Questions and Answers
What is the site of lipid synthesis?
What is the function of the Golgi apparatus in secretory cells?
What is the main function of lysosomes?
What is the primary function of mitochondria?
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What is unique about the inner membrane of mitochondria?
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What is the function of peroxisomes?
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What is the composition of the Golgi apparatus membrane?
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What is the fate of transport vesicles that bud from the smooth ER?
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What is the function of the smooth ER in cell growth?
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What is unique about mitochondrial DNA?
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Study Notes
Mitochondrial Membrane
- Many foldings of the inner membrane form shelves with attached oxidative enzymes
- Inner cavity (matrix) contains dissolved enzymes that extract energy from nutrients
- Enzymes in the matrix work with oxidative enzymes on the shelves to oxidize nutrients, forming CO2 and water, and releasing energy
- Liberated energy is used to synthesize ATP, which is then transported out of the mitochondrion and diffuses to release energy where needed for cellular functions
Replication of Mitochondria
- Mitochondria are self-replicative
The Nucleus: Control Center of the Cell
- Nucleus contains large quantities of DNA (genes)
- Nucleus is the control center, directing cell activities
- Nuclear membrane is a double bilayer membrane, continuous with the endoplasmic reticulum, with numerous nuclear pores
- Chromatin (condensed DNA) is found in the nucleoplasm
- Nucleolus is an accumulation of RNA and proteins, not membrane-delimited, and functions to form ribosomal subunits
- Nucleolus enlarges when the cell is actively synthesizing proteins
Transport Across Cell Membranes
- Simple diffusion: down an electrochemical gradient, not carrier-dependent, no metabolic energy required, and passive
- Facilitated diffusion: down an electrochemical gradient, carrier-mediated, more rapid than simple diffusion, and passive
- Primary active transport: against an electrochemical gradient, requires direct input of metabolic energy (ATP), and carrier-mediated
- Secondary active transport: co-transport
Cell Membrane Components
- Na+, K+-ATPase (Na+–K+ pump) transports Na+ from intracellular to extracellular fluid and K+ from extracellular to intracellular fluid, maintaining low intracellular [Na+] and high intracellular [K+]
- Site of lipid synthesis: phospholipids and cholesterol
Golgi Apparatus
- Membrane composition similar to smooth ER and plasma membrane
- Composed of 4 or more stacked layers of flat vesicular structures
- Receive transport vesicles from smooth ER and process substances to form lysosomes, secretory vesicles, and cytoplasmic components
Lysosomes
- Formed from budding Golgi apparatus
- Contain hydrolytic enzymes (acid hydrolases) for intracellular digestion of damaged cellular structures, food particles, and unwanted matter
- Fuse with pinocytotic or phagocytic vesicles
Peroxisomes
- Similar to lysosomes but formed by self-replication or budding from smooth endoplasmic reticulum
- Contain oxidases (hydrogen peroxide and catalase) to oxidize poisonous substances (e.g., alcohol)
Mitochondria (Powerhouse)
- Primary function: energy extraction from nutrients
- Contain DNA similar to that found in the cell nucleus
- Matrix contains large amounts of dissolved enzymes
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Description
This quiz covers the structure and function of mitochondrial cristae, including the inner membrane, oxidative enzymes, and matrix. Learn about how mitochondria extract energy from nutrients to produce carbon dioxide, water, and energy.
