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Questions and Answers
Which of the following is NOT a function performed by cells?
Which of the following is NOT a function performed by cells?
Which type of cell is primarily responsible for the synthesis and secretion of mucus?
Which type of cell is primarily responsible for the synthesis and secretion of mucus?
What does the cytoplasm of a eukaryotic cell primarily consist of?
What does the cytoplasm of a eukaryotic cell primarily consist of?
Which of the following statements is true about muscle cells?
Which of the following statements is true about muscle cells?
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What aspect differentiates specialized cells from basic cells?
What aspect differentiates specialized cells from basic cells?
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What is the primary function of cells in the intestine?
What is the primary function of cells in the intestine?
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Which of the following cell types is involved in ion transport?
Which of the following cell types is involved in ion transport?
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How many named cell types are there in the human body?
How many named cell types are there in the human body?
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What is the primary function of the inner nuclear membrane?
What is the primary function of the inner nuclear membrane?
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Which pigment is primarily found in melanocytes and keratinocytes?
Which pigment is primarily found in melanocytes and keratinocytes?
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What type of pigment increases with age as residual bodies of lysosomal activities?
What type of pigment increases with age as residual bodies of lysosomal activities?
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What is contained within a nucleosome?
What is contained within a nucleosome?
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Crystals of Reinke can be found in which type of cells?
Crystals of Reinke can be found in which type of cells?
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The outer nuclear membrane is connected to which structure?
The outer nuclear membrane is connected to which structure?
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Which component is NOT part of the chromatin structure?
Which component is NOT part of the chromatin structure?
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What defines the role of lipofuscin in cells?
What defines the role of lipofuscin in cells?
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What is one of the main functions of the Golgi complex?
What is one of the main functions of the Golgi complex?
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What characteristic distinguishes lysosomes from peroxisomes?
What characteristic distinguishes lysosomes from peroxisomes?
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Which type of biological structure is involved in the packaging of secretory products?
Which type of biological structure is involved in the packaging of secretory products?
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What pH level is most favorable for the activity of lysosomal enzymes?
What pH level is most favorable for the activity of lysosomal enzymes?
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What are two key components found within the matrix space of the mitochondria?
What are two key components found within the matrix space of the mitochondria?
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What type of vesicle is responsible for the ingested materials within a cell?
What type of vesicle is responsible for the ingested materials within a cell?
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How do peroxisomes replicate?
How do peroxisomes replicate?
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What is a common characteristic of mitochondria?
What is a common characteristic of mitochondria?
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What is the primary function of proteasomes?
What is the primary function of proteasomes?
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Which of the following best describes the composition of ribosomes?
Which of the following best describes the composition of ribosomes?
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Polyribosomes or polysomes are significant for which of the following reasons?
Polyribosomes or polysomes are significant for which of the following reasons?
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What role do microtubule-associated proteins (MAPs) play?
What role do microtubule-associated proteins (MAPs) play?
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What structural property differentiates intermediate filaments from microtubules and microfilaments?
What structural property differentiates intermediate filaments from microtubules and microfilaments?
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Which type of protein is primarily involved in the elongation of axons?
Which type of protein is primarily involved in the elongation of axons?
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Which form of polyribosomes synthesizes proteins for cellular use?
Which form of polyribosomes synthesizes proteins for cellular use?
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What is a common characteristic of microtubules?
What is a common characteristic of microtubules?
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What is the average thickness of the cell membrane?
What is the average thickness of the cell membrane?
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Which type of protein is known to be loosely associated with the inner membrane surface?
Which type of protein is known to be loosely associated with the inner membrane surface?
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Which component comprises the majority of the cell membrane by volume?
Which component comprises the majority of the cell membrane by volume?
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What is the function of cholesterol in the cell membrane?
What is the function of cholesterol in the cell membrane?
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Which type of carbohydrate is typically attached to proteins in the plasma membrane?
Which type of carbohydrate is typically attached to proteins in the plasma membrane?
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What characterizes the amphipathic nature of phospholipids?
What characterizes the amphipathic nature of phospholipids?
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Which of the following is NOT a category of membrane proteins?
Which of the following is NOT a category of membrane proteins?
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What is the primary function of carbohydrates on the plasma membrane?
What is the primary function of carbohydrates on the plasma membrane?
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What type of cells contain vimentin?
What type of cells contain vimentin?
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Which structure is primarily involved in the control of microtubule polymerization?
Which structure is primarily involved in the control of microtubule polymerization?
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What is the main function of microfilaments in cells?
What is the main function of microfilaments in cells?
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Which of the following best describes glial fibrillary acidic protein?
Which of the following best describes glial fibrillary acidic protein?
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Which of the following statements about centrioles is incorrect?
Which of the following statements about centrioles is incorrect?
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Which inclusion is primarily responsible for storing triglycerides and cholesterol in adipose cells?
Which inclusion is primarily responsible for storing triglycerides and cholesterol in adipose cells?
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What is the primary role of neurofilaments in the cells?
What is the primary role of neurofilaments in the cells?
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Which type of pigment is hemosiderin, and where is it typically found?
Which type of pigment is hemosiderin, and where is it typically found?
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Study Notes
Cytology Lecture Two
- Cells are the fundamental structural and functional units of living organisms.
- They exhibit diverse specializations performing survival, growth, and reproduction activities.
- Cells are self-replicating, self-regulating, and self-governing biological systems.
- Cellular functions include metabolism (absorption, synthesis, respiration, excretion), growth, regeneration, irritability (excitability), movement, reproduction, and aging and death.
- There are around 100 trillion (1012) cells in the human body.
- More than 250 different cell types exist.
- Cell shapes vary, including round, oval, columnar, multipolar, polygonal, cylindrical, fusiform, pyramidal, and pyriform.
- Cell size ranges from 5µm to 120µm in diameter.
- Cells have diverse functions depending on their type.
Cell Components
- Cell membrane: A trilaminar layer (2.5 nm diameter) acting as a selective barrier.
- Composed of lipids (50% by weight), proteins (50% by weight), and carbohydrates.
- Lipids make up 90% of the membrane's volume.
- Membrane proteins are categorized into integral, peripheral, pumps, channels, receptors, linkers, and enzymes.
- Phospholipids: Amphipathic molecules forming a bilayer; hydrophilic heads face water, hydrophobic tails face away.
- Cholesterol: Modulates membrane fluidity and integrity.
- Carbohydrates: Attached to proteins (glycoproteins) and lipids (glycolipids), forming the glycocalyx, important for cell-cell recognition and interaction.
Cytoplasm
- The material outside the nucleus and within the plasma membrane.
- Composed of cytosol (aqueous solution), organelles (specialized structures), cytoskeleton (protein filaments), and inclusions (non-living substances).
- Cytosol: Contains water, dissolved proteins, salts, sugars, etc.
- Organelles perform various cellular functions; examples include ER, ribosomes, mitochondria, Golgi complex, endoplasmic reticulum, lysosomes, peroxisomes, proteasomes.
- Cytoskeleton: Supports and mediates intracellular movement. Subdivided into microtubules, intermediate filaments, and microfilaments.
Organelles
- Endoplasmic reticulum (ER): A continuous network involved in protein and lipid synthesis.
- Rough ER has ribosomes, synthesizes proteins for export.
- Smooth ER: Lacks ribosomes; synthesizes lipids, carbohydrates, and detoxifies substances.
- Golgi complex (apparatus): Processes, modifies, and sorts proteins and lipids.
- Lysosomes: Contain hydrolytic enzymes for degrading waste materials.
- Peroxisomes contain oxidative enzymes breaking down substances like H2O2.
- Mitochondria: Sites of cellular respiration. Have their own DNA and ribosomes. Contain cristae creating folds.
- Endosomes and Phagosomes: Membrane-bound structures involved in endocytosis and intracellular transport; including heterophagosomes (ingested) and autophagosomes (self).
- Proteasomes: Degrade damaged and misfolded proteins.
- Ribosomes: Sites of protein synthesis. Composed of rRNA and protein subunits (large and small). Free ribosomes or attached to rough ER.
- Polyribosomes (polysomes): Involved in protein synthesis.
Cytoskeleton
- Microtubules: Tubular structures involved in cell shape, intracellular transport, and cell division(e.g., formation of the mitotic spindle). Composed of tubulin heterodimers (alpha and beta tubulin).
- Intermediate filaments: Provide mechanical stability and strength. Formed from tetramers of rod-like proteins.
- Microfilaments (actin filaments): Thin, flexible protein filaments important for intracellular transport, cytokinesis (cell division). Composed of G-actin.
Centrioles
- Located near the nucleus, involved in cell division, and the formation of cilia and flagella.
- Consist of 9 triplets of micro tubules.
Cell Renewal
- Different cell types vary in their renewal rates.
- Renewing cells (e.g., skin cells) divide rapidly.
- Stable cells (e.g., liver cells) divide under certain conditions.
- Static cells (e.g., nerve cells) do not generally divide.
Cell Cycle
- A highly regulated series of events leading to cell growth and division including Interphase (Gap 1, S phase, Gap 2), and Mitosis.
- G1: Cell growth, RNA and protein synthesis.
- S phase: DNA replication.
- G2: Cell growth, preparation for cell division.
- Mitosis: Nuclear division.
Nucleus
- Oval, elongated, or flattened in shape and contains the genetic material (DNA).
- Composed of nuclear envelope (double membrane), chromatin, nucleolus (involved in ribosome synthesis), and nucleoplasm (the content of the nucleus other than the chromatin and nucleolus).
Inclusions
- Metabolically inactive substances, including lipid droplets, glycogen granules, pigments (e.g., melanin, lipofuscin), and crystals.
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Description
This quiz covers the fundamental aspects of cytology, focusing on the structure and functions of cells. Explore the diversity in cell types, shapes, sizes, and components, as well as their roles in living organisms. Test your knowledge on cellular metabolism, reproduction, and biological systems.
