Chapter 2: Cell Basics & Microscopy, Gram Staining Flashcards
What do ALL cells have?
Cytoplasmic membrane
Cytoplasm
Genome
Ribosomes
Metabolism
Evolution
What do SOME cells have?
Differentiate
Exchange genetic info
Communicate
Movement
Genes code for ____ which creates ____ for metabolism
- RNA
- proteins
protein catalysts of the cell that accelerate chemical reactions
Enzymes
DNA chromosome is replicated prior to cell division
DNA replication
DNA gene is read to produce RNA (same language)
Transcription
RNA message is read to make protein (changing language)
Translation
Results of cells having the nutrition they need and ability to replicate
Growth
The smallest distance by which two objects can be separated and still be distinguished
resolution
requires fixation/freezing conditions that damage or alter cells
electron microscopy
Types of electron microscopy
Transmission and Scanning
electrons pass through the specimen surface and reveal internal structures
Transmission electron microscopy
electrons scan the surface of the specimen and reveal the external structures in 3D
Scanning electron microscopy
Types of light microscopy
Bright-field
Phase-contrast/Differential contrast
Dark field
How do light microscopes work?
Light passes through multiple lenses and through the specimen. Useful for examining cells while they are alive.
Bright-field microscopy
light passing through the cell directly forms the image
Phase contrast/Differential contrast microscopy
exploits the phase change of light passing through an object varying thickness and density to produce an image, watching live cells move/mitosis
Dark-field microscopy
illuminating rays are directed from the side, so only scattered light enters the microscope, watching live cells move/mitosis
What is the purpose of staining?
to provide contrast
True or False: Staining can be used to colorize a cell OR colorize the background surrounding a cell.
TRUE
Does staining kill cells?
YES
Flood the prepared specimen with a basic dye
Simple stain
acidic dye, which is repelled by cell walls leaving clear cels on a dark background
Negative stain
Morphology
cell shape
True or False? Morphology DOES NOT predict physiology, ecology, phylogeny, etc. of a prokaryotic cell
TRUE
Coccus
Spherical or ovoid
Chain
strepto-
Cluster
staph-
Diplococci
pairs
Bacili
rod/cylindrical
Spirillum
spiral shape
A ________ is smaller than a _______ which, in turn, is smaller than a ________.
- Virus
- Bacteria
- Human cell
A ________ is smaller than a _______ which, in turn, is smaller than a ________.
- Virus
- Bacteria
- Human cell
Compared to Eukaryotes, Bacteria and Archaea have ________ surface-area-to-volume ratios, causing ________ nutrient exchange and growth rates.
- Higher
- Faster
What is the bacterial cell wall composed of?
peptidoglycan
Gram Stain Procedure
- Fix organisms with heat
- Crystal violet treatment
- Iodine treatment
- Decolorization (ethanol)
- Counter stain safranin
Cell wall of gram positive cells
huge peptidoglycan layer
Cell wall of gram negative cells
Thin peptidoglycan layer
Pink stain
gram negative
Purple stain
gram positive
Difference between gram positive and gram negative bacteria
Gram Positive:
- THICK cell wall
- has lipoteichoic acids in cell wall
- has an S layer
Gram Negative:
- THIN cell wall
- has outer layer of LPS (lipopolysaccharide)
- does not have S layer