1.3.2 Disaccharides

• What type of reaction forms a disaccharide from two monosaccharides?

  Condensation reaction
• Maltose is composed of two glucose molecules.
• Which monosaccharides form sucrose?

  Glucose and fructose
• Lactose is found in milk and dairy products.
• What is released during the formation of a glycosidic bond?

  Water
• Match the disaccharide with its composition:

  Maltose ↔️ Glucose + Glucose

  Sucrose ↔️ Glucose + Fructose

  Lactose ↔️ Glucose + Galactose
• The formation of maltose from glucose is represented as: $Glucose +$$Glucose \rightarrow Maltose +$$H_{2}O$.H_{2}O
• Common disaccharides include maltose, sucrose, and lactose.
• The glycosidic bond is formed through a condensation reaction.
• What are the two main types of glycosidic bonds?

  $\alpha$ and $\beta$
• Sucrose is a non-reducing sugar due to the absence of reactive aldehyde or ketone groups.
• Disaccharides are formed when a water molecule ($H_{2}O$) is eliminated.
• Which type of reaction forms a glycosidic bond?

  Condensation
• There are two main types of glycosidic bonds: $\alpha$ and $\beta$.
• What is a glycosidic bond?

  A covalent bond
• A glycosidic bond forms through a condensation reaction, where a water molecule is eliminated
• Steps involved in the formation of a glycosidic bond

  1️⃣ Two monosaccharides align

  2️⃣ A condensation reaction occurs

  3️⃣ A water molecule is eliminated

  4️⃣ The glycosidic bond forms
• Glycosidic bonds link monosaccharides to form polysaccharides.
• Which carbon atoms are linked in an $\alpha$-glycosidic bond?


  C1 and C4
• An example of a disaccharide formed by an $\alpha$-glycosidic bond is maltose
• Which type of glycosidic bond links glucose and galactose in lactose?

  $\beta(1 \rightarrow 4)$
• Sucrose is composed of glucose and fructose linked by an $\alpha(1 \rightarrow 2)$ glycosidic bond.
• Sucrose is a non-reducing sugar because it lacks free aldehyde or ketone groups.
• Which two monosaccharides form lactose?

  Glucose and galactose
• Lactose is a reducing sugar due to the free aldehyde group in glucose.
• Maltose is composed of two glucose molecules linked by an $\alpha(1 \rightarrow 4)$ glycosidic bond, making it a reducing sugar.
• Match the disaccharide with its monosaccharide composition and glycosidic bond type:

  Sucrose ↔️ Glucose + Fructose, $\alpha(1 \rightarrow 2)$

  Lactose ↔️ Glucose + Galactose, $\beta(1 \rightarrow 4)$

  Maltose ↔️ Glucose + Glucose, $\alpha(1 \rightarrow 4)$
• Maltose is a disaccharide composed of two glucose molecules linked by an $\alpha(1 \rightarrow 4)$ glycosidic bond
• Maltose acts as a reducing sugar due to the presence of a free aldehyde group.
• Steps in the formation of a disaccharide through a condensation reaction

  1️⃣ Two monosaccharides join together

  2️⃣ A glycosidic bond forms

  3️⃣ A water molecule is eliminated
• Match each disaccharide with its composition:

  Maltose ↔️ Glucose + Glucose

  Sucrose ↔️ Glucose + Fructose

  Lactose ↔️ Glucose + Galactose
• Disaccharides are formed through a condensation reaction.
• What is a glycosidic bond?

  Covalent bond linking monosaccharides
• There are two main types of glycosidic bonds: $\alpha$ and $\beta$ bonds
• Sucrose is composed of glucose and fructose linked by an \alpha(1 \rightarrow2)</latex> glycosidic bond.
• What is lactose composed of?

  Glucose and galactose
• Lactose is composed of glucose and galactose linked by a \beta(1 \rightarrow 4)</latex> glycosidic bond
• Maltose is a reducing sugar due to a free aldehyde group.
• What is the process called where a disaccharide is broken down into monosaccharides by adding water?

  Hydrolysis
• Match each disaccharide with its enzyme and products:

  Maltose ↔️ Maltase → Glucose + Glucose

  Sucrose ↔️ Sucrase → Glucose + Fructose

  Lactose ↔️ Lactase → Glucose + Galactose