Microbiology

Question 1

Acquired pellicle

Answer 1

Thin coating of saliva that covers teeth
Made of salivary glycoproteins, carbohydrates and amino acids

Lubrication
Reservoir of ions
Protect from minor acid attack
Semi-permeable, allows for diffusion of ions during demin and remin

Question 2

Biofilm - role and composition of biofilm

Aka plaque

Answer 2

Aggregation of bacteria, bacterial communities

Biofilm matrix made of hydrated EPS (extracellular polymeric substances) that enable adhesion of biofilm to tooth surface

Question 3

Sugar transport pathways of bacteria

+ what does fluoride do

Answer 3

In carbohydrate excess: Shovel
Glucose permease - low affinity but high volume uptake
Mainly anaerobic respiration: lactate dehydrogenase produces lactic acid

In carbohydrate scarcity: Teaspoon
PEP-PT (phosphoenolpyruvate-mediated phosphotransferase) system - high affinity, low volume uptake
Pyruvate lyase fermentation produces ethanol (to reoxidise NADH), formation of acetyl CoA produces acetic acid. Formic acid somewhere

Fluoride inhibits enolase and thus reduces production of PEP - under limited glucose, inihibits transport system thus reduces bacterial metabolism and growth