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cell biology questions

1) For each of the following four macromolecules, list their:
i) Monomer(s).
ii) Functional groups.
iii) Linkage type.
iv) Primary function.
Macromolecules:
a) Carbohydrates
b) Proteins
c) Lipids
d) Nucleic acids

2) Show how a peptide bond forms between the two amino acids, glycine and valine. Draw the structural formulas for the reactants and the product. Label the functional groups and linkages present. 
Glycine + valine → ?

3) Chocolate milk has been a choice for many athletes, as it is a good source of protein, carbohydrates, and lipids. Suppose you were to conduct nutrient testing on a sample of chocolate milk. Describe
a) The tests you would perform and the reagents you would use.
b) The results you would expect to find.

Solution Preview

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For each of the following four macromolecules, list their
. i) Monomer(s).
. ii) Functional groups.
. iii) Linkage type.
. iv) Primary function.
Macromolecules:
. a) Carbohydrates
i.
Based on the formula (CH2O)n. "C" stands for "carbo". H2O stands for "hydrate". The the name carbohydrate.

Carbohydrate have between 3 to 7 carbons. Most monosaccharides have Triose sugars that is 3 carbon. Pentose sugars have 5 carbon and Hexose have 6 carbon skeleton. Single mononmer unit of carbohydrates are simple sugars such as monosaccharide or disaccharide. The monosaccharide typically contain three, five, six, or more carbon atoms. Different types of monosaccharides have the same chemical formula and are called isomeric. Examples of monosaccharide or simple sugar are glucose, galactose, and fructose. (1)

Glucose - Glucose is an essential monosaccharide to every species. It has important role in metabolism. Glucose is use for metabolism and as a source of nutrient. Bacteria can use glucose for their energy metabolism. There are other six carbon monosaccharides, which are fructose and galactose. These molecules are converted into glucose for energy. (1)

These are the monomers of glucose.
ii. Functional group - All carbohydrates have the carbonyl functional group (C=O) along with a number of hydroxyl functional groups ( C---OH).
Aldehydes have the carbonyl group at the end of the molecule and glucose is an example of an aldehyde sugars (aldose). Sugar is the most common monosaccharide in all species. Fig. 1 is a picture of the monosaccharide glucose with carbonyl functional group ( C = O ) along with a hydroxyl functional groups ( C---OH ). One form of sugars is aldehydes that have the carbonyl group at the end.

Purves's Life: The Science of Biology, 7 edition.
Ketone Sugars (Ketoses)
In a ketone sugar, the carbonyl group is not at the end of the sugar. Fructoe is one of the most common monosaccharide ketone sugars. Fig. 2 showed the structure of ketone sugar.

Campbell's Biology, 5th Edition.
iii. Linkage type - In carbohydrate, the two monomer subunit monosaccharides is linked together to make a disaccharide molecule. They form glycosidic linkage between the monomers. For example, a carbon from one monomers is connected to the carbon of another monomers.

Glucose + glucose --- maltose

Fig. 3. Campbell's Biology, 5th Edition

Glucose + fructose --- sucrose

Fig. 4. Campbell's Biology, 5th Edition
Polysaccharided are along chains of monosaccharides that can be used for energy storage and structure. There are two kinds of configurations : alpha versus B configurations
Alpha linkage forms starch and glycogen, which are chains of monosaccharides.
Beta ...

Solution Summary

Single monomer unit of carbohydrates are simple sugars such as monosaccharide or disaccharide. The monosaccharide typically contain three, five, six, or more carbon atoms. Different types of monosaccharides have the same chemical formula and are called isomeric. Examples of monosaccharide or simple sugar are glucose, galactose, and fructose. (1) Polysaccharides are along chains of monosaccharides that can be used for energy storage and structure. There are two kinds of configurations : alpha versus B configurations Alpha linkage forms starch and glycogen, which are chains of monosaccharides. Beta linkage forms cellulose, which are not able to be broken down by human digestive system. The Primary Functions of carbohydrate are 1) energy storage and 2 ) structure. The main function of carbohydrates is short term storage in which sugars is converted to energy. A secondary function is intermediate - term energy storage ( as in starch for plants and glycogen for animals). (3) The second function of carbohydrate is that they provide structure - alpha and Beta configurations determine the functions of the carbohydrates. The hydroxyl bond distinguishes alpha and Beta configurations: a) alpha linkage will form starch and glycogen; b) Beta linkage will form cellulose - The most abundant carbohydrate on Earth is cellulose that has a beta -1, 4 glycosidic linkages that are chemically very stable. The beta linkage cannot be broken down.

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