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DNA (Making Proteins has the steps : Transcription, Translation, and RNA…

- - - - The 2 nucleic acids are rewritten from DNA to RNA , the DNA is the template for assembling a sequence of RNA nucleotides. RNA molecule mRNA carries genetic message from DNA to protein synthesizing areas of the cell
        
        RNA polymerase (enzyme) separates two DNA strands and join RNA nucleotides to the DNA template strand. RNA Poly assembles polynucleotides in one direction and starts from scratch.
        
        The promoter is the DNA sequence where the RNA polymerase attaches. The terminator: is where the end of transcription is ( in bacteria). Promoter is upstream from terminator, the stretch in between is transcription unit
        
        Initiation , Elongation, Terminination
        
        Initiation: After RNA poly bonds to promoter, DNA unwinds, polymerase initiates RNA synthesis at start on temp strand
        
        Elongation: Polymerase moves downstream , unwinding DNA elongating RNA transcript DNA reforms double helix
        
        Termination: the RNA transcript is released and polymerase detaches from the DNA
  - - - There is a change in language. Goes from nucleotide sequences of mRNA to amino acid sequences of polypeptide. Ribosomes are the site of translation, that facilitates the linking of amino acids into a polypeptide chain
        
        Transfer RNA (tRNA) : transfers an amino acid form the cytoplasmic pool of amino acids .
        
        Initiation , Elongation, Termination
        
        Initiation: mRNA, tRNA bearing the first amino acid fo the polypeptide, and small ribosomal subunit , attached by the large ribosomal subunit makes the translation initiation complex
        
        Elongation : amino acids are added one by one to the previous amino acid at the C terminus . The ribosome and the mRNA are move relative to each other , codone by codone. Empty tRNAs released from E site return to cytoplasm
        
        Termination: When a ribosome reaches a stop, A site accepts a protein shaped like a tRNA instead of the aminoacyl t RNA. The release factors frees the polypeptide from ribosome. Two ribosomal units and other components disassociate with the hydrolysis of two GTP molecules
        
        Transfer RNA has the anticodon, and aminoacyl-tRNA synthetases .
  - - - RNA splicing - large portions of RNA molecules are removed and remaining portions are reconnected
        
        Introns- intervening sequences, the non coding segments of nucleic acid that lie between coding regions
        
        Exons- usually being translated into amino acid sequences.
        
        Spliceosomes : removes introns , a large complex made of proteins and small RNAs
        
        Ribozymes: RNA molecules the function as enzymes.
- - - - Polynucleotide strands have directionality. 5' end has the phosphate group, 3' end has the (-OH group of sugar)
- - - - DNA polymerase III makes a new strand by reading nucleotides on template strand and adding one nucleotide the T to an A
        
        The lagging strand is made by DNA Polymerase III , making Okazaki fragments, then the gaps left , are filled by ligase , joining sugar phosphate backbones into a DNA strand
  - - - DNA Primase- primer is required to bind at the origin . Primers- short RNA synthesized by primers
        
        DNA Polymerase III- makes new strand from information on remplate strand . Reading A makes a T. 5' to 3'.
        
        DNA Polymerase I- removes primer with RNase H and fills in gaps
        
        DNA ligase- creates Okazaki fragments.
- - - - NUcleotide excision repair- a DNA repair system Enzymes detect and repair damaged DNA , nuclease cuts damage at two points. Repair synthesis by DNA polymerase, and ligase seals the free end