Lesson 9-10

Question 1

Structural protein of the epithelial cells:

Answer 1

Keratin (intracellular).

• insoluble in water
• is not attacked by proteolytc enzymes, an cannot replace proteins in the diet.

Question 2

What makes the stability of keratin?

Answer 2

the numerous disulfide bond of cysteine.

Cysteine may account for 24% of the total amino acids

Question 3

Synthesis of Keratin:

Answer 3

In the not-yet keratinized cells of the skin pre-keratin will be produced. The cells of the skin during maturation will be keratinized. The cells of stratum basale go upwards and during the stratification of the cells keratin containing stratum corneum will be formed.

Question 4

Degradation of keratin:

Answer 4

• can not be degradated in the organism.

Question 5

Extracellular matrix components:

Answer 5

Collagen, elastin, fibronectin, laminin and proteoglycans.

Question 6

Collagen:

Answer 6

• extracellular (only animals)
• the basic unit of structure is a triple helix structure called tropocollagen and each polypeptide chain usually has 1000 amino acid residues.

Question 7

Important amino acids in collagen:

Answer 7

hydroxylysine, hydroxyproline

Question 8

Hydroxylations on Pro are performed by an enzyme called?

Answer 8

Proline hydroxylase, which is an enzyme that requires Vitamin C as a cofactor in the reaction (prevents the oxidation of Fe2+ to Fe3+ in proline hydroxylase enzyme).

Question 9

Lys-aldehyde + Lys-aldehyde result in:

Answer 9

condensation: cross linkage

Question 10

Degradation of collagen:

Answer 10

• Microbial collagenase

- Tissue collagenase

Question 11

Protein in the connective tissue:

Answer 11

Elastin.

primarily composed of the amino acids: Gly, Pro (Lys).

Question 12

Elastin is made by?

Answer 12

linking many soluble tropoelastin molecules to make a massive insoluble, durable crosslinked array.