Questions and Answers
Which two domains consist of prokaryote cells?
Describe the major difference between prokaryotic and eukaryotic cells in the location of their DNA.
Prokaryotic DNA is not membrane enclosed and is located in the nucleoid, while eukaryotic DNA is membrane-bound and located in the nucleus.
What is a cell wall?
A rigid structure outside of the plasma membrane; in plants, the cell wall is made of cellulose.
What is the plasma membrane?
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What is a nucleoid?
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What is cytoplasm?
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What are flagella?
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Why are cells so small?
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What are microvilli and how do these structures relate to the function of intestinal cells?
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Describe the nuclear envelope.
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What is the nuclear lamina?
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What is the nuclear matrix?
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What are the two components of chromatin?
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What is the function of ribosomes?
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Describe the location and product of free ribosomes.
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Describe the location and product of bound ribosomes.
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List all the structures of the endomembrane system.
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List and describe three major functions of the smooth ER.
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What does the ER do with secretory proteins?
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What are the functions of the ER?
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What happens to a transport vesicle when it arrives at the Golgi?
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What is a lysosome?
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Describe the process of intracellular digestion of particles engulfed by phagocytosis.
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Describe autophagy.
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What happens in Tay Sachs disease? Explain the role of lysosomes in Tay Sachs.
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What are food vacuoles?
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What are contractile vacuoles?
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What are central vacuoles in plants?
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List at least three functions/materials stored in vacuoles.
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What is the endosymbiont theory? Summarize three pieces of evidence that support the model of endosymbiosis.
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What is the function of mitochondria?
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What is the function of chloroplasts?
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Explain the important role of peroxisomes.
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What is the cytoskeleton?
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What are three roles of the cytoskeleton?
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Name the three main types of fibers that make up the cytoskeleton.
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What is the role of centrioles?
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Compare and contrast cilia and flagella.
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Give two functions of intermediate filaments.
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What are the three functions of the cell wall?
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What is the middle lamella?
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What are the intracellular junctions between plant cells?
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Study Notes
Prokaryotic vs Eukaryotic Cells
- Prokaryote cells belong to two domains: Bacteria and Archaea.
- Prokaryotic DNA is located in the nucleoid and is not membrane-enclosed, while eukaryotic DNA is housed in a membrane-bound nucleus.
Cell Structures
- The cell wall is a rigid structure outside of the plasma membrane, made of cellulose in plants.
- The plasma membrane encloses the cytoplasm of the cell, maintaining the cell's integrity.
- Cytoplasm refers to the contents within the plasma membrane, excluding the nucleus in eukaryotic cells.
Cellular Motility
- Flagella serve as locomotion organelles for certain bacteria.
Cellular Size and Surface Area
- Cells remain small due to the need for a sufficient surface area to facilitate material exchange with the surroundings.
Microvilli
- Microvilli are long projections that increase surface area without significantly increasing volume, enhancing nutrient absorption in intestinal cells.
Nuclear Structure
- The nuclear envelope, a double membrane, encloses the nucleus and separates it from the cytoplasm.
- The nuclear lamina is a network of protein filaments that provides structural support to the nuclear envelope.
- The nuclear matrix extends throughout the nucleus, organizing genetic material for proper functioning.
Chromatin and Ribosomes
- Chromatin consists of DNA and proteins and plays a key role in gene regulation.
- Ribosomes, made of RNA and protein, are essential for protein synthesis and can be found freely in the cytosol or bound to the endoplasmic reticulum (ER).
- Free ribosomes produce enzymes for sugar breakdown.
- Bound ribosomes produce proteins for membrane insertion.
Endomembrane System
- The endomembrane system includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.
Functions of the Endoplasmic Reticulum (ER)
- The smooth ER is involved in lipid synthesis, detoxification of drugs, and various metabolic processes.
- Secretory proteins are packaged into transport vesicles from the transitional ER and sent to the Golgi apparatus.
Golgi Apparatus and Lysosomes
- Transport vesicles fuse with the Golgi apparatus, which dispatches vesicles that may contain recycled enzymes.
- Lysosomes are membranous sacs filled with hydrolytic enzymes that digest macromolecules; they operate best in an acidic environment.
Lysosomal Functions
- Lysosomes play a role in intracellular digestion through phagocytosis, merging with food vacuoles to break down nutrients. Macrophages are human cells that carry out phagocytosis.
- Autophagy involves lysosomes degrading damaged organelles.
Vacuoles
- Food vacuoles are formed by phagocytosis, while contractile vacuoles help expel excess water from freshwater protists.
- Central vacuoles in mature plant cells serve multiple functions, including storage and growth.
Endosymbiont Theory
- The theory posits that early eukaryotic ancestors engulfed non-photosynthetic prokaryotic cells, leading to a mutual relationship.
- Evidence includes the presence of double membranes, independent ribosomes and DNA within mitochondria and chloroplasts, and their ability to grow and reproduce autonomously.
Organelles and Their Functions
- Mitochondria are the sites of cellular respiration, generating ATP from energy sources such as sugars and fats.
- Chloroplasts, found in plants and algae, are responsible for photosynthesis.
- Peroxisomes break down harmful hydrogen peroxide in the body.
Cytoskeleton
- The cytoskeleton is a network of fibers composed of microtubules, microfilaments, and intermediate filaments, providing mechanical support and shape to the cell.
- It aids in cellular motility and organizes cell activities.
Cilia and Flagella
- Cilia and flagella share structural similarities but differ in movement patterns; cilia act like oars, while flagella have longer, whip-like movements.
Cell Wall and Junctions
- The plant cell wall provides protection, maintains cell shape, and prevents excessive water uptake.
- The middle lamella is a sticky polysaccharide layer that connects adjacent plant cells via plasmodesmata, allowing small molecules to pass between cells.
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Description
Test your knowledge with flashcards from Chapter 6: A Tour of the Cell. This quiz covers important concepts like prokaryotic and eukaryotic cell structures and the differences in DNA location. Perfect for mastering cell biology basics!