damage the plant.2
Question: How do antioxidants help plants cope with high light density?
Answer: Antioxidants can neutralize reactive oxygen species, protecting the plant from damage caused by excess light energy.3
Question: What role do Xanthophylls play in protecting plants from excess light?
Answer: Xanthophylls are yellow-orange pigments that can slow the formation of reactive oxygen species, helping to mitigate the effects of high light density.3
Question: What is photorespiration and when does it occur?
Answer: Photorespiration occurs when the enzyme rubisco adds O2 instead of CO2 to RuBP. This is a problem because rubisco can use both CO2 and O2 as substrates, and using O2 is less efficient for the plant.3
Question: How does photorespiration impact carbon and energy in a plant?
Answer: When rubisco acts as an oxygenase, it leads to a loss of carbon and energy for the plant, reducing the efficiency of photosynthesis.4
Question: How have some plants evolved to avoid photorespiration?
Answer: Some plants, known as C4 plants, have evolved a mechanism to concentrate CO2 around rubisco, minimizing the oxygenase activity and reducing photorespiration.4
Question: What is the significance of cell-free solar-to-starch efficiency?
Answer: Cell-free solar-to-starch efficiency refers to the efficiency with which artificial systems can convert sunlight into starch. This research aims to improve the efficiency of photosynthesis beyond what is currently possible in natural systems.45
Question: What were the two major steps in the evolution of photosynthesis?
Answer: The two major steps in the evolution of photosynthesis were:
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The development of two photosystems.5
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Endosymbiosis, where an ancient eukaryotic cell engulfed a photosynthetic bacterium, leading to the development of chloroplasts.5
Question: What is Horizontal Gene Transfer (HGT)?
Answer: HGT is the transfer of genetic material between organisms that are not related through descent. This process can lead to the acquisition of new traits and the rapid evolution of species.5
Question: What are three mechanisms of Horizontal Gene Transfer?
Answer: Three mechanisms of HGT are:
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Conjugation: Direct transfer of DNA between bacteria through a pilus.5
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Transformation: Uptake of free DNA from the environment by bacteria.5
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Transduction: Transfer of DNA between bacteria via a bacteriophage (virus).5
12.
Question: Give examples of HGT in nature.
Answer: Examples of HGT include:
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Transfer of carotenoid genes from fungi to aphids.6
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Transfer of ubiquitin genes from insects to fungi.6
Question: What is the significance of HGT in the evolution of photosynthesis?
Answer: HGT has likely played a role in the evolution of photosynthesis by allowing the transfer of genes related to photosynthetic processes between different organisms.567
Question: What is the focus of research on mosquito-fungus interactions?
Answer: Research on mosquito-fungus interactions aims to understand the ecological relationships between mosquitoes and fungi, particularly those that inhabit the mosquito gut. This research may have implications for controlling mosquito populations and the diseases they transmit.7
Question: What does the regeneration phase of the Calvin cycle accomplish?
Answer: The regeneration phase of the Calvin cycle regenerates 3 molecules of RuBP from 5 molecules of triose phosphate.8
Question: What is the function of Photosystem II (PSII) in photosynthesis?
Answer: Photosystem II supplies electrons to the beginning of the electron transport chain.1
Question: What is the role of Photosystem I (PSI) in photosynthesis?
Answer: Photosystem I energizes the electrons with a second input of light energy, providing enough energy to reduce NADP+.1
Question: What is the Z-scheme in photosynthesis?
Answer: The Z-scheme is a model that describes the flow of electrons through the electron transport chain during photosynthesis, involving both photosystems and various electron carriers.1
Question: What are plastoquinone and plastocyanin?
Answer: Plastoquinone and plastocyanin are electron carriers within the photosynthetic electron transport chain.1
Question: What is the function of the cytochrome b6f complex in photosynthesis?
Answer: The cytochrome b6f complex is a protein complex involved in the electron transport chain, responsible for transferring electrons between plastoquinone and plastocyanin. It also contributes to proton accumulation in the thylakoid lumen.12
Question: What are the two sources of protons in the thylakoid lumen during photosynthesis?
Answer: The two sources of protons are:
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Production through water oxidation in PSII.2
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Pumping of protons by the cytochrome b6f complex.2
Question: What is cyclic electron transport and what is its purpose?
Answer: Cyclic electron transport is an alternative pathway for electrons that increases the production of ATP while decreasing the production of NADPH. This pathway is activated when the need for ATP is higher than the need for NADPH.2
Question: What role does ferredoxin play in cyclic electron transport?
Answer: Ferredoxin is an electron carrier that shuttles electrons from PSI back to the cytochrome b6f complex during cyclic electron transport, contributing to the increased production of ATP.2
Question: Can red maple leaves perform photosynthesis?
Answer: Yes, red maple leaves can perform photosynthesis. Although they contain anthocyanin pigments that give them their red color, they still have chlorophyll, the primary pigment for photosynthesis.9
Question: Can white plants perform photosynthesis? If not, what is their carbon source?
Answer: White plants like the Indian Pipe (Monotropa uniflora) cannot perform photosynthesis because they lack chlorophyll. Instead of producing their own food, they obtain carbon from nearby trees through mycorrhizal fungi that connect their roots to the tree’s roots. They are considered myco-heterotrophic plants.910
Question: What are the three main approaches in biological research?
nswer: The three main approaches in biological research are:
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Ecology (fieldwork): Studying organisms and their interactions in their natural environment.7
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Computational Biology (‘dry-lab’): Using computational tools and data analysis to study biological systems.7
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Experimental Biology (‘wet-lab’): Conducting laboratory experiments to investigate biological phenomena.7
Question: What is the significance of Zancudomyces culisetae?
Answer: Zancudomyces culisetae is a parasitic fungus that infects mosquitoes.
