Questions and Answers
What are the basic structural and functional units of all multicellular organisms?
Cells can arise from spontaneous generation.
False
Which of the following cell types are considered somatic cells?
What type of cells do not contain a nucleus?
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What structure regulates the passage into and out of the nucleus?
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The main function of the ___ is to maintain homeostasis.
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Match the following cell features with their descriptions:
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Which components are found in the eukaryotic cell's membrane?
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What type of filament consists of flexible chains of actin molecules?
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Which cellular structure is responsible for regulating cell division?
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Study Notes
Overview of Cells
- Cells serve as the fundamental structural and functional units of multicellular organisms.
- Essential for maintaining homeostasis.
- Composed of two primary components: all organisms consist of cells, and cells arise only from pre-existing cells.
Types of Cells
- Somatic Cells: Body’s building blocks.
- Sex Cells: Involved in reproduction.
Classification by DNA Structure
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Prokaryotic Cells:
- No nucleus.
- Cell walls primarily made of peptidoglycan.
- Lack membrane-bound organelles.
- Examples: Have pili, fimbriae for adhesion, and flagella for movement.
- Size: Ranges from 0.5 to 100 µm.
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Eukaryotic Cells:
- Contain a nucleus.
- Cell walls (if present) are made of cellulose or chitin (in fungi).
- Possess membrane-bound organelles allowing compartmentalization.
- Examples: Have cilia or flagella for movement.
- Size: Ranges from 10 to 150 µm.
Key Differences: Animal vs. Plant Cells
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Animal Cells:
- Generally smaller, lack cell walls.
- Do not possess plastids.
- Many small vacuoles, single prominent Golgi complex, possess centrosome and centrioles.
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Plant Cells:
- Larger, have a rigid cell wall made of cellulose.
- Contain plastids.
- Typically have a larger central sap vacuole.
- Have simpler units and a prominent Golgi complex (dictyosomes).
- Lack centrosome and centrioles.
Common Features of Cells
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Cell Membrane:
- Acts as a barrier between internal and external environments.
- Provides shape, size, and selective permeability.
- Facilitates cellular communication.
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Cytoplasm:
- Contains organelles and cytosol, the fluid part mostly composed of water.
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Organelles:
- Subcellular structures with specific functions.
Structure of the Cell Membrane
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Layers:
- Mucopolysaccharide/carbohydrate layer.
- Outer protein with antigen and receptor sites.
- Lipid bilayer characterized by a fluid mosaic model, comprising phospholipids, cholesterol, and glycolipids.
- Inner protein layer with channels/pores and transporters.
Cellular Projections
- Cilia: Short projections that move fluids across the cell surface.
- Flagella: Longer projections that facilitate whole-cell movement, notable in sperm cells.
Nucleus
- Typically contains one nucleus per cell, except for red blood cells and platelets.
- Muscle cells can be multinucleated.
- Functions include regulating metabolic activities and housing genetic material (DNA).
Chromosomes
- Composed of DNA and proteins, containing thousands of genes.
- Structure consists of a single DNA molecule associated with packing proteins.
Parts of the Nucleus
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Nucleolus:
- Small, RNA-rich body responsible for ribosome synthesis and cell division regulation.
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Nuclear Envelope:
- Double membrane separating the nucleus from the cytoplasm, with outer and inner membranes.
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Nuclear Pore:
- Protein-embedded openings that regulate material exchange between the nucleus and cytoplasm.
Cytoskeleton
- Network of protein filaments for structural support.
-
Types of Filaments:
- Microfilaments: Flexible chains of actin molecules.
- Intermediate filaments: Ropelike fibers formed from various proteins.
- Microtubules: Structures that can elongate and shorten to aid in cell function.
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Description
Explore the fundamental concepts of cells in this quiz. Understand the differences between somatic and sex cells, and learn about prokaryotic and eukaryotic cells. This quiz covers key topics essential for understanding cellular structure and function.
