ganiceWorksheet 3: Organic molecules
This section will dealt with the main organic molecules in living things: carbohydrates, fats ( lipids ), proteins and nucleic acids.
Web site name: Florida State College Jacksonville
Web URL: http://web.fscj.edu/David.Byres/foodfiles.htm
1) What does the body use carbohydrates for? One of the main jobs of carbohydrates is to provide fuel for the body to do its job. So if we want to run or walk somewhere or play sports or even work -- all of those activities use carbohydrates. It is our main energy source and helps the body maintain energy.
2) What two chemicals are given out when carbohydrates are burned? If carbohydrates (made of carbon, hydrogen, and oxygen) are burned completely, they give off carbon dioxide and water.
3) Why can cows survive on grass, but not humans? If carbohydrates (made of carbon, hydrogen, and oxygen) are burned completely, they give off carbon dioxide and water. ____________________
Move down to the section “How sweet is your sugar?”
What is the sweetest chemical listed here? __________________________
Lactose is found in milk. Why does milk not taste very sweet?
Lactose free milk is milk that has been treated with an enzyme (lactase) to destroy the lactose so those who are intolerant can get all the benefits of real milk. Usually those people cannot breakdown lactose in their stomach and intestines because they lack the enzyme. The milk itself will be slightly sweet because lactose is not very sweet but the hydrolysis product are sweet.
6) Plants and animals typically contain a lot of glucose. Most soft drinks such as Coke, Pepsi and Sprite contain fructose instead of glucose. Why is this?
Thus the two main considerations will be the cost of sweetener per unit of the soft drink produced. For the soft drinks that are promoted on the basis of their low calorific contents, the calorific value of sweeteners becomes more important. Also glucose may be used in drinks that are intended to provide quick energy as glucose gets absorbed by the blood faster.
Web site name: John Jay College; New York
Web URL: http://web.jjay.cuny.edu/~acarpi/NSC/11-nutrients.htm ( or http://www.visionlearning.com/library/module_viewer.php?mid=61
Read the section “Nutrients and Biochemistry”
7) What three chemical elements are found in carbohydrates? Carbohydrates are made of carbon, and contains hydrogen and oxygen atoms. Carbon is the base atom and oxygen, and hydrogen is bonded to the carbon. The ratio of hydrogen to oxygen is 2:1. _____________
8) Look at the diagram of glucose. How many Carbon (C) atoms does it have?
9) What two molecules are joined to form sucrose?
The reaction is a condensation reaction so in addition to the disaccharide water is also a product. N.B. glucose + glucose -> maltose + water (not sucrose)
glucose + fructose -> sucrose + water
10) What is the difference between starch and glycogen?
Glycogen, also known as animal starch, is a source of energy that can be found in animals only. Glycogen consists of a single molecule and its structure is branched purely. Starch is made of two molecules and their structure is composed of a chain and branch component. Starch, the same with glycogen, is another source of energy that can be found in plants only.
11) List four common foods that contain starch : Bread, Rice, Vegetable, and Legumes ________________________ _____________________________________________________________
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