Please enable JavaScript.

Coggle requires JavaScript to display documents.

Ch 16/17 (DNA (James Watson and Francis Crick (Development (Psychological,…

- - - - consists of monomers of nitrogenous bases
        
        Thymine
        
        Adenine
        
        Cytosine
        
        Guanine
        
        the"ribbons" in simplified double helix diagrams represent the sugar-phosphate backbones
        
        light blue is used to show more recently synthesized strand
        
        sometimes the double-stranded DNA molecule is shown simply as two straight lines
        
        antiparallel, sub units run in opposite directions
        
        presence of two strands accounts for the now-familiar term double helix
        
        flattened "ladder style" diagrams of DNA depict the sugar-phosphate backbones like the side rails of a ladder
        
        Read 3' to 5' end (old strand)
        
        Write 5' to 3' end (new strand)
    - - Psychological
      - Anatomical
      - Biochemical
    - - cells repair their DNA
      - packaged together with proteins in a chromosome
  - - - transformation, change in genotype and phenotype due to the assimilation of external DNA
      - studied two strains of the bacterium Streptococcus
        
        S (smooth) strain caused pneumonia in mice
        
        it is pathogenic because the cells have an outer capsule that protects them from an animals immune system
        
        R (rough) strain lack a capsule and are non pathogenic
  - - - "bacteria eaters"
      - phages
    - - little more than DNA or sometimes RNA enclosed by a protective coat
      - protein coat
  - - - Agitated the mixture in a blender to free phage parts outside the bacteria from the cells
      - Centrifuge the mixture so that bacteria formed a pellet at the bottom of test tube; free phages and phage parts, remained in the liquid (lighter)
      - mixed radioactively labeled phages with bacteria. The phages infected the bacterial cells
      - measured the radioactivity in the pellet and the liquid
    - - unlike batch 1, phages were grown with radioactive sulfur, which was incorporated into phage protein (pink)
      - phages were grown with radioactive phosphorus which was incorporated into phage DNA (blue)
  - - - two DNA strands are separated, each parental strand can now serve as a template for a new comp strand
      - nucleotides comp to the parental strands are connected to form the sugar- phosphate backbones of the "daughter" strands
      - parental molecule has 2 complementary strands of DNA, each base is paired by hydrogen bonding with its specific partner
    - - Semi conservative
        
        2 strands of the parental molecule separate, each functions as a template for synthesis of new comp strand
      - Dispersive model
        
        each strand of both daughter molecules contains a mixture of old and new synthesized DNA
      - Conservative model
        
        2 parental strands reassociate after acting as templates for new strands
- - - - Leading strand, moving towards the replication fork
      - Lagging strand, DNApolymerase ust work in the direction away from the replication fork
      - Okazaki fragments, lagging strand that is synthesized as a series of segments
      - DNA ligase, what fragments are joined toegther by
  - - - DNA ploymerase 2 makes the Okazaki gragment 1
      - DNA pol 3 detaches
      - Primase makes RNA primer
      - fragment 2 is primed
      - DNA pol1 replaces RNA with DNA, DNA ligase forms bonds between DNA fragments, lagging strand is complete
  - - - DNA polymerases, catalyze the synthesis of new DNA at a replication fork
        
        most DNA polymerases require a primer and a DNA template strand
        
        Each nucleotide that is added to a growwing DNA strand is a nucleoside triphosphate
      - intial nucleotide strand is a short RNA, pimer
      - synthesized by the enzyme, primase
  - - - helicase unwinds molecules of single strand binding protein stabilize the unwound template
      - molecules of single strand binding protein stabilize the unwound template strands
      - leading strand is synthesized continuously in the 5' to 3' direction by DNA
      - primase begins to synthesize of the RNA primer for the fifth Okazaki fragment
      - DNA pol 3 is completing synthesis of fragment 4. When it reaches the RNA primer on fragment , detaches and begins adding DNA nucleotides to 3' end
      - DNA pol1 removes the primer from 5' end of the fragment 2, replacing it with DNA nucleotides added one by one to 3' end
      - DNA ligase joins the 3' end of fragment 2 to the 5' end of fragment 1
- - - - domains
        
        often have a modular architecture consisting of discrete regions
        
        shuffling may result in the evolution of new proteins
        
        exons code for the different domains in a protein
    - - cell translates an mRNA message into protein with help
        
        anticodon
        
        each carries a specific amino acid on one end
        
        anticodon base-pairs with a complementary codon on mRNA
      - transfer amino acids to the growing polypeptide in a ribosome
- - - - nucleotide pair insertions or deletions
      - single nucleotide pair substitutions
  - - - silent mutations
        
        have no effect on the amino acid produced by a codon because of redundancy in the genetic code
      - missense mutations
        
        still code for an amino acid but not the correct amino acid
      - nucleotides pair substitutions
        
        replaces one nucleotide and its partner with another pair of nucleotides
      - nonsense mutations
        
        change an amino acid codon into a stop codon, most lead to a nonfunctional protein
- - - - Bacteria transferred to medium with lighter isotope
      - DNA sample centrifuged after first replication
      - bacteria cultures in medium with heavy isotope
      - DNA sample centrifuged after second replication
    - - Eukaryotes
        
        bubble expands, then fuse and synthesize of the daughter strands is complete
        
        single straight binding proteins, bind to the unpaired DNA strands
        
        Topoisomerase, enzyme that helps relieve this strain by breaking and rejoining DNA strands
        
        Chromatin, DNA precisely combined with proteins
        
        fit into nucleus thrugh an elaborate system of packing
        
        histones, responsible for the first level of chromatin
      - Prokaryotes
        
        origin of replication, unwind and unzip, replication bubble, break in half, 2 daughter DNA molecules
        
        replication fork is a Y shaped region where the parental strands of DNA are being unwound
        
        Helicases enzymes untwist the double helix at replication forks
- - - - Translation
        
        produces mRNA
        
        splicesomes, consist of variety of proteins and several small RNAs that recognize the splice sites
        
        prokaryotes, translation of mRNA can begin before transcription has finished
        
        RNA splicing, removes introns and joins exons
        
        exons, translated into amino acid sequences
        
        introns, noncoding regions
        
        synthesisof RNA using information in DNA
        
        RNA enable it to function as an enzyme
        
        contain functional groups that may participate in catalysis
        
        RNA may hydrogen bond with other nucleic acid molecules
        
        can form 3 dimensional structure RNA
        
        codons, mRNA base triplets, read in the 5' to 3' end direction
        
        reading frame, in order fro the specified polypeptide to be produced
        
        genetic code is nearly universal, shared by the simplest bacteria and the most complex animals
        
        1 more item...
        
        genes can be transcribes and translated from one species to another
        
        3 more items...
      - Transcription
        
        synthesis of polypeptide
        
        RNA polymerase
        
        pries the DNA strands apart and joins together the RNA nuclotides
        
        RNA is complementary to DNA template strand
        
        RNA polymerase does not need primer
        
        Elongation
        
        3 more items...
        
        Termination
        
        Initiation
        
        ribosomes
        
        RNA processing, before the genetic messages are dispatched to the cytoplasm
        
        During RNA processing,both ends of the primary transcript are altered
        
        Eukaryotes, nuclear envelope separates transcription from translation
        
        nuclear envelope separates the processes of transcription andtranslation
        
        RNA undergoes processing before leaving nucleus
        
        transcription initiation complex, completed assembly of transcription factors and RNA polymerase 2 bound to promoter
        
        TATA box, crucial in forming the initiation complex in Eukayotes
        
        eukaryotic promoter
        
        several transcription fators bind to DNA
        
        transcription initiation complex forms
        
        transcription factors, mediate the binding of RNA polymerase
      - Metabolic Defects
        
        1902, Archibald Garrod
        
        thought symptoms of an inherited disease reflect an inability to synthesize a certain enzyme
        
        synthesize and degrade molecules in a series of steps
        
        sugested that genes dictate phenotypes through enzymes that catalyze specific chemical reactions
    - - colleagues identified three classes of arginine-deficient mutants
      - each lacked different enzyme necessary for synthesizing arginine
      - One enzyme hypothesis
        
        cells placed in minimal medium. Nutritional mutants identified
        
        cells subjected to X-rays
        
        nutritional mutants placed in vials with variety of media
        
        cells placed on complete medium
        
        vials observed for growth
        
        surviving cells from colonies
- - - - shortening of telomeres might protect cells from cancerous growth by limiting number of cell divisions
      - evidenc eof telomerase activity in cancer cells, allow them to persist
- - - - Template strand
        
        provides template for ordering the sequence of complementary nucleotides in mRNA transcript
        
        used as template is determined by orientation of the enzyme that transcribes the gene
        
        depends on the DNA sequences associated with the gene
        
        always the same strand for a given gene
    - - terminator
        
        sequence signaling the end of transcription
      - transcription unit
        
        stretch DNA that is transcribed
      - promoter
        
        where RNA attaches
    - - triplet code
        
        words of a gene are transcribed into complimentary nonoverlaping three-nucleotide words of mRNA
        
        translated into a chain of amino acids, forming polyopeptide
        
        series of nonoverlaping, three nucleotide words