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| Griffith's bacterial transformation experiment discovered: (1920s) |
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Definition
| a biochemical genetic material exists |
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| strains that secrete capsules that look smooth and cause fatal infections in mice, immune system doesn't kill bacteria, strains that don't secrete capsules look rough and are not deadly |
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| have no bacteria in blood |
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| bacterial transformation experiment |
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| genetic material from the heat-killed type S bacteria had been transferred to the living type R bacteria & was passed on to offspring |
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| Avery, MacLeod, & McCarty (1940s) |
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Definition
| used purification methods to reveal that DNA is the genetic material (added DNase, RNase, and proteases, only DNase had an effect. only purified DNA from type S could transform type R.) |
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| studying T2virus effecting e Coli, Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. |
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| a complete complement of an organisms genetic material |
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| in living cell, DNA is associated with... |
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| an array of different proteins to form chromosomes |
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| building blocks of DNA (and RNA) |
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| phosphate group, pentose sugar (deoxyribose), nitrogenous base( purines:A,G, pyrimidines:C,T) |
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| phosphate group, pentose sugar(ribose), nitrogenous base (purines: A,G pyrimidines: C,U) |
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| conventional numbering system |
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Definition
| sugar carbons 1' to 5', base attached to 1', phosphate attached to 5' |
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| nucleotides covalently bonded |
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| phosphate group links 2 sugars |
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| bases on the inside, stabilized by hydrogen bonding |
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| allows proteins in to bind and affect gene expression |
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| semiconservative, conservative, dispersive |
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| newly made strands/original strands |
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| matthew meselson & franklin stahl |
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Definition
| double helix & semiconservative replication |
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Term
| semiconservative replication |
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Definition
| 2 parental strands separate, serve as templates. End result: 2 new double helices with the same bind sequence as original. |
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Definition
| forms replication bubble that forms 2 replication forks |
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Term
| origin of repication eukaryotic vs prokaryotic |
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Definition
| eukaryotes have multiple origins of replication, prokaryotes only have 1 |
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Definition
| binds to DNA and travels 5' to 3' using ATP to separate strands and move fork forward |
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| relieves additional coiling ahead of replication fork |
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| single-strand binding proteins |
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Definition
| keep parental strands open to act as templates |
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| major enzyme responsible for reading off the base pairs and making new ones, covalently links nucleotides, forms the bond at the sugar-phosphate backbone |
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Term
| deoxynucleoside triphosphates |
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Definition
| originally has 3 phosphates, 1 gets cleaved off and releases energy, breaking covalent bond forms pyrophosphate |
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Term
| 2 problematic enzymatic features of dna polymerase |
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Definition
1. unable to begin DNA synthesis without DNA primase making a short RNA primer, RNA primer will be removed and replaced with DNA later
2. DNA polymerase can only work 5' to 3' |
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Definition
| DNA synthesized as 1 continuous molecule, DNA primase makes 1 RNA primer, DNA polymerase 3 attaches nucleotides in 5' to 3' |
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| DNA synthesized 5' to 3' but as Okazaki fragments |
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Definition
| found on the lagging strand, short RNA primer made by DNA primase at the 5' end and then DNA laid down by DNA polymerase |
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Term
| in BOTH leading & lagging strands |
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Definition
| RNA primers will be removed by DNA polymerase 1 and filled in with DNA, DNA ligase joins adjacent DNA fragments |
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Definition
| fuses daughter & parent segments |
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| helicase, ssbp, topoisomerase |
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Term
| DNA replication is accurate for 3 reasons: |
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Definition
1. hydrogen bonding between correct pairs is stronger/more stable than mismatches
2. active site of DNA polymerase unlikely to form bonds if pairs are mismatched
3. DNA polymerase removes mismatched pairs |
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Term
| characteristics of DNA polymerases |
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Definition
| BC of gene duplication, most genomes have several polys, speed, fidelity, & completeness |
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"TTAGGG"
plastic tip of a shoelace, prevents unraveling: series of short nucleotide sequences repeated at the ends of eukaryotic chromosomes |
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| telomere at 3' does not have a complementary strand |
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| lose 30-200 bp telomere every time |
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| solutiom for 3 prime overhang, otherwise chromosomes would become progressively shorter. 99% of all cancers have high levels of telomerase |
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| eukaryotic chromosome structure |
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Definition
| typically may be hundreds of millions of base pairs long |
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Definition
| composed of chromatin (DNA-protein complex) |
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| 3 levels of DNA compaction |
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Definition
| wrapping, 30-nm fiber, radial loop domains |
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Definition
| DNA wrapped around histones to form nucleosome, shortens length of DNA molecule 7-fold |
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| current model suggests asymmetric, 3D zigzag of nucleosomes. shortens length of another 7 fold |
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Definition
| interaction between 30-nm fibers and nuclear matrix, each chromosome located in discrete territory, level of compaction of chromosomes not uniform (heterochromatin, euchromatin- have the genes you need) |
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| level of compaction (most compact ---> least compact) |
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Definition
| metaphase, heterochromatin, euchromatin |
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| order of enzymes in the lagging strand |
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Definition
| Helicase ---> Topoisomerase ---> Primase ---> DNA polymerase ---> DNA ligase |
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Definition
| Untwists the double helix at replication forks to make two parental strands available as template strand |
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| Starts an RNA chain from scratch that will eventually be replaced by DNA nucleotides (remember nucleotides come from DNA polymerase). |
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| A segment of DNA that is functional: it specifies the arrangement of amino acids that will make a functional product |
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Definition
| Start with DNA, TRANSCRIPTION makes RNA, TRANSLATION makes proteins |
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Term
| 3 differences between RNA & DNA: |
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Definition
1. Sugar is ribose (not deoxyribose)
2. RNA does bind to the base uracil rather than thymine
•(A-U C-G)
3. Single-stranded |
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Term
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Definition
| information contained in a gene is copied (transcribed) to mRNA. mRNA carries this info outside of the nucleus to ribosomes. Only 1 strand of DNA is used to copy the message to mRNA. From DNA template, a complimentary mRNA is made |
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Term
| What are the three steps of transcription? |
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Definition
| Initiation, elongation, termination |
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Definition
RNA synthesis (making) begins with the help of RNA polymerase which binds at promoter region of gene.
• Sigma factor binds to RNA Polymerase and to Promoter
• DNA strands are separated to form ‘open complex’ |
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Definition
RNA polymerase travels along the template strand continuing to make the mRNA using free RNA nucleotides
• opposite strand to template is ‘coding strand’
• A/U, G/C rule
• made in 5 to 3 direction |
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Definition
| RNA polymerase continues on template until a termination signal is encountered, the “terminator”. |
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• New mRNA (primary transcript/pre-mRNA) is modified before exiting nucleus
• Poly A tail added to 3' end and a cap is added to 5' end: enable transcript to exit nucleus, tells ribosome where to attach, and promotes longevity in cytosol
• Introns: unexpressed regions of DNA are removed during splicing; carried out by spliceosome
• Exons: the expressed regions, remain |
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| A 3 base sequence: triplet code |
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| information carried by mRNA is translated using tRNA and rRna to make a protein |
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Definition
• 1. Initiation: initiation of Protein synthesis
• 2. Elongation: Elongation of the protein
• 3. Termination |
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Term
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Definition
| Requires initiation factors, energy, start codon. Small subunit binds to mRNA and moves along till start codon is encountered. At start codon, tRNA binds to the first binding site on large subunit. |
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Term
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Definition
| Aminoacyl tRNA brings a new amino acid to the A site. Binding occurs due to codon/ anticodon recognition. Elongation factors hydrolyze GTP to provide energy to bind tRNA to A site. Peptidyl tRNA is in the P site. Aminoacyl tRNA is in the A site |
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Term
| Termination (Translation) |
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Definition
When a stop codon is found in the A site, translation ends
Recognized by release factors. Completed polypeptide attached to a tRNA in the P site and stop codon in the A site. Release factor binds to stop codon at the A site. Bond between polypeptide and tRNA hydrolyzed to release polypeptide. Ribosomal subunits and release factors disassociate |
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