Antibodies

Question 1

What are antibodies?

Answer 1

Glycoproteins that are provoked by antigens

Question 2

List two functions of antibodies.

Answer 2

Antigen recognition, and recruitment of other immune cells and molecules

Question 3

Antibodies are found in serum and __________ ________.

Answer 3

Interstitial fluid

Question 4

Antibodies prevent virus and bacteria entry through ____________.

Answer 4

Neutralisation

Question 5

_______________ facilitate destruction of pathogens via opsonisation, and induce development of inflammation.

Answer 5

Antibodies

Question 6

What is neutralisation?

Answer 6

Antibodies block antigenic activity of many pathways

Question 7

What is opsonisation?

Answer 7

Antibody coats microbe, and targets it for phagocytosis

Question 8

What is agglutination?

Answer 8

Antibody induces microbe clumping

Question 9

What is complement activation?

Answer 9

Antibody:antigen complexes activate the complement proteins (of the classical pathway), resulting in lysis

Question 10

All IgG antibodies have four chains (two light, weighing 23kD, and two heavy, weighing 50-70kD, chains), linked by ___________ bonds.

Answer 10

Disulphide

Question 11

____________ regions have amino acids from 1 to 113.

Answer 11

Variable

Question 12

Constant regions have amino acids from 111 to ____.

Answer 12

214

Question 13

Antigen binds to the variable region, while the constant region is involved in _________ _________.

Answer 13

Effector function

Question 14

True or false: variable regions differ from antibody to antibody.

Answer 14

True

Question 15

True or false: an IgG antibody has three identical antigen binding sites.

Answer 15

False

Question 16

Hypervariable regions (HR) form most of the _________ ___________ for the binding of the antibody to the antigen.

Answer 16

Contact residues

Question 17

What other term is used to refer to hypervariable regions?

Answer 17

Complementary determining region

Question 18

_____ is Y-shaped, composed of three 50 kD fragments after pepsin digestion.

Answer 18

IgG

Question 19

Two ______ fragments bind antigen, and one F’c fragment is involved in effector function.

Answer 19

F’ab

Question 20

F’ab and F’c ________ are flexible, and can adopt numerous orientations, to suit binding.

Answer 20

Regions

Question 21

Describe IgG antibodies.

Answer 21

Most common Ig in serum. Consist of two y heavy chains and two k or i light chains, with two binding sites. Four subclasses of IgG exist (IgG1, IgG2, IgG3, and IgG4 (differ in amino acids)). IgG1, 2, and 3 can cross the placenta. IgG3 is the most effective for complement activation. IgG1 and IgG3 bind with high affinity to receptors on phagocytes, and are best for opsonisation

Question 22

Which antibody class does the below passage describe?

Represents 5-10% of serum Ig. Exists as a pentamer, with five monomeric units, joined by disulphide bonds, with ten antigen binding sites. It is the first Ig produced in a primary response to antigen, binds more efficiently than other Igs to viruses, and is proficient at neutralising.

Answer 22

IgM

Question 23

Describe IgA antibodies.

Answer 23

10-15% of serum Igs. Most commonly-secreted Ig in breast milk, saliva, tears, and mucus, and exist as a dimer of two monomers linked by a joining (J)-chain. Bind bacteria and viruses, preventing their attachment. They help to prevent newborn infections in the first months of life. They have four binding sites

Question 24

Which antibody class does the following description outline?

Exists only as a monomer, and found in low levels in serum. Its role in serum is uncertain, and it does not bind complement, or cross placenta. It is not known for opsonisation and neutralisation abilities, and has two identical binding sites, with Δ heavy chains.

Answer 24

IgD