Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
|
genetic material
|
both prok and euk CELLULAR organisms are ds-DNA
virus:ds or ss, DNA or RNA genes assembled on chrom's (all genetic material of a cell or virus is the genome) |
|
|
genetic information
|
sequence order of the purine and pyrimidine in the polynucleotide chains of DNA and/or RNA provides the info for assembly of all prot and functional RNA's.
|
|
|
what is a gene
|
stretch of DNA(RNA)the specifies the aa sequence
unit of complementation(cistron) unit of mutation(outdated) unit of expression(outdated) unit of inheritance(outdated) |
|
|
alleles
|
(diff forms of same gene and located at the exact same psotion in genome)
>400 of e.coli trpA gene dominant,recessive,co-dominant cells can be homo,heteo,hemi duplicate genes located at diff positions on genome arent alleles of each other |
|
|
steps in genetic info flow
|
1.DNA poly(rep):start at origin of rep,primer,make lead/lag strands
DNA 2.RNA pol(transcr):one strand template,start at promotors,no primer RNA 3.ribo&tRNA (transl):codons read,begin at start/end at stop PROTEIN |
|
|
genetics of prok and euk
|
(rep,trancrip/lation, occur in ALL organisms)
1.prok have 1 circular chrom in the cyto 2.euk have lots linear chrom in the nucleus 3.euk genes have coding/non (in/extrons) |
|
|
size, numbers, shapes of chromosomes in domain of life
|
bacteria:mycoplasma .58
streptomyces 8.66 archaea:nanoarchaeum .49 sufolobus 2.99 eukarya:giardia 12 tetrahymena 210 |
|
|
gene expression in prokaryotes
|
chrom & rib in the cyto allow for coupling of translation to transcription
several genes are transcribed from a common promotor to a single long mRNA |
|
|
gene expression in eukaryotes
|
1.separation of scrip/lation: chrom in nucl,ribo in cyto
2.genes split into ex/introns 3.1mary script must be extensively processed before exported to ctyo for translocation(mRNA) |
|
|
DNA double helix: major and minor grooves and protein contact points
|
proteins interact with DNA mainly by binding to atoms of bases exposed in the major groove.
(minor:small at top major:deep, next one down) |
|
|
inverted repeats
|
form stem-loop in dsDNA
binding sites for proteins,including transcriptional regulators provide info for the formation of stem-loop structures in RNA |
|
|
effect of heat on DNA
|
ds from .8-1 relative abs
Tm=85degC melting=1-1.2 ss levels at ~1.2 |
|
|
supercoiled DNA
|
relaxed covalently closed
(break one strand) relaxed nicked circular (rotate one end of broken strand around helix and seal) supercoiled circular DNA [inside cells DNA is highly supercoiled and associated with proteins] |
|
|
enzymes are necessary to increase or decrease DNA supercoiling:gyrase and topoisomerases
|
number of strands passed thru and resealed=less supercoiled
topoI:figure 8 topoII and gyrase:egg shaped (such enzymes are essential for replication transcription and DNA repair) |
|
|
organization of prokaryotic chromosomes
|
DNA is tightly compressed into nucleoids and spreads when cells are gently lysed.
|
|
|
in eukaryotes DNA is packaged with histones into nucleosomes
|
chromatin fiber
euchro/htereochromatin highly condensed,duplicated chromosomes of dividing nucleus |
|
|
non-chromosomal genetic elements
(types of extrachromosomal elements) |
1.virus:UQ in pro and euk
2.plasmid:UQ in prok, in mito of fungi/plant, sometimes in yeast and protezo 3.mito and chlor DNA:remmants of bacterial chroms only in euk |
|
|
viruses
|
DNA or RNA
some are integrated into host chrom's for replication often are responsible for diseased state of host |
|
|
plasmids
|
small(circular,linear) of DNA, replicate independently of cellular chrom's
carry info for own replication not essential for normal cell metab,growth,reproduction survival advantages |
|
|
types of plasmids
|
fertility(transfer of DNA)
resistance(Abiotic) bacteriocin(pduce toxins) virulence(disease-causing) cryptic(unknown) |
|
|
mito and chloro DNA's
1-5 |
both contain mtDNA and cpDNA
circular, similar to prok code for small # of indispensable proteins contain genes for proteins involved in oxidative phosphorylation and photosynthesis and 2 RNA's |
|
|
mito and chloro DNA's
6-8 |
chrom's are episomes and dont follow mendelian inheritance
circular,linear DNA plasmids can be present in mito of fungi and plants chlor of some algae are non-pathogenic small circular ds-plamidlike RNA |
|
|
transposable elements
(semiautonomous genetic elements) |
(segments of DNA that can move from on eplace on a chrom or genome to another)
replicate of a chrom(plasmid or virus) |
|
|
transposable elements
in prokaryotes(have at least 4 transposons) |
1.insertion sequences(IS):carry genes required for movement to new locations
2.transposons:carry other genes in addition to ones for movement 3.genetic elements that proliferate by hopping around in the genomes of their hosts and are transmitted to other cells like viruses 4.conjugative transposons(cells produce sex pili) |
|
|
transposable elements in eukaryotes(have at least 2 transposons)
|
1.DNA resembling prok transposons
2.retrotransposons:elements that exist as DNA in the genomes but are transcribed into an RNA copy which is used for template for RT into a DNA copy inserted at a new location in the genome. |
|
|
DNA replication
|
1953 Watson&Crick:predicted is semiconservative
1958 Messelson&Stahl:confirmed its conservative. |
|
|
properties of DNA polymerases
|
synthesize DNA 5'-3'
require template and primer(can be DNA or RNA) exonuclease 3'-5' I&II have a 5'-3'exonuclease for the degradation of primers during rep III w/ DNA repair prot 5'-3' |
|
|
DNA strand elongation
|
1.DNA pol use deoxyribonucleoside tri-P as substrates and addthem to 3'
2.DNA pol are processive and add one nucleotide to infor by complementary bases in the template strand |
|
|
functions of primers and templates in DNA synthesis
|
1.RNA pol dont need primer
2.primases are RNA pol 3.primers are ~30 nucleotides 4.DNA pol start synthesis at 3'-OH of RNA primers |
|
|
DNA replication:initiation
|
begins at origin of rep
prok,have 1 origin on chrom euk,each chrom has many origins DNA rep is bidirectional only some plasmid or viral DNA are unidirectional mode (best origin of replication is ori-C of the e.coli chrom) |
|
|
DNA replication starts at...
|
origins of replication
The ori-C site of e.coli is 245bp long with 11 GATC/CTAG Dam methylation sites and 4DnaA boxes Dam:deoxyadenosine methyl transferase |
|
|
DNA replication:the process
|
1.rep bubble made by binding DnaA protein to ori-DNA
2.DNA helicase (DnaB) unwinds 3.ss are kept separate by ss binding protein (SSB) 4.primase (DnaG) makes RNA primers |
|
|
DNA replication:elongation
|
lead/lag strand replication
|
|
|
elongation continued...
GTC:sites for the intiation of RNA primer synthesis |
gyrase,helicase,okazaki fragments, primase
|
|
|
completion of lagging strand synthesis
|
1.pol III starts at primer and replicates until it reaches primer of prior okazaki fragment
2.III released from lagging, and snaps back to start new fragment 3.I degrades primer bw fragment in 5'-3', fills gap 4.ligase seals last gap |
|
|
bidirectional replication
|
rep starts at origins of rep and goes in both directions until one rep complex collides with another going in the opposite direction
|
|
|
termination of replication
|
most bacterial chrom have rep termination sites
euk and viruses termination appears to occur when rep complexes collide. |
|
|
proofreading and editing
|
mismatch in pairing at the terminal base pair causes the DNA pol to pause:the last base in the new strand is removed by 3'-5' exonuclease of the pol before rep continues.
|
|
|
replication of linear chromosomes: the end problem
|
no primer synthesize DNA at the ends of chromosomes bc theres no template for primase to make primer
DNA pol cant replace RNA primer bc it cant synthesize 3'-5' and cant initiate 5'-3' unless it is primed |
|
|
replication of linear chromosomes (some solutions to the end problem)
|
linear chrom of some bacteriophages have ss cohesive ends and are circularized after entry into the host cell
|
|
|
replication of linear chromosomes(soln #2 to the end problem)
|
ends of some linear chromosomes and plasmids are covalently closed hairpin structures.
|
|
|
replication of linear chromosomes (soln#3 to the end problem)
|
some linear chromosomes replicate by initiation from a nucleotide linked to a protein
|
|
|
replication of linear chrom (soln#4)
|
euk solve by extending their 3' by means of a RT that has its own RNA template:telomerase
(some telomeres are 100-200Kb) |
|
|
antibiotics that block DNA replication
|
ciprofloxacin GyrA of gyrase
trimethoprim reductase |
|
|
inhibitors of DNA synthesis
|
4-quinolone:2hex
nalidixix acid:2hex,N,OH ciprofloxacin:3hex,N,NH,F,OH mitomycin C:hex,2pent,NH2 novobiocin:6hex |
