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128 Cards in this Set

  • Front
  • Back
Genome
The complete set of information for a cell
Gene
The sequence of nucleotides in DNA that may code for a single gene product
Plus strand of DNA
The strand of DNA that is the opposite of the strand that is transcribed into messenger RNA
Minus strand of DNA
The stranded DNA that is transcribed in the messenger RNA
3' 5'
DNA polymerase
An enzyme used in the replication of DNA
RNA polymerase
The enzyme used in transcription
mRNA
RNA that carries the information from DNA to the ribosome
rRNA
RNA to composes part of the ribosome
tRNA
RNA to bring specific amino acids to the ribosome
Genomics
The science that deals with the analysis of a DNA sequence
Codon
The triplet of nucleotides in mRNA that codes for a specific amino acid
Stop codon
Codons that do not code for specific amino acids, but stop the production of a protein
Anticodon
The triple of nucleotides in TR and a that identifies the specific amino acid transported by the RNA
Deoxyribose and Phosphate
Alternating units that compose the backbone of the strand of the DNA molecule
mRNA
Made diring transcription
tRNA
Type of RNA that transports amino acids to the ribosome for protein synthesis
Constitutive enzymes
Enzymes that are not subject to regulation by induction or repression
Inducers
Metabolites that activate gene transcription
Adenine, Thymine, Cytosine, Guanine
The chemical composition of DNA
mRNA
Made during transcription
tRNA
The type of RNA that transports amino acids to the ribosome for protein synthesis
Prokaryote
mRNA is not processed
mRNA does not contain introns
translation and mRNA begins as it is been transcribed
mRNA is often polycistronic
translation began at the first AUG that follows a ribosome binding site
Gene
Functional unit of the genome
encodes a "gene product" usually a protein
Central dogma of biology
Flow of information from DNA to RNA protein
most common direction of information flow
Transcription
Process that copies the information encoded by DNA into RNA
(one of two-part process of gene expression)
Translation
Process that copies the information encoded to buy DNA into RNA
(second to of two-part process of gene expression)
Base pairing
Characteristic bonding A to T and G to C to
fundamental and functionality of DNA
DNA replication
Creating a second DNA molecule identical to the original open parentheses making a copy)
generally bidirectional -- proceed the opposite direction creating an ever expanding bubble of two identical replicated portions of chromosome
-- semiconservative -- each of the two molecules generated contain one original strand and one new strand
Semiconservative
Each of two molecules generated contains one of the original strand and one newly synthesized strain
DNA polymerase
Enzyme that synthesizes DNA using an existing strand as a template to synthesize the complementary strand
RNA polymerase
Enzyme that synthesizes RNA using one strand of DNA as a template
Promoter
Nucleotide sequence to which RNA polymerase binds to initiate transcription
(site where transcription will began)
orients the RNA polymerase in one of two possible directions
Terminator
Sequence of nucleotides in the DNA that when transcribed permits to complementary regions of the resulting RNA to base pair forming a hairpin loop structure. This causes the RNA polymerase to stall -- results in disassociation from DNA template and release of RNA
mRNA
Place important role in translation.
Type of RNA molecule that is translated during the process of protein synthesis.
Temporary copy of genetic information -- carries encoded instructions for synthesis of specific polypeptide or group of polypeptides
Codon
Series of three nucleotides that code for a specific amino acid (sequence of any combination of four nucleotides)
Number of codons
64 different codons
3 stop codons
remaining 61 codons translate to 20 different amino acids
Stop codons
UAA
UAG
UGA
Start codon
AUG (Methionine)
Sense codons
61 codons
-- codes to specific amino acid
Nonsense codons
3 codons
-- code for termination
Ribosome
Site of translation
Polypeptide chain
Sequence of amino acids held together by peptide bonds (covalent)
Peptide bond
Covalent bond formed between C00H group of one amino acid and NH2 group of another amino acid. (Important reaction and synthesis of protein)
Genetic code
Correlates each series of three nucleotides with one amino acid.
Practically universal.
Used nearly by every living thing
Poly A tale
Series of approximately 200 adenine derivatives that are added to the 3' end of an mRNA transcript in eukaryotic cells.
Thought to stabilize the transcript and enhanced translation
Splicing
Process that removes specific segments of the transcript -- necessary because eukaryotic genes aren't always contiguous: they are often interrupted by non-coding nucleotide sequences
Introns
Part of eukaryotic chromosome that does not code for a protein; removed from the RNA transcript before the mRNA is translated
-- intervening sequences transcribed along with the expressed regions (exons) generating precursor mRNA
Exons
Expressed regions
portions of eukaryotic genes are expressed; interrupted by introns
Gene regulation
Some are routinely expressed were others are either turned on or off by certain conditions
Constitutive enzymes
Constantly synthesized -- genes that encode these enzymes are always active.
Usually play indispensable roles in the central metabolic pathways (example: glycolysis)
Inducible enzymes
Not regularly produced: synthesis is turned on by certain conditions
-- often involved in the utilization of specific energy sources (example: galactogidase)
Repressible enzymes
Routinely synthesized, they can be turned off by certain conditions.
-- generally involved in biosynthetic pathways such as those that produce amino acids
Repressor
Regulatory protein that blocks transcription -- accomplishes this by binding to DNA at a region (operator) located immediately downstream of a promoter. -- effectively prevents RNA polymerase from progressing past that region (blocks transcription)
Activators
Regulatory protein facilitates transcription -- binding of activater to DNA enhances ability of RNA polymerase to initiate transcription at that promoter
Operator
Region located downstream of the promoter to which a repressor can bind
Gene expression
Two separate but interrelated processes:
transcription and translation
Mutations
Modification in the sequence of DNA in a gene often resulting in an alteration in the protein encoded by the gene
Mutants
Changed organisms
Gene transfer
When bacteria acquires genes from other bacteria -- this provides new genetic information to the cell
Spontaneous mutations
Those that occur in the natural environment.
-occur infrequent and randomly
Base substitutions
Most common type of mutation which results from a mistake during DNA synthesis, when an incorrect base is incorporated into the DNA
Point mutation
A mutation where only one base pair is changed.
-this mistake in and corporation is passed on to the cells progeny, often resulting in an incorrect amino acid being incorporated into the protein encoded by the gene
Types of point mutations
Missense mutation
Silent mutation
Nonsense mutation
Missense mutation
A point mutation which results in the substitution of a different amino acid
-frequently results in the synthesis of a protein that still partially functions
Nonsense mutation
A mutation that changes a codon that normally encodes an amino acid to a stop codon
Knockout mutation
(null)
Any mutation that totally and activates the gene resulting in a strain that is unable to grow at all unless tryptophan is added.
Silence mutation
The change in a nucleotide or nucleotide sequence that may not lead to any observable change
Frameshift mutation
The deletion or addition of a nucleotide shifts the codons of the DNA when it is transcribed into mRNA
Transposable elements
Transposons (jumping genes)
special segments of DNA that can move spontaneously from one site to another in the same or different DNA molecules (process called transposition)
the gene usually suffers a knockout mutation in transposition
Induced mutations
The isolation of certain mutants through use of mutagens, chemicals or radiation that can increase the frequency of mutations leased 1000 full
Chemical mutagens
Alkylating agents -- highly reactive chemicals --(nitrosoguanidine)
Radiation mutagens
UV light and x-rays
X-rays
Cause several types of damage: single and double strand breaks in DNA, and alterations in the basis. Double strand breaks often result in deletions that are lethal
UV light
Causes covalent bond formation between adjacent thymine molecules on the same strand of DNA resulting in the formation of thymine dimers. The covalent bond distorts the DNA strands so much that the dimer cannot fit properly into the double helix, and the DNA is damaged. The DNA cannot be replicated nor can genes be transcribed beyond the site and damage
Gene transfer
Naturally between bacteria by three different mechanisms:
-- DNA mediated transformation
-- transduction
-- conjugation
Transformation
Involves the transfer of naked DNA in the environment to recipient cells. If the cell walls of the bacteria rupture, death, and prolonged decline of bacterial growth, long circular molecules of chromosomal DNA that are tightly jammed in the bacteria break into several hundred pieces as they explode to the broken cell walls
-- can occur naturally in a wide variety of gram-positive and gram-negative bacteria
Transduction
Mechanism of horizontal gene transfer between bacteria in which the bacterial DNA is transferred inside a phage code
Conjugation
Mechanism of horizontal gene transfer in which the donor cell must physically contact the recipient cell
Competent
Recipients cells that have the unusual ability to take up and integrate donor DNA into their chromosome
Bacteriophage
Bacterial viruses that can transfer bacterial genes from one cell to another by the process of transduction.
-protein coat that surrounds the genetic material of the virus
-infect bacteria by transferring only their nucleic acid into the sale
Plasmids
Very common in the microbial world.
-play key roles in the lives of Archaea, Eucarya and bacteria.
Plasmids in bacteria
Usually covalently closed, circular double-stranded DNA molecules.
-are all replicons
-usually provide the cell with useful but not essential capabilities.
-replicate using the enzyme of the cell in which they are found
-most readily transferred by conjugation (some carry all of the genetic information they need for transfer)
Narrow host range plasmids
Plasmids that can multiply in only one species of bacteria
Broad host range plasmids
Plasmids that can multiply in many different species of bacteria
R plasmids
(Resistance) - confer resistance to many different anti-microbial medications and heavy metals, such as mercury and arsenic.
-commonly found in the hospital environment
-can be transferred to bacteria that are sensitive to into microbials and heavy metals and therefore can for simultaneous resistance to several anti-microbials and heavy metals encoded by the R genes
F plasmid
(Fertility) - self transmissible plasmid.
-codes for the synthesis of a structure, the sex or F pilus,
F+
The donor cell containing the F plasmid
F-
The recipient cell that does not contain F plasmid
Steps of Plasmid Transfer
1. Contact between donor and recipient cell
2. Mobilization or activation of DNA transfer
3. Plasmid transfer
4. Synthesis of funcional plasmid inside the recipient and donor cells
Step 1/plasmid transfer
The sex pili of the donor cells recognize and bind to specific receptor sites on the cell walls of the recipient cells.
The sex pili likely act as grappling hooks, pulling the two cells together
Step 2/plasmid transfer
The plasmid becomes mobilized for transfer when a plasmid-encoded enzyme cleaves one strand of the plasmid at a specific nucleotide sequence, termed the origin of transfer. This results in the formation of a single stranded DNA molecule with a free end
Step 3/plasmid transfer
Within minutes of the F+ cell contacting the F- cell, a single strand of the F plasmid, beginning at the origin of transfer, enters the F- cell. (A single strand of the F. plasmid remains in the donor sale)
Step 4/plasmid transfer
Once inside the recipient cell, a complementary strand to the single-stranded transferred DNA is synthesized. Likewise, a strand complementary to the single-stranded plasmid DNA remaining in the donor is synthesized. (Both the donor and recipient cells contain a copy of the F. plasmid and are therefore F+.)
Cured cells
Cells that have lost their plasmid
Biotechnology
The use of microbiological and biochemical techniques to solve practical problems and produce more useful products
Recombinant DNA techniques
Method scientists used to study and manipulate DNA.
-have made it possible to genetically alter organisms to give them more useful traits.
Gene cloning
Procedure where researchers can isolate genes from one organism, manipulate the purified DNA in vitro, and then transfer the genes into another organism.
Restriction enzymes
Type and then sign that recognizes and cleaves a specific sequence of DNA
-naturally occurring enzymes that allow scientists to easily cut DNA into fragments in a predictable and controllable manner
Gel electrophoresis
A procedure used to separate DNA fragments (or other macromolecules) according to their size.
Gel electrophoresis technique
Uses a slab of gel that has the consistency of a very firm gelatin and is made of either agarose, or polyacrylamide. DNA sample is put into a well in the gel; there are generally numerous wells in a gel so that multiple samples can be analyzed simultaneously.
In DNA probes
Single-stranded piece of DNA tagged with a detectable marker and used to detect its complement.
-used to locate specific nucleotide sequences in DNA or RNA samples that have been affixed to a solid surface
Ethidium bromide
Mutagenic dye that binds to the nucleic acid by intercalating between the basis; ethidium bromide stained DNA is fluorescence when viewed with UV light
Genetic engineering
Deliberately altering and organisms genetic information using in vitro techniques
Polymerase chain reaction (PCR)
Technique used to exponentially amplify specific regions of a DNA molecule.
-make it possible to create millions of copies of a given region of DNA in only a matter of hours.
DNA sequencing
Technique used to determine the sequence of nucleotides in the DNA molecule.
Taxonomy
The science the studies organisms in order to arrange them into groups (taxa); involves three interrelated areas -- identification, classification, and nomenclature
Identification
The process of characterizing an isolate in order to determine the group (Taxon) to which it belongs
Classification
The process of arranging organisms into similar or related groups, primarily to provide easy identification and study
Nomenclature
The system of assigning names to organisms
Taxonomical hierarchies
Arrangements of taxonomic classification categories:
Taxonomic categories
Species
Genus
Family
Order
Class
Phylum (division)
Kingdom
Domain
Species
Group of related isolates or strains
Genus
Collection of related species
Family
Collection of similar genera
Order
Collection of similar families
Class
Collection of similar orders
Phyllum
Collection of similar classes
Kingdom
Collection of similar Phyla or divisions
Domain
Collection of similar kingdoms
Microscopic morphology
Determination of a microorganisms size, shape and staining characteristics
Metabolic capabilities
Culture characteristics
Examples: Types of sugars utilized or the end products produced
Serology
Use of serum antibodies to detect and measure antigens, or conversely, the use of antigens to detect serum antibodies
Serological typing
Proteins and carbohydrates that vary among strains can be used differentiate strains.
Serovar (serotype)
Strains that have a characteristic serological type
Antibiograms
Antibody susceptibility patterns
DNA hybridization
The extent of nucleotide sequence similarity between two oscillates can be determined by measuring how completely single strands of their DNA will hybridize to one another
DNA base ratio
The relative portion and adenine (A), thymine (T), Guanine (G), and cytosine(C).
Eukaryotes
-mRNA contain introns, which are removed by splicing
-A cap is added to the 5' end of mRNA and a poly A tail is added to the 3' end.
-mRNA transcript is transported out of the nucleus so that it can be translated in the cytoplasm
-mRNA is monocistronic
-Translation begins at the first AUG codon