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Ch. 11 DNA: Structure & Replication - (Biology 1A)
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38
Biology
Undergraduate 1
04/20/2012

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Term
DNA allows for physical traits to be passed from generation to generation. Must be able to: (4 things)
Definition
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.
Term
DNA Purines
Definition
A,G
Term
DNA Pyrimidines
Definition
C,T
Term
RNA Purines
Definition
A,G
Term
RNA Pyrimidines
Definition
C,U
Term
One unit of DNA contains _____ base pairs.
Definition
ten
Term
Opposing DNA strands run:
-Parallel?
-Antiparallel?
Definition
Antiparallel
Term
Meselson and Stahl used density studies to prove DNA replication is...
Definition
semiconservative
Term
Avery, McCarthy and MacLeod did what four things?
Definition
-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.
Term
Franklin used x-ray crystallography to...
Definition
figure the double helix shape of DNA.
Term
Erwin Chargoff discovered what?
Definition
Analyzed amounts of bases and discovered amounts related. (A=T/U and G=C)
Term
Frederick Griffith and bacteria
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).
Term
Hershey and Chase - T2 virus infecting E. Coli
Definition
-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.
Term
Humans have ______ or more DNA polymerases
Definition
twelve
Term
DNA structure level 1:
Definition
Nucleotides: the building blocks of DNA (& RNA).
Term
DNA structure level 2:
Definition
A strand of DNA - nucleotides linked covalently.
Term
DNA structure level 3:
Definition
Two strands forma double helix (linked via hydrogen bonds).
Term
DNA structure level 4:
Definition
DNA associates with different proteins to form chromosomes.
Term
DNA structure level 5:
Definition
Genome: a complete complement of an organism’s genetic material.
Term
DNA Replication: Bacteria
Definition
Circular DNA, one point of replication.
Term
DNA Replication: Eukaryotes
Definition
Multiple origins or replication.
Term
DNA leading strand synthesis is ________, lagging strand synthesis is _______.
Definition
continuous, discontinuous
Term
DNA Replication 1 - DNA helicase...
Definition
binds to one strand of DNA at the replication fork and travels in the 5’ to 3’ direction using ATP to separate the strands.
Term
DNA Replication 2 - DNA Topoisomerase...
Definition
in responsible for relieving the supercoiling caused by the unwinding of the double helix by DNA helicase.
(enzyme)
Term
DNA Replication 3 - Single-strand binding proteins...
Definition
coat each strand to keep them from binding back together.
Term
DNA Replication 4 - DNA Primase...
Definition
synthesizes short RNA primers. (start points for synthesis)
Term
DNA Replication 5 - DNA polymerase III...
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)
Term
DNA Replication 6 - DNA Ligase...
Definition
joins adjacent DNA fragments. (including Okazaki Fragments)
Term
DNA Replication 7 - Telomerase
Definition
prevents chromosome shortening by attaching many copies of a DNA repeat sequence (telomeres) to the ends of chromosomes.
Term
Telomeres are what?
Definition
-Series of short nucleotide sequences repeated at the ends of eukaryotic chromosomes.
-Protects the end of the chromosomes
-Prevents fusion with other chromosomes.
Term
A chromosomes is...
Definition
-A discrete unit of genetic material.
-Human somatic cells have 46 chromosomes.
Term
Chromatin is...
Definition
-A DNA-Protein complex.
-What chromosomes are made of.
Term
1st level of DNA compaction:
Definition
-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.
Term
2nd level of DNA compaction:
Definition
-30nm fiber.
-Current model suggests asymmetric, 3D zigzag of nucleotides.
-Shortens another 7 fold.
Term
3rd level of DNA compaction:
Definition
-Radial loop domains.
-Loops can be 25,000 to 200,000 nucleotides in length.
Term
Heterochromatin (level of chromosome compaction)
Definition
Highly compacted due to radial loop domains.
Term
Euchromatin (level of chromosome compaction)
Definition
Less compact - radial loop domains are not compact.
Term
End of chapter 11
Definition
Beginning of chapter 12
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