Biomineralization

Question 1

what is biomineralization

Answer 1

its a process by which organisms form minerals

Question 2

what are the stages of biomin?

Answer 2

amorphous: non-ordered no particular morphology, then they crystallize into uniform sizes and shapes

Question 3

what mechanism makes the complex crystallize morphology?

Answer 3

matrix mediated mineralization

Question 4

what is a repeating unit of a crystal?

Answer 4

unit cell-

Question 5

how is initiation of crystal formation achieved?

Answer 5

through heterogeneous nucleation

Question 6

what provides further mechanical support for nucleation?

Answer 6

matrix proteins which are laid down first, produce +ve and -ve charges so that the next ion will come and directly find where to attach- nucleation is bypassed

Question 7

what are the initiator proteins?

Answer 7

phosphoryns, bone sialoprotein II,

Question 8

what are nucleation sites for mineralization? how are they made? what are they made of?

Answer 8

matrix vesicles, formed by budding off from odontoblasts, osteoblasts, and they contain bone sialoprotein II and phosphoryns.

Question 9

where do crystellites deposit specifically?

Answer 9

hole zones of type 1 collagen fibrils

Question 10

what are the key differences between mineralization of dentin and enamel? organic matrix, mineralization process, regulasting proteins, maturation process.

Answer 10

organic matrix: collagen based for dentin, non-collagenous (amelogenins and enamelins in enamel).
Min process: matrix vesicle mediated crystal growth for dentin, crystal elongation for heterogenous nucleation for enamel.
regulating proteins: dentin phosphoprotein, bone sialoprotein for dentin, amelogenins and enamelins for enamel.

Question 11

amelogenins regulate…..and are digested by…

Answer 11

HA crystallite growth, proteases during maturation

Question 12

amelogenins accumulate during the …

Answer 12

secretory stage

Question 13

what are non-amelogenins?

Answer 13

they are deposited during the enamel formation then degraded. two types: 1.enamelin; small degredation during the secretory stage which decreases in the deeper zones of the enamel.
2. ameloblastin which undergoes rapid degredation, and it is a cell adhesion protein

Question 14

major matrix protein of enamel and dentin?

Answer 14

enamel: amelogenin
dentin: collagen type 1, 3

Question 15

other matrix proteins of enamel and dentin?

Answer 15

enamel: non amelogenins including ameloblastin, enamelin, tuftelin
dentin: noncollagenous including denin sialophosphoprotein, dentin phosphoprotein,

Question 16

enamel enzymes?

Answer 16

1. enamelysin: metalloproteinase which cleaves newly secreted enamel as a short-term breakdown, 2. serine proteinase (bulk degredation)