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64 Cards in this Set
- Front
- Back
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DNA basic unit
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-nucleotide made of
phopshate group nitrogenous base (C,A,U,T or G) deoxyribose sugar (core) |
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CUT=
AG= |
pyrimidines (1 ring)
purines (2 rings) |
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DNA structure
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-5' (5 C) end have OH or phosphate
-3' (3 C) have OH -2' has H instead of OH=deoxy -3' end of one attached to 5' end of next sugar -sugar/phosphate make backbone, base off to sides -double stranded helix |
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double stranded helix
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-sugar/phosphate backbone outside of helix
-bases in middle=base paring via H bonding -antiparallel |
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base pairing
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-A with T (2 H bonds)
-G with C (3 H bonds) #A=#T #G=#C |
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AT rich DNA vs GC rich
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-higher temp need to break intermolecular H bonds of GC
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DNA/RNA work in ___direction
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5'-->3'
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DNA replication:
semiconservative replication |
one strand from parent
one strand new ie daughter strand |
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how to tell difference between new strand and old after replication
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-old has more methyl groups
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DNA replication:
origin |
-multiple unwinding sites=origin of replication
-new DNA in made in both directions=replication forks |
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many origins of replication because
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-3 billion base pairs in genome,
-every autosomal cell has genome copy -replicate fast need many sites |
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DNA replication:
unwinding and initiation |
-helicase=unwinds DNA,may cause supercoils (strains helix)
-single strand binding proteins=keep DNA strands unwound -DNA gyrase=prevents supercoils, is topoisomerase -Primase=RNA polymerase makes RNA primer -DNA polymerase=adds nucleotides to 3' end of RNA primer |
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do bacteria have topoisomerase
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yes
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DNA replication:
synthesis |
-DNA polymerase add daughter in 5'-->3'
-since antiparallel get leading strand (continuous 5'->3') & lagging strand (discontinuous 5'->3') |
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lagging strand
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-okazaki fragments
-hops along strand -gaps filled with nucleotides and DNA ligase add sugar phosphate backbone *more prone to error |
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RNA
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-single stranded
-use U instead of T -ribose instead deoxyribose -in nucleus/cytoplasm (DNA only in nucleus) |
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mRNA
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-made by transcription
-carry info from nucleus-->cytoplasm to become protein -eukaryotes: monocistronic -prokaryotes: polycistronic |
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monocistronic
polycistronic |
-mRNA code for 1 product
-many products possible depends on where start translation |
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tRNA
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-cytoplasm
-brings/adds aa -different tRNA for each aa |
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rRNA
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-nucleolus
-make part of ribosome for protein assembly |
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hnRNA
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-heterogenous nuclear
-pre-mRNA -larger+riboproteins in it |
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protein synthesis :
transcription |
-DNA-->mRNA
1)unwind DNA, template strand=antisense (antiparallel/complementary to mRNA) 2) promoter signal start, RNA polymerase bind 3)5'-->3' 4) termination seq 5) DNA helix reforms, hnRNA made |
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protein synthesis:
post transcriptional processing |
-hnRNA-->mRNA need 3 things
1) 5' guanosyl cap 2) poly A tail 3) introns (noncoding) spliced out *occur in nucleus |
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codon
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-represents one aa
*each aa can have multiple codons due to degeneracy/redundancy of genetic code -3 letter=1 word=codon ex) ACC=threonine (aa) |
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degeneracy/redundancy of genetic code
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-mutation in DNA may not be bad ie) different codon but same aa
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protein synthesis:
translation needs (5) translation-->tRNA |
needs mRNA, tRNA, ribosomes,aa, energy
- bound to anticodon and aa -aa bind to CCA -5' of codon line up with 3' of anticodon -tRNA synthetase bind aa to tRNA via GTP |
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protein synthesis:
translation-->ribosomes |
-2 subunits= large small
-bind during protein synthesis -mRNA binding site (1) -tRNA binding site (2) |
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tRNA binding sites of ribosome
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-A site=hold tRNA complex
-P site= binds tRNA attached to growing polypeptide chain |
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protein synthesis:
initiation |
-small subunit look for AUG (start codon) on mRNA
-methionine tRNA (CAU) binds at P site -large subunit binds *need initiation factors for mRNA to bind ribosome initially |
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protein synthesis:
elongation |
-ribosome moves 5'-->3' along mRNA
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protein synthesis:
termination |
termination codon (UGA,UAA,UAG) binds release factor=chain released
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post translational modification
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-help sort protein to target
-fold into secondary structure |
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base pair mutation=
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-called point mutation
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point mutation
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-single nucleotide changed
1)silent=no effect 2)missense=1 aa substituted for another, has effect |
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frameshift mutation
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-insert/delete nucleotides not in multiples of 3
-shifts reading frame |
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mutations inherited (passed on) if
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damage done in germ (sex) cells
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transposons
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jump in/out of genome can cause mutation if jump into coding
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virus only infect host if
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-receptors recognize virus protein coat (capsid)
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DNA containing virus
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-enter nucleus and use host DNA/RNA polymerase machinery
-some only replicate in cytoplasm: if so, need own DNA/RNA polymerase (host's inside nucleus) |
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RNA containing virus
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-replication only in cytoplasm
-virus bring RNA replicase (we dont replicate RNA) |
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retrovirus
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-RNA virus
-reverse transcriptase: RNA-->DNA -new DNA into host genome *only way to destroy viral genome by killing host cells |
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virus uses host ribosomes, aa, enzymes, tRNA to
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turn transcribed genes-->proteins
proteins make virions (viral particles) |
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viral progeny release
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1)host cell lyses (too much virions)/cause apoptosis
2)fuse with membrane=extrusion *if cell lyse, no more host for virus *extrusion keeps host alive |
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productive cycle of virus
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state of extrusion
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are viruses alive
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no, cant reproduce by themselves need host
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bacteriophage
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-virus target bacterial cell
-inject genome into cell only, capsid remains outside of cell -virus enter either lytic cycle OR lysogenic cycle |
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lytic cycle
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-lyses cell really mess cell up
-in this phase call bacteria virulent |
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lysogenic cycle
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-gentler than lytic
-integrate into bacterial genome as provirus |
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bacteria pro or eu?
circular or straight DNA? membrane bound organelles? single celled or multi? |
pro
circular no single |
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plasmid
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-bacterias extrachromosomal material
-allow antibiotic resistance |
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epsiomes
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-type plasmid
- can integrate into genome |
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due to no membrane bound organelles bacteria's transcription/translation occur
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almost simultaneously
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bacteria mRNA polycistronic
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multiple proteins coded in same mRNA strand
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origins of replication in bacteria
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-1since less genes and circular genome
-replication both directions |
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bacteria 3 mechanism to increase diversity
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-transformation
-conjugation -transduction |
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transformation
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foreign chromosome piece (plasmid) into host genome
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conjugation
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-form of sexual reproduction
-male donor transfer genetic to recipient female |
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transduction
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-accidental
-via bacteriophage -one piece of host genome transfered with viral genome integrated into another bacterial genome |
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ability to transcribe gene depends on RNA polymerase being able to
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-access genome
*applies to both pro/eu |
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operons (bacteria)
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-direct RNA polymerase to genome
-made of structural genes, operator genes, promoter gene |
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structural gene
operator gene promoter gene regulator region (order from left to right) above come in two type system |
-codes for protein
-non-transcribable, bind repressor protein -RNA polymerase binds -make repressor protein -regulator,promoter,operator, structural -inducible, repressible |
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inducible system
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need inducer to cause transcription of structural
constantly make repressor protein inducer bind repressor product made only when needed |
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repressible system
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constantly transcribed unless corepressor present
repressor protein inactive corepressor binds and activates it |
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bacteria use repressible/inducible systems to
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control gene expression at transcriptional level
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