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84 Cards in this Set
- Front
- Back
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Diagram of Bacteriophage |
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Basic Steps of Viral Life cycles |
1. Attachment (Adsorption) 2. Injection (Penetration, Eclipse) |
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Attachment |
(Adsorption) -Specific -Cell is not yet infected |
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Injecction |
(Penetration, eclipse) -Viral genome inside host cell -INFECTED |
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Lytic Life Cycle |
1. Transcribe and translate the viral genome (Destroy host cell genome) 2. Replicate the viral genome (assembly with capsid automatic) 3. Lysis of host and release of new viral particles |
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Which are the early genes in the lytic cycle |
Hydrolase: destroy host cell genome why? -all cell energy directed towards viral protein synthesis -create a pool of free dNTP that can be used to replicate viral genome. Capsid proteins: assembly with capsid is automatic |
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What is the late gene in the Lytic cycle |
Lysozyme: poke holes in bacterial cell wall. -to eventually break (in tears - good antibacterial enzyme) |
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Lysogenic Cycle |
1. Integrate viral genome with host genome 2. Normal host activity, including reproduction (indeterminate amount of time) 3. Excision and lytic cycle |
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Provirus |
When virus integrates its genome into the host genome (prophage when its a bacteriophage). Viral genome is replicated when host cell (lysogen) replicates its own genome (or divides) |
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What part of the provirus genome is expressed during the lysogenic cycle? |
Repressor which will prevent the rest of the viral genome from being transcribed. |
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Excision stage of the lysogenic cycle |
After an indeterminate amount of time in normal host cell/lysogenic activity, the cell enters this -requires removal of repressor -Viral genome expressed -Removal of viral genome -->expression --> creation of new viral particles, ect. (lytic cycle) |
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What triggers virus to move out of lysogenic and into lytic stage? |
Natural occurances that trigger protein to change shape -Repressor falls off (viral genome excises and is expressed) Caused by: Strong salt, temp, pH changes |
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Transduction |
Transfer of host genes between hosts using a virus. |
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Productive cycle |
Like the lysogenic cycle but instead of breaking out, the virus buds out (no lysis) -Animal viruses only (can not bud through cell wall) -Budding results in virus being coated in lipid bilayer (envelope) |
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Enveloped viruses can only be...... |
Animal viruses |
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Advantages of the productive cycle |
1. Get a lot more virus (host cell not destroyed) 2. Envelope -a- some immune protection -b- Easier infection (eclipse) |
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(+) RNA |
Virus with RNA genome (mRNA) -Immediately translatable to make viral protein Problem: Host has no enzyme to read RNA and make more RNA (it translates into AA) Solution: enzyme RNA dependent RNA pol (virus just needs to code for enzyme) to copy genome |
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RNA dependent RNA polymerase |
RNA dependent = what it reads RNA polymerase = what it makes Viral enzyme in +RNA that makes complementary (- strand) and vice versa |
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(+) RNA virus Diagram |
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(-) RNA Virus |
Not mRNA = not immediately translatable (template) Virus must carry RNA dependent RNA pol to make (+)RNA to make proteins AND code for it (progeny needs to be packaged with new enzyme) |
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What is the extra step +RNA virus undergo to perform the lysogenic cycle |
They must convert their RNA genome to dsDNA - using RNA dependent DNA polymerase (reverse transcriptase) -Later transcribed and translated using host enzymes. |
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Problems that retroviral viruses pose to humans |
1. Permanently in genome 2. Very rapid mutation |
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Difference between lysogenic cycle b/w RNA and DNA viruses |
1. RNA has to use RNA dependent DNA pol (reverse transcriptase) to go from RNA -> DNA 2. RNA virus can stay permanently in genome. DNA has to replicate itself in order to be inserted in progeny. Can only do this by excising itself from host genome. However using RNA pol - can copy its genome from DNA w/o excising. |
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Why do retroviral virus mutate rapidly |
1. Can mutate during RNA -------[RNA dep DNA pol]------> ssDNA. It is a low fidelity enzyme. 2. Also when host cell transcribes it from its genome to create new (+)RNA to package into virus (RNA pol does not autocorrect) |
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Characteristics of Prion |
(Infectious protein) -no cell membrane/ no cytoplasm -no organelles -no genome -very small -very resistant to things that normally degrade proteins (heat, detergents, acids) |
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What are the two categories of Prions |
1. Normal prions -good. Protect prions 2. Mutant prions -Spongiform encephalopathies) |
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"encephalo-" |
Refers to the brain ex. spongiform encephalopathies (brain infection/problem) |
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Mutant "Bad" Prions can: |
1. Mutation in gene coding for mutant "bad" prion --Mutant "bad" prions accumulate and lead to cell death 2. Can be inherited if mutation is in sperm/egg 4. Can be ingested -Convert good into bad prions (can be decades until symptoms show) |
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Examples of subviral particles |
Prions and Viroids |
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Viroid Characteristics |
-circular (+) RNA -No capsid -self replicating -does not code for proteins |
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How can viroids cause problems? |
It can linearize and then acts as miRNA/ siRNA (base pair with mRNA to create dsDNA which doesn't get translated) -Prevent production of proteins in the cell -More common in plants -Must be co-infected with a regular virus |
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Three shapes of bacteria |
-Round (-coccus/cocci) -Rod-like (-bacillus) -Spiral (-Spirella) |
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What is the shape of E. Coli? |
Rod shaped Bacillus |
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Flagella ("________tricous") |
-Monotrichous -Amphitrichous -Peritrichous |
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Structure of flagella |
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How does flagella move? |
Proton gradient is created over the cell membrane. After protons flow back through, the flagella is spun (hook spins) -Rotation in one direction causes forward motion -Rotation in the other tumbles around to find new direction |
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Chemotaxis description |
Flagella spins in one direction (forward motion) Rotates in the other - tumbles -Towards nutrients -Away from toxins |
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Prokaryotic cell wall made of: |
Peptidoglycan (Amino acids and sugars) |
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Gram positive bacteria |
Thick peptidoglycan cell wall -binds a lot of gram stain- dark purple |
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Gram negative bacteria |
Thin cell wall (smaller amount of peptidoglycan) -Also have inner and outer cell membrane -Tend to be more antibiotic resistance |
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Periplasmic Space |
Gram negative bacteria -Space b/w inner and outer cell membrane -Contribute to antibiotic resistance - can store enzymes here |
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Mesophiles |
Bacteria that live at median temperatures |
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Thermophiles |
Bacteria that live in hot temperatures -Don't burn off a lot of heat - super efficient metabolism |
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Psychrophiles |
Cold temp bacteria -inefficient metabolism - exude a lot of heat (some converted into energy - other into heat) |
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Obligate anaerobe |
-Die in the presence of O2 - Ferment and survive absent of O2 Ex: -Bacteria in gut, in deep puncture wounds, mouth bacteria (in b/w gums -cover in plaque), live in soil. |
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Energy/Nutrient classifications for bacteria |
Energy Source: Photo: Sun Chemo: ATP Where carbon chains come from: Auto: make your own CO2 Hetero: eat other critters |
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Ex Classifications |
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Auxotrophs |
"Auxiliary" bacteria "-" means they cant make something Arg- cant make arginine Leu- cant make leucine lac- can't metabolize lactose AA = cant make Sugars = can't metabolize |
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Binary Fission |
Bacteria reproduction -HUGE increase in population size -NO genetic diversity |
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Lag phase |
Binary fission -First stage -bacteria are getting ready to reproduce -replicating DNA |
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Log phase |
Binary Fission -Exponential growth -In lab want to work with these b/c its when they're healthiest |
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Stationary stage |
Carrying capacity -reproducing as fast as they're dying off (nutrients are limited) |
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Reproduction graph |
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Conjugation |
No change in bacterial population size But change in genetic diversity -Exchange of plasmid |
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F+ Bacterium |
Initiates conjugation (male) -Creates cytoplasmic bridge/sex pillus. |
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Conjugation Diagram |
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Hfr bacteria |
High frequency recombination (F+) -F plasmid incorporated in genome -still has ability to initiate construction of conjugation bridge. -Also transfers part of its own genome (and recombines with other genome - completely replaces its counterpart complimentary genes) |
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Hfr conjugation Diagram |
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Transduction |
Transfer of genes through virus Bacteria + virus = new strain |
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Diagram of ways to get genetic diversity in bacteria |
Happens thru stress |
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Transformation |
Adding naked purified DNA to bacterium to get a new strain |
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Plaque |
Usually represents lysis of the bacteria by virus (in colony) |
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Endotoxins |
Components of Gram (-) -not inherently poisonous but cause an extreme immune reaction. |
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Exotoxins |
Produced by gram neg and pos. -Toxic substances. Used to compete with other bacteria. |
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Glycocalyx |
(Capsule) Sticky layer of polysaccharide "goo" -Makes it more difficult for immune system to eradicate -Adhere to surfaces |
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Important thing to remember about flagella: |
Structure in prokaryotes is different from eukaryotes -Prokary: filament, hook, basla structure, -Eukary: 9+2 arrangement of microtubules |
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Fimbriae |
Structures involved in adhering to surfaces (like capsule/glycocalyx) |
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Plaque |
Clear area in lawn. Resume from death of bacteria and are caused by lyric viruses or toxins |
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In an experiment, facultative anaerobic bacteria that are growing on glucose in air are shifted to anaerobic conditions. If they continue to grow at the same rate while producing lactic acid, then the rate of glucose consumption will: |
Increase 16 fold. (Respiration = 32 ATP. Fermentation is 1/16 production - 2 ATP) |
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How is asexual reproduction in eukaryotes different than prokaryotes. |
Eukary: mitosis Prokary: do not do mitosis |
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Will bacteria that are transferred from a log phase to a fresh culture show a lag phase? |
No because they already have necessary components for population growth. |
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Germination |
The metabolic reactivation of an endospore. (Inside it has genome, r Ibo domes, RNA) |
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Important point about productive cycle |
ONLY FOR ANIMAL CELL VIRUSES -does not happen in bacteria b/c no budding can occur |
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Bacterial reproduction stages |
Lag Log (exponential) Stationary |
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Difference b/w transformation and transduction |
Transformation: Uptake to genetic material (plasmid/chromosomal DNA) Transduction: Transfer from one bacteria to another via lysogenic phage |
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A difference b/w eukary and prokary flagella |
Eurkary = made of microtubules and dynein Prokary = protein flagellin |
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Protoplast |
Osmotically fragile structure -after lysozyme attacks cell wall --(tears, saliva, lytic viruses - destroys peptoglycan) |
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Fimbriae |
Capsule/glycocalyx -Pili - adhering to surfaces |
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Hfr |
A cell with F factor integrated into bacterial genome -good for mapping bacterial genome |
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Fermentation |
NO O2 -reduced by product of glucose given off lactate or ethanol |
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Anaerobic respiration |
glucose metabolism with electron transport and oxidative phosphorylation -No O2 -Others like NO3- |
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What stage of cell division does translocation of a gene from one chromosome to the other occur? |
synapsis - coming together of homologous chromosomes during Prophase I (in meiosis). Crossing over can occur |
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Electrophoresis of DNA with polyacrylamide gel |
DNA fragments separated by size -Negative charge so all travel to ANODE -larger molecules will be closer to cathode Cathode ---> Anode |
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How many acetyl CoA and FADH4 from palmitic acid (saturated fatty acid) - C16H13O2? |
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