Section 5.1 (Exam 1) Flashcards
Cells Are the Fundamental Units of Life
Why are cells small and not big?
High surface area to volume ratio is necessary for survival, it means better exchange of materials across the cell membrane and better waste removal.
Cell theory consists of 4 statements. Name them.
Cells are the fundamental units of life. All organisms are composed of cells. All cells come from preexisting cells. Modern cells evolved from a common ancestor.
What does magnification do?
Increases apparent size
____________ is the clarity of a magnified object which shows how small a distance objects can be close together and appear separate.
Resolution
Light microscopes use glass lenses to focus a beam of light. What is their best resolution?
.2 Micrometers
Electron microscopes can only visualize dead cells. True or False?
True
Electron microscopes have a resolution of?
.2 nanometers
How do electron microscopes work?
Electromagnets are used to focus an electron beam.
How do light microscopes work?
Glass lenses are used to focus a beam of light.
This type of stain can distinguish between tissue types, nuclei, and cytoplasm.
General stain
What can a specific stain highlight?
specific elements within tissue, such as carbohydrates, lipids, connective tissue, muscle, pigments, receptors, and nerve tissue
Bright-field microscopy is ineffective due to very little contrast and detail, unless there are _________________ present.
natural pigments
Phase-contrast microscopy adds contrast to the images by emphasizing the differences in the refractive index within the subject. This enhances light and dark regions within the cell. What is the refractive index?
A measure of how quickly light propagates through a medium
What does differential interference-contract microscopy use?
Two beams of polarized light
Why is stained bright-field microscopy better than bright-field microscopy?
The stain adds contrast and reveals details that were not visible previously.
How does fluorescence microscopy work?
A natural substance of fluorescent dye in a cell binds to a specific cell material, and is stimulated by a beam of light. The fluorescent light is then observed coming from the dye.
Why is confocal microscopy better than fluorescent microscopy?
Rather than just a stimulating beam of light, it involves using emitted light to make the image sharper.
The _________________ is a phospholipid bilayer with embedded proteins that is present on the outer boundary of every cell.
cell membrane
What are 4 key characteristics/responsibilities of the cell membrane?
It is selectively permeable.
It allows cells to maintain an internal environment.
It is important in communication and receiving signals.
It often has proteins for binding and adhering to adjacent cells.
EVERYTHING (even the organelles) in the cell aside from the nucleus is the ____________.
cytoplasm
The fluid part of the cytoplasm is the __________.
Cytosol
Which type of cell has no membrane-enclosed internal compartments?
Prokaryotic
Which type of cell has membrane-enclosed organelles in which different functions occur?
Eukaryotic
