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41 Cards in this Set
- Front
- Back
gene
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series of DNA nucleotides that code for production of a single polypeptide, or mRNA, rRNA or tRNA
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unique sequence DNA
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DNA regions that code for genes
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repetitive sequence DNA
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DNA regions that don't code for gene
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heterochromatin
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area not being transcribed
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euchromatic
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area actively being transcribed
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Central Dogma
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DNA-> RNA -> protein
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nucleotide
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bond together with phosphdiester bonds between 3rd C of 1 and 5C of the other; 3' attached to OH
5' attached to sugar |
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adenine 2 thymine
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2 H bonds
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C 3 G
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3 honds
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complementary strands
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curl 2 helix, form major and minor grooves
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double helix diametyer
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2 nanometers
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DNA replication
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1 x in cell life
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replisome
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2 replisomes proceed in opposite direction on chromosome to make it bidirectional
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replication units of replicaons
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replicated segments on chromosome
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DNA helicase
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unwinds DNA
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DNA polymerase
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adds deoxynucleotide to primer; read new strand in 3' - 5' ; writes 5'-3'
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RNA primase
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starts/primes strand with 10 ribonucleotide
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each nucelotide added to new string
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requires removal of pyrophosphate group, this energy is released and used to drive replication
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lagging strand
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continuously interrured and restarted with new primer (okazaki fragments)
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DNA ligase
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ties fragments together to form continuous strand
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exonuclease
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subunit of DNA polymerage and proofreads each new strand
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telomeres
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repeated 6 nucleotide units (100 - 100 units long) that protect chromosome from erosion
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RNA vs. DNA
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DNA: ds, theymine, deoxyribose, replication, nucleus and mitochondrial matrix
RNA: ss, uracil, ribose, transcription also in cytosol (since no nucleus), can move through pores |
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mRNA
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delivers DNA code for amino acids to cytosol where proteins are manufactured
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rRNA
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combines with protein to form ribosomes (cell complez that directs protein synthesis and catalyzed in the nucleolus)
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tRNA
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collects amino acids in cytosol and transfers them to ribosomes for incorporation into protein
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RNA
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transcription starts at initiation; inititaion factors (proteins) form transcription initiation coplex, promote sequence? ; indication of beginning pt of transcription
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transcription
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requires promotor whereas replication needs primer; promotor tells RNA pol where to start on DNA; primer = short pc of RNA
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Transcription
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RNA pol binds @ promoter, unzips DNA double helix, creates transcription bubble, elongation begins, 1 strand of DNA transcribed (template strand is - anti strand) and the 2nd strand (coding + strand) remains for preventing degradation, Builds in 5-3, much slower then replication, more errors but not transferred to progeny
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Termination
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termination sequence and proteins dissociate RNA pol from DNA in transcription
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Replication
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makes no distinction between genes
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Transcrtiption
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level of gene regulation, proteins called activators and repressor bind to promotor and repress or activate the activity of RNA pol
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Activators and Repressors
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proteins that regulate gene expression; allosterically regulated by cAMP; many proteins can be transcribed from 1 mRNA, so amplifying effect
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primary function of gene regulation in prokaryotes and multicelluar org
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regulate homeostasis inside and outside of the cell
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prokaryotic mRNA
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includes several genes in single transcript (polycistronic)
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eukaryotic mRNA
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monocistronic
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operon
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unit consisting of operator, promotor, and genes of single prokaryotic mRNA
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lac operon
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codes enzymes that allow E. coli to import and metabolize lactose when glucose is not available. low gluc -> hic cAMP to cAMP binds and activates catabolite activator protein -> binds to cap site -> located upstream to lac operon -> promoter is activated -> proteins transcribed -> downstream is lac operator for binind repressor -> repressor inactivated by lactose lac repressor protein will bind to operator unless lactose binds to lac repressor, if no binding -> prevent lac gene transcription, so lactose induces transctiption of lac gene when glucose around
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post transcriptional processing
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all types of RNA go through (in eukaryotes_ for additional regulation
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1 degress transcript
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initia mRNA nucleotide sequence is processed in 3 ways: MAD
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MAD
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processing of 1 degree transcript?
add nucleotide, deletion of nucleotide, modification of nitrogenous base |