Chapter 10: Carbohydrates and Glycoproteins

A comprehensive set of flashcards covering key concepts, definitions, and insights from Chapter 10 on Carbohydrates and Glycoproteins, aiding in exam preparation.

What are carbohydrates frequently attached to in cells?

Lipids and proteins.

What is the most common posttranslational modification of proteins?

Attachment of carbohydrates to proteins.

What term describes the simplest carbohydrates?

Monosaccharides.

What are polysaccharides made of?

Covalently linked monosaccharides.

What is the empirical formula for many carbohydrates?

(CH2O)n.

What do monosaccharides serve as in living systems?

Fuel molecules and fundamental constituents.

What distinguishes a ketose from an aldose?

A ketose contains a keto group; an aldose contains an aldehyde group.

What are the three carbon classification categories of monosaccharides?

Trioses, tetroses, pentoses.

Which monosaccharides are known as hexoses?

Glucose and fructose.

What is a sugar called that has a free aldehyde group and can reduce another compound?

Reducing sugar.

What is glycation?

Nonenzymatic addition of a carbohydrate to another molecule.

What is the function of glycated hemoglobin (A1C) as a biomarker?

Monitoring long-term glucose levels in the blood.

What link connects carbohydrates to proteins in glycoproteins?

O-glycosidic linkages (or N-glycosidic linkages for certain cases).

How can sugars be modified?

By attaching functional groups to carbons other than the anomeric carbon.

What is the significance of phosphorylated sugars in metabolism?

They prevent the sugars from leaving the cell and block alternative ring conformations.

What are oligosaccharides?

Carbohydrates built by the attachment of two or more monosaccharides.

What enzyme catalyzes the formation of glycosidic linkages in oligosaccharides?

Glycosyltransferases.

Diagrammatically, where is the reducing end of an oligosaccharide?

It has a free anomeric carbon atom with reducing activity.

What are disaccharides, and can you name three examples?

Two sugars joined by an O-glycosidic linkage: sucrose, lactose, and maltose.

What role do proteoglycans serve in connective tissue?

They act as lubricants and structural components.

How are mucins defined in terms of their structure?

They have a high carbohydrate content and a tandem repeat region rich in serine and threonine.

What is the role of lectins in the immune system?

Facilitating cell-cell contact, especially during the inflammatory response.

What can poor glycosylation lead to?

Various diseases, including muscular dystrophy and congenital disorders.

What is chitin and where is it commonly found?

A homopolymer of N-acetylglucosamine found in fungal cell walls and exoskeletons of arthropods.

How do viruses like influenza utilize carbohydrates on host cells?

They adhere to cell-surface carbohydrates like sialic acid residues.

What happens after a virus binds to sialic acid residues?

The virus is engulfed, and later viral proteins help it to bud off from the cell.

What percentage of the proteome consists of glycoproteins?

About 50%.

What constitutes the core of N-linked oligosaccharides?

A pentasaccharide core of three mannoses and two N-acetylglucosamines.

What type of linkage is found in glycosaminoglycans?

Repeating units of disaccharides containing amino sugar derivatives.

What is the name of the glial protein commonly affected in glycosylation disorders?

Dystroglycan.

How does α-glucosidase relate to blood glucose management?

It helps further digest oligosaccharides from starch and glycogen.

What is the main structure that may vary across human blood types?

The carbohydrate chain on the surface of red blood cells.

What is the role of glucosinolates in plants?

They act as a defense against herbivory and can be hydrolyzed to release isothiocyanate.

What do the terms alpha (α) and beta (β) refer to in carbohydrates?

The orientation of the hydroxyl group attached to the anomeric carbon.

What constitutes a homopolymer?

Polymers made up of the same type of monosaccharide.

Which polysaccharides are involved in energy storage?

Starch and glycogen.

What is the predominant form of carbohydrate used in the blood?

D-glucose.

How does high blood glucose affect glycation processes?

High concentrations can lead to increased glycation of proteins.

In what form do mammals typically circulate glucose?

As D-glucose in the blood.

What is the importance of water in relation to aggrecan in cartilage?

It cushions and enables aggrecan to spring back after deformation.

What glycosidic linkages bind glucose in glycogen and starch?

α-1,4 linkages.

What prevents phosphorylated sugars from spontaneously leaving the cell?

The addition of phosphoryl groups blocks their interaction with transporters.

Where do most glycosaminoglycans get their negative charges from?

Carboxylate or sulfate groups on the sugar units.

What are lectins and their primary function?

Class of proteins that facilitate cell-cell contact.

What triggers the release of pressurized water bound by glycosaminoglycans?

Exertion of compressive forces, like walking.

What can happen if glycosylation is not properly executed in proteins?

It can lead to dysfunctional proteins and diseases.

Identify the type of sugar that is typically the most abundant in human milk.

Human milk oligosaccharides.

What is a typical characteristic of glycoproteins?

A carbohydrate moiety is covalently attached to a protein.

What do both O- and N-glycosidic linkages facilitate?

They connect carbohydrates to proteins.

Why are advancements in glycobiology significant?

They enable exploration and tracking of biological processes without cell disruption.

How can glycosylation influence disease susceptibility?

Certain types may expose or hide cellular features affecting immune response.

What is the effect of high glucose levels on hemoglobin?

Increased glycated hemoglobin (A1C) levels in diabetes.

What is the commonality of the A, B, and O blood groups?

They share a common oligosaccharide foundation called the O antigen.

What role do glcNac-rich glycosylation patterns play in metabolism?

They indicate nutrient availability in cells.

What forms when an aldehyde reacts with an alcohol in carbohydrate chemistry?

A hemiacetal.

Describe the structure that defines a glycoprotein.

Covalently attached carbohydrate group to a protein.

What is a common use of glycosylation in clinical settings?

Monitoring blood glucose levels through glycated hemoglobin.

What do diastereomers specifically differ in?

Configuration at one or more asymmetric carbon atoms.

How do glycoproteins and proteoglycans differ in composition?

Glycoproteins are protein-dominant, while proteoglycans have a much higher carbohydrate content.

Name a consequence of glycation in proteins.

Alteration of normal biochemical function.

How does a hurricane assist in carbohydrate-protein interactions?

They provide specificity but allow for transient binding.

What is the primary composition of the structural polysaccharide cellulose?

Unbranched glucose polymer with β-1,4 linkages.

What can happen to glucose polymers when not properly stored?

They may undergo degradation or improper linkage.

What is a glycan-binding protein?

A protein that specifically binds to carbohydrate structures.

What is the relevance of blood type in disease susceptibility?

Certain blood types may better avoid certain parasitic infections.

What happens to oxygen levels when erythropoietin is secreted?

It stimulates red blood cell production, increasing oxygen-carrying capacity.

What do oligosaccharides exhibit due to their multiple hydroxyl groups?

They allow for various glycosidic linkages.

What is the primary treatment for diabetes related to glycosidase inhibition?

Administering α-glucosidase inhibitors.