Chapter 2

Cell Wall

Determines the shape of bacteria and provides physical strength to prevent bursting under osmotic pressure.

Murein

Specific type of peptidoglycan found only in bacteria, formed by N-acetylmuramic acid and N-acetylglucosamine.

Lysozyme

An enzyme that breaks B 1,4 bonds in peptidoglycan, found in tears, milk, and mucus.

Gram Positive

Bacteria with a thick murein layer that contains teichoic acids and can be crosslinked using glycine and D-alanine.

Gram Negative

Bacteria with a thin murein layer located between two membranes, with crosslinking occurring between DAP and D-alanine.

Pseudomurein

A type of peptidoglycan found in archaea, contains only L amino acids and features a B-1,3 linkage.

Outer Membrane

Membrane present in gram negative bacteria, comprised of phospholipids and lipopolysaccharides (LPS).

Lipid A

A component of lipopolysaccharides embedded in the outer membrane, acts as an endotoxin.

O-antigen

A component of LPS recognized by antibodies, consisting of a carbohydrate chain of up to 40 sugars.

Mycobacteria

Bacteria with a thin murein layer and a hydrophobic cell wall containing mycolic acids, resistant to gram staining.

Capsule/Slime Layer

A protective layer outside the cell wall, contributing to adhesion and protection against desiccation.

Flagella

Long, whip-like structures that aid in bacterial motility.

Pili

Hair-like appendages on bacteria that facilitate adhesion to surfaces and transfer of DNA.

Hydrophilic

Refers to substances that attract water; peptidoglycan has hydrophilic regions due to its sugar and amino acid composition.

Hypertonic Solution

A solution with a higher ionic strength than cellular contents, leading to cell shrinkage.

Hypotonic Solution

A solution with a lower ionic strength than cellular contents, leading to cell lysis or explosion.

Penicillin Binding Protein

A bifunctional enzyme involved in the synthesis of peptidoglycan and peptide linkages.

Glycosyltransferase

An enzyme that synthesizes the sugar chains in peptidoglycan.

Transpeptidase

An enzyme that facilitates peptide bond formation during peptidoglycan synthesis.

Outer Membrane

A bilayer membrane characteristic of Gram-negative bacteria, containing lipopolysaccharides and serving as a barrier to certain antibiotics.

S-layer

A symmetric layer of proteins or glycoproteins on the surface of some bacteria and archaea, providing protection and structural support.

Slime Layer

A less organized layer compared to the capsule, composed of polysaccharides that helps bacteria adhere to surfaces and evade the immune system.

Flagella

Long, slender appendages that facilitate locomotion in bacteria through rotary motion.

Pili

Short, hair-like structures on the bacteria surface that play crucial roles in attachment and genetic exchange.