Theme 1a Flashcards
Genotype vs phenotype
Genotype: gene(s) inherited by an organism
Phenotype: visible traits of an organism
Where are genes found
Chromosomes
What is gene expression
“Turning on” a gene to produce RNAs and protein
What is protein expression
The type and abundance of proteins in a cell
What is differential regulation of a gene
How much of the gene is on or off
What are the 3 experiments that establish DNA as the hereditary molecule
1) Griffith found a substance that could genetically transform streptococcus pneumonia
2) Avery, MacLeod and McCarthy identified DNA as the molecule that transforms rough s. pneumonia to the infective form
3) Hershey and Chase found the final evidence that established DNA as the hereditary molecule
What is streptococcus pneumonia and what’s the difference between the smooth and rough strains
-bacterial pathogen that causes pneumonia in animals
-smooth (infectious because it has a polysaccharide capsule that protects virus from the host immune system) and rough strain (no polysaccharide capsule no can’t infect)
What was Griffith’s conclusion
Some molecules released when S cells were killed could transform living R cells genetically to the virulent S form. Transformation was permanent and heritable.
How does the experiment work to determine the transforming principle
Eliminate each type of molecule in S cells and see whether transformation of R cells into the S virulent form still occurs
Could be protein, DNA or RNA
What is the transforming molecule
DNA because transformation doesn’t occur
What is the lytic cycle
Massive reproduction of virus resulting in host cell lysis (virulent)
-replication of viral DNA, RNA and protein, bacterial chromosome degradation
-cell lysis and mature phage are released
What is the lysogenic cycle
Replication of viral genome (latent)
-viral DNA inserted into bacterial chromosome by recombination (prophage)
-prophage replicates, genes are inactive
-prophage is inherited in bacterial daughter cells
Can switch to lytic cycle if viral DNA is excised from bacterial chromosome
What is the life cycle of a bacteriophage
-lytic cycle
-viral DNA replicates separately from bacterial chromosome
-lysogenic cycle
-viral DNA is integrated into the bacterial chromosome
What was the result of Hershey and Chase experiment and how did it work
Result (in lytic phase): DNA is injected into E. coli
-label DNA and radioactive isotopes 32p and 35s respectively
-allow infection of E. coli with radioactive bacteriophage
-separate attached bacteriophage and E. coli with blender
-assess presence of 32p (DNA) and 35s (protein) in detached bacteriophage by centrifuge
What would happen if the Hershey and Chase experiment was do in the lysogenic phase
It wouldn’t work because no baby cells
