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40 Cards in this Set
- Front
- Back
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purines
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2 ring nitrogenous bases
A and G |
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pyrimidines
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3 ring nitrogenous bases
T and C |
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bonding between baseS
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C3G
A2T hydrogen bonds DNA with more CG pairs = higher melting point |
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phosphodiester bond
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3rd carbon of one dioxyribose and phoshphate backbone of single strand DNA
5'-3' directionality (5' is C attached to phosphate group) |
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semi-conservative rep
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one old strand and one new strand after replicates
due to bidirectional process |
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DNA polymerase
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needs RNA primer to start (10 nucs)
reads 3'-5' (hard to read; upstream) adds 5'-3' (easy once read, down) leading and lagging strand (okazaki fragments, joined by DNA ligase; semidiscontinuous) Also has built in exonuclease for proofreading |
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replication steps
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1. helicase unzips
2. RNA polymerase builds primer 3. DNA polymerase copies 4. primers removed 5. ligase joins okazakis |
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telomeres
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repeated 6 nuc units 100-1000 long
protect chormosomes frmo being eroded |
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transcription
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only in nucleus or mito matrix; SLOWER than rep
INITIATION: requires promoter recognition = transcription initiation complex (includes RNA polymerase - 3 types in euks) ELONGATION: copied from template strand (antisense; coding strand protects template); builds 5'-3' too; no proofreading TERMINATION: termination sequence |
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consensus sequence
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most commonly recognized promoter sequence by RNA polymerase
anything else close to will bing less strongly and therefore transcribed less often |
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regulation of gene transcription
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most reg: activators and repressors (close to promoter; allosterically regulated by small molecs like cAMP)
consensus sequence similarity posttranscriptional processing in euks |
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operon
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operator
promoter genes for single prok mRNA therefore coding region and regulatory region ie lac operon |
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posttrans processing of primary transcript
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addition of nucs
deletion of nucs modification of nitrogenous bases 5' cap poly-A tail (both protect from exonucleases) introns and exons (snRNPs cut out introns w splicesome) |
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hybridization techniques
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allow scientists to identify nucleotide sequences by binding an unknown sequence with a known
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restriction sites
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typically palindromic sequences 4-6 nucs long
cleaved unevenly for sticky ends |
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recombinant DNA
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DNA joined together artificially (after cut with same restriction endonucleases, and therefore have same sticky ends to join at)
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to screen libraries for appropriate insertion...
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insert gene for antibiotic resistance and lacZ gene
then insert DNA using endonuclease that will CLEAVE the lacZ gene, inserting your DNA inside therefore will have antibiotic resistance and inactive lacZ gene |
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complementary DNA
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produced from reverse transcribing mRNA
doesnt have introns in it! |
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PCR steps
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1 add DNA, DNA primers, special heat resistant polumerase
2. heat to 95 to denature 3. cool to 60 to anneal primers to DNA 4. reheat to 72 to activate polymerase 5 repeat for exponential results and dont need to add more polymerase |
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southern blotting
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ID fragments of known DNA sequence
cut with restriction enzymes resolve with gel electrophoresis (by size) alkaline to denature, transfer to nitrocellulose radio-labeled probe to target visualize with radiographic film |
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Northern blot
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same as southern but identifies RNA fragments
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Western blot
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recognizes proteins using antibodies
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RFLP
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restriction fragment length polymorphisms
identifies INDIVIDUALS according to minute differences in DNA sequences (distance between restriction sites) |
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genetic code is...
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degenerative (more than one series of nucs can code for an a.a.)
unambiguous (but any 2 nucs will code for only one a.a.) almost universal |
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stop codons
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UAA
UAG UGA |
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sedimentation coefficients of ribosomes
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gives speed of particle in centrifuge, is proportional to mass and related to shape and density
Prok: 30S 50S = 70S Euk: 40S 60S = 80S Mito: 55-60S |
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nucleolus
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manufactures ribosomes
transported separately to cytoplasm |
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ribosome parts
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P site - peptidyl - where growing a.a. is
A site - aminoacyl site - 2 GTPs to attach here dehydration rxn catalyzed by peptidyl transferase of ribosome translocated to E site - exit another GTP used |
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posttranslational modifications
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sugars, lipids or phosphate groups may be added
may be cleaved in places separate polypeps may join to form quaternary structure |
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signal-recognition particle
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recognizes 20 aa sequence called signal peptide near front of polypeptide, carries entire ribosome complex to receptor protein on ER - peptide grows across membrane
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point mutation types
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base pair substitution(transition = A/T to C/G; transversion = A to T or C to G)
missense if changes a.a. coding insertion/deletion = frameshift mutation nonsense mutation |
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chromosome mutation types
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deletions
duplications transloccation inversion (last 2 can be caused by transposition - transposable elements (transposons) excise self from chromosome and reinsert selves at another location |
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chromosome components
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8 histones wrapped in DNA = nucleosome
wrap into solenoids, into supercoils entire DNA/protein complex = chromatin (1/3 DNA, 2/3 protein by mass; small amt RNA) |
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chromosome numbers
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23 pairs = 46 chromosomes (double stranded DNA molecs)
23 homologues (code for same traits) diploid means cell has set of homologues |
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cell life cycle
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G1 - first growth phase (cell just split, organelles growing, active protein synth; G1 checkpoint to see if big enough, based on ratio of cytoplasm to DNA, to enter S, otherwise G0)
S - synthesis (replication; sister chromatids G2 - 2nd growth phase (prepares to divide, tubulin for mts; G2 checkpoint for MPF mitosis promoting factor) M - mitosis or meiosis C - cytokinesis interphase = G1 S G2 G0 - nongrowing phase, distinct from interphase, allows for diff cell cycle lengths |
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Mitosis
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nuclear division without genetic change
Prophase - condensation DNA, centrioles to opposite ends, nucleus disappears, sindle app forms) Metaphase - chromosomes along middle Anaphase - sister chromatids split at centromeres, move to opposite ends; cytokinesis may commence Telophase - nuclear membrane reforms, chromosomes decondense, cytokinesis continues |
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centrioles etc during mitosis
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spindle apparatus = asters (mts) radiating from centrioles
kinetochore mts growing from centromeres (centre of chromo) spindle mts - connecting 2 centrioles |
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meiosis
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double nuclear division, generating 4 haploid cells
after replication in S phase = primary spermatocyte/ oocyte P1 - homologous chormos line up along side each other (tetrads), matching genes exact, CROSSING OVER M1 - tetrads align A1 - homologues separate from partners T1 - cytokinesis - haploid cells = secondary sperm/oocs **reduction division*** Meiosis II - looks like normal mitosis |
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nondisjunction
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if during A1 or A2, centromere of chromosome doesnt split
primary (in A1) - cell with 2 extra chromosomes, other missing in A2 = one cell will have extra chromatid, one cell lacking |
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oocyte formation
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stays at primary oocyte from birth to puberty (46 chromosomes, replicated bc after S)
just before ovulation, first mieotic division = polar body and 23 chromosomes in secondary oocyte penetration of sperm stimulates anaphase II of second meiotic division |
