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25 Cards in this Set
- Front
- Back
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What is meant by the semiconservative model?
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Semiconservative
– new DNA contains one parent strand and one daughter strand |
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how are DNA strands held together?
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hydrogen bonds
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what happens at the replicating fork?
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At this point replication occurs. As th replication fork moves along the parental strand DNA each of the unwound single strands combines with new nucleotides
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Leading stand?
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One new strand that is synthesized continuously as the DNA polymerase moves toward the replication fork.
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Lagging stand?
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new DNA strand that is synthesized in pieces as the DNA polymerase moves away from the replication fork.
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structure of DNA?
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FOUR BASES A.T.C.G
PHOSPATE.HYDROGEN BOND. DEOXYRIBOSE SUGAR |
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enzymes involved in replication
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DNA Polymerase
• Synthesizes a new strand; old strand is the template • Multiple types (5 in E. coli; 7 in Eukaryotes) • Two distinct characteristics – cannot start a strand from scratch – only add to the 3’ end of existing strand 14 The Reaction: dNTPs - deoxynculeoside triphosphates Figure 16.12 15 Helicase • Untwists the double helix and separates the two parent strands • SSBP hold strands apart – single-strand binding proteins |
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what is a gene?
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• “A discrete unit of hereditary information
consisting of a specifific nucleotide sequence in DNA” • Relationship |
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transcription?
what is requires |
the synthesis of a complemenary strand of RNA from a DNA template.
- RNA polymerase and a supply of RNA nucleotides - RNA pol. will bind to dna at the promoter - it will assemble free nucleotides inot a new chain - as the chain grows, RNA pol. moves along DNA - RNA synthesis continues until RNA pol. reaches a terminator and when this happens the new single-stranded mRNA and the RNA pol. are released from the DNA. |
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mMRNA
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it carries the codeed info for making specific proteins form DNA to ribosomes, where proteins are synthesized
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Translation?
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involves the decoding of nucleic acids and converting that info into proteins
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degeneracy of the code means?
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there are 64 possible codons but only 20 amino acids which means that amino acids are signaled by several alternative codons
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sense codons? nonsense codons?
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-code for amino acids
-do not code for amino acids |
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tRNA
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along with the ribosome(the site of translation)it will recognize the specific codons and transport the required amino acids.
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anitcodon?
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a sequence of three bases that are complementary to a codon
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details in translation?
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2 rib.subuntits and mRNA + protein factors assemble--)initiator AUG condon is set up--)1st tRNA binds to the start codon, bringing with it the amino acid methionine--)trna recognizes the 2nd codon+ moves it into position on the ribosome--)ribosome joins the a.a. w/ the peptide bond, and the trna mole. leaves the ribosome--)the ribosome then moves along mrna to the next codon--)as the proper a.a. are put in line one by one and peptide bonds form b/w them and polypeptide chain results--)translation will end
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importance of the promoter?
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-DNA sequence that RNA
polymerase attaches to and initiates transcription a-lso regulates how much transcription will occur - where transcrition begins In Prokaryotes - 10 bp upstream of initiation site – RNA polymerase recognizes and binds directly to DNA |
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what direction is RNA synthesized?
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- New RNA is made in 5’ to 3’ direction
– Enzyme adds to 3’ end of growing strand |
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what is the coding, template and complementary strands, and the mRna strand?
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the coding strand is exactly the mRNA strand with replacing T as U.
the TEMPLATE strand is the complementary strand. |
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function of rRNA?
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molecules that combine with ribosomal polypetides to form ribosomes
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in bacteria what is needed for RNA polmerase to recognize the promoter?
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a sigma factor is needed
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where does RNA TC begin?
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10 nucleotides away from the promoter.
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what happens during the tc of the 1st 10 nucleotides?
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Rna polymerase will release its sigma factor causing it to adhere tighter to the DNA.
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ways RNA polymerase differs from DNA polymerase?
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RNA polymerase:
- unwinds and opens DNA by itself; helicase not required - proceeds slower - incorporates ribonucleotides instead of deoxyribonucleotides -uracil instead of thymine -lacks proof-reading function, leaving base pair error about every 10,00 nucleotides |
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what is the difference b/w promoter seq. and an origin?
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a promoter= a DNA seq. that initiates tc
a origin=pt where replication begins |
