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Lecture 12 questions

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Terms in this set (15)

  • what are the 3 components of nucleotides?

    • A group

    • Sugar

    • Phosphate

  • Difference between Nucleosides/Nucleotides?

    Nucleoside = Sugar + base

    • condensation

    • adds a 2° Amine

    Nucleotide = Phosphate + nucleoside

    • condenation

    • connects on the 5 or 3

  • Describe a polynucleotide.

    A continuous chain of nucleotides bonded by phosphodiester bond (sugar + phosphate)

    • phosphodiester bond = backbone

    • connected by 5' and 3'

    • when writing a sequence, it is written from 5' to 3' with the abbreviation in the middle --> 5' AGTC 3"

  • Difference between DNA and RNA?

    DNA = T, deoxyribose, double strand

    • Bases: A, G ,C , T

    RNA = U, ribose, single strand

    • Bases: A, G, C, U

  • What are the key structural features (4) of double-stranded (DS) DNA?

    • two strands --> run in opposite directions

    • antiparallel -->5' end and 3' end

    • phosphate backbones (negative) --> outside helix

    • planar bases (neutral) --> perpendicular to backbones

      • (think of the steps of a spiral staircase)

  • What interactions (2) determine the structural stability of ds DNA

    • london dispersion

    • hydrogen bonding

  • how do proteins interact with nucleic acids?

    salt bridges!

  • What are genes & chromosomes

    Genes = segemtn of DNA that determins the synetheic of a single protein (polypeptide)

    Chromosomes = the X structure and has two parts

    • centromere: middle point of X

    • Telomeres: the ends of the X

  • How is DNA packaged in a cell?

    • DNA wraps around 8+ histones --> creates nucleosome

    • multiple nucleosomes link together to form a continuous chain

      • coils into a thick structure --> forms chromatin fibers

    • fibers condense more tightly packed --> creates chromosomes (X)

  • How is DNA stored in a cell?

    nucleous/mitochondria!

  • Describe Chargaff's rules and the complementarity of ds DNA

    • equal number of A & T bases and G & C bases in ds DNA

    Complemearity tells us...

    • the linearly-ordered bases of a DNA strand are exactly paired across the double helix (A=T, G=C)

      • EX: When A = 10% what are the other bases worth (C,G,T)?

      • A = T = 20% --> 100%-20% = 80 --> C = 40%, G = 40%

  • What is the reverse complement rule?

    • after you find the complement of a DNA 5' to 3' strand (their base-pairs) you write a new strand rewriting the new strand backwards (3' to 5')

    • As you write it, it becomes a new strand and is considered to be 5' to 3'

  • How is a mutations caused by a mutagen propagated in DNA replication?

    • Cells DNA polymerase reads damaged/altered template strand --> incorporate a mismatched/altered nucleotide into newly synthesized daughter stranger

  • What is the "Central Dogma"?

    • Genetic infomation flows in one primary direction

      • Replication (DNA) --> Transcriptions (RNA) --> Translation --> Protein

  • What is semiconservative replication?

    • double helix (ds DNA) unzips down the middle of the base pairs (rungs)

    • each strand acts as a template/mold

    • new floating pieces in the cell rush to attach to the open bases (rungs)

    • creates two separate double helixes (each one containing one new and old strand hence, semisconservative)