150 Questions
Where are the stacks of thylakoids located within chloroplasts?
Grana
Which part of the chloroplast is responsible for carrying out light-dependent reactions?
Photosystem I
What is the main product generated in cyclic photophosphorylation?
ATP
What process describes the production of ATP in photosynthesis?
Photophosphorylation
What is the initial acceptor of electrons in the electron transport chain during light-dependent reactions?
Chlorophyll
Which photosystem provides the excited electrons for cyclic photophosphorylation?
Photosystem I
What is the space between the thylakoids and the outer chloroplast membrane called?
Stroma
What is the main purpose of producing enzymes only when their substrate is present?
To avoid unnecessary enzyme production
How do cells benefit from catabolizing metabolites to produce lots of energy?
By enhancing the efficiency of cellular activities
Why is it important for eukaryotic cells to separate metabolic processes in membrane-bound organelles?
To compartmentalize different metabolic activities
What is the primary role of allosteric regulation in enzyme function?
To regulate enzyme activity based on cellular conditions
How does feedback inhibition contribute to the regulation of metabolic pathways?
By inhibiting excessive accumulation of end products
Which process is associated with controlling enzyme production needed for metabolic pathways?
Synthesizing metabolites only when needed
In what way do cells regulate the availability of cofactors to affect metabolic pathways?
By regulating pathways through cofactor control
Which precursor metabolite is used to produce ribose and deoxyribose for nucleotide biosynthesis?
Ribose 5-phosphate
What is the main source of phosphate for nucleotide biosynthesis?
ATP
Which amino acids contribute to the production of purines and pyrimidines for nucleotide biosynthesis?
Glutamine and Aspartic acid
How are catabolic and anabolic pathways related in terms of energy utilization?
Energy released in catabolic pathways is used to drive anabolic pathways
What term is used to describe reactions that can function as both anabolic and catabolic pathways as needed?
Amphibolic
Which component is NOT part of a nucleotide structure?
Adenine base
What is the role of folic acid in nucleotide biosynthesis?
Aiding in the production of purines and pyrimidines
Which type of organisms use inorganic compounds like H2S as a source of electrons for photosynthesis?
Anoxygenic organisms
In noncyclic photophosphorylation, what is the role of photosystem II?
Replenishes electrons to PS II
Which molecules are produced during the reduction step of the Calvin-Benson cycle?
Glyceraldehyde 3-phosphate (G3P)
What drives the synthesis of glucose by carbon fixation in the light-independent pathway of photosynthesis?
ATP and NADPH
What are amphibolic reactions in metabolism?
Reactions that proceed towards catabolism or anabolism depending on cell needs
What is the ultimate product of the Calvin-Benson cycle?
Glucose
What is the source of electrons for oxygenic organisms during photosynthesis?
H2O
Which process involves the production of sugars, starch, cellulose, glycogen, and peptidoglycan from noncarbohydrate precursors?
Gluconeogenesis
How many reactions are unique to gluconeogenesis?
Four
Which process involves the synthesis of triglycerides from glycerol and fatty acids?
Lipid biosynthesis
What type of amino acid synthesis involves the addition of an amine group from ammonia to a precursor metabolite?
Amination
Which type of lipids require long synthesis pathways and lots of energy for their production?
Waxes
What are essential amino acids?
Amino acids that must be obtained through diet
Which metabolic pathway involves the seven reactions that are simply the reverse of glycolysis reactions?
Gluconeogenesis
What is the role of nicotinamide adenine dinucleotide (NAD+) in metabolic pathways?
Electron acceptor
During dehydrogenation reactions, which molecule loses an electron?
The electron donor
What is the main function of flavin adenine dinucleotide (FAD) in metabolic pathways?
Transfer electrons
In redox reactions, what happens to the electron donor?
Is oxidized
What is the significance of phosphorylation in energy storage?
Adds a phosphate group to molecules
Which statement accurately describes anabolic reactions in cellular metabolism?
Require ATP energy
What type of reactions involve the transfer of electrons in metabolism?
Dehydrogenation
What are organic cofactors also known as?
Coenzymes
What term is used to describe RNA molecules that function as catalysts?
Ribozymes
What is the function of ribosomal ribozymes in eukaryotes?
Process RNA molecules
What determines enzyme-substrate specificity in enzymology?
Complementary shapes of active sites and substrates
Which model describes the phenomenon where the active site of an enzyme changes shape upon substrate binding?
Induced Fit model
How do enzymes affect the activation energy of a chemical reaction?
Decrease it
What can influence the rate of enzymatic reactions?
Temperature, pH, enzyme and substrate concentration, and presence of inhibitors
What might result in the denaturation of enzymes?
A change in shape due to physical or chemical factors.
During glycolysis, how many net ATP molecules are produced?
2
Which stage of glycolysis involves the splitting of glucose into two molecules of pyruvic acid?
Lysis
In glycolysis, which molecule is produced by substrate-level phosphorylation?
ATP
What determines whether pyruvate is directed to the citric acid cycle or fermentation reactions?
Availability of final electron acceptors
Which stage of cellular respiration involves the production of acetyl-CoA?
Synthesis of acetyl-CoA
Where does the production of acetyl-CoA in cellular respiration begin?
Decarboxylation of pyruvic acid
How many stages are involved in cellular respiration?
3
Which metabolic pathway yields the most ATP molecules from the aerobic respiration of glucose?
Embden-Meyerhof pathway
What is the main purpose of fermentation in cells?
To generate NADPH
Which pathway is used by only a few bacteria, utilizes different enzymes, and yields precursor metabolites and NADPH?
Entner-Doudoroff pathway
During aerobic respiration of glucose, where does the citric acid cycle occur?
Mitochondrial matrix
What is the role of the electron transport chain in cellular respiration?
To produce ATP molecules
Which molecule serves as the final electron acceptor in fermentation when complete cellular respiration electron acceptors are unavailable?
NAD+
What is the purpose of the pentose phosphate pathway during glucose catabolism?
To provide precursor metabolites and NADPH for important molecule synthesis
What is the main function of the citric acid cycle?
Generate ATP and FADH2
Where does the electron transport chain take place in eukaryotic cells?
Mitochondrial matrix
What is the primary role of the proton gradient in the electron transport chain?
Generate ATP through chemiosmosis
What distinguishes lithotrophs from most organisms in terms of electron donors?
Harness energy from inorganic compounds
Which cellular component houses the electron transport chains in prokaryotes?
Cytoplasmic membrane
What is the common name for the tricarboxylic acid cycle?
Krebs cycle
Which process utilizes energy from electrons to pump protons across a membrane?
Chemiosmosis
What is the final electron acceptor in the electron transport chain?
Oxygen
What is the primary purpose of synthesizing metabolites only when they are needed?
To avoid wasting energy on unnecessary metabolic processes
How does allosteric regulation contribute to enzyme function?
By modulating enzyme activity based on cellular needs
What is the purpose of feedback inhibition in metabolic pathways?
To prevent the accumulation of excess metabolites
Which mechanism separates metabolic processes in eukaryotes?
Membrane-bound organelles
What is the main function of controlling gene expression in cells?
To control the production of enzymes necessary for metabolic pathways
How do cells benefit from producing enzymes only when their substrate is present?
By conserving energy and resources for necessary processes
In what way do regulatory mechanisms impact metabolic pathways?
By influencing enzyme activity and metabolite synthesis
What is a key role of Catabolizing metabolites to produce lots of energy?
To generate a significant amount of energy for cellular functions
What is the primary function of adenosine triphosphate (ATP) in metabolism?
Storing energy in the bonds
In metabolism, what is the role of catalytic enzymes?
Breaking down nutrients into precursor metabolites
What is the main source of energy for metabolism?
Catabolism
Which process involves assembling larger molecules using precursor metabolites and energy?
Anabolic reactions
What is the primary function of the citric acid cycle in cellular respiration?
Generation of ATP molecules
Which metabolic pathway involves the breakdown of proteins?
Lipid catabolism
In photosynthesis, where do light-independent reactions take place?
Calvin-Benson cycle
What is the main role of the pentose phosphate pathway during glucose catabolism?
Reduction of NADP+ to NADPH
What is the primary difference between oxidative phosphorylation and photophosphorylation?
The source of energy
Which category of enzymes is responsible for joining molecules together?
Ligases
What type of cofactors include ions such as iron, magnesium, zinc, or copper?
Inorganic cofactors
Which mode of action involves rearranging atoms in a molecule?
Isomerases
What is the main function of transferases among the six categories of enzymes?
Transfer functional groups
What is the final product of substrate-level phosphorylation?
ATP
Which enzyme category is involved in oxidizing or reducing reactions?
Oxidoreductases
What distinguishes apoenzymes from complete protein enzymes?
Apoenzymes are inactive until they bind with a nonprotein cofactor.
What is the purpose of chemiosmosis in the electron transport chain?
Synthesizing ATP
Which category of carrier molecules is responsible for creating a proton gradient across a membrane during chemiosmosis?
Ubiquinones
How many molecules of NADH are oxidized to yield approximately 34 molecules of ATP during chemiosmosis?
10
In anaerobic respiration, what serves as the final electron acceptor instead of oxygen?
Sulfate
What is the primary function of cytochromes in the electron transport system?
Transporting electrons
Which process results in the synthesis of ATP through the flow of protons through ATP synthase channels?
Oxidative phosphorylation
During chemiosmosis, what provides potential energy known as a proton motive force?
Oxidation of NADH
What is the role of ribozymes in eukaryotic cells?
Process RNA molecules
How are substrates related to the active sites of enzymes?
Fit onto specifically shaped active sites
What is the consequence of high temperatures on enzyme activity?
Denatures enzymes by changing their shape
What effect does the presence of inhibitors have on enzyme reactions?
Slows down or stops enzymatic activity
How is enzyme-substrate specificity determined?
By the complementary shapes of active sites and substrates
What happens after an enzyme binds to a substrate in catabolism?
The enzyme separates from the two products formed
What model describes the phenomenon where the active site of an enzyme can change shape upon substrate binding?
Induced-fit model
How do physical and chemical factors like temperature and pH affect enzymatic activity?
Denature enzymes, affecting their ability to function
Which type of metabolic reactions break down nutrients into precursor metabolites?
Catabolic reactions
What is the primary function of ATP in metabolism?
Storing and transferring energy
Which process involves the assembly of larger molecules using precursor metabolites and energy?
Anabolic reactions
What is the main outcome of lipid catabolism?
ATP production
During cellular respiration, what role do catalytic enzymes play?
Breaking down nutrients into precursor metabolites
What is the key function of carbohydrate biosynthesis in metabolism?
Synthesizing carbohydrates from simpler precursors
In terms of metabolism, what describes the role of photosynthesis?
Utilizes light energy to build organic molecules from CO2 and water
What is the primary purpose of the tricarboxylic acid cycle in cells?
Oxidizing acetyl-CoA to produce NADH and FADH2 for electron transport chain
What happens when a cell has doubled in size?
It typically divides into two cells
What type of reactions synthesize macromolecules and use ATP energy?
Anabolic reactions
What do oxidation-reduction (redox) reactions involve the transfer of?
Electrons
Which molecules are often required in metabolic pathways as electron carriers?
Nicotinamide adenine dinucleotide (NAD+), nicotinamide adenine dinucleotide phosphate (NADP+), and flavin adenine dinucleotide (FAD)
What is the role of ATP in energy storage?
It stores energy in high-energy phosphate bonds
What is characteristic of catabolic pathways?
They are exergonic and break down nutrient molecules
What occurs during dehydrogenation reactions?
An electron donor loses an electron and is oxidized
What is phosphorylation in the context of cellular processes?
The addition of inorganic phosphate to a molecule to store energy
Where are the two photosystems, PS I and PS II, located within the chloroplast?
Thylakoids
What process generates ATP in photosynthesis through a proton motive force?
Photophosphorylation
Which chlorophyll molecule is excited by transferred energy and passes electrons to the electron transport chain?
Reaction center chlorophyll
What is the primary function of photosystem I in cyclic photophosphorylation?
Provide excited electrons
What is the general term for the light absorption and redox reactions of photosynthesis?
Light-dependent reactions
In photosynthesis, where is ATP synthesized during cyclic photophosphorylation?
By chemiosmosis
What role does the space between thylakoids and the outer chloroplast membrane play in photosynthesis?
It is the stroma where dark reactions occur
What is the primary function of the citric acid cycle?
Synthesize ATP
In the electron transport chain, what is the role of lithotrophs compared to most organisms?
Utilize inorganic electron donors
What is the main source of energy produced in the electron transport chain?
Proton motive force
Which enzymes are responsible for the hydration reactions in the citric acid cycle?
Hydratase enzymes
What is the final electron acceptor in the electron transport chain?
Oxygen
How many ATP molecules are formed for every two molecules of acetyl-CoA that enter the citric acid cycle?
4 ATP
Which organelle houses the electron transport chains in eukaryotic cells?
Mitochondria
What is the process used to generate ATP by utilizing a proton gradient across a membrane?
Chemiosmosis
What is the primary function of photophosphorylation?
Phosphorylation of ADP using inorganic phosphate and energy from light
Which category of enzymes is responsible for splitting molecules without using water?
Lyases
What distinguishes protein enzymes composed of apoenzymes and nonprotein cofactors from complete protein enzymes?
They are not functional by themselves
What is the role of isomerases among the six categories of enzymes?
Rearrange atoms in a molecule
What type of cofactors are made from vitamins and include NAD+ and FAD?
Organic cofactors
How are organic catalysts, like enzymes, different from inorganic catalysts?
Enzymes are not permanently changed in the process
What is the primary function of transferases among the six categories of enzymes?
Transfer functional groups
What is the main purpose of hydrolases among the six categories of enzymes?
Split molecules without using water
Explore the structure of chloroplasts, specifically the arrangement of thylakoids into grana and the stroma. Learn about the two photosystems, PS I and PS II, which are involved in light-dependent reactions. Discover how photosynthesis is divided into light-dependent and light-independent reactions.
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