BIO 1140 - Cell Structure & Varieties Flashcards
What is a Cell?
a small membrane bound unit filled with a concentrated aqueous solution of chemicals with reproduction capacity
What is the Cell Size difference of Prokaryotes and Eukaryotes?
- Prokaryotic cells range from 0.2 to 2.0 µm in diameter
- Eukaryotic cells range from 10-100 µm in diameter
Why are cells small and large organisms made of many small cells?
- The cell surface area determines the amount of substances entering and exiting the cell
- To function, cells must maintain a large surface area to volume ratio
What are the different Nutritional Requirements of Organisms?
Energy Source:
- Phototroph = Light
- Chemotroph = Chemical Compounds (Lithotroph & organotroph)
Carbon Source:
- Photoautotroph = Inorganic
- Photoheterotroph = Organic
- Chemoautotroph = Inorganic
- Chemoheterotroph = Organic
Who built the first Compound Microscope?
Robert Hooke (1665) built the first compound microscope
- two converging lenses
- coined the term ‘cell’
Who first observed living microorganisms?
Anton Van Leeuwenhoek (1670) observed living microorganisms
- Called them animalcules
- 200x magnification
What is the Cell Theory?
- Cells are the fundamental units of life
- All living organisms are composed of cells
- All cells come from preexisting cells
What can we add to the Cell Theory?
- Modern cells evolved from a common ancestor
What is Bright-Field Microscopy?
Unless natural pigments are present, there is little contrast and details are not distinguished
- light passes directly through the cells
What is Phase-Contrast Microscopy?
contrast is increased by emphasizing differences in refractive index (the capacity to bend light)
- enhances light and dark regions in the cell
What is Differential Interference-Contrast Microscopy?
The combined images look as if the cell is casting a shadow on one side
- two beams of polarized light are used
What is Stained Bright-Field Microscopy?
Stains differ greatly in their chemistry and their capacity to bind to cell materials.
- A stain enhances contrast and reveals details not otherwise visible
What is Fluorescence Microscopy?
a natural substance in the cell or a fluorescent dye that binds to a specific cell material is stimulated by a beam of light
- the longer wavelength florescent light is observed coming directly from the dye
What is Confocal Microscopy?
- fluorescent materials are used
- adds a system of focusing both the stimulating and emitted light so that a single plane through the cell is seen
- The result is a sharper two-dimensional image than with standard fluorescence microscopy
When was Electron Microscopy Invented?
- 1931
- Max Knoll and Ernst Ruska invented electron microscope
How does an Electron Microscopy work?
The electron microscope directs electrons through a vacuum at a fluorescent screen or digital camera to create a visible image
What is the Resolution of an Electron Microscopy?
The resolution of electron microscopes is about 2nm (100,000x greater than the eye).
What are the Two Main Types of Electron Microscopy?
- Transmission Electron Microscope (TEM)
- Scanning Electron Microscope (SEM)
What is Transmission Electron Microscopy?
- a beam of electrons is focused on the object by magnets
- Objects appear darker if they absorb the electrons
- If the electrons pass through they are detected on a fluorescent screen
What is Scanning Electron Microscopy?
- electrons aredirected to the surface of the sample where they causeother electrons to be emitted
- These electrons are viewedon a screen
- The tree-dimensionalsurface of the samplecan be seen
What is the Cytoplasm?
Everything inside the cell, except for the nucleus of the cell has one, is termed the cytoplasm
What is the Cytosol?
The cytosol is the fluid cytoplasm not contained inside another compartment
What is the Difference between Prokaryotes and Eukaryotes?
- A prokaryotic cell does not have a nucleus or any other membrane-enclosed internal compartments
- Eukaryotic cells contain membrane-enclosed compartments called organelles
- Nucleus is the most noticeable organelle in eukaryotes
What do all Prokaryotes have?
- A cell membrane
- A nucleoid
- A cytoplasm
- Ribosomes (25 nm in diameter)
What is a Cell Membrane?
The cell membrane encloses the cell, regulating the traffic of materials into and out of the cell, and separating its
interior from the external environment.
What is the Nucleoid?
The nucleoid is a region in the cell where the DNA is located.
DNA is the hereditary material that controls cell growth, maintenance, and reproduction
What are Ribosomes?
Ribosomes are complexes of RNA and proteins in the cytoplasm that are about 25 nanometers (nm) in diameter
- Sites of protein synthesis, where information coded for in nucleic acids directs the sequential linking of amino acids to form proteins