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
What is fertility?
Getting an F- cell attracted to an F+ cell so it can receive a plasmid
What is resistance?
Cells may be resistant to certain antibiotics so there may be a gene w/ resistance to penicillin or others.
If a cell has a resistance gene, the antibiotic cannot kill the cell
What is the difference between nucleoid and plasmid?
The nucleoid is present in ALL bacteria, plasmid is not.
Nucleoid controls all genetics of the cell and codes for proteins, plasmid only contains genes for fertility and resistance
What is cytoplasm?
Water based solution that fills the cell, contains cytosol and organelles
What are ribosomes?
Organelle that performs protein synthesis. 2 subunits (large/small)- large sits atop small in the functional ribosome, each is made of protein and RNA
Centrifugation
Length of time it takes for substance in a mixture to settle out of solution
Svedberg Unit (S)
Sedimentation constant (10^-13seconds)
Svedberg Units of ribosomes in prokaryotic and eukaryotic cells
Type of RNA in each type of cell is different. Eukaryotes are heavier
In Prokaryotes, whole ribosomes of bacteria and archaea are equal at 70S. Bacterial small subunits are 30S, lare are 50S.
In eukaryotes, whole ribosomes are 80S, large subunit 60S, small subunit 40S
What are the 3 parts of flagellum? What is their purpose?
Propel the cell in movement
Fillament- part you can see that moves the cell
Hook- connects fillament to basal body
Basal Body-“motor” that spins in response to ATP
Bacteria are classified by # and location of flagella
What are the 5 classification?
Atrichous- no external flagella- sessile Monotrichous- One flagella Amphitrichous- One at each end Lophotrichous- Tuft at one end Peritrichous- All over
What is an axial filament?
Internal flagella that wraps around cell wall of GRAM NEGATIVE bacteria in spirochetes, then covered with an outer sheath
What are two examples of spirochetes with axial filaments?
Treponema pallidum- Syphilis
Borrelia burgdorferi- Lyme disease
What do sex pili do?
Attaches an F+ cell to an F- bacterial cell to transfer DNA
What are fimbrae and what do they do?
Attach a cell to an object like a rockBristles on the cell surface that help w/ adhesion to other objects, cells, surfaces
What are the inclusions of bacterial cells?
Stored lipids, pigments, gases, metals etc.
What type of cells are capable of endospore formation?
Vegetative cells
What are vegetative cells?
bacterial cells that acquire energy for growth and reproduction from feeding on other living things
They are considered “harmful”
What are some things that may kill a vegetative cell?
Absence of O2, too much heat, chemicals, starvation
How are endospores released? How do they survive?
Released when vegetative cells are disrupted.
Can last indefinitely without energy or nutrients
All about survival of species, not reproduction
What are the characteristics of viruses?
Acellular Can only reproduce in host Inert- Inactive outside host cell Capsid surrounds nucleic acid core Nucleic acid core contains RNA OR DNA Extremely small Geometrically shaped Classified based on shape, host and type of nucleic acid
What is the cytoplasmic membrane of a bacterial cell?
Thin layer of proteins and lipids that surround the cytoplasm and controls the flow of materials in and out of the cell
What is the S layer?
Single layer of protein used for protection/attachment
What is the outer membrane?
Extra layer of protection, controls the flow of materials and can be toxic to mammals when released
What is the actin cytoskeleton?
Long protein fibers that are found just outside the cytoplasmic membrane, contribute to shape of the cell
What is the capsule?
Coating of molecules outside the cell wall.
Protective, adhesive, receptor of functions
AKA Glycocalyx
What are inclusions/granules?
Dense crystals of fat, phosphate or glycogen, stored until needed
What are bacterial microcompartments?
Protein-coated packets used to localize enzymes and other proteins in cytoplasm
What are endospores?
Dormant body found within some bacteria that allows for their survival in adverse conditions
What are nano wires/nano tubules?
Membrane extensions that allow bacteria to transmit electrons or nutrients to other bacteria onto environmental surfaces
