Metabolic Pathways: Glycolysis and the Krebs Cycle

This set of flashcards covers the key concepts related to glycolysis, Krebs Cycle, and the Electron Transport Chain as discussed in the lecture.

Glycolysis

A metabolic process that converts glucose into pyruvate, producing a net gain of ATP and NADH.

Location of Glycolysis in Eukaryotic Cells

Cytoplasm.

Location of Glycolysis in Prokaryotic Cells

Cytoplasm.

Outcome of Glycolysis

Produces pyruvate, ATP, and NADH.

Goal of Glycolysis with Electron Transfer Chain (ETC) present

To produce ATP through substrate-level phosphorylation and generate NADH for the ETC.

Goal of Glycolysis without Electron Transfer Chain (ETC)

To produce ATP and regenerate NAD+ for continued glycolysis.

Type of phosphorylation used in Glycolysis

Substrate-level phosphorylation.

Steps of Glycolysis using substrate-level phosphorylation

Occurs during steps involving the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and phosphoenolpyruvate to pyruvate.

Pre-step to Krebs Cycle

Conversion of pyruvate to Acetyl-CoA.

Location of pre-step to Krebs Cycle in Eukaryotic Cells

Mitochondrial matrix.

Location of pre-step to Krebs Cycle in Prokaryotic Cells

Cytoplasm.

Necessity of the pre-step to Krebs Cycle

Converts pyruvate to Acetyl-CoA, which is required for entry into the Krebs Cycle.

Goal of the Krebs Cycle

To fully oxidize Acetyl-CoA for energy production through NADH and FADH2.

Location of Krebs Cycle in Eukaryotic Cells

Mitochondrial matrix.

Location of Krebs Cycle in Prokaryotic Cells

Cytoplasm.

Outcome of the Krebs Cycle

Produces NADH, FADH2, ATP (or GTP), and carbon dioxide.

Role of NADH+

Serves as an electron carrier to the Electron Transport Chain.

Type of phosphorylation in the Krebs Cycle

Substrate-level phosphorylation.

Location of Electron Transport Chain enzymes in Eukaryotic Cells

Inner mitochondrial membrane.

Location of Electron Transport Chain enzymes in Prokaryotic Cells

Plasma membrane.

Function of NADH dehydrogenase

Accepts electrons from NADH and transfers them to ubiquinone.

Function of Ubiquinone

Transports electrons from NADH dehydrogenase to cytochrome b-c complex.

Function of Cytochrome b-c Complex

Transfers electrons to cytochrome c while pumping protons into the intermembrane space.

Function of Cytochrome Oxidase

Transfers electrons to molecular oxygen and contributes to water formation.

Function of ATP Synthase

Synthesizes ATP from ADP and inorganic phosphate using the proton gradient.

Chemiosmosis

The process by which protons flow back into the mitochondrial matrix through ATP synthase to generate ATP.

Most acidic space in active Electron Transfer Chain (ETC)

Intermembrane space of the mitochondria.

Necessity of forming water at the end of ETC

Prevents the accumulation of electrons and protons, ensuring the continuation of the electron flow and ATP synthesis.

Substrate used by cells anaerobically at the end of ETC

Fermentation substrates like pyruvate or other organic molecules.

Anaerobic use without ETC

Inorganic molecules like nitrate or sulfate can be used as terminal electron acceptors.

Reason for fermentation

To regenerate NAD+ under anaerobic conditions, allowing glycolysis to continue.

Types of fermentation

Lactic acid fermentation in some microorganisms and alcohol fermentation in others, depending on their metabolic pathways.