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Chapter 7
SCC Bio229 - Ch 7
148
Microbiology
Undergraduate 1
03/30/2014

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Term
genetics
Definition
the study of inheritance and inheritable traits as expressed in a organism's genetic material
Term
genome
Definition
entire genetic complement, including genes and nucleotide sequences that connect genes to one another
Term
genes
Definition
specific sequences of nucleotides that code for polypeptides or RNA molecules
Term
nucleotides
Definition
-basic building blocks of the polymers nucleic acids
-each nucleotide made up of a phosphate group attached to a nucleoside (which is a pentose sugar attached to one of five nitrogenous bases)
Term
base pairs
Definition
-the complimentary bases of nucleotides hydrogen bond to one another
-DNA: thymine and adenine form two hydrogen bonds
-RNA: uracil and adenine form two hydrogen bonds
-both: guanine and cytosine form three hydrogen bonds
Term
antiparallel strands of DNA
Definition
one strand runs in the 3' to 5' direction while the other runs in the 5' to 3' direction
Term
chromosome
Definition
-a molecule of DNA associated with protein
-prokaryotes: typically circular and localized in a region of the cytosol called the nucleoid
-eukaryotes: threadlike and most visible during mitosis or meiosis
Term
haploid cells
Definition
prokaryotes only have a single copy of each chromosome
Term
nucleoid
Definition
region of the prokaryotic cytosol containing the cell's DNA/chromosomes
Term
histones
Definition
globular protein found in eukaryotic and archeal chromosomes
Term
gyrase
Definition
enzyme responsible for further folding and super-coiling the entire prokaryotic chromosome
Term
plasmid
Definition
-(prokaryotic) a small, circular molecule of DNA that replicates independently of the chromosome
-each carries genes for its own replication and often for one or more nonessential functions
-types of plasmids (aka factors): fertility (F), resistance (R), bacteriocin, virulence
Term
fertility (F) plasmid
Definition
carries instructions for conjugation
Term
resistance (R) plasmid
Definition
-carries genes for resistance to one or more antimicrobial drugs or heavy metals
-certain cells can transfer resistance to other cells
Term
bacteriocin plasmid
Definition
-carries genes for proteinaceous toxins called bacteriocins, which kill bacterial cells of the same or similar species that lack the plasmid
-in this way, a bacterium can kill off its competitors
Term
virulence plasmids
Definition
carries instructions for structures, enzymes, or toxins that enable a bacterium pathogenic
Term
diploid cells
Definition
eukaryotic cells have two copies of each chromosome
Term
eukaryotic chromosomes
Definition
differ from prokaryotic chromosomes in that they are always sequestered within a nucleus and are all linear (rather than circular)
Term
nucleus
Definition
an organelle containing the DNA within a cell and is surrounded by two membranes called the nuclear envelope
Term
nuclear envelope
Definition
consists of the two membranes that surround the nucleus of a cell
Term
nucleosomes
Definition
-DNA, which has an overall negative charge, wraps around the positively charges histones to form 10 nm diameter beads
-"in other words": beads of DNA bound to a histone in a eukaryotic chromosome
Term
chromatin fibers
Definition
-an association of nucleosomes and proteins found within the chromosomes of eukaryotic cells, 30 nm in diameter
-dispersed throughout the nucleus (except during mitosis)
Term
euchromatin
Definition
-aka "open chromatin"
-in regions of the chromosome where genes are active, the chromatin fibers are loosely packed
Term
heterochromatin
Definition
-aka "closed chromatin"
-inactive DNA is tightly packed
Term
extranuclear DNA of eukaryotes
Definition
-DNA molecules of mitochondria and chloroplasts are circular and resemble the circular chromosomes of prokaryotes
-note: some fungi and protozoa carry plasmids
Term
DNA replication
Definition
-an anabolic polymerization process that allows a cell to pass copies of its genome to its descendants
-semi-conservative b/c each daughter DNA molecule is composed of one original "parent" strand and one new strand
-bidirectional: synthesis proceeds in both directions from the origin
Term
triphosphate deoxyribonucleotides
Definition
-DNA molecules with three phosphate groups linked together by two high-energy bonds
-the building blocks of DNA carry within themselves the energy required for DNA synthesis
Term
origin
Definition
a specific sequence of nucleotides in which DNA replication begins
Term
helicase
Definition
-unwinds/unzips strands
Term
primase
Definition
-sets down an RNA primer
-provides the starting point for replication
-one primer for leading strand
-many for lagging strand: one for each Okazaki fragment
Term
DNA polymerase III
Definition
-lays down most of the complimentary strand
-note: named the "third" due to it being the third DNA polymerase discovered, NOT b/c of the order of function within DNA replication
-also plays role in "proofreading exonuclease function"
Term
DNA polymerase I
Definition
-aka "RNAse"
-removes the RNA nucleotides that were set down by primase (by digesting the primers)
-replaces those with DNA nucleotides
Term
ligase
Definition
-fixes the missing covalent bonds on the sugar-phosphate backbone on the lagging strand
-"in other words": seals the gaps between the adjacent Okazaki fragments to form a continuous DNA strand
Term
leading strand
Definition
**DNA only grows 5' to 3' (only adds to the 3')
-leading strand has the 3' end facing the helicase which allows for smooth adding
-synthesized continuously
Term
lagging strand
Definition
*DNA only grows from 5' to 3' (only adds to the 3')
-lagging strand has the 5' end facing the helicase and the 3' end facing away from the helicase (antiparallel strands)
-nucleotides are added to the 3' ends and replication is fragmented
-fragments called "Okazaki fragments"
-NOT slower than leading, just synthesized discontinuously
Term
stabilizing proteins
Definition
after helicase splits the DNA molecule, stabilizing proteins bind to the strands so that they do not rejoin while replication proceeds
Term
proofreading exonuclease function
Definition
DNA polymerase III recognizes most errors and removes the incorrect nucleotides before proceeding with synthesis
Term
gyrase and topoisomerase
Definition
-these enzymes prevent super-coiling of DNA during replication
-act by cutting the DNA, rotating the cut ends, and then rejoining the cut ends
Term
methylation
Definition
-process in which a cell adds a methyl group to one or two bases that are part of specific nucleotide sequences
-bacteria typically methylate adenine bases and only rarely cytosine bases
-plant and animal cells only methylate cytosine bases
Term
methylation and cellular processes
Definition
1. control of genetic expression
2. initiation of DNA replication
3. protection against viral infection
4. repair of DNA
Term
replication of eukaryotic DNA
Definition
-uses four different DNA polymerases
-thousands of replication origins per molecule
-Okazaki fragments are shorter than those of bacteria
-plant and animal cells methylate cytosine bases exclusively
Term
genotype
Definition
-actual set of genes in an organism's genome
-genotype determines phenotype by specifying what kinds of RNA and which structural, enzymatic, and regulatory protein molecules are produced
Term
phenotype
Definition
refers to the physical features and functional traits of an organism, including characteristics such as structures, morphology, and metabolism
Term
transcription
Definition
-process in which the genetic code from DNA is copied as RNA nucleotide sequences
-occurs in the nucleoid region of the cytoplasm in bacteria
-3 steps: initiation, elongation, termination
Term
translation
Definition
-RNA molecules in ribosomes synthesize polypeptides
-3 steps: initiation, elongation, termination
Term
central dogma
Definition
in genetics, fundamental description of protein synthesis which states that genetic information is transcribed from DNA to RNA and then translated from RNA to polypeptides
Term
4 types of RNA
Definition
transcribed from DNA=
rRNA: forms ribosomes
tRNA: delivers a.a. to ribosomes
mRNA: carries info for making specific proteins from DNA to ribosomes
RNA primer: molecules for DNA polymerase to use during DNA replication
Term
RNA primer
Definition
molecules for DNA polymerase to use during DNA replication
Term
mRNA
Definition
-messenger RNA
-carries genetic information from chromosomes to ribosomes as triplet sequences of RNA nucleotides (codons)
Term
rRNA
Definition
-ribosomal RNA
-combine with ribosomal polypeptides to form ribosomes
Term
tRNA
Definition
-transfer RNA
-delivers the correct amino acids to ribosomes based on the sequence of nucleotides in mRNA
-a sequence of about 75 ribonucleotides that curves back on itself to form 3 main hairpin loops held in place by hydrogen bonding between complimentary nucleotides
-bottom loop contains an anticodon
-acceptor stem for a specific amino acid at its 3' end
Term
initiation of transcription
Definition
a. RNA polymerase binds to a promoter. Sigma factor enhances promoter recognition in bacteria.
b. upon recognition of the promoter, RNA polymerase unzips the DNA molecule which creates a "bubble" as it moves
Term
RNA polymerase
Definition
-enzyme that synthesizes RNA molecules by linking RNA nucleotides that are complimentary to genetic sequences in DNA
-links nucleotides only to the 3' end
Term
promoters
Definition
specific DNA nucleotide sequences, each of which is located near the beginning of a gene, and serves to initiate transcription
Term
sigma factor
Definition
-in bacteria, a polypeptide subunit of RNA polymerase which is necessary for promoter recognition
-variations of sigma factors and promoters affect the amount and kinds of polypeptides produced
Term
elongation of transcription
Definition
a. at about 10 nucleotides away from the promoter region, triphosphate ribonucleotides align opposite their compliments in the open DNA "bubble"
b. RNA polymerase links two adjacent ribonucleotide molecules using the energy phosphate bonds of the first ribonucleotide
c. RNA polymerase moves along the molecule repeating the process and synthesizing mRNA
Term
triphosphate ribonucleotides
Definition
-rATP, rUTP, rGTP, and rCTP
-contains high energy within the phosphate bonds to support the linking of adjacent ribonucleotide molecules and thus anabolism of mRNA
Term
termination of transcription
Definition
-RNA polymerase and the transcribed RNA are released from DNA
-two processes: self-termination or Rho dependent termination
Term
self-termination of transcription
Definition
transcription of DNA terminator sequences causes the RNA to fold, loosening the grip of polymerase on DNA
Term
enzyme-dependent termination of transcription
Definition
Rho pushes between polymerase and DNA, releasing polymerase, RNA transcript and Rho
Term
terminator
Definition
sequence of DNA composed of two symmetrical series: one that is very rich in guanine and cytosine bases, followed by a region rich in adenine bases which causes termination of transcription
Term
transcription differences in eukaryotes
Definition
-RNA transcription occurs in the nucleus
-transcription also occurs in mitochondria and chloroplasts
-3 types of RNA polymerases
-numerous transcription factors
-mRNA processed before translation: capping, polyadenylation, splicing
Term
mRNA processing
Definition
1. capping: guanine nucleotide added to the "front" 5' end of the mRNA molecule
2. polyadenylation: at end of gene, termination proteins cleave the RNA molecule and add 100-250 adenine bases
3. splicing: spliceosome removes introns and splices exons from pre-mRNA in order to make functional mRNA from the exons
Term
pre-messenger RNA
Definition
-newly guanine capped and polyadenylated mRNA molecules
-contain introns and exons
-must be spliced in order to make functional mRNA containing only exon regions
Term
introns
Definition
-noncoding sequences of pre-mRNA that may be thousands of nucleotides long
-introns are removed from pre-mRNA
-"in" refers to intervening sequences
Term
exons
Definition
-coding regions of pre-mRNA that are about 150 nucleotides long
-functional mRNA is made from only these regions of the pre-mRNA
-"ex" refers to the fact that these genes are expressed
Term
spliceosome
Definition
-five small RNA molecules associate with about 300 polypeptides to form a spliceosome
-acts as a ribozyme (ribosome enzyme) to splice pre-mRNA into mRNA
-it removes the introns and splices the exons to produce functional mRNA
Term
ribosomes in translation
Definition
-"polypeptide factories"
-50S subunit + 30S subunit= 70S prokaryotic ribosome
-60S subunit + 40S subunit= 80S eukaryotic ribosome
-smaller subunit shaped to accommodate 3 mRNA codons at a time and also 3 tRNA binding sites
Term
genetic code
Definition
-4 letter alphabet
-genes composed of sequences of 3 nucleotides that specify amino acids
-64 possible arrangements of the four different nucleotides in triplets
-organisms use 20 (or 21) amino acids
-triplets of mRNA molecules=codons
Term
codons
Definition
-triplet of mRNA nucleotides that code for specific amino acids
-1 start= AUG =>met
-3 stops= UAA, UAG, or UGA
Term
anticodon
Definition
-bottom loop portion of tRNA molecule that is complementary to a codon on an mRNA molecule
Term
acceptor stem
Definition
-3' end of tRNA molecule contains an acceptor stem for a specific amino acid
-specific enzymes in the cytoplasm "charge" the tRNA molecule by attaching the appropriate amino acid to the acceptor stem
Term
tRNA binding sites on ribosomes
Definition
-A site: accommodates a tRNA delivering an Amino Acid
-P site: holds a tRNA and the growing Polypeptide
-E site: discharged tRNA's Exit from the E site
Term
initiation of translation
Definition
a. smaller subunit of ribosome attaches to mRNA near start codon AUG
b. anticodon of tRNA^fMet aligns with the start codon on the mRNA and energy from GTP is used to bind tRNA in place at the P site of ribosome
c. larger subunit of ribosome attaches to form an initiation complex- complete ribosome attached to mRNA with binded tRNA at P site
Term
initiation complex
Definition
-forms during initiation of translation
-includes: two ribosomal subunits, mRNA, several protein factors, and tRNA^fMet
Term
elongation of translation
Definition
a. tRNA with the anticodon complimentary to the next codon delivers its amino acid to the A site (elongation factors deliver tRNA along with GTP)
b. a ribozyme in the larger subunit forms a peptide bond between the terminal amino acid of the growing peptide chain
c. using more energy from GTP, ribosome moves forward another codon (translocation) down the mRNA. this transfers each tRNA to the next binding site
d. ribosome releases the "empty" tRNA from the E site
e. the cycle repeats
Term
elongation factors
Definition
-proteins in the translation process escort "charged" tRNA along with GTP to the A site of the ribosome/mRNA complex
Term
translocation
Definition
ribosome moving forward codon by codon
Term
polyribose
Definition
as elongation proceeds, ribosomal movement exposes the start codon in order to allow another ribosome to attach to begin translating another identical polypeptide
Term
termination of translation
Definition
-release factors somehow recognize stop codons and modify the larger subunit of the ribosome to activate ribozymes which sever the polypeptide from the final tRNA
-the ribosome then dissociates from the mRNA into subunits
-polypeptides released at termination may function alone or together in quarternary protein structures
Term
regulation of genetic expression
Definition
-75% of genes are expressed at all times
-other genes are regulated so they are only transcribed and translated when cells need them
->allows cells to conserve energy

-regulation of protein synthesis typically halts transcription
-regulation at level of translation: riboswitch and short interference RNA siRNA
Term
operon
Definition
-special arrangements of prokaryotic genes that play roles in gene regulation
-consists of a promoter and a series of genes
-some operons are controlled by a regulatory element called an operator
Term
operator
Definition
regulatory element in an operon where repressor protein binds in order to stop transcription
Term
repressor protein
Definition
-binds to the operator of an operon in order to halt transcription
-in the absence of a repressor, transcription is induced
Term
regulatory gene
Definition
located outside the operon, codes for the repressor
Term
inducible operons
Definition
-not usually transcribed (usually "off") and must be activated by inducers (can be turned "on")
**usually genes containing instructions for enzymes in a catabolic reaction
-only turned on when the polymer to break down is present
-ie: lac operon
Term
lac operon
Definition
-inducible operon, induced by the presence of lactose
-includes a promoter, an operator, and three genes that encode the proteins involved in the transport and catabolism of lactose
-when lactose is present, allolactose binds to the repressor and deactivates it, in order to allow transcription to occur
*no lactose=no transcription
Term
repressible operons
Definition
-operons that are transcribed continually (usually "on") until deactivated by repressors (can be turned "off)
**usually instructions for enzymes needed for anabolic reactions
-turned off when the polymer to build is in sufficient or plentiful amounts
-ie: trp operon
Term
trp operon
Definition
-consists of a promoter, an operator, and five genes that code for the enzymes to build tryptophan
-when enough tryptophan is present, some will bind to the repressor to "activate" it so that it can bind to the operator and block transcription
Term
corepressor
Definition
-activates the repressor so that it can bind to the operator in an operon system
-ie: tryptophan acts as a corepressor stopping its own synthesis
Term
miRNA
Definition
-micro RNA: short, about 21 nucleotides, RNA molecule
-joins with regulatory proteins to form an RNA silencing complex (RISC) which then binds to the mRNA blocking translation
Term
RISC
Definition
-RNA silencing complex
-either cleaves the mRNA molecule
-or binds to the mRNA molecule, blocking it from the ribosome
Term
siRNA
Definition
-short interference RNA
-similar to primer, becomes incorporated into RISC, which binds to mRNA
-RNA molecule complementary to a portion of mRNA, tRNA, or a gene that binds and renders the target inactive
Term
riboswitch
Definition
-RNA molecule which changes shape in response to environmental conditions such as changes in temperature, or shifts in the concentration of nutrients
-some mRNA molecules act as riboswitches and block ribosomes and translation of the polypeptide they encode
Term
mutation
Definition
-change in the nucleotide base sequence of a genome, particularly its genes
-rare event
-almost always deleterious
-rarely leads to a protein having a novel property that improves the ability of organism and its descendents to survive and reproduce
Term
point mutation
Definition
-a genetic mutation in which only one base pair is affected
-includes: substitutions
Term
frameshift mutations
Definition
-includes insertions or deletions of one base pair
-nucleotide triplets after the mutation are displaced
-typically result in missense or nonsense mutations
Term
silent mutations
Definition
-aka silence
-no real change or effect
-ie: same amino acid from a different codon
Term
missense mutation
Definition
-changing the codon results in a different amino acid
-makes sense, but not the "right" sense
-ie: sickle cell anemia
Term
nonsense mutation
Definition
-changing a base to result in a stop codon
-nearly all nonsense mutations result in nonfunctional proteins
Term
spontaneous mutation
Definition
-occurs during replication and repair as well as recombination
Term
mutagen
Definition
-physical or chemical agent that induces radiation
-includes radiation and several types of DNA-alterating chemicals
-increase rate of mutation 10 to 1000 times
Term
ionizing radiation
Definition
-energizes electrons in atoms, forcing some of electrons out of their atoms; these free electrons strike other atoms and thus creates ions
-ions can break the covalent bonds within sugar-phosphate backbone and induce breaks in chromosomes
-includes X rays and gamma rays
Term
nonionizing radiation
Definition
-causes adjacent pyrimidine bases to covalently bond to one another, forming pyrimidine dimers
-ie: UV light
Term
nucleotide analog
Definition
-compounds that are structurally similar to normal nucleotides
-disrupt DNA and RNA replication and
**causes point mutations
-ie: 5'bromouracil analog of thymine, can pair with guanine instead of adenine
Term
nucleotide-altering chemicals
Definition
-alters the base so that it is misread by RNA
-results in base-pair substitution mutations and missense mutations
-ie: aflatoxins, nitrous acid
Term
frameshift mutations
Definition
-some chemical agents cause insertion or deletion of nucleotide base pairs
-results in nonsense mutations
-ie: benzopyrene, ethidium bromide, acridine
Term
light repair
Definition
mechanism by which prokaryotic DNA photolyase breaks the bonds between ajoining pyrimidine dimers, restoring the original sequence
Term
photolyase
Definition
-prokaryotic enzyme activated by visible light
-breaks pyrimidine dimers in order to restore the original DNA sequence
Term
dark repair
Definition
mechanism by which dark repair enzymes cut out the damaged section (pyrimidine dimers) of DNA from a molecule, creating a gap that is repaired by DNA polymerase I and ligase
-can operate with or without light
Term
base-excision repair
Definition
enzyme removes the incorrect nucleotide base and DNA polymerase I fills the gap
Term
mismatch repair
Definition
-enzyme removes mismatched bases and repairs them
-this is done by detection of unmethylated portions of DNA versus old strands of DNA which are methylated
Term
mutant
Definition
-descendants of a cell that does not successfully repair a mutation
Term
wild types
Definition
cells normally found in nature (the wild)
Term
positive selection
Definition
-involves mutants which gained an ability (such as abx resistance)
-process by which mutants are selected by eliminating wild type phenotypes
-ie: pcn resistant mutants grow on pcn medium while wild types are inhibited
Term
negative selection
Definition
-involves mutants which have lost an ability
-replica plating: wild type and mutants are inoculated and cultured, sterile stamp used to create 2 plates with different mediums, comparison of both cultured plates will show the mutant is capable of growth in only one of the plates
Term
auxotroph
Definition
mutant which has different nutritional requirements than its wild-type phenotype
Term
carcinogens
Definition
chemicals capable of causing cancer
Term
Ames test
Definition
-fast and inexpensive method for screening mutagens
-Salmonella histidine auxotroph which requires histidine in order to grow while the wild type can make histidine
-Salmonella auxotroph mutants are mixed with liver extract and the suspected mutagen
-if suspected agent is a mutagen, it will cause the salmonella auxotroph to "back mutate" the point mutation which allows the salmonella to grow w/out histidine like its wild type
*growth shows that the chemical is in fact a mutagen
Term
genetic recombination
Definition
-exchange of segments, typically genes, between two DNA molecules
-usually homologous sequences
Term
recombinant
Definition
cell or DNA molecule that contain new arrangements of nucleotide sequences from genetic recombination
Term
vertical gene transfer
Definition
-replication of genomes in order to provide copies to their descendants (or progeny)
-passing of genes to the next generation
Term
horizontal (lateral) gene transfer
Definition
-many prokaryotes acquire genes from other microbes of the same generation
-process by which a donor cell contributes part of its genome to a recipient cell, which may be a different species or genus from the donor
-three types: transformation, transduction, or bacterial conjugation
Term
donor cell
Definition
in horizontal gene transfer, a cell contributes part of its genome to a recipient
Term
recipient cell
Definition
-in horizontal gene transfer, a cell that receives part of the genome of a donor cell
-becomes a recombinant organism
Term
transformation
Definition
-method of horizontal transfer in which a recipient cell takes up DNA from the environment such as DNA that may be released from dead organisms
-discovered by Frederick Griffith when he studied two different strains of S. pneumonia in mice
-strain S=fatal, strain R=non fatal, heat-killed S=non fatal.. but live R and heat killed S=fatal and produced live S
Term
competent
Definition
cells that have the ability to take up DNA from their environment
Term
transduction
Definition
-method of horizontal transfer in which DNA is transferred from one to another via a replicating virus
-normal viral infections do not occur
-transduction occurs when a "mistake" in the viral life cycle occurs
Term
bacteriophage
Definition
a virus that parasitizes a bacterium
Term
lytic cycle of infection
Definition
virus injects its DNA, replicates its phage DNA (in transduction- phages mistakenly incorporate some bacterial DNA), assembles new transducing phages, and bursts out of the bacterium
Term
transducing phage
Definition
virus that transfers bacterial DNA from one bacteria to another
Term
lysogenic cycle of infection
Definition
involves the genome of the virus inserting into the bacterial chromosome. replicates its genome each time the bacteria replicates. eventually a trigger will cause it excise and start a lytic infection
Term
generalized transduction
Definition
-a random piece of bacterial chromosome gets packed into virus particle instead of virus genome. uses the lytic cycle.
-any gene can move to new host=>becomes recombinant
Term
specialized transduction
Definition
-relies on the lysogenic cycle
-mistake occurs during excision to initiate lytic cycle
-defective: has some specific bacterial genes near where viral insertion site and left some viral genome behind
-when defective: virus moves to new host and inserts. host becomes recombinant but viral infection is a dead end.
Term
prophage
Definition
viral/phage DNA incorporated into the bacterial chromosome during lysogenic cycle of infection
Term
conjugation
Definition
-method of horizontal gene transfer in which a bacterium containing a fertility plasmid forms a conjugation pilus that attaches and transfers plasmid genes to a recipient
-F plasmid: instructs for pilus & instructions for sending a single stranded copy of itself
-donor cells= F+ and recipient= F-
Term
HFR cells
Definition
-modification of conjugation, the f factor integrates into the chromosome (instead a plasmid within the cytosol)
-HFR= high frequency of recombination strains
-donor= F+ but plasmid is incorporated into the chromosome
-recipient= F- but after conjugation, recipient becomes recombinant and NOT F+
-only a portion of F plasmid (not a full or complete copy) is sent over and thus is not capable of forming a pilus
Term
origin of transfer
Definition
the beginning section of a single strand of F plasmid DNA that transfers to a recipient of conjugation
Term
transposons
Definition
-"jumping genes" discovered by Barbara McClintock
-segments of DNA that transpose (move) themselves from one location in a DNA molecule to another location in the same or different molecule
-occurs between plasmids and chromosomes and within and among chromosomes
Term
transposition
Definition
mutation in which a genetic segment is transferred to a new position through the action of a DNA segment called a transposon
Term
palindrome
Definition
-a region of DNA in which the sequence of nucleotides is identical to an inverted sequence in the complimentary strand
-ie: GAATTC is the palindrome of CTTAAG
-aka: inverted repeat (IR)
Term
inverted repeat (IR)
Definition
-a region of DNA in which the sequence of nucleotides is identical to an inverted sequence in the complimentary strand
-ie: GAATTC is the palindrome of CTTAAG
-aka: palindrome
Term
simple transposon
Definition
-called insertion sequences (IS)
-consist of no more than 2 palindromes and a gene that encodes the enzyme transposase
Term
transposase
Definition
-the enzyme related to transposition
-it recognizes its own inverted repeat (palindrome) in a target site, cuts the DNA at that site, and inserts the transposon (or a copy of it) into the DNA molecule at that site
Term
complex transposons
Definition
contain one or more genes that are not connected with transposition, such as R factors (genes for abx resistance)
Term
R factors
Definition
genes that carry antibiotic resistance
Term
cut and paste transposition
Definition
-the entire transposon is cut and removed from one location and placed into its new location
-done with the use of transposase
Term
replicative transposition
Definition
-transposase allows for copying of the transposon and placing the copy into a new location
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