Questions and Answers
What is the basic structural and functional unit of all living organisms?
cell
Which of the following correctly describes prokaryotic cells?
Who coined the term 'cell'?
Robert Hooke
What is the cell theory?
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Eukaryotic cells do not have membrane-bound organelles.
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Match the following types of microscopes with their functionality:
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The movement of molecules through the membrane where no energy is required from the cell is called ______.
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What type of diffusion occurs when solute molecules move from high solute concentration to low solute concentration?
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What is the role of carrier proteins in facilitated diffusion?
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Facilitated diffusion requires energy from the cell.
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Study Notes
Cellular Basics
- Cells are the fundamental structural and functional units of all living organisms.
- Physiological processes such as respiration, digestion, growth, and development occur at the cellular level.
Types of Cells
- Prokaryotic cells lack a nucleus and membrane-bound organelles; examples include eubacteria and archaebacteria.
- Eukaryotic cells possess a nucleus and membrane-bound organelles; examples include protists, fungi, plants, and animals.
Cell Measurement Techniques
- Most cells are only visible with microscopes which utilize light or electrons for detailed observation.
Modern Microscopy
- Light microscopy (phase contrast) provides high-contrast images of transparent specimens.
- Light microscopy (reflected light) captures light reflected from opaque specimens.
- Fluorescence microscopy visualizes chlorophyll molecules emitting red light.
- Transmission electron microscopy yields detailed images of internal structures.
- Scanning electron microscopy reveals surface details, often artificially colored for emphasis.
Historical Contributions
- Robert Hooke, in the 1600s, improved microscopes and introduced the term "cell."
- Matthias Schleiden and Theodore Schwann established the cell theory in 1839, asserting that:
- All living things consist of one or more cells.
- Cells arise from pre-existing cells through division.
- The cell is the fundamental unit of structure and function.
- An organism's activity is based on the total activity of cells.
- Metabolism and energy flow occur within cells.
- DNA is primarily in chromosomes, while RNA is in the cytoplasm and nucleus.
Cell Membranes
- All cells have membranes; eukaryotic cells contain multiple organelle membranes that regulate metabolic processes.
- Membranes facilitate:
- Molecular passage in and out of cells and organelles.
- Division of cells into compartments for specialized metabolism.
- Surface areas that hold enzymes.
Membrane Composition
- Membranes consist of a bilayer of phospholipid molecules.
- Proteins:
- Intrinsic proteins are partially embedded in the membrane.
- Extrinsic proteins are located outside the membrane.
- Carbohydrate chains aid in cell signaling and structural support.
Membrane Properties
- Growth
- Permeability
- Ability to change
Membrane Transport Mechanisms
- Passive transport does not require energy; molecules move along a concentration gradient.
- Active transport requires energy expenditure.
- Bulk transport involves larger volumes of substances.
Passive Transport Mechanisms
- Diffusion involves solute movement from high to low concentration.
- Osmosis is the movement of water from low to high solute concentration.
Types of Diffusion
- Simple diffusion allows substances to pass directly through the membrane, influenced by concentration gradient.
- Facilitated diffusion requires carrier proteins for molecules to cross the membrane, maintaining selective permeability.
Selective Permeability Mechanisms
- Integral membrane proteins enable selective transport:
- Channel proteins facilitate passage of polar molecules.
- Carrier proteins bind and transport specific molecules.
- Ion channels regulate ion flow across membranes.
Membrane Potential
- A concentration gradient of ions creates a membrane potential, leading to a charge difference across the membrane.
Special Diffusion: Imbibition
- Imbibition is a specific type of diffusion related to water absorption processes.
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Description
Explore the fundamental structures and functions of cells, the basic units of life. This quiz covers the differences between prokaryotic and eukaryotic cells, as well as various physiological processes that occur at the cellular level. Test your knowledge on the essential components and measurements of cells.
