overview Flashcards
What is the acid dissociation constant Ka?
Measure of the strength of an acid
What does a large dissociation constant (Ka) and low pKa suggest?
Strong acid
What does a high pKa indicate?
Weak acid
What is the main acid involved in tooth decay?
Lactic acid
What is the Henderson-hasslebalch equation?
PH= pKa + log10 (base/acid) - FOR WEAK ACIDS
When do buffers have greatest buffering capacity?
When 50% dissociated eg pKa=pH
What is the main buffer and other buffers in saliva?
- BICARBONATE HCO3-
- phosphate
- histatin proteins (rich in histidine)
What is the pH of blood?
7.4
What is electronegativity?
Power of an atom to attract electrons to itself
What are gap junctions?
- direct contact between cells for electrical transmission
- allow current to flow between cells
What is the difference between neural communication and hum oral communication?
Neural
- specific and localised
- quick/rapid response
Humoral
- body-wide
- slow response
- persistent
Which type of hormones can enter the cell?
Steroid hormones
Can peptide transmitters enter the cell?
Yes
What is the most common second messenger?
Ca2+ ions
(CAMP)
What does adenyl cyclase do?
Converts ATP to cAMP in the cytosol
Sequence of cAMP as second messenger?
- transmitter binds to membrane receptor
- G-proteins activated
- ATP to cAMP by adenyl cyclase
- cAMP activates protein kinase
- chemical reaction
Sequence of Ca2+ as second messenger?
- transmitter binds to membrane receptor
- G proteins activated
- activates phospholipase C
- opens Ca2+ channels, Ca2+ influx by diffusion
- binds to a protein
- chemical reaction
What is an enzyme?
Biological catalyst
What are two examples of enzymes in saliva?
- amylase
- maltase
What is standard free energy G and activation energy Ea?
What is the effect of an enzyme on activation energy?
Lowers it
What is Vmax?
The max rate of reaction
What is Km?
Affinity (inverse measurement)
- low Km= saturated with substrate
- high Km= non saturated
Which type of inhibitor can be reversed via increasing substrate concentrations?
Competitive
Optimum pH of trypsin?
7
Optimum pH of pepsin?
3
What is negative feedback control?
Counteracts the change
What is feedforward control?
Altering a behaviour before the signal eg stopping eating before full
What is positive feedback?
Change acts to increase that change
What is a drug?
Chemical substance which effects the function of the body
How would you take a sample of angular cheilitis?
Moist swab
What is an example of a non-selective anger?
Blood agar
What is an example of a selective agar?
Mannitol salt sugar
What three organelles do both prokaryotes and eukaryotes have in common?
- DNA
- cell membrane
- ribosomes
What is the method bacterial cells use to attach to host?
Pili
Gram stain reaction stages?
- film
- crystal violet
- all cells dyed violet
- iodine
- all cells blue-black
- acetone
- gram negative are decolourised
- red dye
- gram positive blue-black, gram negative red
what is an example of an endotoxin?
Prevotella intermedia
What are examples of two bacteria’s which cause periodontitis?
- P gingivalis
- Prevotella intermedia