DNA, Nucleic Acis and Protein Synthesis Mind Map

A descriptive Mind Map for anyone stdying OCR GCE AS Biology A, trying to get thier head around the tricky and complecated topic of Nucleic Acids. It covers Nucleic Acids, DNA, RNA and Protien Synthesis. It took me a long time for this topic to click and stick in my head, when it did i made this to help it stay in my head, but also for other to try to help them, which i hope it does. This Mind Map is great for visusal learners who are stimulated by colours to help them learn. ENJOY!

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  • DNA and Nucleic Acids
    • Nitrogenous Bases
      • Purines
        • Adenine
        • Guanine
          • Cytosine
        • The smaller of the two nitrogenous bases. It has a single carbon ring structure
      • Pyrimidines
        • Thymine
          • Adenine
        • Cytosine
        • Uracil (Only in RNA)
          • The larger of the nitrogenous bases, it has  a double-carbon structure.
        • In DNA and DNA replication Adenine and Thymine will share the 2 hydrogen bonds. However In RNA and RNA replication, Thymine is substituted by Uracil. This is one of the KEY differences between DNA and RNA
        • Phosphate Group
          • Nucleotides
            • Are the monomer of a Polynucleotide, which is a strand of DNA/RNA.
            • Nucleotides are linked together by condensation reaction, causing Polynucleotide, this happens because the phosphate group on the 5th pentose sugar (5') of one nucleotide forms a covalent bond with the Hydroxyl group (OH) of the next nucleotide on the 3rd carbon (3'). These are known as phosphodiester bonds. This forms the sugar-phosphate backbone.
          • Are Acidic, hese DNA and RNA being forms of Nucleic Acids, create a Phosphodiester bond between the Phosphate (PO_4^7) group and the nitrogenous bases
      • DNA
        • DNA stands for- Deoxyribonucleic Acid. The Deoxyribose is the sugar found, and I has one less oxygen atom then that of Ribose.
      • The Double Helix
        • The DNA molecule can vary in length from a few to millions of nucleotides.
        • It is made up of two strands of Polynucleotides and coiled together to form a Helix of DNA.
        • It is held together by Hydrogen bonds between the bases- A and T share 2 H Bonds, while C and G share 3 H Bonds. It looks much like the runs of a ladder. Each strand has a phosphate (5') at one end and as Hydroxyl at the other (3'). This is arranged so that they both run in opposite directions from each other- they are said to be ANTIPARALLEL
      • RNA
        • RNA stands for Ribonucleic Acid. Ribose of the sugar found in it.  RNA is used in forms of it called- mRNA and tRNA.
        • mRNA- Messenger RNA.
        • tRNA- Transfer RNA
        • rRNA- Ribosomal RNA
      • DNA Replication
        • DNA
          • DNA stands for- Deoxyribonucleic Acid. The Deoxyribose is the sugar found, and I has one less oxygen atom then that of Ribose.
        • When a cell prepares to divide , the two strands that make up the Double Helix, part from each other and acts as templates for a new double-stranded DNA molecule. The complementary base pairing rule makes sure that they are identical. this is known as DNA Replication.
        • When the strands of DNA break parts of the strands are let free and aline themselves up with each other, this is copied and then H Bonds form, between the bases, and both new strands of DNA coil up, this is known as Semi-Conservative replication because it takes some of the old parts of the DNA and creates some new ones.
        • Enzymes play a role in this too. DNA Helicase goes along the backbone of the DNA catalysing reactions that break the H Bonds between the bases, this can be seen a the DNA 'Unzipping'. Then another Enzyme, called DNA Polymerase catalysis the reaction between the free nucleotides that form the new Phosphodiester bonds.
        • Replication errors can occur and these can be spontaneous, changing the code and genetics, making changes to what that code will or wont do, this is known as a mutation.
        • Protein Synthesis
          • Transcription
            • Chromosomal DNA is encased in a nuclear envelope to protect it from the cytoplasm of a cell. It is also to big to leave this envelope, so in Eukaryotic cells, they produce smaller chains of RNA to send to the Ribosome for protein synthesis.
            • DNA Helicase unravels and Unzips the DNA helix and at the start codon. As only one of the two DNA strands carry the DNA code (the Sense strand) the other acts as a template for the RNA to copy itself from.
            • Free RNA nucleotides pair up with the exposed parts of RNA on the antisense strand, and as thymine is not in RNA, Uracil takes its place in binding to Adenine. Phosphodiester bonds form between the RNA Nucleotides with help form RNA Polymerase and then the short RNA chain breaks from its template, and leaves to the Ribosome via nuclear pores of the Nuclear envelope, it is now called mRNA. The DNA then ravels and zips itself back up reforming H Bonds and Phosphodiester bonds.
          • ATP
            • Non of this could have been possible without the energy delivered by ATP. It stands for Adenine Tri Phosphate. Three phosphate groups and a adenine molecule are joined to a ribose sugar, this not only provides energy but also provides energy for most of our bodily functions, its very important.
      • Translation
        • Transcription
          • Chromosomal DNA is encased in a nuclear envelope to protect it from the cytoplasm of a cell. It is also to big to leave this envelope, so in Eukaryotic cells, they produce smaller chains of RNA to send to the Ribosome for protein synthesis.
          • DNA Helicase unravels and Unzips the DNA helix and at the start codon. As only one of the two DNA strands carry the DNA code (the Sense strand) the other acts as a template for the RNA to copy itself from.
          • Free RNA nucleotides pair up with the exposed parts of RNA on the antisense strand, and as thymine is not in RNA, Uracil takes its place in binding to Adenine. Phosphodiester bonds form between the RNA Nucleotides with help form RNA Polymerase and then the short RNA chain breaks from its template, and leaves to the Ribosome via nuclear pores of the Nuclear envelope, it is now called mRNA. The DNA then ravels and zips itself back up reforming H Bonds and Phosphodiester bonds.
        • This takes place in the Ribosome. The Ribosome has 2 sub-units, one large and one small, a protein and a form of RNA called rRNA, helps keep the stability of these sub-units and has a vital part in the next step of protein-synthesis.
        • mRNA bind to a specific site on the ribosome, the ribosome then decode or Translates the sequence.
        • At the bottom of the tRNA their are 3 bases, these bases help code for an amino acid, with the help of a protein at the top of the tRNA.
        • As this can not happen all at one, that chain of amino acids is built up one by one, as this happens peptide bonds form between them, and soon a whole chain is formed. When it is it is known as a Polypeptide chain due to the may peptide bonds formed.

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