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DNA and proteins (Chapter 16 ((Proteins involved with DNA Replication and…

- - - - Helicases- enzymes that untwist the double helix at the replication forks, separating 2 parental strands.
      - Topoisomerase- enxyme that helps relieve this train by breaking, swiveling, and rejoining DNA strands.
      - Single strand binding proteins- bind to the unpaired DNA strands, keeping them from re-paring
      - DNA plymerases- catalyze the synthesis of new DNA by adding nucleotides to the end of a pre-existing chain
      - Nuclease- cuts damaged DNA strands
    - - Chromatin are pieces of a chromosome that consist of DNA, RNA, and proteins.
        
        Chromosomes are a combination of 2 chromatin
        
        DNA and proteins are what make a chromatin, because the chromatin protects the DNA
    - - a DNA nucleotide monomer is made of a nitrogenous base, (Thymine, Guanine, etc.), a sugar deoxyribose, and a phosphate group.one of these is then paired up with others by covalent bonds to make a "ladder" which makes a double helix. the information of genetic inheritance is carried on the nitrogen bases that connect to each other.
- - - - Translation
        
        When a molecule of mRNA is moved through a ribosome, codons are translated into amino acids. the translators are tRNA molecules, each type with a specific anticodon at one end and a corresponding amino acid at the other end. a tRNA adds its amino acid cargo to a polypeptide chain when the anti codon bonds to the complementary codon on the mRNA.
        
        Transfer RNA (tRNA)- function is to transfer an amino acid from the cytoplasmic acid pool of amino acids to a growing polypeptide in a ribosome.
        
        Anticodon- particular nucleotide triplet that base pairs to a specific mRNA codon.
        
        Ribosomal RNA- molecule that forms part of a ribosome, and ribosomes facilitate the specific coupling of tRNA anticodons with mRNA codons during protein synthesis.
    - - Occurs in Nucleus
        
        Elongation- the polymerase moves downstream, unwinding the DNA and elongating the RNA transcript. DNA strands make a double helix again during transcription.
        
        Termination- eventually, the RNA transcript is released, and the polymerase detaches from the DNA.
        
        Initiation- After RNA polymerase binds to the promoter, the DNA strands unwind, and the polymerase initiates RNA synthesis at the start point on the template stand
    - - Alteration of mRNA- enzymes modify 2 ends of a eukaryotic pre-mRNA molecule. modified ends might promote the mRNA leaving the nucleus, and they help protect the mRNA from degradation.
        
        RNA splicing- large portions of the RNA molecules are removed and the left over portions are reconnected.
        
        Introns and Exons- the nono coding segments of nucleic acid in between coding regions are introns. the other regions are exons.
        
        Spliceosome- made of proteins and small RNA, this complex binds to several short nucleotide sequences along an intron, and it joins 2 exons to catalyze the splicing reaction
        
        Ribozymes- RNA molecules that are like enzymes.