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Questions and Answers
Which pigment is known for giving the skin its red color?
Which pigment is known for giving the skin its red color?
Which of these organelles is formed of two subunits?
Which of these organelles is formed of two subunits?
Which structure is NOT part of the cytoskeleton?
Which structure is NOT part of the cytoskeleton?
In which organs is glycogen found in large amounts?
In which organs is glycogen found in large amounts?
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Which of these is NOT classified as an endogenous pigment?
Which of these is NOT classified as an endogenous pigment?
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What are ribosomes composed of?
What are ribosomes composed of?
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What is the role of attached ribosomes?
What is the role of attached ribosomes?
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What structure do centrioles form?
What structure do centrioles form?
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Which of the following is NOT a function of the cytoskeleton?
Which of the following is NOT a function of the cytoskeleton?
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What is the diameter of microtubules?
What is the diameter of microtubules?
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What surrounds the centrioles in a centrosome?
What surrounds the centrioles in a centrosome?
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Which of the following statements about free ribosomes is true?
Which of the following statements about free ribosomes is true?
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What is one of the functions of microtubules?
What is one of the functions of microtubules?
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What is the primary function of microfilaments?
What is the primary function of microfilaments?
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What is the diameter of microfilaments?
What is the diameter of microfilaments?
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Which type of cytoplasmic inclusion is characterized by the storage of nutrients?
Which type of cytoplasmic inclusion is characterized by the storage of nutrients?
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What role do intermediate filaments play in cells?
What role do intermediate filaments play in cells?
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What type of filament is involved in the formation of the mitotic spindle?
What type of filament is involved in the formation of the mitotic spindle?
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What are exogenous pigments?
What are exogenous pigments?
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In which type of cells is fat primarily stored?
In which type of cells is fat primarily stored?
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What is a key feature of cytoplasmic inclusions?
What is a key feature of cytoplasmic inclusions?
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Study Notes
Cell Structure
- Ribosomes: Small particles (15-20 nanometers).
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Types of Ribosomes:
- Attached ribosomes: Attached to endoplasmic reticulum (rER) for secretory protein formation.
- Free ribosomes: Located freely in the cytoplasm for cytoplasmic protein formation.
- Ribosome Structure: Composed of ribosomal RNA and proteins. Formed of two subunits (small and large), both made in the nucleolus.
- Centrosome: Non-membranous organoid, a spherical pale area near the nucleus. Contains two cylindrical centrioles surrounded by a pale centrosphere.
- Centriole Structure: Formed of microtubules (9 peripheral triplets).
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Centrosome Function:
- Acts as a center for mitotic spindle formation during cell division.
- Serves as the basal body for cilia.
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Cytoskeleton:
- Components: Microtubules, microfilaments, intermediate filaments.
- Functions:
- Maintains cell shape
- Stabilizes cell attachments
- Plays a role in cell motility
- Plays a role in cell division
- Microtubules Structure: Rigid, thin, tubular structures (25 nm diameter.) The wall is composed of protein units called tubulin.
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Microtubules Function:
- Determine cell shape
- Intercellular transport
- Form mitotic spindle in cell division, centrioles, basal bodies, and axoneme of cilia.
- Microfilaments Structure: Very thin structures (5 nm diameter) made of actin molecules.
- Microfilaments Function: Involved in cellular movement and cellular contraction, as seen in muscle cells.
- Intermediate Filaments Structure: About 10 nm thick. Many types, differing based on chemical composition. Provides physical support and stability to cells and tissues.
Cytoplasmic Inclusions
- Substances in the cytoplasm due to cell product accumulation; not involved in cellular activities.
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Types:
- Stored food (e.g., glycogen, fat)
- Pigments (e.g., melanin, hemoglobin)
- Crystals
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Stored Food (e.g., glycogen, fat):
- Glycogen is stored in large amounts in liver and muscle cells, visible with PAS staining.
- Fat is stored in fat cells (adipocytes) and stained with Sudan black stain.
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Pigments:
- Exogenous Pigments: Enter the body from outside (e.g., carotenoids from food, dust, tattoo pigments).
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Endogenous Pigments: Formed inside the cell (e.g.,
- Hemoglobin: Important for respiration, gives red color to tissues
- Hemosiderin: From hemoglobin breakdown
- Melanin: Skin, hair, and iris pigment
- Lipofuscin: Residual body pigment)
Self-Exam Questions
- Question 1: Which organelles are formed of two subunits? Answer: Ribosomes
- Question 2: Which organelle acts as a center for mitotic spindle formation? Answer: Centrosomes
- Question 3: Which structures are NOT part of the cytoskeleton? Answer: Myosin filaments
- Question 4: In which organs is glycogen present in large amounts? Answer: Muscles and liver
- Question 5: Which is NOT an endogenous pigment? Answer: Tattoo
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Description
Test your knowledge on cell structure and the roles of ribosomes, centrosomes, and cytoskeleton components. This quiz covers important cellular components and their functions in detail. Perfect for students studying biology or related fields.
