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Questions and Answers
What is the main function of the cell membrane?
What is the composition of the phospholipid bilayer in the cell membrane?
What is the function of receptor-mediated endocytosis?
What is the term for the outer surface of the cell membrane containing carbohydrates?
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What is the purpose of the trilaminar structure of the cell membrane?
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What is the primary function of mitochondria in a cell?
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What is the function of rough endoplasmic reticulum in protein-forming cells?
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What is the characteristic of smooth endoplasmic reticulum in terms of cell type?
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What is the result of cells lacking hormone receptors in dwarfism?
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What is the name of the process by which mitochondria replicate themselves?
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Study Notes
Cell Structure and Function
- The cell is the structural and functional unit of the body, composed of cytoplasm and a nucleus.
Cytoplasm
- Cytosol: the fluid component of cytoplasm
- Organelles:
- Membranous organelles: permanently present in all living cells, performing vital functions
- Non-membranous organelles: also present in cytoplasm
- Cytoskeleton: provides structural support and shape to the cell
- Inclusions: various substances present in the cytoplasm
Cell Membrane
- Surrounds the cell, sometimes too thin to be seen (6-9 nm) under light microscopy
- Special stain: silver (Ag), PAS
- Electron microscopy: trilaminar (trilamellar) structure, formed of three layers (two dark lines and a light line in-between)
- Molecular structure:
- Lipid: phospholipids arranged in a bilayer, with cholesterol within the hydrophobic layer
- Protein: intrinsic (integral) and extrinsic (peripheral) types
- Carbohydrates: form the cell coat (glycocalyx) on the outer surface, composed of glycolipid and glycoprotein
- Functions:
- Protection of the cell
- Selective permeability: controls passage of materials into and out of the cell
- Cell coat functions: adhesion, recognition, rejection, and receptor formation
Clinical Note
- Dwarfism: occurs when cells lack growth hormone receptors, leading to stunted growth
Mitochondria
- Power house of the cell, more abundant in active cells
- Light microscopy: acidophilic when large in number, special stain: iron hematoxylin or Janus green
- Electron microscopy: rounded or oval, with outer smooth membrane and inner membrane folded into cristae
- Functions:
- Synthesis of energy (oxidative phosphorylation)
- Storing of energy in the form of ATP
- Release of energy by transforming ATP into ADP
- Capable of self-replication (by binary fission) due to its own DNA
Endoplasmic Reticulum
- Endo=inside, plasma=cytoplasm, reticulum=network
- Two types: rough endoplasmic reticulum (rER) and smooth endoplasmic reticulum (sER)
- Rough endoplasmic reticulum (rER):
- Abundant in protein-forming cells
- Light microscopy: basophilic (ribosomes)
- Electron microscopy: membranous interconnected tubules (cisternae) with ribosomes attached to the surface
- Functions:
- Synthesis and segregation of protein
- Initial glycosylation of glycoproteins
- Formation of transfer vesicle to be transported to Golgi apparatus for secretion
- Share in the formation of lysosomes
- Smooth endoplasmic reticulum (sER):
- Abundant in steroid-forming cells
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Description
This quiz covers the components of a cell, including cytoplasm, nucleus, membranous organelles, and cell membrane. Test your knowledge of the structural and functional units of the body!
