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Questions and Answers
What is the primary role of the smooth endoplasmic reticulum?
What is the primary role of the smooth endoplasmic reticulum?
Which of the following structures is part of the double membrane-bound organelles?
Which of the following structures is part of the double membrane-bound organelles?
What is the primary function of the nucleus in eukaryotic cells?
What is the primary function of the nucleus in eukaryotic cells?
Which component of the cell is responsible for the storage of Ca+2 ions?
Which component of the cell is responsible for the storage of Ca+2 ions?
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Which element of the cell structure is responsible for maintaining the shape of the nucleus?
Which element of the cell structure is responsible for maintaining the shape of the nucleus?
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What is the primary function of intermediate filaments in a cell?
What is the primary function of intermediate filaments in a cell?
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Which microscopy technique is most suitable for observing live cell details?
Which microscopy technique is most suitable for observing live cell details?
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What process involves the sequential centrifugation of cells to separate their components?
What process involves the sequential centrifugation of cells to separate their components?
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What is the advantage of confocal microscopy over bright-field microscopy?
What is the advantage of confocal microscopy over bright-field microscopy?
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What is the final step in the process of preparing tissues for microscopy?
What is the final step in the process of preparing tissues for microscopy?
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What distinguishes the structure of cilia from that of flagella?
What distinguishes the structure of cilia from that of flagella?
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Which of the following is NOT a function of microtubules?
Which of the following is NOT a function of microtubules?
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What is a primary role of lysosomes within the endomembrane system?
What is a primary role of lysosomes within the endomembrane system?
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Which component of the cytoskeleton is responsible for the internal transport within the cell?
Which component of the cytoskeleton is responsible for the internal transport within the cell?
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What describes the mitochondrion's structure?
What describes the mitochondrion's structure?
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What process do vacuoles primarily facilitate in plant cells?
What process do vacuoles primarily facilitate in plant cells?
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Which is NOT a part of the endomembrane system?
Which is NOT a part of the endomembrane system?
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Which of the following does NOT describe a function of the cytoskeleton?
Which of the following does NOT describe a function of the cytoskeleton?
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What is the primary function of the Rough Endoplasmic Reticulum?
What is the primary function of the Rough Endoplasmic Reticulum?
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What distinguishes the proteins synthesized on free ribosomes from those on bound ribosomes?
What distinguishes the proteins synthesized on free ribosomes from those on bound ribosomes?
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What is the main function of the Golgi apparatus?
What is the main function of the Golgi apparatus?
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Which of the following is NOT a function of lysosomes?
Which of the following is NOT a function of lysosomes?
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What is the role of acid hydrolases within the lysosomes?
What is the role of acid hydrolases within the lysosomes?
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Which statement about peroxisomes is correct?
Which statement about peroxisomes is correct?
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How does the Golgi apparatus exhibit polarity?
How does the Golgi apparatus exhibit polarity?
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Which enzyme in peroxisomes is responsible for breaking down hydrogen peroxide?
Which enzyme in peroxisomes is responsible for breaking down hydrogen peroxide?
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What structure is directly involved in modifying proteins before they reach the plasma membrane?
What structure is directly involved in modifying proteins before they reach the plasma membrane?
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What component primarily makes up ribosomes?
What component primarily makes up ribosomes?
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Which organelle is primarily involved in lipid synthesis and glycogen metabolism?
Which organelle is primarily involved in lipid synthesis and glycogen metabolism?
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What is the primary role of the nucleolus within the nucleus?
What is the primary role of the nucleolus within the nucleus?
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Which component of the cell is characterized by having a double-membrane structure?
Which component of the cell is characterized by having a double-membrane structure?
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Which structure forms the inner surface of the inner nuclear membrane?
Which structure forms the inner surface of the inner nuclear membrane?
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Which of the following is NOT a function of the endoplasmic reticulum?
Which of the following is NOT a function of the endoplasmic reticulum?
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What is a primary function of intermediate filaments?
What is a primary function of intermediate filaments?
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Which microscopy technique provides sharper images by reducing blurring?
Which microscopy technique provides sharper images by reducing blurring?
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Which component is primarily separated during the first centrifugation step at 600 g in differential centrifugation?
Which component is primarily separated during the first centrifugation step at 600 g in differential centrifugation?
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What type of microscopy allows for observing details of live cells and monitoring cell movement?
What type of microscopy allows for observing details of live cells and monitoring cell movement?
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What technique can further separate organelle components using sucrose banding?
What technique can further separate organelle components using sucrose banding?
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What is a key function of the cytoskeleton in cells?
What is a key function of the cytoskeleton in cells?
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In which structure would you find the 9+2 microtubule arrangement?
In which structure would you find the 9+2 microtubule arrangement?
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What is the primary function of mitochondria in cells?
What is the primary function of mitochondria in cells?
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Which of the following correctly describes vacuoles in plant cells?
Which of the following correctly describes vacuoles in plant cells?
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Which cytoskeletal element is primarily responsible for chromosome movement during cell division?
Which cytoskeletal element is primarily responsible for chromosome movement during cell division?
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What distinguishes microfilaments from microtubules?
What distinguishes microfilaments from microtubules?
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Which of the following statements about vesicles is incorrect?
Which of the following statements about vesicles is incorrect?
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What role do microtubules serve in the structure of cilia and flagella?
What role do microtubules serve in the structure of cilia and flagella?
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What occurs to proteins synthesized on bound ribosomes within the endomembrane system?
What occurs to proteins synthesized on bound ribosomes within the endomembrane system?
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Which component is primarily responsible for aiding in the folding of nascent polypeptides in the Rough Endoplasmic Reticulum?
Which component is primarily responsible for aiding in the folding of nascent polypeptides in the Rough Endoplasmic Reticulum?
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How do the fates of proteins synthesized by free ribosomes differ from those produced by bound ribosomes?
How do the fates of proteins synthesized by free ribosomes differ from those produced by bound ribosomes?
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What is a main function of the lysosome in eukaryotic cells?
What is a main function of the lysosome in eukaryotic cells?
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Which sequence accurately describes the secretory pathway for proteins?
Which sequence accurately describes the secretory pathway for proteins?
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How does the Golgi apparatus modify proteins received from the rough ER?
How does the Golgi apparatus modify proteins received from the rough ER?
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What is the primary role of peroxisomes in cellular metabolism?
What is the primary role of peroxisomes in cellular metabolism?
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What distinguishes the lysosomal lumen's acidity from other cellular compartments?
What distinguishes the lysosomal lumen's acidity from other cellular compartments?
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Which type of ribosomal subunits make up a functional eukaryotic ribosome?
Which type of ribosomal subunits make up a functional eukaryotic ribosome?
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Which organelle is primarily described as the 'post office' of the cell?
Which organelle is primarily described as the 'post office' of the cell?
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Study Notes
Eukaryotic Cellular Structure
- Eukaryotic cells have various components, including nuclei, microtubules, Golgi apparatus, actin fibers, and mitochondria. These parts perform different functions essential for cellular activities.
Substructures of Animal & Plant Cells
- Diagrams show animal and plant cells with labeled organelles, including numbered items: plasma membrane, mitochondria, lysosomes, nuclear envelope, nucleolus, nucleus, smooth ER, rough ER, Golgi complex, secretory vesicles, peroxisomes, cytoskeletal fibers, microvilli, cell wall, vacuole, and chloroplast.
Major Components of Eukaryotic Cells
- Plasma membrane: 700 μm².
- Internal membranes & organelles: 7,000 μm².
- Cytoskeleton: 94,000 μm².
Organelles
- Single-Membrane Bound: Smooth Endoplasmic Reticulum, Rough Endoplasmic Reticulum, Lysosome, Golgi Apparatus, Peroxisome, Vacuoles & Vesicles.
- Double-Membrane Bound: Nucleus, Mitochondrion, Chloroplast.
- Non-Membrane Bound: Ribosomes, Proteasomes, Cytoskeleton elements, Cilia & Flagella, Centrosomes, Basal Bodies.
Nucleus
- Typically the largest organelle in animal cells.
- Considered the "control center" of the cell.
- Contains most of the cell's DNA.
- Has a double-membrane structure: outer nuclear membrane, inter-membrane space, inner nuclear membrane.
- Contains nucleoplasm, where the nucleolus synthesizes rRNA.
- Also includes a nuclear lamina composed of lamin proteins lining the inner nuclear membrane surface.
- Contains nuclear pore complexes (NPCs).
Endoplasmic Reticulum (ER)
- A single-membrane bound organelle, extensive network of closed, flattened membrane-bound sacs.
- The ER membrane is continuous with the outer nuclear membrane, and its lumen is continuous with the intermembrane space of the nucleus.
- Divided into two components: rough ER (RER) and smooth ER (SER).
Rough ER
- Immediately adjacent to the nucleus.
- Studded with ribosomes on its cytosolic surface, which synthesize proteins.
- Site of initial protein processing, for proteins exported from the cell, embedded in the plasma membrane, or destined for the Golgi apparatus and lysosomes.
- Nascent polypeptides associate with Rough ER membrane.
- Chaperones assist protein folding; enzyme modifications occur.
Ribosomes
- Sites of protein synthesis (translation), consist of rRNA and proteins.
- Ribosomes may be free (in cytosol) or bound to the rough ER.
- A functional ribosome consists of two subunits (large and small), designated by S values.
Fates of Proteins Synthesized on Bound or Free Ribosomes
- Proteins synthesized on bound ribosomes are destined for: export from the cell, plasma membrane embedding, or the ER, Golgi, or lysosomes.
- Proteins synthesized on free ribosomes are for use in cytosol, nucleus, mitochondria, chloroplasts, peroxisomes.
Golgi Apparatus
- Series of flattened membrane-bound sacs (cisternae).
- Acts as the cell's "post office," receiving, modifying, sorting, and packaging proteins and lipids.
- A polarity exists, with cis, medial, and trans Golgi faces.
- Contains different luminal enzymes for protein modifications. Proteins arrive from rough ER in transport vesicles.
Secretory Pathway
- Movement of proteins from bound ribosomes through rough ER, transport vesicles, cis-Golgi, medial-Golgi, trans-Golgi, transport vesicles, plasma membrane, or lysosomes.
Lysosome
- Animal cell's "digestive system" and "garbage disposal system."
- Contains hydrolytic enzymes (acid hydrolases).
- Breaks down polymers into smaller subunits within the low pH (around 4.8) lysosomal lumen.
- V-class proton pumps bring in H+ and Cl- channels bring in Cl-.
- Digest materials taken up by the cell, digest damaged or aged organelles (autophagy), and are involved in apoptosis.
- Several human diseases are caused by defects in specific lysosomal enzymes, like Tay-Sachs disease, affecting the breakdown of glycolipids and leading to their accumulation.
Phagocytosis
- Process where a cell engulfs a pathogen or other large particle. Phases involve formation of a phagosome, merging with a lysosome, and digestion of contents.
Cellular Structures Delivering Materials to Lysosomes
- Endocytosis, phagocytosis, and autophagy are processes where material is brought into a cell and delivered to lysosomes for breakdown and recycling.
Peroxisomes
- Degrade fatty acids and toxic compounds.
- Contain oxidases which leverage oxygen (O2) to oxidize organic substances and produce hydrogen peroxide (H₂O₂).
- Also contains catalase, which breaks down H₂O₂ into water (H₂O) and oxygen (O₂).
- Self-assembling organelles, "life span" of a day.
- Involved in peroxisomal biogenesis
Endomembrane System
- A group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins.
- Includes the nuclear envelope, endoplasmic reticulum membranes, the Golgi apparatus, vesicles, and lysosomes.
Mitochondrion
- Double-membrane bound organelle.
- Basic structure: outer membrane, intermembrane space, inner membrane with infoldings called cristae, and a lumen termed the matrix.
- Contains circular mtDNA, granules, and mitoribosomes.
- Site of aerobic cellular respiration, referred to as the "powerhouse of the cell".
Vesicles & Vacuoles
- General term for a variety of single-membrane bound sacs.
- Vacuoles (plant cells): storage site for ions and nutrients; uptake of water by osmosis creates pressure to push membrane against cell wall.
Cytoskeleton Elements
- Responsible for maintaining and changing cell shape, internal transport, anchoring internal and external components, cell movement, and chromosome movement during cell division.
- Includes microtubules (polymers of a and ẞ tubulin), microfilaments (polymers of actin), and intermediate filaments (various proteins).
Functions of Microtubules
- Move chromosomes during cell division.
- Form centrioles, basal bodies, and centrosomes.
- Serve as tracks for vesicle and vacuole movement.
- Provide internal scaffolding for eukaryotic cilia and flagella.
Cilia & Flagella
- Locomotor structures (cytoplasmic extensions) that differ in length.
- Cilia are shorter, moving in an oar-like motion.
- Flagella are longer, moving in a whip-like manner.
- They share a 9+2 microtubule arrangement.
Functions of Microfilaments
- Involved in cell contraction (like cleavage furrow formation during cytokinesis).
- Anchor for extracellular elements.
- Play a role in cytoplasmic streaming.
Functions of Intermediate Filaments
- Form a scaffold for the cell.
- Part of the internal lining of the inner nuclear membrane.
Size Range of Cells
- A size chart showing the relative sizes of viruses, bacterial cells, typical human cells, and various cellular components such as mitochondria, lysosomes, ribosomes, plasma membranes, and even a hydrogen atom, ranging from thousands of micrometers down to less than 0.0001 micrometers.
Different Types of Microscopes
- Techniques like bright-field microscopy, phase contrast microscopy, differential interference contrast microscopy, fluorescence microscopy, confocal microscopy, offer different ways to view biological samples and structures.
Preparing Tissues for Microscopy
- Tissues are fixed, embedded into blocks, and are cut into sections using techniques like microtomes to view sections of tissue with a microscope.
Deconvolution Fluorescence Microscopy
- Deconvolution microscopy sharpens fluorescent images by reducing blurring effects due to light and depth-of-field.
Differential Centrifugation
- A method to isolate different cellular components by separating them based on their density and size through centrifugation at different speeds and times. Components like nuclei, mitochondria, plasma membranes, ribosomes, and soluble cytoplasm are separated.
Cell Fractionation and Differential Centrifugation
- Technique for separating components through centrifugal forces.
Equilibrium Density-Gradient Centrifugation
- Method to further separate organelles by density differences within a sucrose gradient medium. Examples of isolated organelles include lysosomes, mitochondria, and peroxisomes, separated by density.
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Description
Test your knowledge on eukaryotic cellular structures and organelles. This quiz covers components of both animal and plant cells, detailing their functions and relationships. Ideal for students studying cell biology or related subjects.
