Podcast
Questions and Answers
Which of the following is NOT a membranous organelle?
Which of the following is NOT a membranous organelle?
- Ribosomes (correct)
- Golgi complex
- Mitochondria
- Lysosomes
What is the role of the cell membrane in relation to cell structure?
What is the role of the cell membrane in relation to cell structure?
- It generates energy for the cell.
- It determines the shape of the cell and maintains its structure. (correct)
- It is responsible for protein synthesis.
- It transports waste materials out of the cell.
Which component is NOT part of the fluid mosaic model of the cell membrane?
Which component is NOT part of the fluid mosaic model of the cell membrane?
- Phospholipid bilayer
- Rigid proteins (correct)
- Cholesterol
- Proteins
Which membranous organelle is primarily responsible for energy production?
Which membranous organelle is primarily responsible for energy production?
What structure do you see under high power in an electron microscope when viewing the cell membrane?
What structure do you see under high power in an electron microscope when viewing the cell membrane?
Which of the following statements about the phospholipid bilayer is TRUE?
Which of the following statements about the phospholipid bilayer is TRUE?
What is the selective permeability of the cell membrane responsible for?
What is the selective permeability of the cell membrane responsible for?
Which organelle is involved in protein secretion?
Which organelle is involved in protein secretion?
Which of the following organelles is classified as a membranous organelle?
Which of the following organelles is classified as a membranous organelle?
What is the primary function of the Golgi complex in a cell?
What is the primary function of the Golgi complex in a cell?
Which type of microscopy is most suitable for observing membranous organelles?
Which type of microscopy is most suitable for observing membranous organelles?
Which of the following best describes the characteristics of lysosomes?
Which of the following best describes the characteristics of lysosomes?
Which organelle is primarily responsible for synthesizing proteins?
Which organelle is primarily responsible for synthesizing proteins?
What is the role of the cell membrane in relation to membranous organelles?
What is the role of the cell membrane in relation to membranous organelles?
Which dye is used in basic histology to stain acidic structures like DNA?
Which dye is used in basic histology to stain acidic structures like DNA?
Acidophilic structures are primarily stained by which type of dye?
Acidophilic structures are primarily stained by which type of dye?
What is formed when a damaged organelle is enclosed within a bilayer membrane?
What is formed when a damaged organelle is enclosed within a bilayer membrane?
What accumulates in nerve cells and cardiac muscle cells over time?
What accumulates in nerve cells and cardiac muscle cells over time?
Which organelle is responsible for the synthesis of secretory proteins?
Which organelle is responsible for the synthesis of secretory proteins?
Which of the following stains is used to observe the Golgi complex?
Which of the following stains is used to observe the Golgi complex?
Which organelle functions in glucose metabolism specifically in liver cells?
Which organelle functions in glucose metabolism specifically in liver cells?
What type of lysosome contains indigestible materials such as pigments or lipids?
What type of lysosome contains indigestible materials such as pigments or lipids?
What structure is typically associated with producing steroid hormones?
What structure is typically associated with producing steroid hormones?
Which of the following does NOT facilitate the secretion of proteins outside the cell?
Which of the following does NOT facilitate the secretion of proteins outside the cell?
What property do the phosphate heads of phospholipid molecules exhibit?
What property do the phosphate heads of phospholipid molecules exhibit?
Which type of protein crosses the lipid bilayer and can protrude from both membrane surfaces?
Which type of protein crosses the lipid bilayer and can protrude from both membrane surfaces?
What is the primary function of cholesterol in the plasma membrane?
What is the primary function of cholesterol in the plasma membrane?
What is the role of the glycocalyx in cells?
What is the role of the glycocalyx in cells?
During phagocytosis, what is formed when the cell encloses solid materials within its membrane?
During phagocytosis, what is formed when the cell encloses solid materials within its membrane?
What is one potential fate of pinocytotic vesicles after engulfing extracellular fluid?
What is one potential fate of pinocytotic vesicles after engulfing extracellular fluid?
Which type of membrane protein is bound to one of the two membrane surfaces?
Which type of membrane protein is bound to one of the two membrane surfaces?
What characteristic do the fatty acid chains of phospholipids have?
What characteristic do the fatty acid chains of phospholipids have?
What is the primary role of the Smooth Endoplasmic Reticulum (SER) in steroid secreting cells?
What is the primary role of the Smooth Endoplasmic Reticulum (SER) in steroid secreting cells?
How does the Rough Endoplasmic Reticulum (RER) contribute to protein synthesis?
How does the Rough Endoplasmic Reticulum (RER) contribute to protein synthesis?
What is the structural characteristic of the Golgi apparatus?
What is the structural characteristic of the Golgi apparatus?
Which of the following cells would typically have a well-developed Golgi apparatus?
Which of the following cells would typically have a well-developed Golgi apparatus?
What occurs to the SER in the context of the RER?
What occurs to the SER in the context of the RER?
What feature indicates the presence of ribosomes in the RER?
What feature indicates the presence of ribosomes in the RER?
What is the main function of SER in liver cells?
What is the main function of SER in liver cells?
The trans face of the Golgi apparatus is characterized as being:
The trans face of the Golgi apparatus is characterized as being:
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Study Notes
Membranous Organelles
- Cell membrane - responsible for cell shape, structure, and selective permeability
- Mitochondria - responsible for energy production (ATP)
- Rough endoplasmic reticulum (RER) - responsible for protein synthesis (secretory) and synthesis of lysosomal enzymes
- Smooth endoplasmic reticulum (SER) - responsible for phospholipid synthesis and steroid hormone synthesis in specific cells; regulates calcium levels in muscle cells
- Golgi complex - responsible for packaging, sorting, and secretion of proteins, lipids, and carbohydrates
- Lysosomes - responsible for the degradation of materials inside the cell
Non Membranous Organelles
- Ribosomes - responsible for protein synthesis; attached to RER or free in the cytoplasm
- Microfilaments - made of actin and involved in cell shape, movement, and muscle contraction
- Intermediate filaments - provide structural support and resist tension within cells
- Microtubules - composed of tubulin, provide structural support, cell movement such as flagella and cillia, and involved in cell division
- Centriole - involved in the formation of microtubules and spindle fibers during cell division.
- Cilia - responsible for movement of fluids and particles across the surface of cells
- Flagella - responsible for cell motility (e.g. sperm cells)
Structure of the Cell Membrane (Fluid Mosaic Model)
- Composed of three key components
- Phospholipid bilayer: forms a barrier between the inside and outside of the cell
- Cholesterol: contributes to membrane fluidity
- Proteins: act as channels, receptors, enzymes, and structural support
Endocytosis
- The process of bringing large molecules into the cell by engulfing them in vesicles
- Phagocytosis (cell eating): ingests solid materials, like bacteria
- Pinocytosis (cell drinking): ingests extracellular fluid and dissolved contents
Microscopy and Staining
- Light Microscope (LM)
- Acidophilia: stained by acidic dyes (eosin) to highlight basic structures (proteins in the cytoplasm)
- Basophilia: stained by basic dyes (hematoxylin) to highlight acidic structures (DNA in the nucleus)
- Electron Microscope (EM)
- Electron dense: areas that absorb electrons
- Electron lucent: areas that allow electrons to pass through
Staining Methods
- Hematoxylin & Eosin stain
- Used to visualize the nucleus (basophilic) and cytoplasm (acidophilic)
- Janus Green B
- Specific for Mitochondria
- Silver impregnation
- Used to visualize Golgi complex and certain tissue structures
- Immunohistochemical staining
- Uses antibodies to detect specific molecules (e.g. specific proteins) in cells and tissues
Golgi Apparatus
- Stacks composed of 3-10 flattened, slightly curved, smooth cisternae with two sides
- Cis-face (entry/ immature face): convex, towards the RER
- Trans-face (exit/ mature face/ secretory): concave, towards the cell membrane
Lysosomes
- Responsible for the degradation of materials inside the cell
- Heterolysosomes: lysosomes that digest materials taken into the cell from the outside (e.g. phagocytosis)
- Autophagosomes: lysosomes that digest damaged organelles or other cellular components
- Residual bodies: indigestible material left after lysosomal degradation
- Lipofuscin pigment: a type of residual body found in nerve cells and cardiac muscle cells
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