Module 4 Flashcards
What are the key components in the structure of bacteria?
Bacterium chromosome FImbriae Nucleoid Plasma Membrane Cell Wall Ribosomes Capsule Flagella
What is the function of the cell wall of bacteria?
It is a rigid macromolecule layer that provides strength to the cell, protects the cell fro osmotic lysis and confers cell shape.
what is Mycoplasmas?
A group of pathogenic bacteria prokaryotes that lack cell walls.hey have a mesh like structure of peptidoglycan>
Where does bacteria store DNA.
Mitochondrial DNA is stored in the cytoplasm because bacteria do not have a nucleus.
What is bacteria cell wall made up of?
Peptidoglycan which is a mesh-like structure, consisting of a carbohydrate backbone, tetrapeptide side chains and peptide cross bridges.
What is transpeptidase?
The enzyme that cross-links the peptidoglycan chains to form rigid cell walls.
What factor is responsible for the differences in Gram stain reactions?
Structural differences between cell walls of gram-positive and gram-negative Bacteria
What are the structural differences of gram positive and gram negative bacteria and what impact does the structure of on gram stain reactions?
Gram positive bacteria have a very thick layer of peptidoglycan in their cell wall which traps crystal violet and masks the red safranin die. Alternative gram negative bacteria has a thinner layer of peptidoglycan as well as an inner and out layer which means crystal violet is easily rinsed away, revealing the red safranin dye.
What is the function of bacterial flagella>
Allows some bacteria to be capable of movement in liquid medium
What are the three major structural components of flagellum?
Long Filament which extends into surrounding medium. The Hook which is the curved section connecting the filament to the cell surface.
Basal Body which anchors the flagellum into the cell
membrane by special disc-shaped structures called Plates or Rings.
Describe the chemotaxis response?
Chemotaxis: bacteria move along a concentration gradient towards a chemical attractant (positive) OR away from a chemical repellent (negative)
how is chemotaxis initiated?
Bacteria sense the change in chemical concentration
outside the cell over TIME “temporal gradients” and thus
respond to the change in concentration as the cell moves
What is the function of Fimbriae?
They are Structures with adhesive properties that
cause bacteria to stick/adhere to surfaces. However not all bacteria have it, it is an inherited trait.
What is a Glycocalyx?
A gelatinous polysaccharide and / or polypeptide outer covering
What are the two forms of glycocalyx?
organized into a defined structure attached firmly to cell
wall = CAPSULE
disorganized without cell shape, attached loosely to cell
wall = SLIME LAYER
