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Questions and Answers
What is the smallest living unit of any organism?
Which scientist is known for first discovering and naming cells?
Which of the following is NOT one of the tenets of cell theory?
What distinguishes prokaryotic cells from eukaryotic cells?
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Which type of microscope uses a beam of electrons to create an image?
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Which of the following is a characteristic of prokaryotes?
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Which of the following is an example of a eukaryotic organism?
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What component do all prokaryotic cells possess?
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What is the primary function of the cell wall?
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Which component of the cell membrane faces away from water?
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Which type of protein is responsible for transporting large molecules across the cell membrane?
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What does the fluid mosaic model describe about the cell membrane?
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Which statement is true about animal cells concerning the cell wall?
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Which organelle is primarily responsible for the production of ATP?
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What is the main function of lysosomes within a cell?
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Which type of cell contains a true nucleus and membrane-bound organelles?
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What is the primary role of the rough endoplasmic reticulum?
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Which organelle is involved in detoxification of drugs?
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Which component of the cytoskeleton is primarily responsible for maintaining cell shape?
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What is the function of vacuoles in plant cells?
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Which structure within the nucleus is responsible for ribosome production?
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Which of the following statements is true regarding prokaryotic cells?
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What is the primary role of chloroplasts in plant cells?
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Study Notes
History of Cell Discoveries
- Robert Hooke (1665) was the first to observe and name cells, using a microscope to examine non-living cork.
- Anton Van Leeuwenhoek (1673) is considered the "Father of Microscopy". He examined pond water and samples from a human mouth, drawing organisms that are now known as bacteria.
The Cell Theory (1800s)
- All living things are made up of cells (Schleiden & Schwann).
- Cells are the basic unit of life.
- Cells come only from other cells (Virchow), verifying Lorenz Oken's suggestion from 50 years prior.
Microscopes
- Light microscopes allow light to pass through a sample to create an image.
- Stains are sometimes used with light microscopes to reveal important structures.
- Electron microscopes utilize a beam of electrons focused by magnetic fields, providing higher resolution images.
- Electron microscopes are only used to observe non-living organisms.
Prokaryotic Cells
- Lack organelles and a nucleus.
- Always unicellular.
- Cells are not specialized.
- The only examples are bacteria.
Eukaryotic Cells
- Have organelles and a nucleus.
- Usually multicellular.
- Cells can be specialized, having a specific function (e.g. nerve cell, muscle cell).
- Examples include animals, plants, fungi, and protists.
Prokaryotic vs. Eukaryotic
- Prokaryotes are small and primitive with cell walls and cell membranes.
- Prokaryotes contain DNA (nucleoid and plasmid), ribosomes, and cytoplasm, but lack a true nucleus and membrane-bound organelles.
- Prokaryotes divide by binary fission.
- Eukaryotes have a true nucleus and membrane-bound organelles.
- Eukaryotes, like prokaryotes, possess cell membranes and may have cell walls.
- Eukaryotes can be unicellular or multicellular.
- Some eukaryotes have cilia.
- Eukaryotic cells divide through mitosis or meiosis.
Cytoplasm
- The fluid portion of the cell outside the nucleus is called the cytosol.
- Organelles are "little organs" within the cytoplasm.
Organelles
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Nucleus - Controls cell activities and contains DNA.
- Contains a nuclear envelope with two membranes (each a lipid bilayer).
- The outer layer is continuous with the rough ER, while the inner layer has nuclear pores that regulate the movement of proteins, RNA, and molecules in and out.
- The nucleolus is the site of ribosome production.
- Contains a nuclear envelope with two membranes (each a lipid bilayer).
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Endoplasmic Reticulum (ER)
- Rough ER: Contains ribosomes, responsible for producing products for export.
- Smooth ER: Lacks ribosomes and synthesizes membrane lipids, detoxifies drugs (found in the liver).
- Ribosomes - Produce proteins using coded instructions from DNA, either attached to the ER or free in the cytoplasm.
- Golgi Bodies/Apparatus - Package and transport cell products out of the cell, and produce lysosomes.
- Mitochondria - Site of energy production (ATP) and contain their own DNA. Mitochondrial DNA can self-replicate.
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Lysosomes - Filled with enzymes that remove cellular "junk".
- Autolysis: Self-destruction.
- Autophagy: Recycling cell parts.
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Peroxisomes - Site of filtering toxic materials.
- Contain catalase.
- Naturally found in the liver.
- Cytoskeleton - Involved in support, transport, and reproduction of the cell.
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Vacuoles - Sac-like structures that store extra sugar, water, salt, and waste.
- Plant cells have a central vacuole that holds water and increases rigidity.
- Unicellular organisms have a contractile vacuole that pumps excess water out of the cell.
Chloroplasts (Plants Only)
- Convert solar energy and CO2 into chemical energy (glucose).
The Cell Wall
- Tough, outer layer outside the cell membrane.
- Found in plants (cellulose), fungi (chitin), and some bacteria (peptidoglycan).
- Provides support and protection.
- Not found in animal cells.
The Cell Membrane (Lipid Bilayer)/Plasma Membrane
- Thin, flexible barrier that separates, regulates, and communicates.
- Separates: Forms a boundary around the cell.
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Regulates: Controls what enters and leaves the cell.
- Semi-permeable/selectively permeable: Selects which molecules can pass in an out.
- Communicates: Allows the cell to interact with its environment.
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Structure: Composed of two organic compounds:
- Phospholipids: A double layer of lipids with hydrophilic heads facing towards water and hydrophobic tails facing inwards away from water.
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Proteins:
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Integral proteins: Span the entire cell membrane.
- Channel proteins: Open all the time.
- Carrier proteins: Open and close to carry large molecules in and out (e.g. glucose).
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Peripheral proteins: Located on the periphery (inside and out).
- Act as receptors and cell markers.
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Integral proteins: Span the entire cell membrane.
- Fluid Mosaic Model: The cell membrane acts like a fluid, composed of multiple components.
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Description
Explore the fascinating timeline of cell discoveries from Robert Hooke's initial observation to the formulation of the cell theory in the 1800s. This quiz delves into the invention of microscopes, the distinction between prokaryotic cells, and the foundational principles that govern cellular biology.
