Antibody Structure and Function

Question 1

What antibody exists in two forms?

Answer 1

IgA, secretory form and non-secreted form

Question 2

What is the structure of antibody?

Answer 2

two light chains, two heavy chains

Question 3

Which antibody has the shortest half life?

Answer 3

IgE

Question 4

Which antibodies neutralize?

Answer 4

IgG, IgA

Question 5

What antibody opsonizes?

Answer 5

IgG

Question 6

What antibodies activate complement?

Answer 6

IgM, IgG

Question 7

What antibody transports across epithelium (to gut, resp tract, urinary tract, mother’s milk)?

Answer 7

IgA

Question 8

What antibody can transport across the placenta?

Answer 8

IgG

Question 9

Can IgM participate in opsonization? Why or why not?

Answer 9

No, not without complement because immune cells do not have IgM receptors

Question 10

What antibodies have a J chain?

Answer 10

IgM (pentamer joined by J chain), IgA secretory form

Question 11

What is the T piece?

Answer 11

The secretory piece of IgA, resists acid hydrolysis

Question 12

What does papain digest?

Answer 12

yields three fragments, 2 Fab, 1 Fc

cleaves the interchain disulfide bonds

Question 13

What does pepsin digest?

Answer 13

yields 2 fragments, 1 F(ab)2, 1 Fc

Question 14

What two regions are in the variable region of Ab?

Answer 14

framework residues, hypervariable region