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Introduction Nucleic acids are macromolecules made up of smaller nucleotide subunits. They carry genetic information, form specific structures in a cell or carry out specific roles in a cell. Found in all living things and viruses.* The two most common are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
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Structure Nucleotides consist of A nitrogenous base A pentose sugar A phosphate group*
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DNA Used primarily for the carrying of hereditary information and the recipe for making proteins. DNA contains four different types of nucleotides that differ in their nitrogenous base only. The four bases are: Adenine, Guanine, Cytosine and Thymine.
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DNA The shape of DNA is a double helix, where two nucleotide strands run anti-parallel to each other. It looks like a twisted ladder where the sugar and phosphate groups make up the sides and the nitrogenous bases make up the rungs.
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DNA The nucleotides are held together by two types of bonds. Phosphodiester bonds link the phosphate group of one nucleotide to the sugar of an adjacent nucleotide along the side of the double helix. The nitrogenous bases are held together by hydrogen bonds across a rung.
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DNA In DNA, Adenine will only bind with Thymine and Guanine will only bond with Cytosine based on the number of hydrogen bonds each can form. A and T each form 2 while C and G each form 3.
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RNA Unlike DNA, RNA is single stranded and generally much shorter in length. RNA uses nucleotides Adenine, Cytosine and Guanine, but instead of Thymine, it uses another pyrimidine, Uracil. There are three different types of RNA. They all play important roles in protein synthesis.
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mRNA 1) Messenger RNA decodes the DNA code (“protein recipe”) and takes it from the nucleus to the ribosome.
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tRNA 2) Transfer RNA brings amino acids to the ribosome to be incorporated into the newly forming polypeptide chain.
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rRNA 3) Ribosomal RNA is what makes up the ribosomes, where proteins are made in the cell.
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Other Important Nucleic Acids 1) Adenosine Triphosphate (ATP) which is the energy currency of the cell. 2) NAD, FAD, GDP and NADP, which are high energy electron carrying molecules used in cellular respiration or photosynthesis.
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Introduction Protein production relies on complex interactions among organelles. Protein synthesis is important because nearly all cell processes require proteins. Ex: A spider produces proteins in order to spin a web and humans produce hemoglobin in order to transport oxygen to all the cells and take carbon dioxide away.
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Protein Synthesis Protein synthesis refers to making proteins. It occurs in a 6 step process in all cells: 1. The DNA that codes for a protein is copied onto a similar molecule called messenger RNA (mRNA). This happens in the nucleus and is called transcription.
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Protein Synthesis Remember RNA uses Uracil instead of Thymine, so when DNA has an Adenine molecule, the RNA molecule will have a Uracil bound to it.
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Protein Synthesis 2. The messenger RNA carries the coded message from the nucleus to ribosomes in the cytoplasm. It exits the nucleus through the nuclear pore.
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Protein Synthesis 3. A ribosome clamps onto the mRNA and the code for protein (codons) begins to get translated into amino acids, the building blocks of protein.
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Protein Synthesis 4. Special molecules called transfer RNA (tRNA) bring the amino acids the recipe calls for to the ribosome in the correct sequence specified by mRNA.
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Protein Synthesis 5. Two tRNAs can be at the ribosome at one time. When two are there, one will attach its amino acid to the amino acid of the other one, creating a chain of amino acids. Once this happens, that tRNA leaves and the one with the chain moves to its place.
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Protein Synthesis 6. Once the entire mRNA is read by the ribosome all the parts will separate. The amino acid chain will then fold into a functional protein. The others will wait for another chance at translation.
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