Prokaryotic Profiles: The Bacteria and Archaea Part 2 Flashcards
Cell envelope
Lies outside of the cytoplasm
Composed of two OR three basic layers
3 possible components of cell envelope
- Cell membrane
- Cell wall (peptidoglycan)
- Outer membrane
Cell membrane is found in _____ instances
ALL
Cell wall is found in ____ bacteria
Most
Outer membrane is found in ______ bacteria
Some
Peptidoglycan cell wall
Repeating framework of long glycan chains cross-linked by short peptide fragments
Peptidoglycan cell walls are present in _____ bacteria
Most
What does the peptidoglycan cell wall do?
Provides strength to resist rupturing due to osmotic pressure
What do “-cillins” do?
Block the synthesis of a cell wall
What color are gram positive bacteria?
Purple
What color are gram negative bacteria
Red
What is included in the cell envelope of a gram positive cell?
One membrane (cytoplasmic membrane) Cell wall- thick peptidoglycan layer
Do gram positive cells have an outer membrane?
No
Are gram positive cells more or less complicated than gram negative cells?
Less
What is included in the cell envelope of a gram negative cell?
Inner membrane (cytoplasmic membrane) Cell wall (thin layer of peptidoglycan) Outer membrane (Lipopolysaccharide)
What is a common gram negative cell?
Staph cocci
What is a common gram positive cell?
E colli
Lipopolysaccharides are located in….
The outermost layer of the outer membrane in gram NEGATIVE bacteria
Lipid A portion of lipopolysaccharides
An endotoxin, causes fever and shock
Endotoxins are ____ of a lipolysaccharide’s structure
Part
not secreted, etc
First step of gram staining
Crystal violet is added to cells in a smear
What does crystal violet do?
It stains all cells the same purple color
Step 2 of gram staining
Gram’s iodine is added
What is Gram’s iodine?
A stabilizer that causes the dye to form large complexes in the peptidoglycan meshwork of the cell wall
Which cells are more effected by Gram;s iodine?
The thicker gram-positive cell walls are able to more firmly trap the large complexes than those of gram negative cells.
What is the third step in gram staining?
Application of alcohol
What does the application of alcohol do?
Dissolves lipids in the outer membrane and removes the dye from the peptidoglycan layer- only in gram negative cells
Fourth step of gram staining
Safranin (red dye) application
What does safranin do?
Demonstrates the presence of gram negative bacteria by dying them red.
What is acid-fast bacteria?
Neither gram positive or gram negative
Acid fast bacteria have a cell wall most similar to….
Gram-positive
Acid fast bacteria contain what in the cell wall?
Mycolic acid (a wax) in the cell wall
What must you use to identify acid-fast bacteria?
The acid fast stain
What are some important acid-fast bacteria?
Tuberculosis
Leprosy
What makes acid-fast bacteria resistant to staining?
Mycolic acid
What animals are carriers of leprosy?
Armadillos
What is a protoplast?
A gram-positive cell that has had its cell wall (peptidoglycan) lost (mutation or chemical treatment)
What is a spheroplast?
A gram-negative cell that has its cell wall (peptidoglycan) lost (mutation or chemical treatment)
What is a cytoplasmic membrane?
A lipid bilayer with proteins embedded
Bacterial cell membranes contain primarily phospholipids (__%–__% of the membrane mass) and proteins (__%–__% of the membrane mass)
30-40
60-70
The cytoplasmic membrane of bacteria contains enzymes of ________ and ___ _________
Respiration
ATP synthesis
Why do prokaryotes contain enzymes of ATP synthesis?
Because prokaryotes lack mitochondria
What is a major action of the cell membrane?
To regulate the passage of nutrients into and out of the cell
The cytoplasm of prokaryotes contains the DNA in the ____
Nucleoid
Cytosol is ___-___% water
70-80
What else is contained in the cytoplasm?
Soluble proteins, salts and carbohydrates
The cytoplasm is the site for what?
Nearly all chemical reactions
The DNA of most bacteria is..
Single circular bacterial chromosomes
IN bacterial cells,, DNA is aggregated in a dense area called the..
Nucleoid
Many bacteria contain other, extrachromosomal DNA called..
Plasmids
Plasmids may contain..
Virulence factors (plasmids give bacteria things like antibiotic resistance)
The size of a prokaryotic ribosome is ____ while the size of a eukaryotic ribosome is ___
70S
80S
What are the two subunits of a prokaryotic ribosome?
30S and 50S
Prokaryotic ribosomes are 60%______ and 40%_____
rRNA
Protein
What do prokaryotic ribosomes do?
Translate mRNA into proteins