Carbohydrates Overview and Classification
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Questions and Answers

What is the blood group when neither GalNAc nor galactose is present?

  • AB
  • A
  • O (correct)
  • B

Humans can digest cellulose due to the presence of specific enzymes.

False (B)

What is the primary role of SGLT-1 in the absorption of monosaccharides?

Transport of glucose and galactose with Na+

Normal blood glucose concentration is maintained at about ____ mM.

<p>5</p> Signup and view all the answers

Match the following carbohydrates with their characteristic bonds:

<p>Starch = Alpha glycosidic bonds Cellulose = Beta glycosidic bonds Oligosaccharides = Disaccharides Disaccharides = Creates monosaccharides</p> Signup and view all the answers

What is the primary function of glycoproteins?

<p>Cell-surface recognition and antigenicity (D)</p> Signup and view all the answers

Proteoglycans are primarily composed of proteins with high carbohydrate content.

<p>False (B)</p> Signup and view all the answers

What are glycosaminoglycans (GAGs) known for?

<p>Their ability to bind large amounts of water and produce a gel-like matrix.</p> Signup and view all the answers

The blood group is A if the terminal sugar on the glycan is __________.

<p>GalNAc</p> Signup and view all the answers

Match the following carbohydrate structures with their characteristic:

<p>Proteoglycan = Rich in carbohydrates and associated with core proteins Glycoprotein = Rich in proteins with attached carbohydrates Glycosaminoglycan = Ability to bind water and form gel-like matrices Starch = Polysaccharide used for energy storage</p> Signup and view all the answers

Which of the following statements is true regarding starch?

<p>Starch consists of amylopectin and amylose. (C)</p> Signup and view all the answers

Glycoproteins contain repeating disaccharide units in their structure.

<p>False (B)</p> Signup and view all the answers

What role do membrane-bound glycoproteins play in the body?

<p>They participate in various cellular phenomena including recognition and signaling.</p> Signup and view all the answers

What is the general formula for carbohydrates?

<p>(C.H2O)n (B)</p> Signup and view all the answers

Monosaccharides are classified based on the presence of aldehydes or ketones.

<p>True (A)</p> Signup and view all the answers

Name two types of polysaccharides.

<p>Starch and glycogen</p> Signup and view all the answers

A disaccharide forms when two monosaccharides are linked by a __________ bond.

<p>glycosidic</p> Signup and view all the answers

Match the following terms with their descriptions:

<p>Monosaccharide = The simplest form of carbohydrates Disaccharide = Formed by two monosaccharides Polysaccharide = Complex carbohydrates made of many monosaccharides Glycogen = Storage form of glucose in animals</p> Signup and view all the answers

Which of the following is NOT a type of carbohydrate?

<p>Nucleotide (C)</p> Signup and view all the answers

Cellulose is a storage polysaccharide found in plants.

<p>False (B)</p> Signup and view all the answers

What is the difference between aldoses and ketoses?

<p>Aldoses contain an aldehyde group, while ketoses contain a ketone group.</p> Signup and view all the answers

______ is an example of a 6-carbon aldose.

<p>Glucose</p> Signup and view all the answers

Which carbohydrate is primarily used for energy storage in animals?

<p>Glycogen (B)</p> Signup and view all the answers

Flashcards

Alpha glycosidic bond

A type of glycosidic bond found in starch, which can be broken down by human enzymes.

Beta glycosidic bond

A type of glycosidic bond found in cellulose, which humans cannot digest.

SGLT-1

A protein that transports glucose and galactose into intestinal mucosal cells, using sodium as a co-transporter.

GLUT-5

A protein that transports fructose into intestinal mucosal cells.

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GLUT-2

A protein that transports glucose from the intestine into the bloodstream.

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Starch

A type of polysaccharide that is composed of many glucose molecules linked together in a chain.

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Amylose

A linear, unbranched chain of glucose molecules linked by alpha-1,4-glycosidic bonds.

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Amylopectin

A branched chain of glucose molecules linked by alpha-1,4-glycosidic bonds and alpha-1,6-glycosidic bonds at branch points.

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Proteoglycan

A type of macromolecule that consists of a core protein covalently attached to one or more glycosaminoglycan chains.

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Glycosaminoglycan (GAG)

A type of long, unbranched polysaccharide consisting of repeating disaccharide units.

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Glycoprotein

A type of protein with one or more oligosaccharides (glycans) covalently attached to it.

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Glycosylation

The process of adding sugar molecules to a protein.

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Glycosylation

The most common post-translational modification of proteins.

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Carbohydrates

A group of carbonyl compounds, containing aldehydes or ketones, and multiple hydroxyl groups.

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Isomer

Same chemical formula, different structural arrangement.

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Monosaccharide

A single sugar molecule, the simplest form of carbohydrates.

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Aldose

A carbohydrate with an aldehyde group.

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Ketose

A carbohydrate with a ketone group.

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Disaccharide

Two monosaccharides linked together by a glycosidic bond.

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Polysaccharide

A long chain of monosaccharides linked together by glycosidic bonds.

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Cellulose

A structural polysaccharide found in plant cell walls.

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Glycogen

A storage polysaccharide found in animals.

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Study Notes

Carbohydrates Overview

  • Carbohydrates are a group of carbonyl compounds (aldehydes or ketones) that also have several hydroxyl groups.
  • Their general formula is (C⋅H₂O)ₙ.
  • Isomers have the same formula but a different structure.
  • Examples of isomers include fructose and glucose, both with the formula C₆H₁₂O₆.

Carbohydrate Objectives

  • Recognize the general structure of carbohydrates
  • Classify carbohydrates (monosaccharides, disaccharides, oligosaccharides, polysaccharides)
  • Recognize disaccharides
  • Recognize polysaccharides
  • Explain carbohydrate-modified protein structures and their functions
  • Explain carbohydrate digestion

Carbohydrate Classification

  • Classification is based on the number of monomer units
  • Monosaccharides: one sugar unit (e.g., glucose, fructose)
  • Disaccharides: two sugar units (e.g., sucrose, lactose)
  • Oligosaccharides: a few sugar units
  • Polysaccharides: many sugar units

Monosaccharides

  • Further classified by the type of carbonyl group (aldose or ketose) and the number of carbons (triose, tetrose, pentose, hexose, heptose, etc.)
  • Examples include:
    • Glyceraldehyde (a triose)
    • Ribose (a pentose)
    • Glucose (a hexose)
    • Fructose (a ketohexose)

Disaccharides

  • Formed by the joining of two monosaccharides through a glycosidic bond
  • Common examples are:
    • Maltose (glucose + glucose)
    • Sucrose (glucose + fructose)
    • Lactose (galactose + glucose)

Polysaccharides

  • Large polymers of monosaccharides
  • Used for energy storage (starch, glycogen) or structural support (cellulose, chitin)
  • Examples include:
    • Starch (energy storage in plants)
    • Glycogen (energy storage in animals)
    • Cellulose (structural component in plant cell walls)
    • Chitin (structural component in exoskeletons and fungal cell walls)

Protein-Carbohydrate Structures

  • Carbohydrates can be attached to proteins to form glycoproteins.
  • These attachments can affect the protein's function, such as cell recognition or immune response.
  • These can also be combined with proteins to form proteoglycans, which are usually found in the extracellular matrix.
  • Examples are Glycosaminoglycans (GAGs).

Carbohydrate Digestion

  • Enzymes break down glycosidic bonds in carbohydrates.
  • Amylases break down starch in the mouth and small intestine.
  • Cells lining the small intestine have enzymes that further break down disaccharides into monosaccharides.
  • Monosaccharides are then absorbed into the bloodstream.
  • Cellulose is not digestible by humans.

Carbohydrate Absorption

  • Monosaccharides are absorbed into the intestinal cells.
  • Specific transport proteins (e.g., SGLT-1, GLUT-2, GLUT-5) aid in the absorption process.
  • Monosaccharides are then transported to other parts of the body.

Carbohydrate Metabolism

  • Carbohydrates are central to energy metabolism.
  • The blood glucose level (often around 5 mM) is carefully regulated.
  • Fluctuations can lead to various symptoms and health problems (hyperglycemia, hypoglycemia).

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Description

This quiz covers the essential concepts of carbohydrates, including their structure, classification, and functions. You'll explore different types of carbohydrates such as monosaccharides, disaccharides, oligosaccharides, and polysaccharides, as well as their roles in digestion and protein modification.

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