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Questions and Answers
What did Robert Hooke contribute to the field of cell biology in 1665?
What did Robert Hooke contribute to the field of cell biology in 1665?
Robert Hooke coined the term 'cells' to describe the tiny boxes he observed in cork.
Which scientist is credited with the first observation of unicellular microorganisms and what did he call them?
Which scientist is credited with the first observation of unicellular microorganisms and what did he call them?
Anton van Leeuwenhoek observed unicellular microorganisms and referred to them as 'animalcules.'
What conclusions were drawn by Matthias Schleiden and Theodor Schwann in the 19th century regarding cells?
What conclusions were drawn by Matthias Schleiden and Theodor Schwann in the 19th century regarding cells?
Schleiden concluded that all plant parts are made of cells, while Schwann stated that all animal tissues are made of cells.
What significant contribution did Watson and Crick make to cell biology in the 1950s?
What significant contribution did Watson and Crick make to cell biology in the 1950s?
What major theory did Rudolf Virchow propose about the origin of cells in 1858?
What major theory did Rudolf Virchow propose about the origin of cells in 1858?
What are the three main postulates of cell theory established in the 19th century?
What are the three main postulates of cell theory established in the 19th century?
How does the cell theory relate to microscopy?
How does the cell theory relate to microscopy?
What is the maximum resolution achievable by an electron microscope?
What is the maximum resolution achievable by an electron microscope?
How did Anton van Leeuwenhoek enhance the field of microscopy?
How did Anton van Leeuwenhoek enhance the field of microscopy?
Where do cells fall on the spectrum of life in terms of size?
Where do cells fall on the spectrum of life in terms of size?
Name one subtype of light microscopy and its unique feature.
Name one subtype of light microscopy and its unique feature.
What role does DNA play in cell division?
What role does DNA play in cell division?
What does the term 'confocal microscopy' refer to?
What does the term 'confocal microscopy' refer to?
What intersection does modern cell biology find itself at?
What intersection does modern cell biology find itself at?
What is the smallest living entity?
What is the smallest living entity?
How do viruses differ from living entities?
How do viruses differ from living entities?
What defines a living entity when it comes to energy utilization?
What defines a living entity when it comes to energy utilization?
Can prions be considered living entities, and why?
Can prions be considered living entities, and why?
What characteristic do all living entities share regarding reproduction?
What characteristic do all living entities share regarding reproduction?
Explain why viruses cannot be classified as living organisms.
Explain why viruses cannot be classified as living organisms.
What defines the cell as the smallest living entity?
What defines the cell as the smallest living entity?
Explain the significance of microscopy in cell biology.
Explain the significance of microscopy in cell biology.
Summarize the three main components of cell theory.
Summarize the three main components of cell theory.
How do prokaryotic cells differ from eukaryotic cells in their structure?
How do prokaryotic cells differ from eukaryotic cells in their structure?
What role does ribosomes play in cells?
What role does ribosomes play in cells?
Identify two requirements that all living entities must meet.
Identify two requirements that all living entities must meet.
What is meant by the term 'self-replicating RNA' in the origin of cells?
What is meant by the term 'self-replicating RNA' in the origin of cells?
Discuss the role of the plasma membrane in cellular function.
Discuss the role of the plasma membrane in cellular function.
What can be classified as a living entity?
What can be classified as a living entity?
Name one distinguished characteristic that separates living cells from non-living entities.
Name one distinguished characteristic that separates living cells from non-living entities.
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Study Notes
The Cell as the Smallest Living Entity
- The origin of the term "cell" is attributed to Robert Hooke in 1665.
- Hooke described "tiny boxes" observed in cork but believed them to exist only in plants and fungi.
- Anton van Leeuwenhoek, a Dutch tradesman and scientist, pioneered microscopy and crafted over 25 hand-made microscopes.
- He is credited with the discovery of unicellular microorganisms, blood cells, protozoans, bacteria, vacuoles, spermatozoa, and striated muscle fibers.
History of Cell Discovery
- In 1838, Matthias Schleiden, a German botanist, concluded that all plant parts are made of cells.
- In 1839, Theodor Schwann, a German physiologist, stated that all animal tissues are made of cells.
- Rudolf Virchow, a German physician, rejected the prevailing theory of spontaneous generation and proposed that cells arise from pre-existing cells.
Cell Theory
- The Cell Theory postulates:
- All organisms consist of one or more cells (Schleiden & Schwann).
- The cell is the basic structural unit of all organisms (Schleiden & Schwann).
- All cells arise from pre-existing cells – "omnis cellulae cellula" (Virchow).
- The Cell Theory establishes the cell as the fundamental unit of life and the basis for reproduction.
Microscopy in Cell Biology
- Microscopy played a pivotal role in the development of the Cell Theory.
- Pioneering studies utilized light microscopes.
- Techniques such as brightfield, phase contrast, differential interference contrast, and fluorescence microscopy have all contributed to the understanding of cellular structures.
- Confocal microscopy allows for the generation of 3D images of living cells.
- Time-lapse imaging, a technique that allows for the observation of cellular processes in real time, provides deeper insights into cell movement and function.
- Super high-resolution microscopy achieves resolutions below 100 nanometers, making it possible to study structures at the nanometer scale.
- Electron microscopy (SEM and TEM) provides detailed images of cellular structures at a higher magnification than light microscopy but only on dead cells.
Viruses and Prions
- Viruses, prions, and viroids are not considered living entities because they do not:
- Use their own energy
- Grow on their own
- Respond to stimuli
- Reproduce independently
- Viruses are infectious particles containing genetic material surrounded by a protein coat, capable of infecting all organisms.
- Prions are infectious proteins that can cause neurodegenerative diseases.
- Viroids are infectious RNA molecules that mainly infect plants.
Key Facts
- The cell is the smallest unit that can be definitively said to be alive.
- Cells are bound by a plasma membrane, contain cytoplasm, have genetic material, and have the ability to synthesize proteins.
- Eukaryotic cells contain membrane-bound organelles.
- Living entities harness energy, respire, grow and develop, reproduce, and respond to stimuli.
- The first cell is thought to have arisen by the enclosure of self-replicating RNA and associated molecules within a membrane composed of phospholipids.
- Antibodies are used in immunocytochemistry (cells) and immunohistochemistry (tissues) to detect specific proteins.
- The confocal microscope allows for the generation of 3D images of cellular structures.
- Super high-resolution microscopy allows for imaging at the nanoscale, providing insights into cellular structures and processes.
- Cells are the building blocks of all living organisms, from tissues to organs, to organ systems, finally resulting in an organism.
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