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Questions and Answers
What did Anton van Leeuwenhoek observe using a single lens microscope?
What did Anton van Leeuwenhoek observe using a single lens microscope?
- Plant cells in a leaf
- Live cells in pond water (correct)
- Bacterial colonies on agar
- Fungi growing on bread
Which statement is part of modern cell theory?
Which statement is part of modern cell theory?
- Only multicellular organisms consist of cells.
- All organisms are made of multiple tissues.
- Cells can spontaneously generate from non-living matter.
- All living cells arise from pre-existing cells. (correct)
Which type of cells do not have membrane-bound organelles?
Which type of cells do not have membrane-bound organelles?
- Eukaryotic cells
- Prokaryotic cells (correct)
- Plant cells
- Animal cells
What is the primary function of the nucleus in a cell?
What is the primary function of the nucleus in a cell?
What does the cell membrane primarily control?
What does the cell membrane primarily control?
What is the role of ribosomes found in eukaryotic cells?
What is the role of ribosomes found in eukaryotic cells?
Which component provides structural support to plant cells?
Which component provides structural support to plant cells?
What is the term used for the gel-like substance found within a cell?
What is the term used for the gel-like substance found within a cell?
Which statement accurately summarizes the findings of Francisco Redi regarding spontaneous generation?
Which statement accurately summarizes the findings of Francisco Redi regarding spontaneous generation?
What was the purpose of the long, twisted necks of Pasteur's swan-neck flasks?
What was the purpose of the long, twisted necks of Pasteur's swan-neck flasks?
Which of the following is NOT one of the main tenets of the Cell Theory?
Which of the following is NOT one of the main tenets of the Cell Theory?
Who is credited with coining the term 'cell' and in which year?
Who is credited with coining the term 'cell' and in which year?
How long did it take for the Cell Theory to be formulated?
How long did it take for the Cell Theory to be formulated?
Which of the following best describes the main outcome of Pasteur's experimentation with swan-neck flasks?
Which of the following best describes the main outcome of Pasteur's experimentation with swan-neck flasks?
Which contributor to the Cell Theory invented the first compound microscope?
Which contributor to the Cell Theory invented the first compound microscope?
What did Pasteur's predictions about the sterility of boiled broth involve?
What did Pasteur's predictions about the sterility of boiled broth involve?
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Study Notes
Spontaneous Generation
- Francisco Redi's experiment with three jars (open, gauze-covered, sealed) demonstrated that macroorganisms do not spontaneously generate.
- Pasteur's work with swan-neck flasks proved microorganisms don't arise from spontaneous generation; the broth remained sterile unless the necks were broken, allowing contamination.
- Pasteur established that microbial growth results from microorganisms rather than a "life force."
Cell Theory
- Formulated by Theodor Schwann and Matthias Schleiden, consisting of three fundamental principles:
- All organisms are composed of cells.
- All existing cells arise from pre-existing living cells, eliminating spontaneous generation.
- Cells are the basic unit of life.
- The development of the microscope played a crucial role in establishing the Cell Theory, taking over 173 years to formulate (1665-1838).
Contributors to Cell Theory
- Janssen: Inventor of the first compound microscope.
- Robert Hooke (1665): Observed cork and named "cells" from Latin ‘cellula’.
- Anton van Leeuwenhoek: Used a single lens microscope for live cell observation, introducing "animacules."
- Matthias Schleiden: Proposed that plants are made of cells.
- Theodor Schwann: Concluded that all animals consist of cells and published the first statement of the Cell Theory.
- Rudolf Virchow: Added that all cells come from pre-existing cells.
Modern Cell Theory
- Modern principles include:
- All living things consist of one or more cells.
- Living cells arise from pre-existing cells by division.
- Cells are fundamental units of structure and function.
- The activity of an organism depends on independent cell activities.
- Metabolism occurs within cells.
- Cells contain DNA in chromosomes and RNA in the nucleus/cytoplasm.
- Chemical composition of similar species' cells is consistent.
- Hereditary information (DNA) is transferred between cells.
- All cells share basic chemical composition.
Types of Cells
- Cells are the smallest units capable of performing life functions, categorized into two types:
- Prokaryotic: Lack membrane-bound organelles, simpler internal structure, primarily unicellular organisms like bacteria.
- Eukaryotic: Contain membrane-bound organelles and are primarily multicellular organisms.
Parts of the Cell (Organelles)
- Organelles are specialized structures within a cell.
- Cell Membrane: Outer layer, regulates movement in/out of the cell; composed of a phospholipid bilayer.
- Cell Wall: Found in plant cells and bacteria, providing support and protection.
- Nucleus: Directs cellular activities, surrounded by a nuclear membrane, containing DNA.
- Nuclear Membrane: Two layers with openings to allow material exchange with the cytoplasm.
- Chromosomes: Structures made of DNA within the nucleus, carrying genetic information.
- Nucleolus: Located inside the nucleus, responsible for RNA production for protein synthesis.
- Cytoplasm: Gel-like substance within the cell, housing organelles and hereditary material.
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