Theme 3.7

Collagen has which of the following functions? All of these Forming extracellular support structures Forming external materials such as hair Contributing to the cell wall in mammals

1

Which of the following statements explains why antibodies bind such a wide range of antigens? Question 2 options: Each antibody can bind to many antigens The sequence of each antibody can be changed after protein synthesis so it better binds an antigen There are millions of genes for antibodies The genes for antibodies are rearranged prior to translation

1

Which of the following statements about antibodies is false (select all correct answers)? Question 2 options: Binding of a single antigen by a single antibody is sufficient to trigger an immune response Both the light and heavy chains are important for binding to antigens Antibodies contain a single antigen binding site Each antibody is selective for a single antigen due to changes in the variable region

123

Which of the following residues is most likely to be found in the helix-helix interface (i.e., the region where the helices contact each other) of a keratin coiled-coil? Question 2 options: Ser Cys Met Pro

2

Which of the following statements about antibodies is true (select all correct answers)? Question 4 options: Antibodies are fibrous proteins Antibodies have multiple subunits Heavy antibodies contain heavy chains, whereas light antibodies contain light chains Antibodies catalyze the destruction of antigens

2,4

If an antigen has a region of hydrophobic character near a positively charged region, what might the antibody variable region look like? Question 1 options: No antibody could bind to this antigen Purely hydrophobic A mixture of hydrophobic and positive charges A region of hydrophobic residues next to a few negatively charged residues

3

When do antibodies trigger an immune response? Question 5 options: When there are many other antibodies already present When bound to a single antigen When crosslinking two non-identical antigens When crosslinking two identical antigens

3 Antibodies present

A binding pocket of a protein contains a patch of hydrophobic residues and a single Lys. Which of the following features of a ligand would increase binding with this protein (select all correct answers)? Question 1 options: Hydrogen bonding groups A positive charge A negative charge A hydrophobic region

A negative charge A hydrophobic region

Which of the following features do all fibrous proteins have in common? Question 3 options: A lack of tertiary structure A pattern of repeating sequence An α-helical secondary structure A quaternary structure of 2 or 3 coils

A pattern of repeating sequence

Which of the following features contributes to a higher probability that a sequence will form a coiled coil (select all correct answers)? Question 2 options: A repeating pattern of polar amino acids on one side of α-helix A repeating pattern of hydrophobic amino acids on one side of an α-helix A repeating pattern of oppositely charged amino acids A repeating sequence of seven amino acids

A repeating pattern of polar amino acids on one side of α-helix A repeating pattern of hydrophobic amino acids on one side of an α-helix A repeating pattern of oppositely charged amino acids A repeating sequence of seven amino acids

In some autoimmune diseases, antibodies develop that bind with DNA. These same antibodies often also bind to cell membranes. Which of the following statements correctly accounts for this observation? Question 5 options: Both lipids and nucleotides are somewhat hydrophobic DNA and lipid bilayers share a common functional group Antibodies that bind to a saccharide, such as galactose, on the cell surface are also capable of binding to the saccharides in DNA Some antibodies are not very specific, and so bind to many different types of molecules

DNA and lipid bilayers share a common functional group

Before recombinant insulin was commonly available, insulin was isolated from organisms for use in humans. Based on the alignment below (of the A chain of insulin), which of the shown organisms would be the one most likely to generate an immune response in a human?

Guiena pig has the most differences in amino acid sequence

Collagen has which of the following secondary structures? Question 1 options: Random coil α-helix None of these β-sheet

None of these

Which structural feature of keratins is responsible for their ability to form long-lasting structures? Question 4 options: The amino acid residues in keratin are particularly resistant to being broken down The globular nature of the monomers Keratin does not form long lasting structures The fibrous structure of the keratin monomers means the filaments are particularly stable and can cross-link

The fibrous structure of the keratin monomers means the filaments are particularly stable and can cross-link

The sequences of a protein found in many species are aligned, and it is observed that the 1st, 4th, 8th, 11th, etc. amino acid is V, L, or I. The other residues in the protein are usually polar. Which of the following statements is most likely to be true? The observation does not indicate any significant sequence conservation The protein could be a collagen The protein could be a keratin The protein is unlikely to be fibrous

The protein could be a keratin

Which of the following statements about the structure of collagen are true (select all correct answers)? Question 1 options: Collagen lacks tertiary structure The primary structure of collagen has no obvious pattern Collagen's secondary structure is α-helical The triple helix of collagen is a type of quaternary structure

The triple helix of collagen is a type of quaternary structure

Why is it important that antibodies have a symmetrical quaternary structure? Question 3 options: To create two identical binding sites for antigens To ensure a stable structure To enable binding to many different antigens To create a variable region

To create two identical binding sites for antigens

Which region of an antibody is most important for binding to antigens? Question 4 options: Variable loops Constant heavy chain Constant light chain Disulfide crosslinks

Variable loops