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| DNA allows for physical traits to be passed from generation to generation. Must be able to: (4 things) |
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1. Carry genetic information - must contain all the necessary information to replicate the organism.
2. Undergo replication - be copied with high degree of accuracy.
3. Undergo transmission - must be transferable from parent to offspring.
4. Allow for genetic variation - variation within and between species must be possible. |
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| One unit of DNA contains _____ base pairs. |
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Opposing DNA strands run:
-Parallel?
-Antiparallel? |
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| Meselson and Stahl used density studies to prove DNA replication is... |
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| Avery, McCarthy and MacLeod did what four things? |
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-Biochemically isolated macromolecules from Griffiths S-Strain bacteria.
-Based their work on Griffiths.
-Concluded DNA is genetic material.
-Added DNA and RNA digesting enzymes to samples to keep trace elements from altering results. |
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| Franklin used x-ray crystallography to... |
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| figure the double helix shape of DNA. |
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| Erwin Chargoff discovered what? |
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| Analyzed amounts of bases and discovered amounts related. (A=T/U and G=C) |
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| Frederick Griffith and bacteria |
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Definition
-Streptococcus pneumoniae
-Strains that secrete capsules look smooth (S) and can cause fatal infections in mice.
-Strains that look rough ® do not secrete capsules, infections are not fatal.
-Mice injected with heat-killed type S survive.
-Mice injected with live R and heat-killed S die.
-Blood contains living type S (transformation). |
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| Hershey and Chase - T2 virus infecting E. Coli |
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-DNA found inside capsid
-Shearing force of blender will separate the phage coat from the bacteria.
-35S will label proteins only, 32P will label DNA only.
-Results support DNA jets injected and in the genetic material. |
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| Humans have ______ or more DNA polymerases |
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| Nucleotides: the building blocks of DNA (& RNA). |
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| A strand of DNA - nucleotides linked covalently. |
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| Two strands forma double helix (linked via hydrogen bonds). |
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| DNA associates with different proteins to form chromosomes. |
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| Genome: a complete complement of an organism’s genetic material. |
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| DNA Replication: Bacteria |
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| Circular DNA, one point of replication. |
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| DNA Replication: Eukaryotes |
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| Multiple origins or replication. |
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| DNA leading strand synthesis is ________, lagging strand synthesis is _______. |
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| continuous, discontinuous |
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| DNA Replication 1 - DNA helicase... |
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| binds to one strand of DNA at the replication fork and travels in the 5’ to 3’ direction using ATP to separate the strands. |
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| DNA Replication 2 - DNA Topoisomerase... |
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in responsible for relieving the supercoiling caused by the unwinding of the double helix by DNA helicase.
(enzyme) |
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| DNA Replication 3 - Single-strand binding proteins... |
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| coat each strand to keep them from binding back together. |
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| DNA Replication 4 - DNA Primase... |
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| synthesizes short RNA primers. (start points for synthesis) |
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| DNA Replication 5 - DNA polymerase III... |
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Definition
travels in a 5’ to 3’ direction on the template strand as it synthesizes the adjacent strand in a 3’ to 5’ direction. (Deoxynucleoside Triphosphates, two phosphates bonds are broken and energy is used to create the covalent bonds)
-Cannot begin DNA synthesis without primers (made of RNA) from DNA primase. (primers get removed and replaced by DNA polymerase I)
-Can work only in 5’ to 3’ direction (because of phosphates) |
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| DNA Replication 6 - DNA Ligase... |
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| joins adjacent DNA fragments. (including Okazaki Fragments) |
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| DNA Replication 7 - Telomerase |
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| prevents chromosome shortening by attaching many copies of a DNA repeat sequence (telomeres) to the ends of chromosomes. |
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-Series of short nucleotide sequences repeated at the ends of eukaryotic chromosomes.
-Protects the end of the chromosomes
-Prevents fusion with other chromosomes. |
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-A discrete unit of genetic material.
-Human somatic cells have 46 chromosomes. |
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-A DNA-Protein complex.
-What chromosomes are made of. |
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| 1st level of DNA compaction: |
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-DNA wraps around 8 histone proteins to form nucleosome.
-Histones have a net positive charge.
-146 to 147 nucleotides.
-Shortens length of DNA 7 fold. |
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| 2nd level of DNA compaction: |
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-30nm fiber.
-Current model suggests asymmetric, 3D zigzag of nucleotides.
-Shortens another 7 fold. |
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| 3rd level of DNA compaction: |
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-Radial loop domains.
-Loops can be 25,000 to 200,000 nucleotides in length. |
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| Heterochromatin (level of chromosome compaction) |
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| Highly compacted due to radial loop domains. |
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| Euchromatin (level of chromosome compaction) |
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| Less compact - radial loop domains are not compact. |
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