Deck 14: The Extracellular Matrix

Question 1

A medical student sees the dentist because of sore gums.The dentist also notices small hemorrhagic spots under the student's skin.On questioning, the student says that he subsists mainly on the cookies and coffee that are sold at the campus bookstore.His problems are most likely related to:

A)Reduced synthesis of pre-procollagen chains.
B)Inability to hydroxylate prolyl residues in procollagen.
C)Inability to attach carbohydrate groups to procollagen.
D)Defective collagen crosslinking, resulting from impaired activity of lysyl hydroxylase.
E)Inability to convert pre-procollagen to procollagen.

Answer 1

Inability to hydroxylate prolyl residues in procollagen.

Question 2

The sulfated glycosaminoglycans are synthesized in the organelles of the secretory pathway.The immediate biosynthetic source of the sulfate groups is:

A)Sulfosalicylic acid.
B)Phosphoadenosine phosphosulfate.
C)Sulfatide.
D)Cysteine sulfonic acid.
E)S-adenosylmethionine.

Answer 2

Phosphoadenosine phosphosulfate.

Question 3

A 6-year-old boy who has short stature, coarse facial features, delayed mental development, and urinary glycans is most likely to have which of the following conditions?

A)Type 1 diabetes.
B)Hunter syndrome (Type II mucopolysaccharidosis).
C)von Gierke disease.
D)Hemophilia A.
E)Pancreatic cancer.

Answer 3

Hunter syndrome (Type II mucopolysaccharidosis).

Question 4

Spondyloepiphyseal dysplasia is a form of dominantly inherited dwarfism in which cartilage structure is abnormal and endochondral bone formation is impaired.Otherwise, affected patients are in good health.The abnormal cartilage function in this condition is most likely caused by defects in:

A)Type I collagen.
B)Type II collagen.
C)Type III collagen.
D)Type IV collagen.
E)Type VII collagen.

Question 5

Most glycosaminoglycans (GAGs) are covalently bound to a core polypeptide.One GAG, however, is usually found as a free polysaccharide without covalent protein attachment.This GAG is:

A)Chondroitin sulfate.
B)Dermatan sulfate.
C)Keratan sulfate.
D)Hyaluronic acid.
E)Heparan sulfate.

Question 6

When starting a new job in a home for physically handicapped children, the nurse points out a 7-year-old girl who is only 80 cm tall, is wheelchair-bound, and has multiple limb deformities.The nurse tells you that the girl has "glass bones" and had suffered severe fractures on many occasions.This girl most likely has a mutation in one of the genes for:

A)Type I collagen.
B)Type II collagen.
C)Type III collagen.
D)Type IV collagen.
E)Type VII collagen.

Question 7

Patients with Hurler syndrome (complete deficiency of α-L-iduronidase) have mental deficiency in addition to physical deformities, corneal clouding, and valvular heart disease.Their mental deficiency is caused by the accumulation of:

A)α-L-iduronic acid.
B)Heparan sulfate.
C)Chondroitin sulfate.
D)Hyaluronic acid.
E)Keratan sulfate.