32 Cards in this Set
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deoxyribonucleic acid (DNA)
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-the genetic material
-double stranded with each strand containing repeating units of deoxyribonucleotides
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ribonucleic acid (RNA)
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-composed of ribonucleotides
-synthesized from transcription of DNA
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transforming principle
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-live R cells mixed with boiled S cells led to death in mice b/c of presence of S cells in prodgeny cells
-presence of S cells caused R cells to "transform"
-thought to be genetic material b/c 1) genes were being passed 2) genetic material was influencing traits
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protease, RNase & DNase
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-enzymes specific to protein, RNA & DNA, respectively
-breaks down sugar-phosphate backbone in RNA/DNA and breaks polypeptide bonds in protein
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nucleotide
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repeating structural unit of nucleic acids
-composed of a sugar (either deoxyribose/ribose), phosphate and base
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base
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-nitrogen containing that is a portion of a nucleotide in DNA & RNA
-can be A, T, G or C
-U replaces T in RNA
-attach at 1' C
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purines
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-nitrogen base w/ a double ring structure (6C ring = 5C ring)
-adenine & guanine
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pyridimines
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-nitrogenous base w/ a single ring structure
-cytosine, thymine & uracil
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hydrogen bonds
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-connects complimentary base pairs
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deoxyribose, ribose
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-the sugar found in DNA & the sugar found in RNA
-to number carbons, start with exocyclic C as 5' C and then number the other C 4'-1'
-sugars are defining difference b/w nucleotides b/c deoxyribose only has an H at the 2' C position while ribose has an OH at the 2' C
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phosphate
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-attaches to 5' C
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phoshodiester bond
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-strong covalent bonds that join nucleotides by a phosphate group
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Chargaff's rule
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-worked w/ DNA of many different species to analyze the % composition of each base
-found that %A ~ %T and %G ~ %C
-tells us how bases should be paired (complementary)
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Rosalind Franklin
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-used X-ray diffraction to show the double helices of DNA
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X-ray diffraction (Franklin)
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-took DNA as a crystal and shot an X-ray beam into DNA
-when the beam passes thru DNA, it messes up the path and develops an "X" shape on film
-tells us DNA's shape is a double helix
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Watson and Crick
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-from Chargaff, they knew structure of nucleotides and how to pair them
-from Franklin, they knew that DNA was a double helix and how far apart the backbones were
-also used knowledge of chemistry of bonds/angles + electronegativities to make models of DNA with a sugar-phosphate bac…
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antiparallel
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-shape of DNA as determined by Watson and Crick
-strands run in opposite directions and their ends have opposite polarities
-one strand is 5' to 3' and the other strand is 3' to 5'
-RNA is only double stranded if it's antiparallel
-double stranded in mRNA during translation, s…
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major groove, minor groove
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-major groove wider than minor grooves
-both composed of bases
-grooves are independent and don't touch
-proteins recognize bases b/c they're specific/distinctive and bind to DNA by appendages that access the bases thru grooves
-base specificity due to polarity of amino acids …
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B-DNA
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-most stable form of DNA that makes up majority of DNA form in all living cells
-there are 3 other forms of DNA
-2 backbones form ridges and in b/w ridges are grooves
-structure is different from other forms b/c it twists up and to the right
-dynamic and has its own specific p…
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H-DNA
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-triple stranded
-3rd strand can be manufactured in a lab and placed in the major groove or 3rd strand can come from the unraveling of one strand that winds the extra part back up to lay in the major groove
-in living cells it's DNA reorganizing
-if 3rd strand is occupying the ma…
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replication
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-original DNA strands are used as templates for synthesis of new DNA strands
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prokaryote
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-includes bacteria and archaea domains
-defining characteristic is lack of nucleus
-have circular chromosomes
-geneticists' favorite prokaryote is E. coli b/c it's easy to study, it represents a general way to understand most bacterial prokaryotes and can also help w/ medical tre…
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template
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-strand of DNA used to synthesize a complementary strand of DNA or RNA
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semiconservative model of replication
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-copying mechanism suggested by Watson and Crick (correct method of replication)
-DNA can separate by breaking H bonds down the middle and each strand can act as a template to form new nucleotides
-shows that DNA is half conserved in newly formed strands b/c of one parental strand a…
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conservative model of replication
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-both strands of parental DNA remain together following replication
-incorrect model of replication (doesn't exist in nature)
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unwind/melt/denature
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-other forms of separation
-melting is the easiest way to separate in a lab b/c the bonds are boiled
-denaturing uses heat or chemicals but when conditions go back to normal the DNA can come back together as a double strand b/c that is its lowest energy state
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origin of replication
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-nucleotide sequence that functions as initation site for assembly of proteins required for replication
-prokaryotes have a single origin of replication while eukaryotes have multiple origins
-contains DNaA box and AT-rich region
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DNaA box and AT-rich region
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-specific binding site for protein DNaA
-protein DNaA binds to sequence and other DNaA's
-severely bends DNA
-favors an unwinding worse on adjacant AT-rich region
-separates bonds in AT-rich region because they have 2H bonds instead of 3
-open AT-rich region is where replic…
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helicase
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-an enzyme that runs along a single strand to forcibly separate the two strands
-separates DNA in both directions creating 2 replication forks
-area where strands are separated and new strands are being synthesized
-could cause twists of DNA to be overtwisted from the tension of …
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topoisomerase
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-located at each fork to prevent supercoiling so tension doesn't build up and slow down replication
-capable of breaking 1 strands phosphodiester bonds so that the other strand has its backbone intact and can freely rotate
-broken strand is wrapped around the unbroken strand to refo…
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primer, primase
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-primer is a short segment of ~10 nucleotides that initates replication and provides a 3' end for DNA polymerase to bind nucleotides to
-primase is an enzyme that has the ability to form new RNA
-low processivity
-5' to 3' RNA polymerase activity
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DNA polymerase III
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-becomes major replication enzyme in prokaryotes after primase dissociates
-high processivity & 5' to 3' DNA polymerase activity
-17 subunits (single, folded polypeptide)
-B subunit clamps onto the strand, doesn't impede DNA poly. III's ability to slide down strand and is respons…
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BIO 325: Exam 1