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Flashcards in Lecture 56 Deck (17)
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1
Q

Collagen and Elastin function in the ____ ____ matrix, which means they are made within the cell and then secreted out.

A

They function in the EXTRA CELLULAR MATRIX.

2
Q

Collagen genes are located ______ the genome.

A

They are located THROUGHOUT the genome.

3
Q

All collagens have _____-helical structure with the AA ___ in every third position.

A

Triple-helical structure with GLYCINE at every third position.

4
Q

Gly-X-Y structure of collagen is observed where X is usually ____ and Y is either hydroxy_____ or hydroxy_____.

A

X is usually PROLINE, and Y is either hydroxyPROLINE or hydroxyLYSINE.

5
Q

In the process of making collagen in the cell, the mRNA is translated in the _____, then select _____ and _____ residues are hydroxylated, and then only _____ _____ residues are glycosylated. Next, these pro-alpha chains assemble, forming inter and intrachain ______ bridges at the _____-terminal. The triple helix structure is then formed by “zipper-like” folding from the _____-terminal to the _____-terminal, and the procollagen molecule is secreted into the ECM. There, the termini are cleaved, and the collagen molecules self-assemble to form cross-linked _______.

A

Collagen mRNA is translated in the CYTOSOL, then select PROLINE and LYSINE residues are hydroxylated, and then only HYDROXYLYSINE residues are glycosylated. Next, these pro-alpha chains assemble, forming inter and intrachain DISULFIDE bridges at the C-terminal. The triple helix structure is then formed by zipper-like folding from the C-terminal to the N-terminal, and the procollagen molecule is secreted into the ECM. There, the termini are cleaved, and the collagen molecules self-assemble to form cross-linked FIBRILS.

6
Q

The hydroxylation of proline and lysine residues requires two cofactors, _____ and _____.

A

Requires cofactors Fe2+ and VITAMIN C.

7
Q

Lysyl _____ is the enzyme responsible for cross-linking collagen molecules, which requires _____ as a cofactor.

A

Lysyl OXIDASE is the enzyme responsible for cross-linking collagen molecules, which requires COPPER as a cofactor.

8
Q

Copper deficiency leads to ______ disease, whereas Copper buildup leads to ______ disease.

A

Cu deficiency leads to Menke’s disease, and Cu buildup leads to Wilson’s disease.

9
Q

OI (osteogenesis imperfecta) type I is the ____ severe, where as type II is the _____ severe.

A

Type I is the LEAST severe, whereas type II is MOST severe.

10
Q

Type II, III, and IV OI arise from substitutions in the gene for ____1A1 or ____1A2 which results in the change from _____ to another AA with a bulky side chain. This prevents correct folding into the triple helix form.

A

Arise from substitutions in the gene for COL1A1 or COL1A2 which results in the change from GLYCINE to another AA with a bulky side chain.

11
Q

Severity of the 4 types of OI is in this order ___>___>___>___

A

II>III>IV>I

12
Q

Whereas Types II, III, and IV OI arise from point mutations, Type I OI arises from a ______ mutation, so only a little collagen is made while most of the mRNA is degraded.

A

Type I OI arises from a NONSENSE mutation.

13
Q

____ coloring in sclera is characteristic of patients with OI.

A

BLUE coloring of sclera is characteristic of OI.

14
Q

Unlike Collagen, elastin has only a little hydroxy_____ and no hydroxy_____.

A

Elastin has only a little hydroxyPROLINE and no hydroxyLYSINE.

15
Q

In the ECM, elastin interacts with _____. Mutations in _____ lead to Marfan syndrome, which shows a(n) _____ dominant mode of inheritance linked to the ____ gene on chromosome 15.

A

Elastin interacts with FIBRILIN. Mutations in FIBRILIN lead to Marfan syndrome, which shows an AUTOSOMAL dominant mode of inheritance linked to the FBN1 gene on chromosome 15.

16
Q

Marfan syndrome patients are typically tall with _____dactyly, _____ excavatum, and dilation of ____. These patients typically die of ruptured arteries because of weakened arterial walls.

A

These patients are typically tall with ARACHNOdactyly, PECTUS excavatum, and dilation of the AORTA.

17
Q

Lysyl oxidase acts on elastin as well, forming _____ cross-links (allysine residues), which confers elastin’s “stretchiness.”

A

Forming DESMOSINE cross-links