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31 Cards in this Set
- Front
- Back
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conservative model
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use DNA molecule to make entirely new copy
-open, copy, close up |
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semiconservative model
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split old in half and use both as template
-two new, which is half new and half old |
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DNA synthesis requirements
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DNA polymerase - synthesis enzyme complex
template - to be copied primer - with prime hydroxyl group, read the template and assemble sustrates into DNA molecules precursurs - 4 deoxynucleoside triphosphates Mg ion - cofactor enzyme ATP - source of energy |
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5' to 3'
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DNA growth at synthesis
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3' to 5'
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nucleotide joined one at a time
-template is read |
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Events of replication
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initiator protein - binds to an initiation site (origin of replication)
DNA gyrase - unwinds the supercoiling of DNA DNA helicase - (a topoisomerase) protein that unwinds double stranded DNA by breaking H bonds primease - synthesizes an RNA primer DNA polymerase - extemds the strand by addition to the 3' end of the primer; proof reads Single stranded binding proeins - stablizes the single strand |
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Okazaki fragments
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short pieces of DNA adding to the leading strands
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What is different about eukaryotes DNA replication
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undwinds the complex of histones and other proteins in chromatin
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Prokaryote DNA polymerase can move...
Eukaryote DNA polymerase can move... |
P: 1000 nt a second
E: 50 nt a second - suggests that harder to open complicated structure |
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linear chromatin vs circular chromatin
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e: linear
p: circular |
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telomeres
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ends of linear chromosomes
- no presence of 3'OH to which nucleotides can be attached...primers at ends can not be replaced - use telomerase enzyme to place nucleotides |
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recombination
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mechanism that produces crossing over & increases genetic variation
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Holiday Junction
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homo strands line @ break and both invade the other. Come together by ligation
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Gene conversion
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physically changes one allele into another
-1/4 A &3/4 a or 3/4 A & 1/4 a |
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mRNA
tRNA rRNA siRNA miRNA |
mRNA - carries coding instruct for PP chains from DNA ribosome
tRNA - (transfer) link btwn coding sequence in mRNA and aa of PPC rRNA - make up ribosome, site of protein miRNA & siRNA - euk cells and carry out RNAi...help trigger degradation of mRNA or inhibit transl of protein |
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How is transcription controlled?
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-RNA polymerase - bind to DNA
-Promoter region - transcription initiates -Termination region - transcription stops |
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Prokaryotic promoter
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...short sequences necessary for binding RNA polymerase to DNA
-promoter contain two consensus sequences ....-10 (prinbrow) = position the polymerase (TATAAT) ....-35 = improves polymerase binding efficience (TTGACA) |
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Transcription in bacteria
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1) initiation process
2) core + sigma factor attach to promoter 3) DNA is opened 4) nucleotide tirphosphate binds 5) sigma released and polymerase moves from the promoter |
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Termination in bacteria
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termination sequence contains an inverted repeat and repeated nucleotides
...RNA folds into a hairpin loop ...RNA polymerase pauses ...RNA is released ------RHO factor binds to RNA ------polymerase pauses at hairpin loop ------RHO reaches polymerase and releases RNA |
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What controls the initiation of transcription in bacteria?
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the DNA binding proteins. They must open up DNA unwind, and get ready (similar to euks)
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How is gene regulation done?
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controlling transcription
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Binding proteins
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-Helix turn helix
-zinc finger protein -Leucine zipper protein |
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The bacterial operon
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operator - binding site for regulatory proteins that control initiation of transcription
operon - structural genes controlled by one operator |
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bacterial operator control
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NI - represses, induces
PI - induces, induces NR - represses, represses PR - induces, represses |
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Lac operon (bacteria)
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Lactose - energy source for bacteria
-lac operon genes in lactose metabolism ....permease- directs lactose to inside of cell ....B-galactosidase - makes clucose and galactose |
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What did Jacob and Monod find with the Lac operon?
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Lactose induces the production of the lac enzyme
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What does CAP do in bacteria?
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CAP: positive regulator of lac transcription
-by binding at the CAP site, increases transcription -requires cAMP cofactor ....high glucose = low cAMP = blocks cap binding ....lactose and glucose = no transcription |
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What does RANi do?
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reduce the active mRNA molecules which lowers translation
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Differences and similarities of eukaryotic and prokaryotic transcription
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differences
-3 different polymerases (I II III) -Larger promoter and enhancers in upstream region -Post transcriptional RNA processing -RNA transporations similarities -promoter |
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Eukaryotic promoter
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core promoter sequences resemble prokaryotic promoter
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Regulation occurs in every step in process of gene action in eukaryotes
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chromo structure - open/closed configuration
transcription - operonlike control RNA processing - 5' cap, poly A tail, splicing mRNA transportation - nucleus to rough ER |
