Monosaccharides and disaccharides
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All 14 Flashcards — Monosaccharides and disaccharides
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Question
Define a monosaccharide.
Answer
A **single sugar unit** — the **monomer** of a carbohydrate (e.g. glucose, fructose, galactose).
Question
Define a disaccharide.
Answer
A sugar made of **two monosaccharides joined together** (e.g. maltose, sucrose, lactose).
Question
What is the chemical formula of glucose?
Answer
**C₆H₁₂O₆**.
Question
Define isomers.
Answer
Molecules with the **same chemical formula** but a **different arrangement of atoms**.
Question
What is the ONLY difference between alpha- and beta-D-glucose?
Answer
The **direction of the -OH group on carbon 1**: it points **down** in alpha-glucose and **up** in beta-glucose.
Question
Define a condensation reaction.
Answer
A reaction that **joins two molecules** together and **releases a molecule of water** (H₂O).
Question
Define hydrolysis.
Answer
A reaction that **adds water** to **break a bond** — the reverse of condensation.
Question
What bond joins two monosaccharides?
Answer
A **glycosidic bond**.
Question
What are the products when two glucose molecules join by condensation?
Answer
The disaccharide **maltose** **and** a molecule of **water**.
Question
Maltose is made from which two monosaccharides?
Answer
**Glucose + glucose**.
Question
Sucrose is made from which two monosaccharides?
Answer
**Glucose + fructose**.
Question
Lactose is made from which two monosaccharides?
Answer
**Glucose + galactose**.
Question
Why is glucose easy to transport in the blood?
Answer
It is **small and soluble in water**, so it dissolves in the plasma and is carried around the body.
Question
Why is glucose important inside cells?
Answer
It is the **main respiratory substrate** — it is broken down in respiration to release energy (ATP).
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Topic 2.1 hub
Carbohydrates and lipids
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