Protein Synthesis
Alleles are pairs of genes found in certain positions in the chromosomes (see figure 1). Chromosomes are threadlike strands of DNA and protein. Chromosomes are located in the nucleus of most living cells carrying genetic information in the form of genes (see figure 2). Alleles determine the genotype of an organism. The Genotype shows what alleles an organism has by letters either being upper or lower case (see figure 3). These DNA codings determine different traits that the parents can pass on to their offspring. A trait is a genetically determined characteristic. Half of a persons alleles come from the mom and the other half comes from the dad.

Working subunits of DNA are called genes. Every gene has a certain set of instructions with the coding of a specific protein. Genes are mainly used to make a specific protein or protein components for a cell. Also genes are used to pass those instructions to the next generation.

A protein molecule depends on how the amino acids are linked. An amino acid is the building block of a protein (see figure 4). The way the amino acids are sequenced gives the protein a code; which distinguished it from other proteins. Genetic code, located in the DNA, decides the code for the amino acid. The genetic code is made up of the order of nitrogenous bases in the DNA. A nitrogenous base is a molecule that has nitrogen and chemical properties of a base. DNA's nitrogenouse bases are adenine (A), guanine (G), thymine (T), and cytosine (C). RNA's nitrogenous bases are alike to the nitrogenous bases of DNA except for one nitrogenous base which is uracil (U) (see figure 5).

In order for protein synthesis to happen many matrials are needed. For example 20 amino acids, enzymes, DNA, and RNA are important for protein synthesis.

RNA is a nucleic acid that takes instructions from DNA into the cells cytoplasm where protein is made. RNA and DNA are very close related except for two differences. First, the carbohydrate in RNA is ribose and not deoxyribose. Carbohydrates are a group of organic compoumds like sugar and starch; it is a major source of energy to animals and plants. Second, RNA nucleotides consist of pyrimidine uracil instead of thymine. Nucleotides are made up of sugar, phosphate, and a nitrogen base. When nucleotides are joined together they form RNA and DNA.

In the process of making protein, three different types of RNA take place. One type is called ribosomal RNA (rRNA). Ribosomal RNA make ribosomes. Ribosomes are where the amino acids are linked together to produce protein. Ribosomes are located by the membranes of the endoplasfmic reticulum (ER) or in the cytoplasm of a cell (see figure 6).

In addition, to ribosomal RNA; there is also transfer RNA (tRNA). Transfer RNA is in the cells cytoplasm and carries amino acids to the ribosomes to make protein. When protein synthesis is occuring, enzymes link tRNA molecules to amino acids in an specific ordered way. For instance, tRNA molecule N will connect only to amino acid N; tRNA J will connect only to amino acid J.

The third type of RNA is messenger RNA (mRNA). mRNA occurs in the nucleus, messenger RNA recieves the genetic code and takes it into the cytoplasm where protein is being made. In the DNA molecules, messenger RNA is manufactured. While mRNA is being made the genetic information from a DNA molecule is handed down to the mRNA molecule. An enzyme called RNA Polymerase performs mRNA, tRNA, and rRNA synthesis.

Transcription is one of the first processes in the making of protein. In transcription, a complementary strand of mRNA is created depending on the nitrogenious base code of DNA. To start, the enzyme RNA polymerase connects to a part of a DNA molecule in the double helix (a section of the DNA molecule unwinds itself leaving a gene for a protein exposed). While transcriptin is occuring one DNA strand is being used to make RNA and the other strand stays dormant. The enzyme RNA polymerase moves on the