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41 Cards in this Set

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gene
series of DNA nucleotides that code for production of a single polypeptide, or mRNA, rRNA or tRNA
unique sequence DNA
DNA regions that code for genes
repetitive sequence DNA
DNA regions that don't code for gene
heterochromatin
area not being transcribed
euchromatic
area actively being transcribed
Central Dogma
DNA-> RNA -> protein
nucleotide
bond together with phosphdiester bonds between 3rd C of 1 and 5C of the other; 3' attached to OH
5' attached to sugar
adenine 2 thymine
2 H bonds
C 3 G
3 honds
complementary strands
curl 2 helix, form major and minor grooves
double helix diametyer
2 nanometers
DNA replication
1 x in cell life
replisome
2 replisomes proceed in opposite direction on chromosome to make it bidirectional
replication units of replicaons
replicated segments on chromosome
DNA helicase
unwinds DNA
DNA polymerase
adds deoxynucleotide to primer; read new strand in 3' - 5' ; writes 5'-3'
RNA primase
starts/primes strand with 10 ribonucleotide
each nucelotide added to new string
requires removal of pyrophosphate group, this energy is released and used to drive replication
lagging strand
continuously interrured and restarted with new primer (okazaki fragments)
DNA ligase
ties fragments together to form continuous strand
exonuclease
subunit of DNA polymerage and proofreads each new strand
telomeres
repeated 6 nucleotide units (100 - 100 units long) that protect chromosome from erosion
RNA vs. DNA
DNA: ds, theymine, deoxyribose, replication, nucleus and mitochondrial matrix
RNA: ss, uracil, ribose, transcription also in cytosol (since no nucleus), can move through pores
mRNA
delivers DNA code for amino acids to cytosol where proteins are manufactured
rRNA
combines with protein to form ribosomes (cell complez that directs protein synthesis and catalyzed in the nucleolus)
tRNA
collects amino acids in cytosol and transfers them to ribosomes for incorporation into protein
RNA
transcription starts at initiation; inititaion factors (proteins) form transcription initiation coplex, promote sequence? ; indication of beginning pt of transcription
transcription
requires promotor whereas replication needs primer; promotor tells RNA pol where to start on DNA; primer = short pc of RNA
Transcription
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
Termination
termination sequence and proteins dissociate RNA pol from DNA in transcription
Replication
makes no distinction between genes
Transcrtiption
level of gene regulation, proteins called activators and repressor bind to promotor and repress or activate the activity of RNA pol
Activators and Repressors
proteins that regulate gene expression; allosterically regulated by cAMP; many proteins can be transcribed from 1 mRNA, so amplifying effect
primary function of gene regulation in prokaryotes and multicelluar org
regulate homeostasis inside and outside of the cell
prokaryotic mRNA
includes several genes in single transcript (polycistronic)
eukaryotic mRNA
monocistronic
operon
unit consisting of operator, promotor, and genes of single prokaryotic mRNA
lac operon
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
post transcriptional processing
all types of RNA go through (in eukaryotes_ for additional regulation
1 degress transcript
initia mRNA nucleotide sequence is processed in 3 ways: MAD
MAD
processing of 1 degree transcript?

add nucleotide, deletion of nucleotide, modification of nitrogenous base