Questions and Answers
What is the cell theory?
All organisms are composed of similar units of organization called cells.
Who was the first to observe bacteria and protozoa?
Anton Van Leeuwenhoek
Which scientist discovered the nucleus of a cell?
All cells come from pre-existing cells by division.
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What are the two main types of cells?
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Which of the following is found only in plant cells?
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What is the function of the mitochondria?
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The __________ controls movement in and out of the cell.
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Match the following organelles with their functions:
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What are vacuoles and their function?
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Study Notes
Cell Theory
- Also known as cell doctrine; asserts all organisms consist of cells.
Historical Contributions
- Zacharias Jansen created the first compound microscope around 1595 in Middleburg, Holland.
- Robert Hooke, an English scientist, first observed cells in cork around 1663.
- Anton Van Leeuwenhoek discovered bacteria and protozoa, referring to them as "animacules" circa 1673.
- Robert Brown, a British botanist, identified the nucleus of the cell in 1833.
- Theodor Schwann, a German doctor, described animal cells with a nucleus in 1838.
- Matthias Schleiden, a German botanist, detailed plant cells containing a nucleus in 1838.
- Rudolf Virchow proclaimed, “every cell originates from another cell,” in 1855.
Tenets of Modern Cell Theory
- All living organisms are composed of cells.
- The cell is the fundamental structural and functional unit of life.
- Cells arise from pre-existing cells through division.
- Cells contain hereditary information passed during cell division.
- All cells have similar chemical compositions.
- Metabolic processes occur within cells.
Cell Structure and Function
- Cells are the smallest units capable of life functions; examples include amoeba, plant stem, bacteria, red blood cells, and nerve cells.
Types of Cells
- Somatic Cell
- Sex Cell
- Prokaryotic Cell: Lack membrane-bound structures; include bacteria and unicellular organisms.
- Eukaryotic Cell: Contain membrane-bound organelles; include most living organisms.
Cell Parts and Organelles
Surrounding the Cell
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Cell Membrane
- Outer layer controlling movement in/out of cells; a double-layer that acts as a barrier and gatekeeper. Present in both animal and plant cells.
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Cell Wall
- Found mainly in plant cells and bacteria; provides support and protection.
Inside the Cell
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Nucleus
- Directs cell activities; surrounded by a nuclear membrane, contains genetic material (DNA).
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Nuclear Membrane
- Envelopes the nucleus, consisting of two layers that contain openings.
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Chromosomes
- Located in the nucleus; composed of DNA; carry instructions for traits. Humans have 24 pairs.
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Cytoplasm
- Gel-like substance surrounding cell membrane containing hereditary material.
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Endoplasmic Reticulum
- Transports materials within the cell; comes in two types:
- Smooth ER: Lacks ribosomes.
- Rough ER: Ribosomes attached to its surface.
- Transports materials within the cell; comes in two types:
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Ribosomes
- Thousands per cell; responsible for protein synthesis, found on the rough ER and freely within the cytoplasm.
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Mitochondria
- Energy producers through chemical reactions; regulate water levels and recycle proteins, fats, and carbohydrates. Known as the powerhouse of the cell.
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Golgi Bodies
- Known as the protein packaging plant; organize and move materials within and outside the cell.
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Lysosome
- Digestive organelle for proteins, fats, and carbohydrates; can cause cell breakdown if it explodes.
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Vacuoles
- Membrane-bound sacs used for storage, digestion, and waste removal; contain water solutions and support plant cell structure.
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Chloroplast
- Predominantly in plant cells; contains chlorophyll and is the site of photosynthesis.
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Description
Test your knowledge on the Cell Theory and its historical development. This quiz covers key figures such as Zacharias Jansen, Robert Hooke, and Anton Van Leeuwenhoek, along with their contributions to cellular biology. Discover how these scientists paved the way for our understanding of cells.
