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Questions and Answers
According to the cell theory, what is a fundamental characteristic of cells?
According to the cell theory, what is a fundamental characteristic of cells?
What is the primary function of cells with respect to body composition?
What is the primary function of cells with respect to body composition?
If a cell is said to be 10 micrometers in diameter, what is its size relative to a meter?
If a cell is said to be 10 micrometers in diameter, what is its size relative to a meter?
Which of the following is NOT a general function of cells?
Which of the following is NOT a general function of cells?
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What is the typical size range of most cells in the human body?
What is the typical size range of most cells in the human body?
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Which of the following is NOT a primary function of the cytoskeleton?
Which of the following is NOT a primary function of the cytoskeleton?
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What is the main purpose of the nucleolus?
What is the main purpose of the nucleolus?
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Which of the following best describes the primary function of the smooth endoplasmic reticulum (SER)?
Which of the following best describes the primary function of the smooth endoplasmic reticulum (SER)?
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Which cellular component is NOT considered an organelle?
Which cellular component is NOT considered an organelle?
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The Golgi complex plays a key role in modifying and packaging proteins. Which of the following is NOT a function of the Golgi complex?
The Golgi complex plays a key role in modifying and packaging proteins. Which of the following is NOT a function of the Golgi complex?
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Inclusions are considered non-essential to cell survival. Which of the following would be classified as an inclusion?
Inclusions are considered non-essential to cell survival. Which of the following would be classified as an inclusion?
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What distinguishes rough endoplasmic reticulum (RER) from smooth endoplasmic reticulum (SER)?
What distinguishes rough endoplasmic reticulum (RER) from smooth endoplasmic reticulum (SER)?
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The cytoplasm contains several components, including cytosol. What makes up the largest percentage of cytosol/intracellular fluid (ICF)?
The cytoplasm contains several components, including cytosol. What makes up the largest percentage of cytosol/intracellular fluid (ICF)?
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Which component of the plasma membrane is primarily responsible for its selective permeability?
Which component of the plasma membrane is primarily responsible for its selective permeability?
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What is the main function attributed to the glycocalyx?
What is the main function attributed to the glycocalyx?
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Which type of membrane protein is most directly involved in the active transport of molecules across the cell membrane?
Which type of membrane protein is most directly involved in the active transport of molecules across the cell membrane?
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Which surface extension is primarily responsible for increasing the surface area of the cell to facilitate absorption?
Which surface extension is primarily responsible for increasing the surface area of the cell to facilitate absorption?
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Which cell junction is specifically designed to prevent the passage of water and solutes between adjacent cells?
Which cell junction is specifically designed to prevent the passage of water and solutes between adjacent cells?
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What is the primary function of cilia on the cell surface?
What is the primary function of cilia on the cell surface?
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Which of these membrane components are considered 'protein icebergs drifting in a phospholipid sea'?
Which of these membrane components are considered 'protein icebergs drifting in a phospholipid sea'?
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Which is the main defining characteristic of passive transport?
Which is the main defining characteristic of passive transport?
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Which of the following is a function of the plasma membrane?
Which of the following is a function of the plasma membrane?
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Which of the following is a major function of a desmosome?
Which of the following is a major function of a desmosome?
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Which cellular organelle is primarily responsible for the detoxification of organic molecules and the conversion of hydrogen peroxide into water and oxygen?
Which cellular organelle is primarily responsible for the detoxification of organic molecules and the conversion of hydrogen peroxide into water and oxygen?
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During which phase of the cell cycle does DNA replication occur?
During which phase of the cell cycle does DNA replication occur?
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What is the main function of the centrioles during cell division?
What is the main function of the centrioles during cell division?
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Which process is characterized by the division of the cytoplasm, resulting in the formation of two separate daughter cells?
Which process is characterized by the division of the cytoplasm, resulting in the formation of two separate daughter cells?
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In which location within the cell are ribosomes NOT typically found?
In which location within the cell are ribosomes NOT typically found?
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What is a key difference between mitosis and meiosis?
What is a key difference between mitosis and meiosis?
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What characterizes the 'prophase' stage of mitosis?
What characterizes the 'prophase' stage of mitosis?
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Which cellular component is responsible for the production of ATP through aerobic respiration?
Which cellular component is responsible for the production of ATP through aerobic respiration?
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What is the main role of secretory vesicles in the process of exocytosis?
What is the main role of secretory vesicles in the process of exocytosis?
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The telomere is located at which part of a chromosome?
The telomere is located at which part of a chromosome?
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Study Notes
Cytology: The Study of Cells
- Cytology is the study of cells
- Body fluids account for 42 liters in the human body
- Intracellular fluids (ICF) account for 28 liters
- Extracellular fluids (ECF) include plasma (3 liters), lymph, and interstitial fluid (11 liters)
- Intracellular materials include fibers and crystals
Cells: Structural and Functional Units of Life
- Cells are the building blocks of life, produced by the division of preexisting cells
- Cells perform all vital functions
- Cells form intercellular materials and fluids
- Cells are adapted to wide ranges of sizes and shapes
- There are approximately 30-40 trillion cells, 200 types
- Cell surfaces include basal, lateral, and apical surfaces
General Functions
- Cells provide covering and lining
- Cells perform storage
- Cells facilitate movement
- Cells connect tissues
- Cells defend against pathogens
- Cells facilitate communication
- Cells participate in reproduction
Cellular Diversity: Size
- A micrometer (µm) is one-millionth of a meter (10⁻⁶)
- Cells range in diameter from 10-15 micrometers
- Some cells, like neurons, can be larger than 1 meter in length
- Red blood cells (RBCs) have an average diameter of 8 µm
- Ova, or egg cells have an average diameter of 140 µm
Cellular Diversity: Cell Shapes
- Cells exhibit diverse shapes
- Examples of cell shapes include squamous, cuboidal, columnar, polygonal, stellate, spheroid, discoid, fusiform (spindle-shaped), and fibrous
Basic Plasma Membrane Components
- A cell is enclosed by a plasma membrane.
- The membrane is a boundary between the extracellular fluid (ECF) and intracellular fluid (ICF).
- It is 6-10 nm thick.
- It is selectively permeable.
- Phospholipids comprise a bilayer, with water-loving heads and water-repelling tails.
- Proteins are embedded, acting as receptors, enzymes, transport channels, and cell identity markers.
- Glycoproteins (sugary proteins) are on the outside surface.
Plasma Membrane Composition
- The plasma membrane consists primarily of:
- Phospholipids (75%)
- Cholesterol (20%)
- Glycolipids (5-10%)
- Proteins include:
- Transmembrane/Integral proteins
- Peripheral proteins
- Glycoproteins
Functions of Membrane Proteins
- Receptor proteins: bind to chemical messengers
- Enzyme proteins: catalyze specific reactions
- Channel proteins: passageways for ions/molecules
- Transport/Carrier proteins: actively transport molecules
- Cell-identity markers: glycoproteins signaling cell origin
- Cell-adhesion proteins (CAMs): cells adhere to one another
Major Types of Membrane Transport
-
Passive Transport: Moves materials down a concentration gradient (no energy needed).
- Simple Diffusion: Movement of nonpolar molecules, water, and ions
- Facilitated Diffusion: Assisted by membrane protein
-
Active Transport: Moves materials against a concentration gradient (energy needed).
- Primary Active Transport: Uses ATP directly
- Secondary Active Transport: Uses electrochemical gradient established by primary active transport
Glycocalyx
- A fuzzy, sugary coat on top of proteins and lipids on the cell surface.
- Function: protects cell, recognizes as part of the body, and binds tissues.
Surface Extensions of Plasma Membrane
- Microvilli: absorption, increase surface area, microfilaments
- Cilia: movement of materials over cell surface, microtubules
- Flagella: propulsion of sperm cells, microtubules
Cell Junctions
- Tight junctions: interlocked proteins prevent passage of water and solutes
- Desmosomes: very strong, offers resistance to stretching and twisting.
- Gap junctions: connexons allow diffusion of ions, small molecules, and electrical impulses
Nucleus
- The largest organelle in the cell
- A control center for the cell, acting as a 'brain'.
- Contains the instructions to regulate production of other cell parts (100,000 different proteins)
- Has various shapes depending on other cells.
- Uninucleate, multinucleate, or anucleate
- Contains the following components:
- Nuclear envelope
- Nuclear pores
- Nucleoplasm
- Chromosomes
- Nucleolus
Cytoplasm
- Cytosol (ICF): intracellular fluid
- Organelles
- Cytoskeleton
- Inclusions
Cytosol/ICF
- Composed primarily of water (75-90%)
- Proteins (15-20%), mostly enzymes
- Carbohydrates, lipids, amino acids
- Ions (e.g., K+, Na+, Ca++, Cl−)
Cytoskeleton
- Organized proteins forming filaments and tubules.
- Functions: Support, shape, organizes organelles, move materials, and participate in cell division
Inclusions
- Non-essential to cell survival
- Stored cellular products, pigments (melanin), fat droplets, glycogen
- Foreign bodies (dust particles, viruses, intracellular bacteria)
Organelles: Membrane-Bound
- Mitochondria: aerobic respiration, ATP
- Endoplasmic Reticulum (ER): protein synthesis (rough ER) and lipid synthesis/detoxification (smooth ER)
- Peroxisomes: Oxidize substances and break down fatty acids
- Lysosomes: digestive enzymes, breakdown material, and cell waste.
- Golgi apparatus: modifies proteins, packaging, and transports materials
Organelles: Non-membrane Bound
- Ribosomes: protein synthesis
- Centrioles: participate in cell division
Endoplasmic Reticulum (ER)
- Rough ER (RER) has ribosomes, produces proteins
- Smooth ER (SER) lacks ribosomes, synthesizes lipids, detoxifies materials (e.g., alcohol, drugs).
Golgi Complex/Apparatus
- Stacks of cisternae (flattened sacs).
- Modifies, package, sorts, and transports proteins and other materials.
- Involved in secretion.
- Vesicles from the Golgi can become lysosomes
Lysosomes
- Contain digestive enzymes
- Involved in disease defense (endocytosis)
- Waste cleanup
- Cell death (autophagy, autolysis)
Peroxisomes
- Oxidize organic molecules for detoxification.
- Convert hydrogen peroxide (H₂O₂) to water (H₂O) and oxygen (O₂)
- Break down fatty acids
Mitochondria
- Site of aerobic respiration (generating ATP)
- Contain outer and inner membranes (cristae)
- Have their own DNA (mtDNA)
- Abundant in tissues that need high energy (muscle, sperm).
Ribosomes
- Composed of two subunits.
- Sites of protein synthesis
- Found free in the cytosol or bound to RER.
Centrioles
- Cylindrical structures composed of microtubules organized in groups of three.
- Participate in cell division.
- Not found in some cells (RBCs, skeletal muscle cells.)
The Cell Cycle
- Interphase (G₁: growth, S: DNA replication, G₂: growth & preparation)
- Mitosis (Prophase, Metaphase, Anaphase, Telophase)
Mitosis
- Phases: Prophase (chromosomes condense, nuclear envelope breaks down), Metaphase (chromosomes align at the cell's center), Anaphase (sister chromatids separate), Telophase (chromosomes decondense, nuclear envelope reforms).
Early and Late Prophase
- Chromatin condenses into chromosomes
- Nuclear envelope breaks down
- Nucleolus disappears
- Mitotic apparatus forms to connect to chromosomes
Chromosomes
- Organized structures of DNA (with proteins)
- Consists of two identical chromatids held together at the centromere.
Anatomy of Chromosomes
- Single chromosome: single strand of DNA
- Duplicated chromosome: two identical strands of DNA held together at the centromere.
- Parts: Chromatid, centromere, telomeres, short arm, long arm
Metaphase: M for Middle
- Chromosomes line up along the center of the cell
Anaphase: A for Apart
- Sister chromatids separate and move to opposite ends of the cell
Telophase: T for Two
- Chromosomes begin to decondense
- Nuclear envelope reforms
- Nucleolus reforms
- Mitotic apparatus disassembles
Cytokinesis
- Division of the cytoplasm.
- Begins in anaphase and ends with two identical daughter cells.
Meiosis: Reproductive Cell Division
- Two successive stages of nuclear division
- Produces haploid gametes (reproductive cells) from diploid cells
- Meiosis I: Homologous chromosomes pair and undergo crossing-over
- Meiosis II: Sister chromatids separate, creating four haploid cells
Aging and Cells
- Progressive alteration of homeostatic mechanisms
- Changes in structure and function
- Increased vulnerability to stress and disease
- Genetically programmed cessation of division, shortened telomeres, free radical buildup, intensified immune response.
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Description
Test your knowledge on the fundamental characteristics and functions of cells through this quiz. Questions cover topics such as cell theory, organelles, and the roles of different cellular components. Perfect for students studying cellular biology or related subjects.
