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Questions and Answers
What are the two basic parts of the cell?
What are the two basic parts of the cell?
Which of the following is NOT a membranous organelle?
Which of the following is NOT a membranous organelle?
The cell membrane is also known as the plasma membrane.
The cell membrane is also known as the plasma membrane.
True
What is the trilaminar appearance of the cell membrane due to?
What is the trilaminar appearance of the cell membrane due to?
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The head end of a phospholipid is _____, while the tail end is _____.
The head end of a phospholipid is _____, while the tail end is _____.
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Which of the following is NOT a function of protein in the cell membrane?
Which of the following is NOT a function of protein in the cell membrane?
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What is the layer of carbohydrates that is present at the surface of the cell membrane?
What is the layer of carbohydrates that is present at the surface of the cell membrane?
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Which of the following is a major type of endocytosis?
Which of the following is a major type of endocytosis?
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Which of the following describes the process by which large molecules move out of the cell?
Which of the following describes the process by which large molecules move out of the cell?
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Which of the following is a non-membranous organelle?
Which of the following is a non-membranous organelle?
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Ribosomes are composed of rRNA and proteins.
Ribosomes are composed of rRNA and proteins.
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What is the function of ribosomes?
What is the function of ribosomes?
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The endoplasmic reticulum appears rough due to the presence of:
The endoplasmic reticulum appears rough due to the presence of:
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Smooth endoplasmic reticulum lacks ribosomes.
Smooth endoplasmic reticulum lacks ribosomes.
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What is NOT a function of smooth endoplasmic reticulum?
What is NOT a function of smooth endoplasmic reticulum?
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What is the function of mitochondria?
What is the function of mitochondria?
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What is the name of the folds in the inner membrane of the mitochondria?
What is the name of the folds in the inner membrane of the mitochondria?
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The Golgi apparatus is most highly developed in secretory cells.
The Golgi apparatus is most highly developed in secretory cells.
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What is the function of the Golgi apparatus?
What is the function of the Golgi apparatus?
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Lysosomes are membrane-bound vesicles containing enzymes that break down unwanted material.
Lysosomes are membrane-bound vesicles containing enzymes that break down unwanted material.
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What is the name of the primary lysosome that combines with a phagosome?
What is the name of the primary lysosome that combines with a phagosome?
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What is the fate of lysosomes?
What is the fate of lysosomes?
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Peroxisomes detoxify substances by oxidizing them.
Peroxisomes detoxify substances by oxidizing them.
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What is NOT one of the three major components of the cytoskeleton?
What is NOT one of the three major components of the cytoskeleton?
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Microtubules are about 25nm in diameter.
Microtubules are about 25nm in diameter.
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Which of the following is a function of microtubules?
Which of the following is a function of microtubules?
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Microfilaments are about 5nm in diameter and are made of the protein actin.
Microfilaments are about 5nm in diameter and are made of the protein actin.
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Intermediate filaments are so called because their diameter is intermediate between microtubules and microfilaments.
Intermediate filaments are so called because their diameter is intermediate between microtubules and microfilaments.
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Which of these statements about intermediate filaments is FALSE?
Which of these statements about intermediate filaments is FALSE?
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The nucleus is the central, denser, part of the cell.
The nucleus is the central, denser, part of the cell.
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Mature red blood cells do not have a nucleus.
Mature red blood cells do not have a nucleus.
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Study Notes
Cytology: The Cell
- Cells are the fundamental, functional units of tissues and the fundamental unit of life.
- A cell is composed of two main parts: cytoplasm and nucleus.
Cytoplasm Components
- Cell organelles: Structures within the cytoplasm with specific functions.
- Cell inclusions: Non-membrane-bound substances, like pigments or stored nutrients.
- Cytoskeleton: Provides structural support and facilitates movement within the cell.
- Cytosol: The fluid portion of the cytoplasm.
Organelle Classification
- Organelles are classified based on the presence or absence of membranes.
I. Membranous Organelles
- Cell membrane: Separates the cell's cytoplasm from its surroundings, controlling the entry and exit of substances.
- Mitochondria: Powerhouse of the cell, involved in energy production (ATP).
- Rough endoplasmic reticulum (RER): Synthesizes proteins destined for secretion or insertion into membranes. Ribosomes on its surface are responsible for this.
- Smooth endoplasmic reticulum (SER): Synthesizes lipids, steroid hormones, and detoxifies substances.
- Golgi apparatus: Processes, packages, and modifies proteins and lipids.
- Lysosomes: Contain enzymes to break down waste materials and cellular debris.
- Peroxisomes: Break down fatty acids and other substances.
- Secretory vesicles: Store and release substances outside of the cell.
II. Non-membranous Organelles
- Ribosomes: Sites of protein synthesis.
- Proteasomes: Degrade damaged or unnecessary proteins.
- Cytoskeleton: Provides structural framework and facilitates cell movement.
The Cell Membrane
- Structure: The cell membrane is a thin structure separating the cytoplasm from the surrounding environment.
- Composition: The cell membrane is primarily composed of lipids (phospholipids), proteins, and carbohydrates.
- Function: Controls the entry and exit of substances into and out of the cell; it is selectively permeable.
- Molecular structure: A trilaminar appearance, having a lipid bilayer with proteins embedded in it. The heads are hydrophilic (water-loving), and the tails are hydrophobic (water-fearing). Carbohydrates are also attached to proteins and lipids.
Vesicular Transport
-
Endocytosis: The process by which cells absorb external substances by engulfing them in vesicles.
- Phagocytosis: Ingesting larger particles like bacteria.
- Pinocytosis: Ingesting fluid droplets.
- Receptor-mediated endocytosis: Ingesting specific molecules targeted by receptors.
- Exocytosis: The process in which cells expel substances from their internal environment.
Nucleus
- The nucleus is the largest organelle, usually centrally located, and responsible for storing genetic material.
-
Structure: It has four main components:
- Nuclear membrane: Double-layered membrane enclosing the nucleus and continuous with the endoplasmic reticulum.
- Chromatin: DNA organized with proteins forming a complex structure.
- Nucleolus: A dense area within the nucleus where ribosomal RNA is produced.
- Nucleoplasm: The semi-fluid substance within the nucleus.
Other Cellular Components
- Ribosomes: Composed of RNA and proteins, ribosomes are the sites of protein synthesis.
- Mitochondria: Crucial for energy production.
- Golgi Apparatus: Processes, packages, and modifies proteins and lipids.
- Lysosomes: Digestive compartments of the cell.
- Peroxisomes: Involved in various metabolic reactions.
- Proteasomes: Involved in protein degradation.
- Cytoskeleton: Framework for cell support, intracellular transport, and cell shape maintenance. The cytoskeleton includes microtubules, microfilaments, and intermediate filaments.
- Cytoplasmic Inclusions: These are non-membrane-bound substances. Examples include lipid droplets, glycogen granules, pigments (like melanin) and crystals.
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Description
Explore the fundamental concepts of cytology, focusing on the cell as the basic unit of life. This quiz covers key components such as the cytoplasm, organelles, and their classifications. Test your knowledge on how these structures contribute to cellular function and organization.
