Microbiology Exam Questions

Core, cortex, and coat

What are the main three special layers of endospores?

Core

Part of endospore with DNA, ribosomes, and a very low water content, contains high concentration of dipicolinic acid for heat

Inner cell membrane

A highly impermeable membrane that protects the core contents and becomes the cytoplasmic membrane

Cortex

Thick layer of peptidoglycan, maintains dehydration of the core, important for heat resistance

Outer membrane

Lies outside the cortex and functions during spore formation

Spore coat

Composed of keratin like proteins, protects against chemicals, enzymes, and toxins

Vegetative cells

Cells that are used for growth and reproduction, have little resistance to the outside

Inner membrane

Phospholipid bilayer in gram-negative cells with embedded proteins, it acts as a selective permeable barrier, contains transport proteins

Periplasmic space and peptidoglycan

Space between the inner and outer membranes, contains a thin layer of peptidoglycan, rich in enzymes and binding proteins

Periplasmic space and peptidoglycan uses

Provides cell shape and rigidity, involved in nutrient breakdown, cell wall synthesis, and detoxification, osmotic protection

Outer membrane

Asymmetric bilayer with inner phospholipids, and outer lipopolysaccharide, contains porin proteins, anchored to peptidoglycan by lipoproteins

Outer membrane uses

Acts as an additional protective barrier, restricts entry of toxins, detergents, antibiotics, porins allow small hydrophilic molecules in

LPS

Responsible for endotoxic activity and structural ability

Gram-negative

What type of cell is more resistant to antibiotics due to the outer membrane acting as a physical barrier?