Bacterial Structures Flashcards
(42 cards)
What does ‘Prokaryote’ mean?
‘Pro’ meaning before and ‘karyon’ meaning nucleus, nut or kernel
What is a characteristic of prokaryotes?
They do not contain a true nucleus surrounded by a nuclear membrane
Where do all functions take place in prokaryotes?
In the cytoplasm or cytoplasmic membrane
What is the cell envelope?
The outermost structure composed of outer membrane, cell wall, and plasma membrane
What is the cell wall also known as?
Peptidoglycan or murein layer
What is the structure of the cell wall composed of?
Disaccharide-pentapeptide subunits, teichoic acid or lipoteichoic acid
What is the function of the cell wall?
Maintains the shape of the cell and prevents rupture from osmotic pressure
What characterizes a Gram-positive cell wall?
A very thick protective peptidoglycan layer
What are the glycan chains in Gram-positive bacteria made of?
Alternating N-acetyl-D-glucosamine and N-acetyl-D-muramic acid
How does penicillin affect Gram-positive bacteria?
It prevents the synthesis of peptidoglycan
What is a key feature of Gram-negative cell walls?
Composed of outer and inner membranes with a thin peptidoglycan layer
What are the components of the outer membrane in Gram-negative bacteria?
Proteins, phospholipids, and lipopolysaccharide (LPS)
What is Lipid A?
A major constituent of lipopolysaccharide that is toxic
What role does LPS play in Gram-negative bacteria?
Vital in evading host defense and contributing to the negative charge of the bacterial surface
Fill in the blank: Gram-positive bacteria have a _______ cell wall.
thick
Fill in the blank: Gram-negative bacteria have a _______ cell wall.
thin
What is the shape of Gram-positive bacteria?
Spherical, rod-shaped or filamentous
What is the shape of Gram-negative bacteria?
Spherical, oval, straight or curved rods, helical or filamentous
What type of metabolism do Gram-negative bacteria exhibit?
Phototrophic, Chemolithoautotrophic, Chemoorganotrophic
What is the function of teichoic acid?
Contributes to the negativity of the cell wall and may regulate cation movement
What is an acid-fast cell wall characterized by?
A waxy layer of glycolipids and fatty acids (mycolic acid)
Give an example of bacteria with an acid-fast cell wall.
Mycobacterium, Nocardia
What do prokaryotes without a cell wall contain in their membranes?
Sterols
Give an example of a prokaryote that lacks a cell wall.
Mycoplasma, Ureaplasma
