BIO131 final PART 2

What is the Embden-Meyerhof pathway (EM)?

A glycolytic pathway found in all Eukarya and some bacteria that converts D-(+)-glucose into pyruvate while generating ATP and NADH.

What is the Entner-Doudoroff pathway (ED)?

A glycolytic pathway found in Viridiplantae and some bacteria that converts D-(+)-glucose into pyruvate, generating NADH and NADPH.

What role does the oxidative pentose phosphate pathway (PP) play?

It is a shunt found in some bacteria and all Eukarya that bypasses the EM pathway and generates NADPH and other metabolites.

What happens during the link reaction?

Pyruvate is oxidized to acetyl-CoA and CO2, generating NADH.

How does acetyl-CoA enter the Krebs cycle?

Acetyl-CoA enters the Krebs cycle where it is oxidized to CO2, generating NAD(P)H, GTP, and QH2.

What is the function of ATP synthase in cellular respiration?

ATP synthase consumes the proton motive force (Δp) to synthesize ATP.

What is NADH's role in cellular metabolism?

NADH carries electrons to the respiratory chain, facilitating ATP production.

What is substrate-level phosphorylation?

A method of generating ATP directly from metabolic reactions, occurring in the glycolytic and Krebs cycles.

What is the significance of multiple glycolytic pathways?

Different pathways allow organisms to adapt to varying environmental conditions and metabolic needs.

What does fermentation produce and under what conditions does it occur?

Fermentation produces ATP and byproducts like lactate or ethanol in anaerobic conditions.

What is the purpose of the respiratory chain?

The respiratory chain is responsible for transferring electrons from NADH and FADH2 to oxygen to produce ATP.

What does 'anabolic pathway' refer to?

An anabolic pathway builds larger molecules from smaller ones, often using ATP and NADPH.

How is GTP generated in the Krebs cycle?

GTP is produced when succinyl-CoA is converted to succinate.

What is the Calvin-Benson-Bassham cycle primarily used for?

The Calvin-Benson-Bassham cycle is used for CO2 assimilation into organic molecules during photosynthesis.

What happens when RuBisCO catalyzes the oxygenation of RuBP?

It leads to a wasting of carbon that cannot be assimilated, reducing photosynthetic efficiency.

How do organisms with a respiratory chain generate Δp?

Electrons from NADH and FADH2 are transported through complexes, translocating protons into the intermembrane space.

What is the function of cytochrome c in the respiratory chain?

Cytochrome c transfers electrons between protein complexes in the respiratory chain.

What is the role of quinones in the respiratory chain?

Quinones serve as electron carriers that can transport electrons and protons across the membrane.

What occurs during cyclic photophosphorylation?

Electrons are recycled back to photosystem I, generating ATP without producing NADPH.

What is the role of chlorophyll in photosystems?

Chlorophyll absorbs light energy that excites electrons, driving photosynthesis.

What is the relationship between the Krebs cycle and the mitochondrial structure?

The Krebs cycle takes place in the mitochondrial matrix where acetyl-CoA is oxidized.

What is the primary purpose of the glyoxylate shunt?

To allow organisms to utilize acetate and convert it into carbohydrates without losing carbon as CO2.

What are the potential products of D-(+)-glucose catabolism?

The metabolism of D-(+)-glucose produces ATP, NADH, and pyruvate.

How does the body interconvert between ATP and GTP?

ATP can be converted to GTP and vice versa, depending on the cell's requirements.

What is zymology?

Zymology is the study of fermentation and its applications in biotechnology.

In which organisms can anaerobic respiration occur?

Anaerobic respiration can occur in some bacteria and archaea that use alternative electron acceptors.

What is the significance of metabolons in enzymatic pathways?

Metabolons enhance the efficiency of metabolic pathways by clustering related enzymes.

How do light reactions and dark reactions differ in photosynthesis?

Light reactions generate ATP and NADPH using light energy, while dark reactions use ATP and NADPH to assimilate CO2.

What do the terms 'litho-' and 'organo-' refer to in metabolic modes?

'Litho-' refers to inorganic electron donors, while 'organo-' refers to organic electron donors.

What are the main inputs and outputs of the Krebs cycle?

Inputs are acetyl-CoA and outputs are CO2, GTP (or ATP), and reduced cofactors like NADH and QH2.

What are some inhibitors of Krebs cycle enzymes?

Inhibitors include fluoroacetate, which disrupts aconitase activity.

What role does lipoate play in the Krebs cycle?

Lipoate is a cofactor used by the 2-oxoglutarate dehydrogenase complex.

What happens to the protons translocated during electron transport?

They create a proton motive force (Δp) used for ATP synthesis.

What is the significance of Δp in cellular respiration?

Δp represents the energy stored as a difference in proton concentration used to generate ATP.

How does the structure of chloroplasts facilitate photosynthesis?

Chloroplasts contain thylakoid membranes where light reactions occur to generate ATP and NADPH.

What is the primary function of the pentose phosphate pathway?

To produce NADPH and five-carbon sugars for biosynthesis.

How are NADH and NADPH linked in cellular metabolism?

NADH is primarily involved in catabolism, while NADPH is involved in anabolic processes.

What is the outcome of pyruvate conversion in fermentation?

In fermentation, pyruvate is reduced to lactate or ethanol, regenerating NAD+.

What is the purpose of adding phosphate groups to carbon skeletons?

It prepares them for downstream metabolism, enabling ATP synthesis.

How does the respiratory chain prevent NADH accumulation?

By oxidizing NADH through electron transport, avoiding inhibition of glycolysis.

What role does oxygen serve in aerobic respiration?

Oxygen acts as the terminal electron acceptor in the respiratory chain.

What is photolithoautotrophy?

A metabolic mode where organisms use light for energy, inorganic compounds for electrons, and CO2 for carbon.

What distinguishes a heterotrophic organism?

Heterotrophic organisms obtain carbon compounds from other living organisms or organic sources.

How do carboxysomes function in carbon fixation?

Carboxysomes concentrate CO2 around RuBisCO, enhancing the efficiency of carbon fixation.

What is the end product of glycolysis under anaerobic conditions?

The end product of glycolysis under anaerobic conditions is pyruvate.

How is energy harvested in the light reactions of photosynthesis?

Energy is harvested from sunlight to create ATP and NADPH through electron transport.

What is the significance of the Krebs cycle in cellular metabolism?

The Krebs cycle is central for energy production and provides intermediates for biosynthesis.

How does the electron transport chain generate heat?

By using uncoupling agents that dissipate Δp as heat instead of using it for ATP synthesis.

What steps in cellular metabolism rely on substrate-level phosphorylation?

Glycolysis and the Krebs cycle both involve substrate-level phosphorylation.

What effects does the breakdown of phosphoester bonds have on metabolism?

It releases energy for biochemical reactions, although some bond hydrolysis is endergonic.

How is glucose metabolized in glycolysis?

Glucose is converted to pyruvate through a series of enzymatic reactions, generating ATP and NADH.

What reactions are involved in converting malate to oxaloacetate in the Krebs cycle?

Malate is oxidized to oxaloacetate with the production of NADH.

What role does ATP play in the carbohydrate metabolism?

ATP provides energy needed for various biochemical reactions and processes in metabolism.

Why is lactate produced in anaerobic conditions?

Lactate is produced to regenerate NAD+ for continued glycolysis when oxygen is absent.

What enzymes mediate the major steps of glycolysis?

Key enzymes include hexokinase, phosphofructokinase, and pyruvate kinase.

Which organisms absence Krebs cycle to obtain energy?

Chemolithoautotrophic bacteria and archaea do not utilize the Krebs cycle but rely on inorganic electron donors.

What metabolic pathways utilize the products of glycolysis?

Products of glycolysis enter the Krebs cycle, fermentation pathways, or are used for biosynthesis.

What is the role of photosystems in photosynthesis?

Photosystems capture light energy to excite electrons and facilitate their transfer through the electron transport chain.

What are the carbon sources for autotrophic organisms?

Autotrophic organisms use CO2 as their carbon source for building cell materials.

Identify a key difference between aerobic and anaerobic respiration.

Aerobic respiration uses oxygen as the final electron acceptor, while anaerobic respiration uses other compounds.

Which enzyme catalyzes the first step of the Calvin cycle?

Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO).

How is proton motive force generated in the respiratory chain?

By the movement of electrons through protein complexes, leading to proton translocation.

What is the significance of the Calvin cycle in the context of photosynthesis?

The Calvin cycle fixes CO2 into organic molecules using ATP and NADPH generated from light reactions.

Under what conditions does the glycolytic pathway lead to fermentation?

Fermentation occurs under anaerobic conditions when oxygen is unavailable for respiration.

Describe the connection between glycolysis and the Krebs cycle.

Glycolysis produces pyruvate, which is converted to acetyl-CoA that enters the Krebs cycle for further energy extraction.

What do oxidoreductases do in metabolic pathways?

Oxidoreductases are enzymes that catalyze oxidation-reduction reactions, transferring electrons between molecules.

What is the total ATP yield from the complete oxidation of one glucose molecule?

The complete oxidation of one glucose molecule yields approximately 30-32 ATP.

How is ATP synthesized through ion-gradient-coupled phosphorylation?

ATP is synthesized when protons flow back across the membrane through ATP synthase, driven by the ion gradient.

What evolutionary significance does the diversity of electron transport chains have?

It demonstrates the adaptability of organisms to various environments and metabolic strategies.

What are the end products of the Krebs cycle in eukarya?

The end products are 2CO2, GTP (or ATP), NADH, and QH2.

How is oxygen utilized in eukaryotic aerobic respiration?

Oxygen serves as the terminal electron acceptor in the electron transport chain, facilitating ATP production.

What is the role of succinyl-CoA in the Krebs cycle?

Succinyl-CoA is involved in converting to succinate while generating GTP or ATP.

What mechanisms do organisms employ to concentrate CO2 for photosynthesis?

Organisms use carboxysomes, pyrenoids, or specialized pathways like C4 and CAM to concentrate CO2.

How do respiratory uncouplers affect ATP production?

They disrupt the proton motive force, preventing ATP synthesis and dissipating energy as heat.

What are reactive oxygen species (ROS) and how are they generated?

ROS are chemically reactive molecules formed during electron transport when electrons prematurely react with oxygen.

How do secondary metabolites relate to primary pathways like the Krebs cycle?

Secondary metabolites often derive from intermediates in primary pathways, like the Krebs cycle, used in protection and signaling.

Describe the relationship between light intensity and photosynthetic efficiency.

Higher light intensity typically increases photosynthetic efficiency to a certain saturation point, beyond which efficiency may plateau or decline.

What adaptations do plants exhibit to cope with varying light conditions?

Plants adapt through changes in chlorophyll content, leaf thickness, and the ability to switch between different photosynthetic pathways.