Sunday, October 17, 2010

Chapter 3: The Molecules of Cells

Three questions about the chapter:
   1. What are the functional groups of organic compounds?
  They are hydroxyl group, carbonyl group, carboxyl group, amino group, phosphate group and methyl group.
   2. How can we recognize a phosphate group?
  We can do this by seeing the phosphate element into the example, expressed by (P)
   3. How can we recognize a carbonyl group?
  We can do this by seeing the double bond connection between the carbon (C) and the oxygen (O) in the example.
   4. How can we recognize an amino group?
  We can do this by seeing the single bond connection between the nitrogen (N) and the two hydrogens (H) in the example.
   5. What are polymers made of?
  Polymers are made of connected monomers. Poly means many, and mono means single.

Five main facts from the reading:
   1. Carbon - based molecules are called organic compounds.
   2. The variations in carbon skeletons are: length, branching, double bonds, and rings.
   3. Two monomers are connected by a reaction, called dehydration.
   4. Two monomers are broken down by a reaction, called hydrolysis.
   5. The four levels of protein structure are: primary, secondary, tertiary, and quaternary structure.


This diagram shows the specific elements and connections of each of the functional groups of organic compounds and helps us recognize the different groups.


  The introductory section of this chapter talks about lactose.  Milk and other dairy products have long been recognized as highly nutritious foods, rich in protein and minerals necessary for healthy teeth and strong bones. For many people though these health benefits come with a digestive discomfort. Such people suffer from lactose intolerance, or the inability to properly break down lactose, the main sugar found in milk.
   After this the chapter talks about the life's molecular diversity, which is based on the properties of carbon. Carbon-based molecules are called organic compounds. Methane and other compounds composed of only carbon and hydrogen are called hydrocarbons. The chain of carbon atoms in an organic molecule is called a carbon skeleton. The different variations of carbon skeleton are: length, branching, double bonds, and rings. Compounds with the same formula, but different structures are called isomers. The next section of the chapter talks about the characteristic chemical groups, which help determine the properties of organic compounds. A hydroxyl group is consisted of a hydrogen atom bonded to an oxygen atom, which in turn is bonded to the carbon skeleton. In a carbonyl group, a carbon atom is linked by a double bond to an oxygen atom. A carboxyl group is consisted of a carbon double-bonded to an oxygen and also bonded to a hydroxyl group. An amino group is composed of a nitrogen bonded to two hydrogen atoms and the carbon skeleton. A phosphate group is consisted of a phosphorus atom bonded to four oxygen atoms. A methyl group is consisted of a carbon bonded to three hydrogens.
   The next section of the chapter talks about that cells make a huge number of large molecules from a small set of small molecules. Two monomers can be connected to one polymer by a dehydration reaction. During this reaction water is being released. One polymer can be broken down to two monomers by hydrolysis reaction. This reaction needs water to be successful. Monosaccharides are the simplest carbohydrates. The name carbohydrate refers to a class of molecules ranging from the small sugar molecules dissolved in soft drinks to large polysaccharides, such as the starch molecules we consume in pasta and potatoes. The carbohydrate monomers are monosaccharides. Cells link two single sugars to form disaccharides. We also learned about the high-fructose corn syrup and how unhealthy it is for us. After this the chapter talked about polysaccharides, which are long chains of sugar units. Then we learned that fats are lipids that are mostly energy-storage molecules. Lipids are divers compounds that are grouped together because they share one trait -  they mix poorly, if at all, with water. Lipids are hydrophobic, or in other words they do not like water. Phospholipids and steroids are important lipids with a variety of functions. Cells could not exist without phospholipids. The chapter also taught us that anabolic steroids pose health risks, and most of them are illegal, so it is better for us to stay away from them. Proteins, on the other side, are essential to the structures and functions of life. A protein is a polymer constructed from amino acid monomers. Proteins are made from amino acids linked by peptide bonds. Amino acids all have an amino group and a carboxyl group.  A protein's specific shape determines its function. A protein's shape depends on four levels of structure: primary, secondary, tertiary, and quaternary. We also learned that Linus Pauling contributed to our understanding of the chemistry of life. The last two things chapter talked about were the nucleic acids, which are information-rich polymers of nucleotides, and lactose tolerance, which is a recent event in human evolution.

Key Terms:
 1. Carbon skeleton - the chain of carbon atoms in an organic molecule.
 2. Isomers - compounds with the same formula but different structures.
 3. Hydrophilic - water-loving,
 4. Enzymes - specialized macromolecules that speed up chemical reactions in cells.
 5. Monosaccharides - the carbohydrate monomers.
 6. Fat - a large lipid made from two kinds of smaller molecules: glycerol and fatty acids.
 7. Saturated - fats with the maximum number of hydrogens.
 8. Unsaturated - fatty acids and fats with double bonds in the carbon chain.
 9. Anabolic steroids - synthetic variants of the male hormone testosterone.
10. Steroids - lipids whose carbon skeleton contains four fused rings.


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