segments of dna are transferred from one chromosome to another
where does dna replication occur?
cytoplasm, specifically the nucleoid
where does dna replication occur in eukaryotes?
bacterial chromosomes have a single origin of replication, which is where?
a specific sequence of nucleotides recognized by the replication enzymes
eukaryotic chromosomes are larger than bacterial chromosomes so they have how many origins of replication?
what happens once replication is finished?
new chromosome copies remain attached to proteins in cell membrane, this allows copies to seperate during binary fission
how does dna replicate in eukaryotes?
spindle fibers move chromosomes around during mitosis
major enzymes involved in dna replication
dna helicase and dna polymerase
what does dna helicase do?
uncoils the dna helix and seperates the two strands
what does dna polymerase do?
lays down the new nucleotides and forms new strands of dna
what are the short lengths produced on discontinuous dna strands are called what?
what is rna used to make?
where does transcription occur?
where does transcription occur in eukaryotes?
what is the major enzyme responsible for bacterial transcription
how does rna work to transcribe a gene?
rna polymerase binds to the dna at the promoter, then seperates the two strands of dna and begins reading dna in one strand, it attaches rna nucleotides according to the nucleotide sequence in dna, and the rna molecule lengthens
bacterial dna contains no what?
what are introns?
segments of rna that must be removed in order to produce the proper protein later during translation
do eukaryotic rna contain introns?
why are there no introns in bacterial rna?
there is no time to remove introns
how fast does rna work?
translation usually begins before transcription ends (before rna is finished being made, ribosomes are already grabbing it and trying to make proteins using the information already there)
where does transcription and translation occur in eukaryotes?
what are the major structures for bacterial translation?
what are ribosomes made of?
part protein and part RNA
bacterial cells usually have how many ribosomes?
ribosomes read information in rna how many nucleotides at a time?
what are three sets of nucleotides called?
what does a single codon indicate?
a specific amino acid that will be added to the protein
what specific codon does translation begin at?
AUG or the start codon
how are new amino acids delivered?
by pieces of tRNA (transfer rna)
ribosome continues reading codons and adding amino acids until when?
it reaches one of the three stop codons, then the ribosome disnegages and the new protein is released
what are the three types of rna that participate in translation?
mRNA, tRNA, and rRNA
contains the dna message and is the piece of RNA that the ribosome reads
delivers the new amino acids to the ribosome
forms part of the ribosome (the rna part)
why are bacteria able to adjust their metabolism more quickly than eukaryotic cells when the environment changes?
bacterial transcription and translation aren't seperated by compartments
what is a mutation?
change in the nucleotide sequence of dna
what are mutations caused by?
spontaneous or mutagens
spontaneous mutations are due to what?
errors made by dna polymerase during replication
what are mutagens?
chemical or physical agents that cause dna polymerase to make mistakes
how can mutations be repaired?
dna polymerase has a self-checking ability and other enzymes (repair enzymes) patrol dna and detect unusual shapes
what may mutagens be?
radiation or chemicals
what is a radiation mutagen?
gamma rays, xrays, uv
what is a chemical mutagen?
aflatoxins, ethidium bromide, 5-bromouracil
bacteriocidal uv lamps have what peak wavelength?
how do chemical mutagens cause mutations?
by changing the shape of the dna molecule
what mold produces aflatoxins?
what are the most carcinogenic naturally produced substances known?
what are the most commonly contaminated foods by aflatoxins?
peanuts, corn, and wheat
what is ethidium bromide used for?
stain gels after electrophoresis
what is gel electrophoresis used for?
to seperate dna fragments during dna fingerprinting
where does the ethidium bromide bind during gel electrophoresis?
to the dna and is used to located where the bands of dna occur
where is 5-bromouracil commonly used? what for?
in lab to cause mutations for experimental research
where has 5-bromouracil been used out of labs?
to treat cancer
what enzymes are available to prevent/repair mutations?
dna polymerase, photolyass, and endonucleases
dna polymerase has what special function?
a proof-reading function
what is photolyase activated by? what does it do?
light, break thymine diners and allow thymines to reattach to their original bases
what does endonuclease do?
cuts out affected nucleotides after thymine dimers and allows other enzymes to replace them
what test is used to determine if a chemical is a mutagen?
the ames test
what does the ames test use?
a his (histidine negative)
what histodine negative does the ames test use?
how does the ames test work?
chemical being tested and rat liver extract are added to a tube containing salmonella typhimurium
time is permitted for mutations to occur and then the mix is plated on an agar without histidine
growth on agar means that mutations occured
how would a mutagen survive on an agar?
most cells die due to lack of histidine in the media, but mutagens will now be allowed to produce their own histidine and will survive
why is rat liver extract used during the ames test?
chemicals are not mutagenic in their original form but converted to mutagenic compounds by liver enzyme
the ames tests does not just test one compound. why?
enzymes in rat liver produces a variety of molecules when mixed with original chemical, so it is a test of the original compound and all of its variations
what is genetic recombination?
exchange of dna between two chromosomes
what does bacterial recombination require? why?
dna travel from cell to cell because bacterial chromosomes are singular
how do movement of bacterial dna occur?
transformation, conjugation, and transduction
what is transformation?
update of naked dna from the environment
what is conjugation?
direct transfer of dna from one cell to another
what is transduction?
transfer of dna from one bacterial cell to another by a bacteriophage (virus)
how can transformation be improved in a lab?
adding chemicals like mild detergents or passing an electric current through the solution (electroportation)
what do the methods of lab transformation do to the membrane?
ruin it, but not enough to kill it hopefully allowing fragments of dna to pass through
how does conjugation occur?
through direct contact
how do gram-negative bacteria conjugate?
using pilus to attach to the receiving cell and reel it into contact
what species allow conjugation?
genetically equipped with necessary structures
what is passed during conjugation that would give off various resistances?
why are plasmids so highly populated?
copies are only given off during conjugation so both cells have this plasmid genes and they can pass them onto other cells
what is one common conjugation plasmid?
f factor in e. coli (f for fertility)
what does the f. factor in e. coli produce?
the ability to produce pilus
plasmids that give cells the ability to undergo conjugation and pass resistances to other cells are called what?
what happens when a phage infects a bacterial cell?
enzymes will cut up dna so when phage particles are being assembled pieces of bacterial dna may be packed in them
what is genetic engineering?
the process of inserting foreign genes into an organism (this is genetic recombination when it happens naturally)
dna with foreign material inserted in it
recombinant dna (rDNA)
an organism with recombinant dna can be called what?
recombinant, transgenic, or engineered organism
what is the outline for how bacteria are engineered?
bacterial cells are processed and plasmids are collected
seperately, cells with the gene you want to transfer are process and dna is collected
plasmids and dna you want are cut open using enzymes and mixed together
peices of dna with the gene you want will be inserted into some plasmids
recombinant plasmids are inserted into new cells using transformation
what are vectors? what is the vector during genetic engineering?
what enzymes cut open dna and plasmids during genetic engineering?
what is the most commonly engineered bacterium?
what is the most commonly engineered eukaryotic organism?
saccharomyces cerevisiae (yeast)
when are viruses used as vectors?
used to engineer human cells for use in gene therapy
what are restriction enzymes?
bacterial enzymes that destroy phage dna
where do restriction enzymes cut the dna?
specific nucleotide sequences (produce sticky ends)
what are sticky ends? why are they called this?
short, single-stranded lengths; they tend to stick to complementary single strands
why are restriction enzymes useful?
pieces of dna cut with an enzyme can be inserted into the dna of another organism that's been cut with the same thing, they have the same sticky ends
what is complementary dna (cDNA)?
dna with the introns removed
what do introns prevent?
eukaryotic genes from being inserted into bacteria, because they cannot remove introns themself
dna with the introns removed can be produced using what?
transcriptase, enzyme produced by retroviruses
what is a summary of how cDNA works?
we use reverse transcriptase to produce cDNA and that allows us to engineer bacterial cells with eukaryotic genes
what is gene therapy?
genetic engineering of humans in order to treat disease
what kind of virus is usually used in gene therapy?
why are viruses used during gene therapy on humans?
they already have the ability to penetrate human cells and release dna
what attenuated virus is usually used in gene therapy?
adenoviruses (cause respiratory infections, like the common cold)
what has gene therapy successfully been used to treat?
SCID (severe combined immunodeficiency)
what do individuals that have been treated for SCID using gene therapy have a high risk of developing?
what is PCR (polymerase chain reaction)?
process that makes multiple copies of a piece of dna (usually billions) within a couple of hours
the process of pcr runs in cycles of what?
heating and cooling of temps between 60-95 degrees Celsius, temperatures that would denature dna polymerase from mesophiles
pcr requires a heat stable dna polymerase, usually from what thermophilic bacterium?
the is the dna polymerase from t. aquaticus usually referred to as?
what methods are commonly used to insert recombinant dna into cells?
transformation, electroporation, microinjection, gene gun, viruses, and agrobacterium tumefaciens
what is electroporation?
a variation of transformation that uses an electric current to make the cell membrane leaky and allow dna to enter
what is microinjection?
dna can be injected directly into cells using an ultra-fine needle
what is microinjection useful for? why isn't it useful for bacterial cells?
animal cells and yeasts, it may be called microinjection but the needle is far too large for bacterial cells
how do you use a gene gun?
microscopic particles of gold are coated with dna and fire at cells
the gene gun is used for what cells?
how does agrobacterium tumefacians work?
a plant pathogen that has the ability to inject dna into plant cells
agrobacterium tumefaciens is a plant pathogen that causes what?
the ability to inject the dna and cause disease are carried on what plasmid?
ti-plasmid (tumor inducing)
where has agrobacterium tumefaciens been used?
used to engineer crops with various traits (ability to produce own pesticide), the crops produce protein crystals that harm digestive tracts of insects but are harmless to animals and human
what pesticide can plants produce on their own after being injected with agrobacterium tumefaciens?
what are the crops genetically engineered called?
bt crops (bt corn, bt cotton, etc)
what can dna fingerprinting be used for?
to determine paternity, solve crime, trace outbreaks, and detect pathogens
what process is used to make a dna fingerprint?
cut up dna sample, copy it, seperate it, stain it, view it
for fingerprinting what is used to copy dna?
pcr makes multiple copies of fragments
how does seperating dna work with dna fingerprinting?
gel electrophoresis is used to seperate dna fragments according to length, electric current running through gel bath causes fragments to move through the gel, large fragments don't move far and small fragments do, this creates a fingerprint pattern
how do you stain dna in dna fingerprinting?
stained with ethidium bromide, dna gel is not visible so it must be stained to see, gel is soaked in a solution of ethidium bromide and the bromide wedges itself into the dna helix
how do you view dna during dna fingerprinting?
ethidium bromide is fluourescent, so when gel is exposed to uv light the band becomes visible
how can bacteria be identified using fingerprinting?
compare dna of a known species to the unknown species
how is the taxanomic hierarchy same/different with prokaryotes than eukaryotes?
it's the same except that prokaryotes are not assigned to kingdoms
what are subspecies of bacteria called?
stains or serotypes
what is a strain of e. coli?
e. coli 0157:H7
what bacterial family includes e. coli, salmonella, proteus, and other gram-negative intestinal bacteria?
what is the definitive guide to the identification and classification of bacteria?
what three domains can all organisms on earth be divided into?
archaea, bacteria, and eukarya
bacteria domain is divided into more than how many phyla?
what are three of the well-known phyla of bacteria?
proteobacteria, firmicutes, and actinobacteria
what bacteria are usually in the phylum proteobacteria?
what are some well-known proteobacteria?
genera: escherichia, proteus, psuedomonas, neisseria, and salmonella
what does the phylum firmicutes include?
low GC gram-postive bacteria
what are the most well-known gram positive genera in firmicutes?
clostridium, bacillus, lactobacillus, staphylococcus, and streptococcus
what is GC content?
the percent of base pairs in an organisms dna are that are guanine-cytosine (GC is below 50%)
what does the phylum actinobacteria include?
high GC gram-positive bacteria
actinobacteria are often what?
well known actinobacteria include what genera?
streptomyces and mycobacterium
more than how many species of fungi are known so far?