1.2 - Carbohydrates (monosaccharides) Flashcards
What are carbohydrates, and how are they structured?
Carbohydrates are carbon molecules combined with water. They vary in size, with some being small and others large.
Why is carbon central to the existence of life on Earth?
Carbon atoms readily form bonds with other carbon atoms, creating a backbone for various molecules. This versatility allows the formation of a vast array of molecule types and sizes, enabling the diversity of life. Carbon-containing molecules are called organic molecules.
What is unique about the chemical composition of organic molecules in living organisms?
Organic molecules are based on a small number of chemical elements, with relatively few types of atoms attaching to carbon.
What are monomers and polymers? Provide examples.
Monomers: Small, individual molecules such as monosaccharides, amino acids, and nucleotides.
Polymers: Long chains formed by joining monomers, e.g., carbohydrates and proteins
Which four elements are most biological molecules made from?
Carbon, hydrogen, oxygen, and nitrogen
What is the monomer unit in carbohydrates, and how do these units combine?
The monomer unit is a sugar, or saccharide.
Single monomers are monosaccharides.
Two monomers combine to form a disaccharide.
Many combine to form polysaccharides.
What are monosaccharides, and what is their general formula?
- Sweet-tasting, soluble substances with the formula (CH2O)n, where n is between 3 and 7.
- Examples include glucose, galactose, and fructose.
What type of sugar is glucose, and what are its isomers?
- Glucose is a hexose (6-carbon) sugar with the formula C6H12O6
- It has two isomers: α-glucose and β-glucose.
What are reducing sugars, and how do they work in chemical reactions?
Reducing sugars are sugars that can donate electrons (or reduce another chemical). Examples include all monosaccharides and some disaccharides (e.g., maltose).
What is reduction in chemistry?
Reduction is a chemical reaction involving the gain of electrons or hydrogen.
What is the purpose of Benedict’s test?
Benedict’s test detects reducing sugars by observing their ability to reduce copper(II) sulfate in Benedict’s reagent to copper(I) oxide.
What is Benedict’s reagent composed of?
Benedict’s reagent is an alkaline solution of copper(II) sulfate.
Outline the steps to test for reducing sugars using Benedict’s test
1) Add 2 cm³ of the food sample (in liquid form) to a test tube. Grind with water if necessary.
2) Add an equal volume of Benedict’s reagent.
3) Heat the mixture in a gently boiling water bath for 5 minutes.
4) Observe the color change: Blue → Orange-brown if a reducing sugar is present
What indicates the presence of reducing sugars in Benedict’s test?
Formation of an insoluble red precipitate of copper(I) oxide, with a color change from blue to orange-brown.
