Term
Reproductive Strategies: Bacteria and Archaea |
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Definition
Haploid only, asexual
- Binary fission (most common)
- Budding
- Filamentous
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Term
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Definition
:in cyabacterium where cells are held within the cell wall of the parent cell until they are released |
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Term
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Definition
Includes DNA replication/partition and cytokinesis
- Single origin of replication
- Proteins needed for DNA synthesis (Replisome)
- Origins separate - move in both directions
- Cell elongates as replication continues
- Chromosomes separate (septum form.) - cells divide
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Term
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Definition
- Selection of site for septum
- Assembly of Z ring (Z = a motor protein)
- Linkage of Z ring to plasma membrane (cell wall)
- Assembly of cell wall
- Constriction of cell and septum formation
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Term
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Definition
: new peptidoglycan forms only at the central septum
- FtsZ determines site of cell wall growth
-FtsZ may recruit PBPs (penicillin binding protein) for synthesis of septum |
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Term
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Definition
:Similar to cocci divisome but elongate prior to septation
-MreB determines cell diameter and elongation as Z ring forms in center |
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Term
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Definition
1. Single copy plasmid R1 replicates
2. ParM is anchored to ParC and ParR, which attach to the origin of each plasmid
3. ParM elongates, thereby pushing each plasmid to opposite poles of the dividing cell
4. Newly replicated cells with plasmid; the Par proteins will not be synthesized until the cell readies for division |
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Term
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Definition
Increase in cellular constituents
Growth refers to population growth rather than individual cells
Growth curve observed when microorganisms are cultivated in batch culture
Usually ploteed as a logarithm of cell number vs. time
1. Lag phase
2. Exponential (log) phase
3. Stationary phase
4. Death phase |
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Term
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Definition
- Cell synthesizing new components
- Varies in length |
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Term
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Definition
- Rate of growth and division is constant and maximal
- Population is most uniform in terms of chemical and physical properties during this phase.
-Growth can be balanced or unbalanced due to change in nutrient levels or change in environmental conditions |
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Term
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Definition
Bactive cells stop reproducing or reproductive rate is balanced by death rate
Possible reasons: no resources, waste, no more space |
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Term
Stationary Phase and Starvation Response |
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Definition
Entry into stationary phase due to starvation and other stressful conditions activates survival strategy
- morphological changes (endospore formation)
- decrease in size, protoplast shrinkage, and nucleoid condensation
- RpoS protein assists RNA polymerase in transcribing genes for starvation proteins |
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Term
Senescence and Death Phase |
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Definition
2 Hypotheses
-cells are viable but not culturable (VBNC)
- Programmed cell death
:fraction of the population genetically programmed to die (commit suicide) |
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Term
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Definition
:grow optimally in the presence of NaCl or other salts at a concentration above or about 0.2M. |
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Term
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Definition
:cell wall, proteins, and plasma membrane require high salt to maintain stability and activity |
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Term
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Definition
When exposed to acidic conditions: when inernal pH gets low, the cells can exchange extracellular K+ for intracellular protons
When exposed to alkaline conditions:
-Modification of cell wall to protect cytoplasmic enzymes
-Use Na+ motive force in addition to proton motive force
-Secreted enzymes are able to work alkaline environment |
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Term
Adaptations of thermophiles |
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Definition
Protein structure stabilized by a variety of means:
- more H bonds
- more proline
- chaperones
Histone-like proteins stabilize DNA
Membrane stabilized by variety of means
-more saturated, more branched and higher molecular weight lipids
- ether linkages (archaeal membranes) |
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Term
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Definition
- O2 is ultimate e- acceptor
- In the presence of O2 organisms will be doing aerobic respiration |
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Term
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Definition
- NO3- (nitrate) or NO2- (nitrite) are final e- acceptors
- Reactive oxygen species (ROS), are produced by metabolic reactions when the cell is exposed to O2 (toxic to cell) |
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Term
Conditions Influencing the Effective Antimicrobial Agent Activity |
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Definition
- Population size
- Population composition
- Concentration or intensity of an antimicrobial agent
- Duration of exposure
- Temperature
- Local environment
>pH, viscosity, and concentration of organic matter
>biofilms
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Term
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Definition
- Boiling will not destroy spores and does not sterilize
- Destroys viruses, fungi, and bacteria
- Degrades nucleic acids, denatures proteins, and disrupts membranes |
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Term
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Definition
-Carried out using an autoclave (heat + pressure)
- Effective against all types of microorganisms including spores
- Quality control - includes strips with Geobacillus stearothermophilus |
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Term
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Definition
Deoxyribonucleic acid
:genetic instructions to carry 0ut metabolism and reproduction |
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Term
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Definition
Ribonucleic acid
:expresses the information in DNA |
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Term
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Definition
:build cellular structures and do cellular work |
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Term
The Flow of Genetic Information |
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Definition
- Central Dogma
the pathway from DNA ro RNA to protein is gene expression
-From one generation to the next
DNA stores genetic information
information is duplicated by replication and is passed on to the next generation
- DNA divided into genes
transcription yields RNA. Copy of specific genes
translation uses information in mRNA to synthesize a polypeptide |
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Term
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Definition
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Term
Single stranded binding proteins (SSB) |
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Definition
keep strands apart for replication to occur |
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Term
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Definition
breaks one strands of DNA to relieve tension / prevents supercoiling |
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Term
DNA gyrase (topoisomerase) |
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Definition
also introduces negatie supercoiling to help compact bacterial chromosome |
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Term
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Definition
synthesizes short complementary strands of RNA (~10 nucleotides) to serve as primers needed by DNA polymerase |
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Term
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Definition
join the Okasaki fragments |
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Term
Events at the replication fork in E. coli |
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Definition
- DnaA proteins bind oriC (origin of replication) causing
bending and separation of strands
- Helicase separates strands, SBB attach
- Primerase synthesis RNA primer
- Lagging and leading strand is synthesized
- DNA polymerase I removes RNA primers
- Okazaki fragments are joined by DNA ligase
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Term
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Definition
DNA ligase forms a phosphodiester bond between 3'-hydroxyl of the gorwing strand and the 5'-phosphate of an Okazaki fragment |
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Term
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Definition
- Carried out by DNA polymerase III
- Removal of mismatched base from 3 end of growing strand
by exonuclease activity of enzyme
- This activity is not 100% efficient |
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Term
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Definition
- Defined as a polynucleotide sequence that codes for a functional product, e.g. polypeptide, tRNA, rRNA
- Has a fixed start point and end point
- Codons are found in mRNA and code for single amino acids
- Promoter is located at the start of the gene
>the recognition/binding site for RNA polymerase
>functions to orient polymerase
-Leader sequence is transcribed into mRNA but it's not
translated into amino acids |
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Term
Transcription occurs in 3 phases: |
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Definition
1. Initiation: RNA pol holoenzyme binds to the promoter
2. Elongation: the RNA chain is extended
3. Termination: RNA pol detaches from the DNA, after the transcript is made |
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Term
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Definition
- Final step in expression of protein encoding genes
- mRNA sequence is translated into amino acid sequence of polypeptide chain (process = translation)
- An understanding of the genetic code is necessary before translation is studied
- Codon: genetic code word, 3 bp long
specifies amino acid
anticodon on tRNA is complementary
Start codon/Stop codon |
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Term
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Definition
-Synthesis of proteins using mRNA as template
-Occurs at the ribosomes
- tRNA and rRNA are essential in this process |
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Term
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Definition
Tertiary structure
Contains the anticodon
Complementary to the codon
binds the codon
3' end of tRNA binds amino acid |
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Term
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Definition
- Attachment of amino acid to tRNA
- Catalyzed by aminoacyl-tRNA synthetases
- at least 20 each specific for single amino acid and for all the tRNAs to which each may be properly attached (cognate tRNAs) |
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Term
Elongation Cycle (transpeptidation) |
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Definition
- Sequential addition of amino acids to growing polypeptide
- Consists of 3 phases:
1. aminoacyl-tRNA binding
2. transpeptidation reaction
3. translocation
-involves several elongation factors (EFs)
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Term
Final stage in elongation: Translocation |
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Definition
3 simultaneous events
-peptidyl-tRNA moves from A site to P site
-ribosome moves down one codon
-empty tRNA leaves P site
requires GTP hydrolysis |
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Term
Termination of protein synthesis |
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Definition
-takes place at any one of three stop codons
-release factors (RFs)
aid in recognition of stop codons
3 RFs function in prokaryotes
-GTP hydrolysis required |
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Term
Protein Maturation and Secretion |
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Definition
-Protein function depends on 3-D shape
-Occurs as post translational event
>requires folding
>association with other proteins
>delivered to proper subcellular or
extracellular site |
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Term
Protein Folding and Molecular Chaperones |
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Definition
-Molecular chaperones
>proteins that aid the folding of nascent
polypeptides
>protect cells from thermal damage
heat-shock proteins
>aid in transport of proteins across
membranes |
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Term
Protein Folding
Bacteria vs. Eukaryotes |
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Definition
Domains:
- Structurally independent regions of polypeptide
- Separated from each other by less structured portions of
polypeptide
In eukaryotes:
- domains fold independently right after being synthesized
-molecular chaperones not as important
In bacteria:
- polypeptide does not fold until after synthesis of entire polypeptide
-molecular chaperones play important role
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Term
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Definition
Stable, heritable changes in sequence of bases in DNA
-point mutations most common
>from alteration of single pairs of nucleotide
-larger mutations are less common
>insertions, deletions, inversions, duplication, and
translocations
Mutations can be spontaneous or induced |
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Term
Mutations in Protein Coding Genes |
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Definition
Point Mutations
- in protein-coding genes can affect protein structure
-Are named according to if and how they change the encoded protein
-The most common types are: silent, missense, nonsense, and
frameshift mutations
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Term
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Definition
Proofreading
-correction of errors in base pairing made during replication
-errors corrected by DNA polymerase
Other DNA repair mechanisms also exist
Excision Repair
-corrects damage that causes distortions in double helix
-two types of repair systems are known
>nucleotide excision repair
>base excision repair
>both remove the damaged portion of the DNA strand |
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Term
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Definition
-Extensive DNA damage leads to initiation of the SOS response
-This system is not a single repair mechanisms but a set of different mechanisms that collaborate to rescue the cell.
-In order to save the cell, the SOS repair can introduce mutations into severly damaged DNA
-"Repair" refers to saving the integrity of the circular chromosome even if incorrect bases are introduced
- "Mutate or die"
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Term
Creating Genetic Variability |
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Definition
Mutations are subject to selective pressure
-each mutant form that survive becomes an allele, an alternate form of a gene
Recombination is the process in which a donor DNA molecule replaces a segment of a host genome or is inserted into a host genome
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Term
Horizontal Gene Transfer in Bacteria and Archaea creates recombinants |
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Definition
HGT is the transfer of genes from one independent, mature organism to another
-stable recombinant has characteristics of donor and recipient
Important in evolution of many species
-expansion of ecological niche, increased virulence
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Term
Horizontal Gene Transfer Mechanisms |
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Definition
Occurs in the 3 mechanisms evolved by bacteria to create recombinants
-Conjugation
-Transformation
-Transduction
Genes can be transferred to the same or different species
The donor DNA has 4 possible fates in the recipient |
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Term
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Definition
-Integration of donor DNA
-Donor DNA self-replicates - plasmid
-Donor DNA cannot self-replicate
-Heat restriction |
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Term
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Definition
:the transfer of DNA from one bacterium to another, following cell-to-cell contact
-Initiated by a special pilus protruding from the donor cell
-Conjugation requires the presence of special transferable plasmids
-A well-studied example in E. coli is the fertility factor (F factor)
contains 2 replication origins
oriV used in nonconjugating
oriT used during DNA transfer |
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Term
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Definition
:the process in which bacteriophages carry host DNA from one cell to another
2 basic types
Generalized transduction: can transfer any gene from a donor to a recipient cell
Specialized transduction: can transfer only a few closely linked genes between cells |
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Term
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Definition
:the process of importing free DNA into bacterial cells
Cells must be "competent" - can be induced
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Term
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Definition
Viruses - protein and nucleic acid
Viroids - only RNA
Virusoids- only RNA
Prions - proteins only |
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Term
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Definition
:a noncellular particle that must infect a host cell, where it reproduces
-Obligate intracellular parasites
-Subverts the cell's machinery and directs it to produce viral particles
-Single nucleic acid (DNA or RNA) contained within a protective protein capsid
-All life froms can be infected by a virus
-Tissue damage and cell death accounts for the destructive effects seen in many viral diseases |
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Term
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Definition
Virion:
-Complete virus particle (ready to infect)
-Consists of >1 molecule of DNA or RNA enclosed in a coat of protein
-may have additional layers
-Although cannot reproduce independent of living cells nor carry out cell division, can exist extracellularly |
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Term
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Definition
-All virions contain a nucleocapsid which is composed of nucleic acid (DNA or RNA) and a protein coat
-Can be enveloped or naked viruses |
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Term
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Definition
-Large macromolecular structures which serve as protein coat of virus
-Protect viral genetic material and aids in its transfer between host cells
-Made of protein subunits called protomers
-Helical, icosahedral, or complex |
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Term
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Definition
-Many viruses bound by an outer, flexible, membranous layer called the envelope
Viral Envelope Proteins
-Envelope proteins, which are viral encoded, may project from the envelope surface as spikes or peplomers
>viral attachment
>identification
>enzymatic activity
>play a role in nucleic acid replication |
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Term
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Definition
-Diverse nature of genomes
-May have single or double stranded DNA or RNA
-Size of nucleic acid varies
-Genomes can be segmented or circular |
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Term
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Definition
-Mechanism used depends on viral structure and genome
-Steps similar |
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Term
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Definition
-Virus's envelope spikes bind to receptors on surface of host cell
-Lipid bilayer of viral envelope fuses with host cell membrane
-Nucleocapsid is released into the cytoplasm |
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Term
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Definition
Nonenveloped viruses and enveloped - different ways
Nonenveloped: virus's capsid proteins bind to receptors on cell surface and receptor mediated endocytosis- nucleic acid is extruded from the endosome into cytoplasm
Enveloped: virus's envelope spikes bind to receptors on cell's surface - increased acidity allows nucleocapsid to escape from the endosome into cytoplasm |
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Term
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Definition
:compresses and injects nucleic acid directly in cell |
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Term
Classification of Viruses |
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Definition
-Genome composition
-Capsid symmetry
-Envelope
-Size of the virion
-Host range |
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