Chapter 4 & 6.1- Bacteria, Archaea and Functional Anatomy of Prokaryotic Cells and Viruses Flashcards
What is the glycocalyx?
Outermost part of a bacterial cell (some DONT have one)
- Viscous, usually made of polysaccharides or polypeptides or both
- 2 types: capsule:firmly attached to cell and slime:loosely attached to cell
How many strains of Streptococcus are there? What are they?
Rough (R. strain) and smooth (S. strain)
R=non-virulent
S=virulent
What are the characteristics of the Streptococcus S. strain?
- Cannot be found by phagocytes: enables the bacteria to avoid being consumed by WBC’s
- Attaches to objects
- Can act as nutrients/energy when a normal food source is not available
What is a cell wall?
Surrounds plasma membrane of many cells, including bacteria
Made of Peptidoglycan
Repeating units of NAG/NAM linked with a tetrapeptide
Provides structural support
What is a tetrapeptide?
4 amino acids
What are gram-positive bacteria?
Multiple layers of peptidoglycan that make up cell wall almost exclusively
Thicker wall with no outer membrane
Techoic acid present in cell wall attaches to lipid heads
What are gram-negative bacteria?
Single layer of peptidoglycan forming a thin cell wall
Also has an outer membrane
No techoic acid in cell wall
Slightly more susceptible to lysis
What is peptidoglycan?
Cross-linked chains of polysaccharides that form the rigid part of bacterial cell walls (strong but flexible)
Glycan chains and peptide fragments
What is techoic acid?
Polymers containing glycerol that appear in the walls of gram-positive bacteria. Attaches to lipid heads.
What are mycoplasmas?
Type of bacteria that lacks a cell wall but has a stabilized cytoplasmic membrane to prevent the cell from bursting and is resistant to lysis
Mycoplasmic pneumoniae= walking pneumonia
What is the plasma membrane?
A selectively permeable layer that separates the inside of the cell from the outside.
- Small molecules
- Water
- Non-polar molecules
- Non-ionic molecules
What is the plasma membrane composed of?
Phospholipid bilayer
Hydrophilic phosphate heads and hydrophobic fatty acid tails
Integral and peripheral proteins scattered around bilayer creating a mosaic appearance
What are integral proteins?
Contact the hydrophobic core of the phospholipid bilayer
What are peripheral proteins?
Do not reach or contact the hydrophobic region of the phospholipid bilayer
What is a nucleoid?
Found in prokaryotic cells as they have no nucleus. Contains a single circular chromosome that attaches to inside of plasma membrane
Controls the cell and its proliferation
What is a plasmid?
double stranded, circular chromosome that contains genes involved in resistance/fertility
F+ cells have plasmid
F- cells have no plasmid
How does an F- cell become an F+ cell?
F+ cells will attach to F- cells and transfer a copy of its plasmid through the conjugal bridge turning an F- to an F+. An F- may also just absorb a plasmid from its surroundings.
How does an F+ cell become an F- cell?
During starvation, a bacterial cell may expel its plasmid to save on energy