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53 Cards in this Set
- Front
- Back
nucleosides |
five-carbon sugar bonded to nitrogenous base |
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nucleotides |
nucleoside (five-carbon sugar & nitrogenous base) with one to three phosphate groups added A, T, C, G, U |
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direction to read DNA |
5' - 3' |
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Purines |
A and G (2 rings) |
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pyrimidines |
C, U, T (1 ring) |
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Huckel's rule |
determines number of electrons in purines and pyrimidines |
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Chargaff's rules |
purines and pyrimidines are equal in number in a DNA molecule, A=T, C=G |
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most DNA is shaped as: |
B-DNA (right-hand helix) |
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what would cause DNA to change from its helical shape |
high concentrations of GC or salt can change B-DNA to Z-DNA (zigzag shape) |
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reannealed |
DNA strands brought back together removal of heat, alkaline pH, or chemicals like formaldehyde or urea |
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denatured |
DNA strands are pulled apart heat, alkaline pH, chemicals like formaldehyde and urea |
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histone proteins |
what DNA wraps around (H2A, H2B, H3, H4) |
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nucleosomes |
DNA wound around histone proteins |
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stabilization histone protein |
H1 |
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chromatin |
DNA and associated histones. resides in nucleus |
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heterochromatin |
dense, transcriptionally silent DNA that appears dark under light microscopy |
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euchromatin |
less dense, transcriptionally active DNA that appears light under light microscopy |
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telomeres |
ends of chromosomes. high GC content to prevent unraveling of DNA. partially shortened during replication, which may be partially reversed by telomerase |
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centromeres |
middle of chromosomes, hold sister chromatids together until separated during anaphase. high GC content to maintain strong bond between chromatids |
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replisome (replication complex) |
set of specialized proteins that assist the DNA polymerases |
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helicases |
unwind DNA at an origin of replication |
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replication fork |
on either side of an origin of replication, after unravelling |
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origin of replication |
where DNA unravels from. 1 in prokaryotes, many in eukaryotes |
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single-stranded DNA-binding proteins |
keep unwound strands of DNA from reannealing or being degraded during replication |
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supercoiling |
causes torsional strain on DNA molecule |
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DNA topoisomerases |
release torsional strain caused by supercoiling by making nicks in the DNA molecule |
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primase |
small RNA primer that allows synthesis of end nucleotides (cannot be synthesized without adjacent nucleotide to hook on to) |
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DNA polymerase II |
prokaryotes, reads template DNA 3' to 5', synthesize strand 5' to 3' |
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DNA polymerase alpha, delta, epsilon |
eukaryotes, reads template DNA 3' to 5', synthesize strand 5' to 3' |
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leading strand |
replicated in the direction of unraveling, requires only one primer |
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lagging strand |
replicated from fork to end (away from the unraveling molecule), synthesized in segments (okazaki fragments) with multiple primers |
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okazaki fragments |
sections formed during replication of the lagging strand |
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DNA polymerase I |
prokaryotes, removes primers and fills in with DNA |
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RNase H |
eukaryotes, removes primers |
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DNA polymerase delta |
prokaryotes, fills in primer areas with DNA |
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DNA ligase |
fuses DNA strands together to create one complete molecule |
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ongocenes |
develop from mutations of proto-oncogenes, promote cell cycling. may lead to cancer |
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proto-oncogenes |
code for proteins that stimulate cell division, prevent cell differentiation or regulate apoptosis |
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tumor suppressor genes |
code for proteins that reduce cell cycling or promote DNA repair |
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Nucleotide excision repair |
fixes helix-deforming lesions of DNA via cut-and-patch process that requires an excision endonuclease |
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base excision repair |
fixes nondeforming lesions of the DNA helix by removing the base, leaving an apurinic/apyrimidine site |
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AP endonuclease |
removes damaged sequence, which can be filled in with correct bases |
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recombinant DNA |
DNA composed of nucleotides from two different sources |
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DNA cloning |
introduces fragment of DNA into vector plasmid |
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restriction enzyme (endonuclease) |
cuts both plasmid and fragment, leaving them with sticky ends |
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Genomic Libraries |
large fragments of DNA, including both coding and noncoding regions of the genome. cannot be used to make recombinant proteins or for gene therapy |
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cDNA libraries (expression libraries) |
contain smaller fragments of DNA, only include exons of genes expressed by the sample tissue. can be used to make recombinant proteins or for gene therapy |
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hybridization |
joining of complementary base pair sequences |
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polymerase chain reaction (PCR) |
automated process by which millions of copies of DNA sequence can be created from a very small sample by hybridization |
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southern blotting |
used to detect the presence and quantity of various DNA strands in a sample |
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gene therapy |
method of curing genetic deficiencies by introducing a functional gene with a viral vector |
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knockout mice |
created by deleting a gene of interest |
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transgenic mice |
created by integrating gene of interest into germ line or embryonic stem cells of developing mouse |