The+Genetic+Code

The Genetic code (HL)

Vocabulary:
Chromosomes : "Any of several threadlike bodies, consisting of chromatin, that carry the genes in a linear order" "A threadlike structure of nucleic acids and protein. Located centrally in the nucleus of living cells. Mainly carries genetic information in the form of genes.

Cytoplasm : "Area in which most cellular process occurs." "Main material within a living cell or the protoplasm within it (excluding the nucleus)

DNA :(Deoxyribonucleic acid):

"Molecule containing the biological instructions that make each species unique. As well as the instructions it provides to organisms it is from adult organisms to their offspring during reproduction." DNA is an extremely long macromolecule that is the main component of chromosomes and is the material that transfers genetic characteristics in all life forms, constructed of two nucleotide strands coiled around each other in a ladder like arrangement. The ladder is composed of a par of chemical groups identified as base pairs (specifically four types mentioned below) with the side pieces composed of alternating phosphate and deoxyribose units and the rungs composed of the [|purine] and pyrimidine bases adenine, guanine, cytosine, and thymine: the genetic information of DNA coded in the sequence of the bases and is transcribed as the strands unwind and replicate."
 * self-replicating material
 * Present in all living organisms
 * Main constituent of chromosomes
 * Carrier of genetic information

DNA (double helix) : Term used to describe the DNA structure. It is a winding double-stranded chemical structure creating a twisted-ladder looking structure. The reason DNA is shaped in such a way is due to its ability and purpose to pass along biological instructions precisely.



Diploid : A cell or nucleus contains two complete sets of chromosomes being one from each parent. An organism is composed of diploid cells "Having two similar complements of chromosomes."

Gamete : "A [|mature] sexual reproductive [|cell], as a sperm or egg, that unites with another cell to form a new organism (zygote)."

Gene :"the basic physical unit of heredity; a linear sequence of nucleotides along a segment of DNA that provides the coded instructions for synthesis of RNA, [|which], when translated into protein, leads to the [|expression] of hereditary character."
 * unit of heredity
 * transfered from parent to offspring
 * Determines particular characteristics of offspring (proteins coded directly by genes)
 * Specific part of nucleotide which forms part of a chromosome
 * The order of monomers in a polypeptide or nucleic acid depend on the order of the gene sequence
 * Synthesized by cell (or virus)

Nucleus : A specialized, usually spherical mass of protoplasm encased in a double membrane, and found in most living eukaryotic cells, directing their growth, [|metabolism], and reproduction, and functioning in the transmission of genic characters. The nucleus is a dense organelle present in most eukaryotic cells. It is usually a rounded structure and is bounded by a membrane (double membrane) containing genetic material.

Protein : "any of numerous, highly varied organic molecules constituting a large portion of the mass"
 * Any of a class of nitrogenous organic compounds
 * composed of one or more long chains of amino acids making them relatively large molecules
 * Essential to the life of all organisms
 * structural components of body (tissues,hair,collagen,muscles as well as activity with enzymes and antibodies)

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Objective:

The Double Helical Structure of DNA:
What is DNA made up of? DNA is made of chemical building blocks called nucleotides. The building locks are composed of three main parts. 1. Phosphate group  2. Sugar group  3. 1 of four nitrogen bases (Adenine (A), Thymine (T), Cytosine (C), Guanine (G))  In order to complete a strand of DNA nucleotides bond/link into chains with the alternating sugar groups and a phosphate group. The nitrogen bases are vital to understand the instructions of DNA as the order or sequence of these bases determines the specific biological instructions in a strand of DNA. Sequences are composed of six letters and may instruct for target phenotypes (visible traits where genotypes are the biological traits) such as eye color, height or ear lobes. Every DNA sequence instructed to create a protein is known as a gene. Gene sixes vary greatly in the amount of bases in a human ranging from 1,000 to 1 million. The genome of a human being how ere, contain up to 3 billion bases composed of up to 15,000-20,000 genes of 23 pairs of chromosomes. What does DNA do? DNA contains the instructions for the functioning of any organism to develop, survive and reproduce (undergo all functions of life). DNA sequences are converted into biological messages in order to carry out such functions as well as produce proteins as they are complex molecules that are responsible for most of the work in a human body. DNA sequences and Proteins? Proteins are made in a two-step process. It is in this case where enzymes begin to apply. Enzymes read the information in a DNA molecule where it then transcribes it to form a molecule called messenger ribonucleic acid or mRNA (intermediary molecule). From this step, translation then takes place to convert the message into amino acids which are the fundamental building blocks of proteins. This message then instructs the exact amino acids to link in a specific and precise order to produce specific proteins. There are 20 types of amino acid placed in many orders. How does this all apply to the DNA double helix structure? The DNA double helix is a double stranded chemical structure creating a twisted-ladder looking structure. The reason DNA is shaped in such a way is due to its ability and purpose to pass along biological instructions precisely. The strands of the double helix are anti-parallel as they run in opposite directions. The sugar-phosphate group however, is the backbone of the structure located on the outside of the helix (which can be thought of as the sides) complimenting the inside containing the bases. The bases are composed of two base pairs. Either adenine-thymine or cytosine-guanine which form either a two hydrogen bond or a three-hydrogen bond respectively. The DNA is unzipped leaving one side with the un-paired bases (like a comb) where each split half then becomes the original strand in order for a complimentary strand to be created. The split strand is then matched to another and once the doubling is completed two new copies of the original strand are then created.

The Chromosome A principle of cell division is that the genetic information passed on to the resulting cells is exactly the same as it was before the process. This ensures that each organ of the body is able to achieve its purpose. The information is preserved through the use of chromosomes. Chromosomes are long strands of Delix NA and proteins that are found in the nucleus, they contain many genes. DNA solely resides in the nucleus.

Human beings are a diploid organism and thus have 46 chromosomes that are paired up to form 23 pairs of chromosomes in our somatic (normal) cells. When a human being copulates with another it passes on 23 chromosomes that are found in sex cells called (gametes). These get coupled with the other humans so that these chromosomes result in zygotes and the offspring also has a total of 23 paired chromosomes.

DNA continuace:

Through the process of cell division, the DNA strand begins to partly unzip at one end due to breaking of hydrogen bonds. This can be seen through the middle image below.

As it is seen corresponding nucleotides (sugar based units) will then join their respective couples at each end of the DNA chain. Since adenosine can only form a hydrogen bond with thymine (A--T) and guanine can only form a hydrogen bond with cytosine (G--T) the new complementary DNA strands that are produced will be exactly the same as the DNA strand previous to the separation. This ensures that the same genetic information prevails.

The DNA as seen above lies in a sequence of bases. Each three bases is an amino acid. These three bases are known by the "Triplet Code" that allows a total of 64 permutations known as codons. Codons allow to create the total of 20 amino acids. Different codons can create the same amino acid.

Protein Synthesis:

It is worth to note, that DNA can only undergo this procedure in the nucleus, where as protein synthesis occurs in the cytoplasm. media type="custom" key="25007330" The video above explains the process that DNA undergoes so that a protein can be created.
 * DNA becomes RNA through a similar unzipping process.
 * Sugar unit is changed to ribose, and thymine is replaced by uracil.
 * MRNA positions itself on a sub-unit of a ribosol, used for protein assembly.
 * MRNA calls a TRNA, the first three nucleotides must match with the MRNA for the TRNA to attach.
 * The amino acids of several TRNA strands get bonded together for each three nucleotides that bond with the TRNA.
 * The amino acid chain starts growing and it also begins to twist in the shape that is crucial for its purpose.
 * Once the chain is completed, the protein is done.
 * Hundreds of proteins can be produced per second.

DNA Profiling:
"DNA has had a huge impact on everything from genealogy to even the court system." Every person can have a profile identified solely using DNA thus aiding in investigations such as forensic or paternity cases. DNA yields a lot of information however the way it is processed and analyzed is where DNA profiling is involved.

In such cases DNA can be found in a very tiny amount but even the smallest amount would suffice for further investigation. First a polymerase chain reaction is used to amplify a minute amount of DNA. This has to be done because a large amount is needed for testing. DNA can be found from semen, blood, tissues, finger nails, saliva etc.

Gel Electrophoresis is key in DNA profiling. In Gel electrophoresis there are fragments of DNA which move in an electric field and are distinguished and separated by their size.

Organisms have short sequences of bases which repeat and are called satellite DNA. The length of these sequences vary from person to person thus allowing identification of an individual. The DNA is copied using PCR then cut up in small fragments using restriction enzymes. According to the size and charge as previously mentioned the gel electrophoresis separates the DNA. From this a pattern of bands from the gel is formed and it is most likely that no two will be the same allowing to identify different people. In crime scene investigations this is used as they most similar bands of DNA are matched to that of a suspects and the DNA found in a crime scene. For a paternity test the same thing is employed looking for similarities between a father and child.



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