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Questions and Answers
Who discovered cells in 1665?
Robert Hooke
What did Anton van Leeuwenhoek call the small creatures he observed in pond water?
Animalcules
All cells come from pre-existing cells is a part of the Cell Theory.
True
Which of the following statements are part of the Cell Theory? (Select all that apply)
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What notable theory did Louis Pasteur disprove?
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Match the following contributors to their discoveries related to cells:
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Viruses are made up of cells.
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What are the exceptions to the Cell Theory mentioned?
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What are some fields that have been influenced by the Cell Theory?
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What was developed first in the 1550s?
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Thiomargarita namibiensis is a prokaryotic cell.
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What is the primary difference between prokaryotic and eukaryotic cells?
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What organelle is responsible for producing ATP?
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Which of the following is NOT a membranous organelle?
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Match the following cell organelles with their functions:
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The __________ is the control center of the cell.
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Study Notes
Discovery of Cells
- 1665: Robert Hooke observed cork under a microscope, describing cells as tiny boxes or a honeycomb structure, initially believing they only existed in plants and fungi.
- 1673: Anton van Leeuwenhoek examined pond water, discovering single-celled organisms he called "animalcules," realizing that cells were present in animals as well as plants.
- 19th century: Louis Pasteur conducted experiments that disproved the Theory of Spontaneous Generation, enhancing the understanding of cell origins.
Cell Theory
- All organisms are composed of one or more cells.
- The cell serves as the basic unit of life.
- Cells arise from pre-existing cells, reinforcing the continuity of life.
- Modern Cell Theory includes:
- All living things are made entirely of cells.
- Cells function as both structural and functional units.
- Genetic information is transmitted from cell to cell during division.
- All cells share a similar chemical composition.
- Energy transformations necessary for life occur within cells.
Exceptions to Cell Theory
- Viruses, which exhibit characteristics of life, are not composed of cells and thus challenge the definition of life in relation to cell theory.
- The origin of the first cell is ambiguous; no definitive first cell exists since the precise definition of a cell is not established.
- Mitochondria and chloroplasts have their own DNA and can replicate independently, distinguishing them from the rest of the cellular structure.
Contributions of Cell Theory
- Medicine: Advancements in diagnostics, disease treatment, and understanding cellular functions.
- Agriculture: Enhanced crop biotechnology and pest resistance through knowledge of plant cells.
- Biotechnology: Development of genetic engineering techniques and therapeutic applications based on cell manipulation.
- Other fields: Broader implications in environmental science, pharmacology, and molecular biology stem from cell theory's principles.
Cell Size and Diversity
- Thiomargarita namibiensis is one of the largest known prokaryotic cells.
- Cells exhibit diversity in size, structure, and function, forming the basis of life.
History of Cell Biology
- Development of microscopy and cell theory has evolved significantly since the 1550s.
- The first compound microscope was developed in 1558, leading to the discovery of "animalcules" in 1670.
- Microscopy advancements continued until the present, facilitating explorations into cell structure.
Development of Cell Theory
- The formal development of cell theory took place in the mid-19th century, emphasizing that all living organisms are composed of cells.
- Key contributors included Robert Brown (1858) who discovered the nucleus as a prominent organelle.
Cell Types
- Two main types of cells exist:
- Prokaryotic Cells: Simple, lack membrane-bound organelles, and include bacteria.
- Eukaryotic Cells: Complex, contain membrane-bound organelles, and comprise plant, animal, and fungi cells.
Common Features of Cells
- All cells share basic architectural features, including:
- Cell Membrane: Selectively permeable boundary.
- Cytoskeleton: Network of fibers providing structural support and transport (includes actin, intermediate filaments, microtubules).
Membranous Organelles
- Eukaryotic cells feature various membranous organelles, each with distinct functions:
- Nucleus: Contains DNA and regulates gene expression.
- Nucleolus: Produces ribosomes.
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Endoplasmic Reticulum:
- Rough ER: Studded with ribosomes, synthesizes proteins.
- Smooth ER: Synthesizes lipids and detoxifies.
- Golgi Apparatus: Modifies, sorts, and packages proteins for secretion.
- Lysosomes: Contain enzymes for digestion.
- Glycosomes: Store glycogen.
- Vacuoles: Storage and maintenance of turgor pressure in plant cells.
- Mitochondria: Produce ATP through cellular respiration.
- Chloroplasts: Site of photosynthesis in plant cells.
Cell Analogy Performance Task
- Students are encouraged to create analogies of a cell as familiar models, such as schools or factories, to better understand cell functions and structures.
Announcements
- Long quizzes on Cell Theory and Cell Ultrastructure scheduled.
- Preparation for lab activity requires specific materials, including microscope slides and methylene blue.
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Description
Explore the fascinating history of cell theory, including pivotal discoveries made by scientists like Robert Hooke and Anton van Leeuwenhoek. This quiz covers the early observations that shaped our understanding of cells in plants and animals. Test your knowledge of these groundbreaking advancements in biology.
