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Questions and Answers
What is the primary function of mitochondria?
What is the primary function of mitochondria?
Mitochondria and chloroplasts are exactly the same structure and serve the same function.
Mitochondria and chloroplasts are exactly the same structure and serve the same function.
False
What theory suggests that mitochondria and chloroplasts originated from engulfed prokaryotic cells?
What theory suggests that mitochondria and chloroplasts originated from engulfed prokaryotic cells?
Endosymbiont theory
Chloroplasts contain the green pigment called _______.
Chloroplasts contain the green pigment called _______.
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Match the following organelles with their primary functions:
Match the following organelles with their primary functions:
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Which of the following is a function of peroxisomes?
Which of the following is a function of peroxisomes?
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The cytoskeleton is only involved in cell support and has no role in cell motility.
The cytoskeleton is only involved in cell support and has no role in cell motility.
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What are the three main types of fibers that make up the cytoskeleton?
What are the three main types of fibers that make up the cytoskeleton?
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Chloroplasts contain membranous sacs called _______ that are stacked to form a granum.
Chloroplasts contain membranous sacs called _______ that are stacked to form a granum.
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Match the following components to their descriptions:
Match the following components to their descriptions:
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What structures are present in the centrosome of animal cells?
What structures are present in the centrosome of animal cells?
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What is the diameter range of intermediate filaments?
What is the diameter range of intermediate filaments?
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Cilia and flagella have identical beating patterns.
Cilia and flagella have identical beating patterns.
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What is the function of dynein in cilia and flagella?
What is the function of dynein in cilia and flagella?
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Intermediate filaments support cell shape and fix organelles in place.
Intermediate filaments support cell shape and fix organelles in place.
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What are plant cell walls primarily made of?
What are plant cell walls primarily made of?
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Microfilaments are built as a twisted double chain of ______ subunits.
Microfilaments are built as a twisted double chain of ______ subunits.
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The layer of pectins found between primary walls is called the ______.
The layer of pectins found between primary walls is called the ______.
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Match the following cellular structures with their functions:
Match the following cellular structures with their functions:
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Which of the following statements is true regarding microfilaments?
Which of the following statements is true regarding microfilaments?
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Match the following extracellular components with their descriptions:
Match the following extracellular components with their descriptions:
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Motile cilia are typically found in large numbers on the cell surface.
Motile cilia are typically found in large numbers on the cell surface.
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Which statement about the extracellular matrix (ECM) in animal cells is true?
Which statement about the extracellular matrix (ECM) in animal cells is true?
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Prokaryotes, fungi, and plant cells all possess cell walls.
Prokaryotes, fungi, and plant cells all possess cell walls.
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What is the primary role of microtubules in cilia and flagella?
What is the primary role of microtubules in cilia and flagella?
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Study Notes
General Biology Lecture 5: Cell Structure and Function
- Lecture covered cell structure and function, including microscopy techniques and cell fractionation.
- Cells are typically too small to be seen without a microscope.
- Microscopes magnify images using light passing through specimen and glass lenses.
- Key microscopy parameters:
- Magnification - ratio of image size to real size
- Resolution - clarity of the image; minimum distance of two distinguishable points
- Contrast - visible differences in brightness between parts of the sample
- Cell fractionation isolates organelles from cells using centrifuges.
- Differential centrifugation separates cell components based on density and size.
- Eukaryotic cells have internal membranes.
- These membranes compartmentalize cellular functions.
- Prokaryotic cells lack a nucleus and membrane-bound organelles.
- All cells (prokaryotic and eukaryotic) have a plasma membrane, cytosol, chromosomes, and ribosomes.
- Prokaryotic cells have no nucleus and their DNA is in a region called nucleoid. They have no membrane-bound organelles, and their cytoplasm is bound by the plasma membrane.
- Eukaryotic cells have a nucleus that is surrounded by a double membrane and have membrane-bound organelles.
- The cytoplasm is the region between the nucleus and plasma membrane.
Cell Size Limitations
- Metabolic requirements limit cell size.
- The surface area-to-volume ratio of a cell is critical.
- As a cell increases in size, its volume grows proportionally more than its surface area, making it harder to effectively transport necessary substances.
- The plasma membrane is a selective barrier that controls what enters and exits the cell.
Eukaryotic Cell Structures
- Diagram and description of a eukaryotic cell structure
- Structures like the nucleus, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, vacuoles, mitochondria, and chloroplasts, and the cytoskeleton.
The Nucleus: Control Center
- The nucleus contains most of the cell's genetic material (DNA) organized into chromosomes.
- Chromatin is the combination of DNA and proteins.
- DNA condenses to form chromosomes during cell division.
- The nucleolus is the site of rRNA synthesis.
- The nuclear envelope, a double membrane, encloses the nucleus and separates it from the cytoplasm, with nuclear pores regulating the entry and exit of molecules.
Ribosomes: Protein Factories
- Ribosomes are complexes made of ribosomal RNA (rRNA) and protein, responsible for protein synthesis.
- Two types of ribosomes: free ribosome in the cytosol or bound ribosomes on the ER or nuclear envelope.
Endomembrane System
- Endomembrane system includes nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, and plasma membrane.
- These components work together to regulate protein traffic.
- The ER is a network of membranes continuous with the nuclear envelope.
- Rough ER (studded with ribosomes) is involved in protein synthesis and modification.
- Smooth ER (lacks ribosomes) synthesizes lipids, detoxifies drugs and poisons, and stores calcium ions.
- Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.
- Lysosomes are membrane-enclosed sacs containing hydrolytic enzymes that break down macromolecules.
- Vacuoles are large vesicles that have many functions (food vacuoles, contractile vacuoles, and central vacuoles).
- Central vacuoles store water, inorganic ions, and nutrients and play a major role in plant growth.
Mitochondria and Chloroplasts: Energy Conversion
- Mitochondria are the sites of cellular respiration (ATP generation from oxygen).
- Chloroplasts are the sites of photosynthesis (light energy to chemical energy) in plants and algae.
- Peroxisomes are oxidative organelles. - Peroxisomes break down fatty acids, and detoxify harmful substances.
Cytoskeleton: Internal Support and Motility
- The cytoskeleton is a network of fibers that helps support the cell and maintain its shape.
- Components: microtubules (thickest), microfilaments (thinnest), and intermediate filaments (in diameter range).
- Microtubules are involved in cell division, guiding organelle movement and cell shape.
- Microfilaments are responsible for cell movement, muscle contraction, and cytoplasmic streaming, often containing the motor protein myosin.
- Intermediate filaments are more permanent structures that support cell shape.
- Centrosomes and centrioles are structures found in animal cells that organize microtubules.
- Cilia and flagella are microtubule extensions that project from some cells. - Cilia and flagella differ in their beating patterns. These organelles are powered by the motor protein dynein.
Extracellular Components and Connections
- Plant cells have walls that maintain their shape and prevent excessive water uptake (made mainly of cellulose fibres).
- Animal cells have an extracellular matrix (ECM).
- Components like collagen, proteoglycans, and fibronectin.
- ECM proteins are linked to receptor proteins in the plasma membrane called integrins, thereby communicating with and influencing the cell.
- Cell junctions fasten cells together to help tissues coordinate and transport materials.
- Types of junctions include plasmodesmata (plant cells), tight junctions, desmosomes, and gap junctions (animal cells)
Summary of Concepts
- Cells are complex systems, and none of their components work in isolation.
- Cellular activities depend on the coordinated interaction of multiple components.
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Description
This quiz covers Lecture 5 of General Biology, focusing on cell structure and function. It discusses microscopy techniques, cell fractionation, and the differences between eukaryotic and prokaryotic cells. Test your understanding of the essential concepts related to cell components and their functions.
