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According to the endosymbiotic theory, what is the origin of eukaryotic cells?
According to the endosymbiotic theory, what is the origin of eukaryotic cells?
The endosymbiotic theory was first proposed by the Russian botanist Konstantin Mereschkows.
The endosymbiotic theory was first proposed by the Russian botanist Konstantin Mereschkows.
True
What is the primary function of mitochondria?
What is the primary function of mitochondria?
ATP synthesis and apoptosis
What does the term 'symbiosis' refer to?
What does the term 'symbiosis' refer to?
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The theory of endosymbiosis suggests that mitochondria and chloroplasts are the remnants of formerly free-living prokaryotes.
The theory of endosymbiosis suggests that mitochondria and chloroplasts are the remnants of formerly free-living prokaryotes.
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What is the main function of the outer mitochondrial membrane (OMM)?
What is the main function of the outer mitochondrial membrane (OMM)?
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What are the folded structures present in the inner mitochondrial membrane known as?
What are the folded structures present in the inner mitochondrial membrane known as?
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What is the phospholipid found in the inner mitochondrial membrane of eukaryotes that is commonly found in bacterial membranes?
What is the phospholipid found in the inner mitochondrial membrane of eukaryotes that is commonly found in bacterial membranes?
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The mitochondrial matrix contains mitochondrial ribosomal RNA and DNA.
The mitochondrial matrix contains mitochondrial ribosomal RNA and DNA.
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What two general categories does cellular respiration utilize chemical energy stored in molecules to produce?
What two general categories does cellular respiration utilize chemical energy stored in molecules to produce?
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Cellular respiration that occurs in the presence of oxygen is referred to as anaerobic respiration.
Cellular respiration that occurs in the presence of oxygen is referred to as anaerobic respiration.
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What are the two primary steps involved in oxidative phosphorylation?
What are the two primary steps involved in oxidative phosphorylation?
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What does the term 'electrochemical gradient' refer to?
What does the term 'electrochemical gradient' refer to?
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Where are the electron carriers used in the electron transport chain located?
Where are the electron carriers used in the electron transport chain located?
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The terminal electron acceptor in the electron transport chain is oxygen.
The terminal electron acceptor in the electron transport chain is oxygen.
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What is the name of the proton pump that uses the electrochemical gradient to synthesize ATP?
What is the name of the proton pump that uses the electrochemical gradient to synthesize ATP?
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What is the primary role of coenzymes NAD+ and FAD in cellular respiration?
What is the primary role of coenzymes NAD+ and FAD in cellular respiration?
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Study Notes
Main Functions of Intercellular Compartments
- Cytosol: Protein synthesis, many metabolic pathways
- Nucleus: Contains genome (DNA, RNA), and ribosome assembly
- Endoplasmic Reticulum (ER): Synthesis of lipids and proteins
- Golgi Apparatus: Protein modification, packaging of proteins and lipids
- Lysosomes: Degradation of cellular material
- Endosomes: Sorting and recycling
- Mitochondria: ATP synthesis, apoptosis
- Chloroplasts: Photosynthesis, ATP synthesis
- Peroxisomes: Oxidation of toxic molecules
Origin of Eukaryotic Cells: The Endosymbiotic Theory
- The endosymbiotic theory is an evolutionary theory of eukaryotic cell origin from prokaryotes.
- It was first proposed by Konstantin Mereschkowski and later supported by Lynn Margulis with microbiological evidence.
- This theory suggests that eukaryotic organelles evolved from symbiotic relationships with individual single-celled prokaryotes (bacteria and archaea).
- Symbiosis describes a close and long-term biological interaction.
- The theory proposes that organelles like mitochondria and chloroplasts were once free-living prokaryotes that were engulfed by another prokaryote.
- Evidence supporting this theory includes:
- Binary fission of mitochondria and chloroplasts, which is similar to bacteria
- Circular DNA inside these organelles is similar to bacterial DNA
The Big Leap: Energy Supply
- Aerobic Respiration: Converts energy stored in food molecules (e.g., glucose) into chemical energy stored in ATP in the presence of oxygen. A byproduct is carbon dioxide.
- Photosynthesis: Uses energy from sunlight to build carbohydrates from carbon dioxide and water. Oxygen is released as a byproduct.
Mitochondria: Structure and Function
- Aerobic Respiration: Converts energy stored in food (glucose) into ATP in the presence of oxygen. Carbon dioxide is a byproduct.
- Outer Mitochondrial Membrane (OMM): Contains enzymes with diverse metabolic functions, including those that break down monoamines (e.g., dopamine, serotonin). Also contains porins, which are permeable to molecules like ATP and sucrose.
- Inner Mitochondrial Membrane (IMM): Has a high protein-to-lipid ratio (3:1). Folds called cristae increase the membrane surface area and contain machinery for aerobic respiration and ATP production. Rich in cardiolipin, a phospholipid characteristic of bacterial membranes.
Mitochondria and Cellular Respiration
- Cellular Respiration: Uses chemical energy of carbohydrates and lipids to produce ATP.
- Aerobic Respiration: Cellular respiration in the presence of oxygen.
- Substrate-level Phosphorylation: Releases enough energy to drive phosphorylation of ADP to ATP during reactions like glycolysis. Glycolysis breaks down glucose to pyruvate.
- Oxidative Phosphorylation: Transfers chemical energy to electron carriers, creating a gradient that powers ATP synthesis.
Coenzymes/Electron Carriers
- Some coenzymes can exist in oxidized or reduced states that accept or donate electrons.
- Examples: NAD+ (oxidized), NADH (reduced); FAD (oxidized), FADH2 (reduced)
Mitochondrial Oxidative Phosphorylation
- Oxidative phosphorylation — is the fourth stage of cellular respiration in animal cells.
- It involves two main steps:
- Step 1: Transfer of electrons through complexes I-IV (the electron transport chain), which pumps protons resulting in an electrochemical gradient.
- Step 2: Movement of protons down the gradient through ATP synthase drives ATP synthesis.
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