chapter 7 section 7

Question 1

Why are carbohydrates considered information carriers?

Answer 1

Their structural variability allows them to encode complex biological information.

Question 2

What are glycoconjugates?

Answer 2

Proteins or lipids covalently linked to oligosaccharides or polysaccharides.

Question 3

What enzymes “write” the sugar code?

Answer 3

Glycosyltransferases, glycosidases, and other carbohydrate-modifying enzymes.

Question 4

What is the glycome?

Answer 4

The complete set of glycans and glycoconjugates made by a cell or organism under specific conditions.

Question 5

What does glycomics study?

Answer 5

The structure, quantity, and function of glycans and glycoconjugates in cells, tissues, or organisms.

Question 6

What is glycan microarray technology used for?

Answer 6

Characterizing interactions between glycans and glycan-binding proteins or enzymes.

Question 7

How many glycan-binding proteins (GBPs) and processing enzymes are known?

Answer 7

More than a thousand; the human glycome likely contains hundreds of thousands of structures.

Question 8

Why is glycosylation important in biology?

Answer 8

It is the most abundant and diverse post-translational modification, influencing metabolism, development, and disease.

Question 9

What biological processes depend on glycoconjugate-mediated information transfer?

Answer 9

Cell migration, cell–cell interaction, immune response, blood clotting, and more.

Question 10

What are lectins?

Answer 10

Proteins that bind carbohydrates with high specificity and affinity.

Question 11

What is the role of lectins in biology?

Answer 11

hey act as translators of the sugar code.

Question 12

How do lectins mediate biological information transfer?

Answer 12

By forming specific complexes with glycoconjugates.

Question 13

What is the purpose of leukocyte rolling?

Answer 13

to migrate white blood cells to sites of inflammation.

Question 14

What proteins mediate leukocyte rolling?

Answer 14

Selectins.

Question 15

Where are selectins found?

Answer 15

On leukocytes (L-selectin) and on vascular endothelial cells (P- and E-selectins).

Question 16

What domain allows selectins to bind carbohydrates?

Answer 16

The N-terminal extracellular lectin (LEC) domain.

Question 17

How many types of selectins exist?

Answer 17

Three: E-selectin, L-selectin, and P-selectin.

Question 18

How do L-selectin and P-selectin differ in rolling?

Answer 18

L-selectin mediates weaker adherence and faster rolling; P-selectin promotes stronger adherence and slower rolling.

Question 19

How are selectins expressed during inflammation?

Answer 19

Exposure to signals like histamine, hydrogen peroxide, or bacterial endotoxins triggers their expression on cell surfaces.

Question 20

Where are P-selectins stored before being expressed?

Answer 20

In intracellular granules, quickly transported to the membrane upon stimulation.

Question 21

What are galectins?

Answer 21

family of proteins with carbohydrate recognition domains (CRDs) that bind β-galactosides.

Question 22

Which processes involve galectins?

Answer 22

Cell adhesion, growth regulation, inflammation, immunity, and cancer metastasis.

Question 23

Give examples of galectins linked to human disease

Answer 23

One associated with heart attack risk; another implicated in inflammatory bowel disease.

Question 24

What is the structure of human galectin-1?

Answer 24

A dimer of antiparallel beta-sandwich subunits with lactose-binding sites at opposite ends.

Question 25

How are galactose-binding residues stabilized in galectin-1?

Answer 25

By a hydrogen-bonded network of four water molecules, even without ligand.

Question 26

What is C-reactive protein (CRP)?

Answer 26

A pentraxin-family lectin that limits tissue damage, acute inflammation, and autoimmune reactions.

Question 27

How does CRP function?

Answer 27

Binds phosphocholine on damaged membranes via a calcium-mediated hydrophobic pocket.

Question 28

What clinical use does CRP have?

Answer 28

CRP tests help assess the risk of coronary artery disease.