2010年9月17日金曜日

Ch.3 The Molecules of Cell

WHY DO ISOMERS HAVE DIFFERENT PROPERTIES?
The chemical properties of compounds are decided by the way the compounds react in different environments which is in turn decided by the need for bonding. Isomers are compounds with same molecular formula but different structural formula. This means that though the number of carbon and hydrogen atoms are the same, the bonding is different, and so one might be an alkane while another of the isomer could be an alcohol all meaning they react in pretty different ways. For example, CH3CH2OH and CH3OCH3 are structural isomers but have different boiling points.

WHAT IS HFCS? WHY IS THERE A PROLEM WITH IT?
HFCS is made from corn, and in the mid 1970s we had an excess of corn crops in America. At the same time sugar prices were high, which meant that food prices were higher for the consumer. It was very cheap to produce and at the same time, it was six times sweeter than cane sugar. This is how it started. However there is a problem with HFCS. Sucrose and dextrose can both be broken down in your body before they ever make it to our liver, however fructose does not. It reaches to your liver. HFCS is used for fast food, sodas, cereal, energy bars, and more. Scientists found out that not fructose cause the body to burn sugar as opposed to burning fat. It has been found that our metabolism veers towards fat storage when consuming high levels of fructose. Therefore, HFCS contributes to obesity not only by our brains don't know that our stomachs are full, but also by causing the body to burn sugar rather than fat in our cells.

WHAT ARE THE BAD AFFECTIONS FOR USING ANABOLIC STEROIDS?
Anabolic steroids can harm your health by long-term use or excessive doses. These effects include harmful changes in cholesterol levels. It causes acne, high blood pressure, liver damage, and dangerous changes in the structure of the left ventricle of the heart. Also if you are a sport man, muscle that is built by steroids is considered as cheating. You are not allowed to use steroids. Steroids are only sold at a black market which smuggled or even counterfeit drugs are sold to users.


KEY TERMS
-Carbon Skeleton: the chain of carbon atoms in an organic molecule
-Isomer: compounds with the same formula but different structures
-Hydroxyl Group: consists of a hydrogen atom bonded to an oxygen atom, which in turn is bonded to the carbon skeleton
-Carbonyl Group: linked by a double bond to an oxygen atom. If the carbon of the carbonyl group is at the end of a carbon skeleton, the compound is called an aldehyde. If it's within the chain, the compound is called a ketone
-Carboxyl Group: consists of a carbon double-bonded to an oxygen and also bonded to a hydroxyl group. It acts as an acid by contributing an H+ to a solution and becoming ionized
-Amino Group: composed of a nitrogen bonded to two hydrogen atoms and the carbon skeleton. It acts as a base by picking up an H+ from a solution.
-Phosphate Group: consists of a phosphorus atom bonded to four oxygen atoms. It's usually ionized and attached to the carbon skeleton by one of its oxygen atoms
-Methyl Group: consists of a carbon bonded to three hydrogens
-Enzymes: specialized macromolecules that speed up chemical reactions in cells
-Glycogen: excess sugar that animals store in the form of another glucose polysaccharide

-Phospholipids: the major component of cell membranes. They contain TWO fatty acids attached to glycerol


SUMMARY
     Most of the molecules that a cell makes are composed of carbon atoms. Those molecules, carbon-based, are called organic compounds. Carbon shares electrons with other atoms in four covalent bonds. Methane and other compounds composed of only carbon and hydrogen are called hydrocarbons. Carbon skeleton, the chain of carbon in an organic molecule, can be unbranched as in butane, or branched, as in isobutane. It also includes double bonds, as in 1-butene and 2-butene. They have the same molecular formula, C4H8, but differ in the position of their double bond. Those compounds are called isomers. To determine the properties of organic compounds, we separate them into six chemical groups by their characteristics.
1) Hydroxyl group
2) Carbonyl group
3) Carboxyl group
4) Amino group
5) Phosphate group
6) Methyl group
     There are four main classes of large biological molecules. Carbohydrates, lipids, proteins, and nucleic acids. Cells make macromolecules by joining smaller molecules into chains called polymers. Polymers can be broken down. To digest them, a cell carries out hydrolysis, which is to add water and makes them into OH and H.
     Monosaccharides(CH2O) are the simplest carbohydrates. For example, glucose and fructose are two of them. These can form more complex sugars by hooking with single-unit sugars. Cells construct a disaccharide from two monosaccharides by dehydrating. By dehydration reaction, one oxygen will be left, which is called maltose. HFCS is cheaper than sugar and easier to mix into drinks and processed food since fructose is used, instead of glucose. However it has a problem for obesity. Animals store excess sugar in the form of another glucose polysaccharide, called glycogen in our liver and muscle cells.  Cellulose is the most abundant organic compound on Earth. It is a polymer of glucose. Most animals do not have enzymes that can hydrolyze the glucose linkages in cellulose, so it is not a nutrient for humans. However it contributes to digestive system health. Insects use chitin and crustaceans to build their exoskeleton.
     We store lipids in our body. A fat is a large lipid made from two kinds of smaller molecules, used for energy storage. Cells cannot exist without phospholipids, the major component of cell membranes. They are similar to fats but they contain two fatty acids, instead of three. Anabolic steroids are are synthetic variants of the male hormone testosterone. It builds up muscle and bone mass in males, but it is considered as drug, and it is illegal to use it for human body. Proteins are essential to the structures and functions of life. It is constructed from amino acid monomers. They structure cells, and organisms and participate in everything they do. Proteins need amino acids to like by peptide bonds. A protein has a specific shape that determines its function. The dependence of protein function on a protein's specific shape becomes clear when proteins are altered. In a process called denaturation, polypeptide chains unravel, losing their specific shape and, as a result, their function.
     The primary structure of a protein is its unique sequence of amino acids. In it, there is a secondary structure that holds alpha helix and pleated sheet. There is tertiary structure that has polypeptide, single subunit of transthyretin. And then quaternary structure, that has transthyretin, with four identical polypeptide subunits.



dehydration.gif

This diagram shows a dehydration reaction builds a polymer chain. The short polymer ends with H. And a monomer starts with HO, and ends with H. Between the short polymer and the monomer, H and HO form H2O, and the short polymer and the monomer get together to make a longer polymer. This is a dehydration reaction. It happens a lot our bodies. 


5 FACTS: 
1) Most of the world population is lack of lactase. We are not able to digest milk based food.
2) Organic compounds are the carbon based compounds.
3) Hydrophobic is water fear. It does not dissolve in water. Hydrophilic dissolves in water easily.
4) There are six functional groups. They are all hydrophilic, but methane. Also they are similar.
5) The four basic biological molecules. Carbohydrate, Protein, Lipid, Nucleic Acid.

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