Biological molecules

DEHYDRATION SYNTHESIS AND HYDROLISIS

   Dehydration synthesis joins monomers together by taking H2O away, hence the dehydration part of the name. On the other hand, hydrolysis is the exact opposite of dehydration synthesis it is the breaking of polymers into units by adding H2O. Here is a link to a video that shows you a better understanding of these two concepts: http://youtu.be/_Ai5NyQ_ttE

This is dehydration synthesis. See how it is taking away the H2O and then the two monomers bond together with the oxygen and become a polymer.

     This is hydrolysis. See how they are ADDING H2O which causes the polymers to split apart and become monomers.

CARBOHYDRATES

The name comes from hydrated carbons. Carbohydrates empirical formula is (CH2O)n where n equals the number of times the chain is repeated. Carbs are made up of C,H and O and have a ratio of 1carbon:2hydrogen:1oxygen. 

There are a couple different types of carbohydrates. The first type is monomers which are monosaccharaides. Specific examples are glucose, fructose, ribose and deoxyribose. Another type of carbohydrates are disaccharides, this is when 2 monosaccharaides join together. Some examples are; glucose+glucose forms maltose, glucose+fructose form sucrose and galactose+glucose form lactose. The last type is polysaccharides. This is when many saccharides are joined together forming what looks like a chain. There are 4 different types of polysaccharides that i will go deeper on and explain them a bit more, which are cellulose, starch, glycogen and chitin. 

     Cellulose is a long chain without any side chains. One can remember this by thinking of celery and how celery is straight just like the chain of glucose molecules. Plants use cellulose as protection and structure, it is in the cell walls of plants. The linkage between the carbon atoms of sugars are different than the bonds in starch and glycogen, no mammal can break this bond. This is why we cannot digest cellulose(fiber). 

     Starch is made up of many glucose molecules linked together in a straight chain with a few side chains. Plants store their energy as starch. Below is a picture of a starch chain, notice how it only has one side chain.

  Glycogen is made up of many glucose molecules linked together with many side chains, unlike starch that only has a few. Glycogen is very important to us animals. We store our energy as glycogen in our liver and muscles.  Below is a picture of a glycogen chain. Again notice how it has more than just one side chain. If this picture was extended then you would be able to see how it has many side chains as suppose to starch. 

  

  The last polysaccharide is chitin. It is made by animal and fungi. Chitin is made of long glucose chains linked with covalent bonds, which are very strong. It makes structures like exo-skeleton, fingernails, claws and beaks. This is was chitin looks like structurally.

A main function if carbohydrates is energy. When the bonds between carbon atoms are broken, the energy is released and can be used by cells. Starch stores energy in plants, and glycogen stores energy in animals. Another function is structural. Cellulose is the major structural and protection compound in plants.

 

 

 

LIPIDS

     There are 4 main uses for lipids and they are long term storage for energy, insulation and protection, they make some hormones(ie. steroids) and they are the structure of the cell membrane. The structure of a lipid is made up of Carbon, Hydrogen and Oxygen, just like a carbohydrate. However, in a lipid there is no set ratio for these elements. There are three types of lipids and they are triglycerides(neutral fats), phospholipids and steroids.

     Triglycerides are composed of three fatty acids bonded to one glycerol. The fatty acids contain a long chain of carbons with an acid end. The glycerol is a small three carbon chain with three alcohol(OH) groups. The fatty acid and glycerol bond together via dehydration synthesis. There are two types of triglycerides which are saturated and unsaturated fats. The difference between these two types of triglycerides are that in a saturated fat there is no double bonds in the carbon chains of the fatty acids, where in a unsaturated fat there is one or more double bonds. Also, a saturated fat is solid at room temperature, come from animals and are considered unhealthy. A unsaturated fat is liquid at room temperature, come mostly from plants and are considered healthy.



 

     Phospholipids are used to make up the two layered cell membrane of all cells. They are similar to a triglyceride but the third fatty acid group of a triglyceride is replaced by an inorganic phosphate group (PO4 3-). A phospholipid has a polar head that is water soluble(hydrophilic) and the non-polar tail is not water soluble (hydrophobic). There are a couple different ways that they display phospholipids. Here are some of them:

 

 

 

   A steroid is the last type of lipid I will be talking about. Steroids look different than all the rest of the lipids. They are made up of four carbon ring and the molecules are fused together. They kind of look like four honeycombs stuck together. The use of steroids is to create some hormones, cholesterol and vitamin D. Some types of steroids are testosterone, estrogen, cholesterol and vitamin D.

 

 

PROTEIN

     The functions of a protein is structural because they help make up all structures in living things for example, actin and myosin are muscle proteins, keratin is found in like nails and hair, collagen is found in bones, teeth, cartilage etc. Another function of a protein is functional, they help our bodies functioning properly and to digest our food. This is done by enzymes, which are proteins that are catalysts which speed up reactions and control all cell activities. The final function of a protein is they can act as a food source, once we have used up all of our carbohydrates and fats, proteins will be used for energy. However, proteins are worth the least amount of energy that is why they are saved for the last resort.  Proteins are made up of carbon, hydrogen, oxygen, nitrogen and maybe sulfur but in no set ratio. Proteins are chains of amino acids that bond together via dehydration synthesis. An amino acid has three parts: Amine Group (NH2 or HH3+) which acts as a base(accepts H+), Carboxyl Group (COOH or COO-) and it acts as an acid (donates H+) and the R Group which have twenty different combinations. When amino acids bod together they bond with a peptide bond which is formed between carbon and hydrogen and one water molecule is lost. If only two amino acids are together it is called a dipeptide if the chain becomes three then it is called a tripeptide. After that, when the protein chain has more than three amino acids it is called a polypeptide. Every protein is different because the order of amino acids are different.

 

 

   The levels of Protein Structure:

       Primary structure is simply when the amino acids bond together with peptide bonds. The protein depends on the order of the amino acids, if they are not in the right order then the protein may not be able to do its job.

       Secondary structure is when hydrogen bonds form between the amino acids positive (amine group, NH3+) from one amino acid and negative(carboxyl group) from a different amino acid. This bond makes the chain twist into either an alpha helix or a beta pleated sheet.

       Tertiary structure happens between the R Groups. The interactions is between  + and - attractions and sulfur sulfur bridges. The positives and negatives will attract each other and the same charges will repel each other. That makes the structure to fold into a highly specific 3-dimentional shape. The shape determines the protein's job or role it will play in the body.

      Quaternary structure is not seen in all proteins, this is where two or more molecules join together with an ionic bond to form a functional protein. Some examples are Insulin with two subunits or Hemoglobin with four subunits.

 

 

NUCLEIC ACIDS

 

   Nucleic acids are acidic molecules that are found in the nucleus of cells. There are two type and they are deoxyribonucleic acid(DNA) and ribonucleic acid (RNA). All nucleic acids are made up of units called nucleotides which are made up of three sub-molecules: Pentose sugar(ribose or deoxyribose), Phosphate, Nitrogen base (purine or pyrimidine). Adenine and Guanine are purines, they have two rings and are both found in DNA and RNA. Cytosine, Thymine and Uracil are pyrimidine's, they have only one ring and Cytosine is found in both RNA and DNA, however, Thymine is found in DNA and Uracil is found in RNA. A purine always matches up with a pyrimidine in a nucleic acid. A memory trick for a purine is "Its got 2 be GAp". The 2 represents the two rings and the GA represent Guanine and Adenine. A memory trick for pyrimidine is that "CUT the pyramid". The CUT stands for Cytosine, Uracil and Thymine and the pyramid reminds one of the single blocks the Egyptians had to cut for the pyramids, therefore it has one ring.

 

  A DNA strand is composed of nucleotides and a sugar phosphate backbone. The nucleotides go together with their complementary base pair, which is A-T and G-C. Adenine and Thymine bond together with two hydrogen bonds and Cytosine and Guanine bond together with three hydrogen bonds. The sugar phosphate backbone is formed after all of the complementary bases are paired up then it twist into a double helix. The main function a DNA is to direct and control all cell activities by making proteins and enzymes. The also contain all of the genetic information necessary to make one complete organism.

 

   Some of the difference between RNA and DNA is that DNA is confined to the nucleus and RNA can move to the cytoplasm. RNA has ribose sugar instead of deoxyribose and RNA has Uracil instead of Thymine like DNA. DNA is a double helix as suppose to RNA is a single helix. There are three types of RNA (mRNA, tRNA, and rRNA) and there is only one type of DNA. RNA's function is mainly to assist DNA in making proteins.

 

    Adenosine Triphosphate:

ATP is also thought of as a nucleic acid because it has a similar structure as a nucleotide. The only difference is that it has three phosphate groups instead of one. In a ATP molecule there is three phosphates (Triphosphate) a sugar and an adenine (Adenosine). ATP is the energy source of the body. This is because it takes a lot of energy to put two phosphate molecules together so when they are broken apart a lot of energy is released.