Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
57 Cards in this Set
- Front
- Back
|
Darwin's theory of evolution |
Luria and delbruck |
|
|
Luria and delbruck |
Darwin's theory of evolution |
|
|
Frederick griffith |
Transformation |
|
|
Transformation |
Fredrick Griffith |
|
|
DNA is the genetic material |
Avery, MacLeod, and McCarthy; Hershey and Chase |
|
|
Avery, MacLeod, and McCarty; Hershey and Chase |
DNA is the genetic material |
|
|
Genetic exchange between cells (conjugation) |
Lederberg and Tatum |
|
|
Genetic exchange through viral infection (transduction) |
Zinder and Lederberg |
|
|
Lederberg and Tatum |
Genetic exchange between cells (conjugation) |
|
|
Zinder and Lederberg |
Genetic exchange through viral infection (transduction) |
|
|
Benzer |
Structure of a gene |
|
|
Structure of a gene |
Benzer |
|
|
Meselson and stahl |
Semi-conservative DNA replication |
|
|
Semi-conservative DNA replication |
Meselson and Stahl |
|
|
Brenner, Jacob and Meselson |
Existence of mRNA |
|
|
Existence of mRNA |
Brenner, Jacob and Meselson |
|
|
Genetic code |
Crick; Nirenberg |
|
|
Crick; Nirenberg |
Genetic code |
|
|
Gene regulation (lac operon) |
Jacob and Monod |
|
|
Jacob and Monod |
Gene regulation (lac operon) |
|
|
Gram + |
Easier to clear Thick PG later and a cell membrane Strong physical barrier |
|
|
Gram - |
Harder to clear. Think PG layer, an outer lipopolysaccharide layer and an inner membrane Physical and chemical barrier |
|
|
Why use bacteria? |
1.haploid- easy to see mutations 2. Easy to grow 3. Short generation time 4. asexual reproduction 5. Easy to count 6. Easy to isolate 7. Easy to store 8. Easy to genetically manipulate |
|
|
Cell density formula and assumptions |
[original cell]= (#colonies/volume plated)(dilution factor) in cfu/mL Assume all cells are viable, each colony results from one cell |
|
|
Storage of bacteria |
In cyroprotectant (50% glycerol) Viable for 20 years if store at -80 degrees Celsius If spores, can be freeze dried & stirednin fridge |
|
|
Genetic exchange in bacteria |
Transformation: uptake from surroundings Conjugation: transfer dna cell to cell Transduction: new dna through bacteriophage infection |
|
|
T4 phage |
Hydroxymethylcytosine instead of cytosine- extra methyl group to protect from EcoRI (cuts unmethylated GAATTC sequence) Infects Ecoli bacteria Has ~150 genes Iinear dsDNA, large phage contractile tail |
|
|
Lamda phage |
Linear ds DNA, long tail |
|
|
Lytic cycle |
1. Adsorption 2. Infection 3. Early gene expression 4. Viral DNA replication 5. Late genes expressed 6. Morphogenesis/ Packaging 7. Lysis ~ 100 particles resleased -based on T4 |
|
|
Prophage |
DNA from a phage that has become integrated into the host cells DNA |
|
|
Lysogen |
Bacterium containing a prophage/ that has integrated phage DNA in it's genome. |
|
|
Lysogeny |
Process of phage DNA integration into host cell genome ex.cholera |
|
|
Lysogenic cycle |
1. Adsorption 2. Injection 3. Viral DNA circularizes 4. Decision phase 5. Transcription of vital genes 6. Integration 7. Host cell replication 8. Induction 9. Lytic cycle - used lamda as model |
|
|
Virulent phage |
Phage that can only do the lytic cycle T4 phage |
|
|
Temperate phage |
Phage that does both lytic cycle and lysogenic cycle Lamda phage |
|
|
Titre |
Concentration of a phage stock/ process of determining phage stock concentration - assumes # of plaques= number of phage played (not perfect dues to EOP) - #phage/mL= (#plaques/volume plated)(dilution factor) in pfu/mL |
|
|
Efficiency of Plating |
Fraction of phage particles in a stock that can for plaques 1= all can form plaques. Lytic phage:0.3-near1 (All correctly formed phage should be able to form a plaque) Lysogenic phage: very very low (most phage integrate, few plaques form spontaneously) |
|
|
Multiplicity of infection (MOI) |
# phage/ bacterium Determines how many bacteria will be infected in a culture MOI<1 not all bacteria will be infected- less phage than bacterium MOI>1 each bacterium infected by multiple phage- more phage than bacteria |
|
|
Host range depends on |
- bacteria-phage receptor compatibility - restriction modification system of bacterium -cell machinery compatibility |
|
|
Why use phage? |
1. Haploid 2. Multiply clonally 3. Short generation times 4. Easy to cross phage strains 5. Easy to select mutants 6. Simple systems with small genomes |
|
|
Coinfection |
Infection of bacteria with multiple phage at a high MOI, phage interact in host cell -recombination: interaction of mutant genes of phages - complementation: interaction of mutant proteins |
|
|
Classical genetics (what it is, problem, advantage) |
- isolate mutants affected in specific function based on phenotype - group mutations into alleles (complementation) - localize mutations on DNA - study functions of identified genes Find phenotype first the genes that account for phenotype Problem: limited in what you can isolate (needs observable phenotype) Advantage: don't need to know a specific sequence |
|
|
Reverse genetics (what it is, problems) |
- clone gene of interest - mutate gene in vitro - return altered gene to organism - assess function of gene by determining phenotype Find gene first then see what phenotype the gene affects Problem: need to know sequence first (organisms and genes), genes can interact wi each other and the environment so might not produce and observable phenotype. Prone to experimenter bias |
|
|
Mutant vs strain |
Mutant: an organism that differs from the wt as a result of a change in it's dna sequence- derived in lab for bacteria - strain: bacterial variant found in nature (not necessarily wt) |
|
|
Isogenic |
Two organisms that differ by one allele. |
|
|
Missense mutation |
Changes a codon to encode a different amino acid, could affect protein structure/function -conservative: new aa has similar properties -non-conservative: new aa has different properties |
|
|
Large scale mutations |
Deletion: usually a major phenotypic change Insertion: big effect of inserted into essential gene Inversion: gene intact? Less effect. Gene interrupted? Big effect ex. Separated gene from promoter. Translocation: if inserted into another gene= big effect- incomplete gene transfer, separation of gene from promoter |
|
|
Suppression (pseudoreversion) |
Mutation at second site restores original phenotype (suppresses original mutation) |
|
|
Reversion frequency |
#revertants/# total mutant bacteria Frequency of reversion to wt |
|
|
Intergenic supression |
Mutation In different gene suppresses the mutant phenotype, done by: - interaction suppressor - overproduction suppressor - bypass suppressor - dosage suppressor - informational suppressor |
|
|
Interaction suppressor |
interaction suppressor: suppresses a mutation that disrupts protein-protein interactions |
|
|
Overproduction suppressor |
Overcomes the effect of mutation by overproduction of mutant proteins (original mutation decreased protein production) can occur in promoter to upregulate gene |
|
|
Bypass suppressor |
Turns on a new pathway that eliminates the need for the mutant gene |
|
|
Dosage suppressor |
Increases the concentration of stabilizing factor to stabilize the functional but unstable mutant proteins (original mutation must destabilize protein) ex. Chaperones |
|
|
Informational suppressor |
Alters translation machinery so that the original mutation is misread, results in functional protein |
|
|
Conditional mutations |
Does not always show a mutant phenotype Permissive condition: acts like wt Restrictive condition: mutant phenotype is observed Types: - auxotrophic mutant - ts temperature sensitive - suppressor sensitive |
|
|
Non-conditional mutations |
Displays mutant phenotype under all conditions Null phenotype- wt phenotype not present Leaky phenotype: some of the phenotype present |
