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Questions and Answers
Which type of cytoplasmic organelle is characterized by an absence of membranes?
Which type of cytoplasmic organelle is characterized by an absence of membranes?
What is the approximate thickness of the cell membrane as observed under electron microscopy?
What is the approximate thickness of the cell membrane as observed under electron microscopy?
Which feature allows the cell membrane to regulate the transport of substances?
Which feature allows the cell membrane to regulate the transport of substances?
Which of the following is NOT classified as a membranous organelle?
Which of the following is NOT classified as a membranous organelle?
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Which type of microscopy allows observation of the cell membrane in detail?
Which type of microscopy allows observation of the cell membrane in detail?
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What is the purpose of the Golgi apparatus in eukaryotic cells?
What is the purpose of the Golgi apparatus in eukaryotic cells?
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Which of the following cells is the smallest among the types mentioned?
Which of the following cells is the smallest among the types mentioned?
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Which structure appears as a dense thin line at low magnification in electron microscopy?
Which structure appears as a dense thin line at low magnification in electron microscopy?
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What are the main lipid components of the cell membrane?
What are the main lipid components of the cell membrane?
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Which type of proteins extend across the lipid bilayer of the cell membrane?
Which type of proteins extend across the lipid bilayer of the cell membrane?
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What percentage of the cell membrane is composed of carbohydrates?
What percentage of the cell membrane is composed of carbohydrates?
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What is the primary function of the cell coat (glycocalyx)?
What is the primary function of the cell coat (glycocalyx)?
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Which of the following is NOT a method of transporting materials through the cell membrane?
Which of the following is NOT a method of transporting materials through the cell membrane?
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What characterizes phagocytosis?
What characterizes phagocytosis?
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What role does cholesterol play in the cell membrane?
What role does cholesterol play in the cell membrane?
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Which of the following processes involves specific receptors during endocytosis?
Which of the following processes involves specific receptors during endocytosis?
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What is the primary function of mitochondria in the cell?
What is the primary function of mitochondria in the cell?
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Which feature differentiates the inner membrane of mitochondria from the outer membrane?
Which feature differentiates the inner membrane of mitochondria from the outer membrane?
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What type of DNA do mitochondria possess that allows them to replicate independently?
What type of DNA do mitochondria possess that allows them to replicate independently?
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Which of the following is a common manifestation of mitochondrial diseases?
Which of the following is a common manifestation of mitochondrial diseases?
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What substance is high in the mitochondrial matrix, indicating its role in oxidative metabolism?
What substance is high in the mitochondrial matrix, indicating its role in oxidative metabolism?
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What is the likely consequence of abnormal mitochondrial DNA?
What is the likely consequence of abnormal mitochondrial DNA?
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Where are respiratory chain enzymes located within the mitochondria?
Where are respiratory chain enzymes located within the mitochondria?
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How does mitochondrial number correlate with cellular activity?
How does mitochondrial number correlate with cellular activity?
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Which condition is characterized by mitochondrial encephalomyopathy and lactic acidosis?
Which condition is characterized by mitochondrial encephalomyopathy and lactic acidosis?
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What is one of the key functions of the Golgi apparatus?
What is one of the key functions of the Golgi apparatus?
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Which structure in the Golgi apparatus faces the cell surface?
Which structure in the Golgi apparatus faces the cell surface?
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Which of the following is a characteristic finding in MERRF?
Which of the following is a characteristic finding in MERRF?
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What type of vesicle carries proteins from the rough endoplasmic reticulum to the Golgi apparatus?
What type of vesicle carries proteins from the rough endoplasmic reticulum to the Golgi apparatus?
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In the case of the 32-year-old woman, which of her symptoms aligns with MELAS?
In the case of the 32-year-old woman, which of her symptoms aligns with MELAS?
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Which Golgi apparatus function involves modifying proteins by adding carbohydrate groups?
Which Golgi apparatus function involves modifying proteins by adding carbohydrate groups?
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What type of granules can condensing vacuoles mature into within the Golgi apparatus?
What type of granules can condensing vacuoles mature into within the Golgi apparatus?
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Study Notes
Cytoplasmic Organelles
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Cell (Plasma) Membrane
- Bounding membrane of each cell
- Also known as plasma membrane, plasmalemma, or unit membrane
- Encloses cellular contents and regulates transport of substances
- LM: invisible
- EM: thin line (7.5-10 nm), trilaminar structure (two electron-dense lines separated by an electron-lucent zone)
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Mitochondria
- Vary in number and size
- LM: Rods, granules, or filaments
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EM: Enclosed by two membranes, each with a trilaminar unit membrane
- Outer membrane: Smooth, contains porin, freely permeable to molecules
- Inner membrane: Folded into cristae (increases surface area), location of respiratory chain enzymes and ATP synthetase, impermeable to small ions
- Matrix: Filled with oxidative enzymes and dense granules that store Ca+
- Responsible for ATP production (powerhouse of the cell)
- Number increases in cells with high metabolic activity
- Contains its own DNA, ribosomes, mRNA, and tRNA, so it can divide independently
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Golgi Body
- Membranous organelle located between the nucleus and the periphery
- Secretory apparatus of the cell
- LM: Negative Golgi image (darkly stained granules and fibrils) visible in intensely basophilic cells (e.g., plasma cells) with special staining techniques
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EM: Consists of flattened vesicles (stacks), transfer vesicles, and macrovesicles (condensing vacuoles)
- Flattened vesicles: Elongated, parallel sacs arranged in stacks, sites of protein concentration
- Transfer vesicles: Carry proteins from the rough ER to the Golgi
- Macrovesicles: Large vesicles, mature into secretory vesicles or secretory granules
- Functions: Packaging and storage of proteins, modification of proteins, formation of secretory proteins, renewing the cell membrane, and formation of lysosomes.
Mitochondrial Myopathies
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A group of genetic disorders affecting mitochondrial function, specifically in energy-demanding cells like muscle and nervous cells
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Can manifest as:
- Muscle weakness: especially in extra-ocular muscles (Mitochondrial myopathy)
- Degenerative diseases of the central nervous system: loss of optic nerve fibers, cerebellar tissue, or brain white matter degeneration
- Metabolic disturbances: high levels of lactic acid
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Inherited maternally: Can manifest at any age
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Diagnosis: muscle biopsy and analysis of mitochondrial DNA
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MELAS: Mitochondrial encephalomyopathy, lactic acidosis, and recurring stroke-like episodes
- Other findings: muscle weakness, tonic-clonic seizures
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MERRF: Myoclonic epilepsy with ragged red fibers
- Other findings: generalized seizures
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Description
Test your knowledge on cytoplasmic organelles, including the cell membrane and mitochondria. This quiz covers their structure, function, and importance in cellular metabolism. Perfect for students studying cell biology or related fields.
