Topic 3 The chemistry of life

Topic 2 Molecular Biology Review
**Review all the “understanding” statements at the beginning of each section.
Key facts
14. Monosaccharides are the simplest carbohydrates and include glucose, galactose, and fructose.
15. Disaccharides include two monosaccharides bonded together. Examples are maltose, lactose, and sucrose.
16. Polysaccharides are long chain carbohydrates, and include starch, glycogen and cellulose.
17. In animals glucose is carried by the blood to transport energy to cells all through the organism.
18. Lactose in animals provides energy to young mammals until they are weaned from their mothers.
19. Glycogen is used in animals to store energy in the liver and muscles.
20. In plants, fructose makes fruit sweet tasting. This attracts animals, allowing dispersal of the seeds in the
21. Sucrose is the form of carbohydrates that is transported by the plant’s phloem (vascular tissue). It represents
an energy source.
22. Cellulose is used in plants to produce fibers that allow the construction of the cell wall.
23. In condensation two simple molecules are joined together to form a larger molecule. When this occurs
water is formed.
24. In hydrolysis larger molecules are broken down into smaller molecules. Water molecules are used up in this
25. Four functions of lipids include: energy storage, heat insulation, buoyancy, and they are an essential part of
cellular membranes.
26. Both lipids and carbohydrates serve to store energy.
27. Lipids store twice the amount of energy as an equal mass of carbohydrates. However, carbohydrates are
more easily digested than lipids to release their energy. Also, carbohydrates are water soluble and are easier to
28. Because lipids are insoluble in water, they do not cause problems with osmosis in cells.
Complete the following.
1. Identify the structural formula for glucose.
2. Identify the structural formula for ribose.
3. Identify the general formula for a fatty acid.
4. Identify the general structure for glycerol.
5. Identify the general structural formula for a triglyceride
6) What three elements do they contain? What is the ratio of H:O?
7) What is their function?
8) What is the difference between a mono, di and polysaccharide?
9) When two monosaccharides combine, the process is called________, requires__________, and gives off a
__________molecule (be able to draw two glucose molecules undergoing this process)
10) When a disaccharide is broken down into two monosaccharides, the process is called____________, _________is
released and a________molecule needs to be added.
11. Large molecules of organic compounds are called macromolecules and are made up of specific sub-units. What are
the subunits of:
a. carbohydrates ______________________
b. lipids _______________________
12. Identify whether the following are mono, di or polysaccharides: glucose, cellulose, maltose, galactose, ribose,
glycogen, lactose, starch, fructose, sucrose
13. Identify whether the following are found in plants or animals: glucose, cellulose, maltose, galactose, ribose, glycogen,
lactose, starch, fructose, sucrose
14. What are basic properties and functions of: glucose, cellulose, maltose, galactose, ribose, glycogen, lactose, starch,
fructose, sucrose
15. What monosaccharide is carried by the blood to transport energy to cells throughout the body?
16. What is the value of fructose to plants?
17. What disaccharide provides energy to young mammals before they are weaned?
18. What disaccharide transports energy in the phloem of plants?_________________
19. Of what value is cellulose to plants?
20. Where in animals would one find energy stored as glycogen?__________________
21. Explain what, in general, happens in all condensation reactions.
22. Explain what, in general, happens in all hydrolysis reactions.
23. Tell whether the following represents hydrolysis or condensation.
a. amino acid + amino acid --------- dipeptide + water ______________
b. glucose + fructose ----------- sucrose + water ________________
c. glycogen + water ----------- monosaccharides ________________
d. lipid + water ---------------- glycerol + fatty acids ________________
24. How do lipids provide buoyancy in animals?
25. What form of lipids provide energy storage in plants?______________ in animals?______________
26. What two major macromolecules provide energy to living organisms?
27. Of these two, which allows the most rapid release of energy?
28. Are lipids or are carbohydrates soluble in water?________________
29. Which of the compounds used to store energy is most often used for long-term storage?_________________
30) Discuss three functions of lipids.
31) What two molecular groups are found at either end of a lipid?
32) Compare the amount of energy in 1gram of lipid versus 1 gram of carbohydrates.
33) Discuss two ways in which lipids and carbs are similar and two ways they are different.
34) Describe the difference between a saturated fat/lipid and one that is unsaturated. Be able to recognize a diagram of
35) Distinguish between saturated fats, monounsaturated fats and those that are polyunsaturated.
36) Distinguish between polyunsaturated fats that are “cis” versus those that are “trans”. Be able to recognize a diagram
of each.
37) Which fats listed in #8 are considered “bad”?
38) A lipid is composed of 3_________ ________ and a ___________glycerol molecule.
39) Describe the relationship between a person’s saturated fat intake and their chance of developing coronary heart
40) What does BMI stand for?
41) What is the equation used to calculate BMI?
42. Compare the use of carbohydrates and lipids in energy storage.