Module 6 Science Of Cooking Worksheet Homework Help

Carbohydrates

 

Model 1. Simple sugars like glucose and fructose are small monosaccharides. Table sugar is a dimer of fructose and glucose and is therefore called a disaccharide. Many sugars joined together in a polymer can make starch or cellulose (depending on the arrangement of bonds), and by analogy, another name for a polymer like starch or cellulose is a polysaccharide. Because we perceive both simple sugars (like glucose and fructose) and dimers like sucrose and lactose as sweet – all of these monosaccharides and disaccharides are commonly called sugar. Polymers like starch are tastless to humans – only when acid or enzymes break starch down into its component sugar monomers/monosaccharides do we experience the sweet taste.

 

Figure 7.1. Sucrose (i.e. table sugar) is a dimer of glucose and fructose.

 

Figure 7.2. Glucose can form hydrogen bonds with water

All sugars are made entirely of carbon, hydrogen and oxygen atoms joined by covalent bonds – this is what makes them examples of carbohydrate, Cn(H2O)n. Because sugars have so many H-O groups, they readily form hydrogen bonds[1] with water – this makes it easy to dissolve sugars in water. Sugars are also small which helps them dissolve readily in water. The hydrogen bonding capacity of sugars allows them to retain moisture in baked goods. It is this “wet sugar” that forms the sticky matrix that holds granola bars together, and gives glazes a glossy appearance.

 

 

Questions:

1. Chemists call glucose and fructose isomers. Using Figure 7.1, can you determine how glucose and fructose are chemically related? (Hint: count the number of carbons, hydrogens and oxygens in both molecules).

 

 

 

 

 

 

2. Consider the structure of glucose. Each has the basic molecular formula C_nH_nO_n  where n = the number of each atom. Record that formula in the table below. Now, rewrite the molecular formula in the following format: C_n(H₂O)_n

 

Molecular formula for glucose

	Glucose
CnHnOn
Cn(H2O)n

 

Using this information, and the information, explain why glucose is an example of carbohydrate?

 

 

 

 

 

 

Model 2. Starch is also carbohydrate. In nature, starch is found most often in one of two forms: amylose or amylopectin.  If you examine the structure of amylose or amylopectin in Figure 7.3, you will notice that each is a combination of repeating units. The same molecular piece is repeated over and over again. Amylose and amylopectin are polymers – where poly = “many”. The unit of repetition is called a monomer. In amylose and amylopectin, the monomer unit is a glucose.

Figure 7.3. Amylose and Amylopectin. Two types of starch.

 

For humans, carbohydrates like the amylose and amylopectin in starch are ready sources of glucose and therefore ready sources of energy. Each large glucose polymer is broken down by enzymes into glucose monomers, and the monomer glucose is an excellent source of energy for human metabolism.

Figure 7.4. Cartoons of large amylose and amylopectin polymers

 

3. Using Figures 7.3 and 7.4, compare the structure of amylose to that of amylopectin.
   1. Explain why amylose is called a 1,4-linked polymer of glucose

 

 

 

1. Explain why amylopectin is called a 1,4 and 1,6 linked polymer of glucose?

 

 

 

1. Are your answers consistent with the fact that amylose is a linear (“like a line”) polymer of glucose while amylopectin is a branched polymer of glucose? Explain how.

 

 

 

 

 

Model 3. But there are other types of carbohydrate that humans cannot digest – for example, wheat bran is rich in another carbohydrate called cellulose.  Cellulose is also a polymer of glucose. Indigestible carbohydrate is a component of fiber. Fiber is defined as material in our plant foods that our digestive enzymes can’t breakdown into absorbable nutrients[2]. Cellulose is one of those indigestible materials. Cellulose forms the structure that holds the plant up and is one of the most abundant polymers on earth. Most animals cannot digest cellulose, but microorganisms like bacteria and fungi can, which is how plant material rots in nature.

Figure 7.5. Amylose and Cellulose

 

 

Questions:

 

4. The structure of cellulose is compared to amylose in Figure 7.5.
   1. How are amylose and cellulose structurally similar?

 

1. How are amylose and cellulose structurally different?

 

1. Based on the structures of amylose and cellulose, when can you conclude about why humans cannot digest cellulose? Use the words bonds and enzyme in your answer. Drawing on the structures above may help.

 

 

 

 

 

 

5. Expand the definition of fiber by rewriting it to include the words cellulose, glucose and covalent bonds.

[1] Remember, a hydrogen bond is a ionic-type non-covalent interaction between a partially positive hydrogen and a partially negative oxygen, it is weaker than a covalent bond

[2] On Food and Cooking, McGee, p. 258

Carbohydrates

 

Model 1. Simple sugars like glucose and fructose are small monosaccharides. Table sugar is a dimer of fructose and glucose and is therefore called a disaccharide. Many sugars joined together in a polymer can make starch or cellulose (depending on the arrangement of bonds), and by analogy, another name for a polymer like starch or cellulose is a polysaccharide. Because we perceive both simple sugars (like glucose and fructose) and dimers like sucrose and lactose as sweet – all of these monosaccharides and disaccharides are commonly called sugar. Polymers like starch are tastless to humans – only when acid or enzymes break starch down into its component sugar monomers/monosaccharides do we experience the sweet taste.

 

Figure 7.1. Sucrose (i.e. table sugar) is a dimer of glucose and fructose.

 

Figure 7.2. Glucose can form hydrogen bonds with water

All sugars are made entirely of carbon, hydrogen and oxygen atoms joined by covalent bonds – this is what makes them examples of carbohydrate, Cn(H2O)n. Because sugars have so many H-O groups, they readily form hydrogen bonds[1] with water – this makes it easy to dissolve sugars in water. Sugars are also small which helps them dissolve readily in water. The hydrogen bonding capacity of sugars allows them to retain moisture in baked goods. It is this “wet sugar” that forms the sticky matrix that holds granola bars together, and gives glazes a glossy appearance.

 

 

Questions:

1. Chemists call glucose and fructose isomers. Using Figure 7.1, can you determine how glucose and fructose are chemically related? (Hint: count the number of carbons, hydrogens and oxygens in both molecules).

 

 

 

 

 

 

2. Consider the structure of glucose. Each has the basic molecular formula C_nH_nO_n  where n = the number of each atom. Record that formula in the table below. Now, rewrite the molecular formula in the following format: C_n(H₂O)_n

 

Molecular formula for glucose

	Glucose
CnHnOn
Cn(H2O)n

 

Using this information, and the information, explain why glucose is an example of carbohydrate?

 

 

 

 

 

 

Model 2. Starch is also carbohydrate. In nature, starch is found most often in one of two forms: amylose or amylopectin.  If you examine the structure of amylose or amylopectin in Figure 7.3, you will notice that each is a combination of repeating units. The same molecular piece is repeated over and over again. Amylose and amylopectin are polymers – where poly = “many”. The unit of repetition is called a monomer. In amylose and amylopectin, the monomer unit is a glucose.

Figure 7.3. Amylose and Amylopectin. Two types of starch.

 

For humans, carbohydrates like the amylose and amylopectin in starch are ready sources of glucose and therefore ready sources of energy. Each large glucose polymer is broken down by enzymes into glucose monomers, and the monomer glucose is an excellent source of energy for human metabolism.

Figure 7.4. Cartoons of large amylose and amylopectin polymers

 

3. Using Figures 7.3 and 7.4, compare the structure of amylose to that of amylopectin.
   1. Explain why amylose is called a 1,4-linked polymer of glucose

 

 

 

1. Explain why amylopectin is called a 1,4 and 1,6 linked polymer of glucose?

 

 

 

1. Are your answers consistent with the fact that amylose is a linear (“like a line”) polymer of glucose while amylopectin is a branched polymer of glucose? Explain how.

 

 

 

 

 

Model 3. But there are other types of carbohydrate that humans cannot digest – for example, wheat bran is rich in another carbohydrate called cellulose.  Cellulose is also a polymer of glucose. Indigestible carbohydrate is a component of fiber. Fiber is defined as material in our plant foods that our digestive enzymes can’t breakdown into absorbable nutrients[2]. Cellulose is one of those indigestible materials. Cellulose forms the structure that holds the plant up and is one of the most abundant polymers on earth. Most animals cannot digest cellulose, but microorganisms like bacteria and fungi can, which is how plant material rots in nature.

Figure 7.5. Amylose and Cellulose

 

 

Questions:

 

4. The structure of cellulose is compared to amylose in Figure 7.5.
   1. How are amylose and cellulose structurally similar?

 

1. How are amylose and cellulose structurally different?

 

1. Based on the structures of amylose and cellulose, when can you conclude about why humans cannot digest cellulose? Use the words bonds and enzyme in your answer. Drawing on the structures above may help.

 

 

 

 

 

 

5. Expand the definition of fiber by rewriting it to include the words cellulose, glucose and covalent bonds.

[1] Remember, a hydrogen bond is a ionic-type non-covalent interaction between a partially positive hydrogen and a partially negative oxygen, it is weaker than a covalent bond

[2] On Food and Cooking, McGee, p. 258