Chp. 16, 17 & 20 : Gene Expression & Regulation Flashcards
(146 cards)
When did Fred Griffith conduct his experiment?
1920s
What did Fred Griffth study?
Pneumococcus bacteria
What is the S- strain of Pneumococcus bacteria?
pathogenic due to the presence of polysaccharide capsule
What is the R-strain of Pneumococcus bacteria?
nonpathogenic lacks capsule
What was the general protocol/results of Fred Griffith’s experiment?
Injected live S bacteria= dead mouse
Injected live R bacteria= live mouse
Heat killed S bacteria= live mouse
Injected heat killed Sbacteria & live R bacteria= dead mouse
What was the conclusions of Fred Griffith’s experiment?
If the pathogen is dead then how did the mouse die?
Determined that a transforming principle led to the genetic material from S bacteria to transfer in to the live R bacteria
When did Avery, McCarthy and MacLeod’s experiment occur?
1940s
What was the purpose of Avery, McCarthy and MacLeod’s experiment?
Was trying to find what the transforming principle was
What was the general protocol for Avery, McCarthy, and MacLeod’s experiment?
isolate the effects of components in S bacteria
he used enzymes to block proteins, lipids, carbohydrates, DNA and RNA
What were the findings/ results of Avery, McCarty, and MacLeod’s experiment?
Found that when DNA was blocked, transformation of R to S did not occur, however with other macromolecules it did occur
this led to him believing that DNA is the transforming material→ disputed amongst many scientists.
When did the Hershey-Chase experiment occur?
1950
What was the purpose of the Hershey-Chase experiment?
confirm DNA is genetic material
What are bacterophages>
viruses that attack bacteria-
phages cause transformation is bacteria; must be injecting bacteria with genetic material
What was the general protocol of the Hershey-Chase experiment?
labeled phage with radioactive isotopes of P32 and S35
P32- DNA
S35- proteins
What were the findings/ conclusions of the Hershey-Chase experiment?
radioactivity found in bacteria infected with P32 labeled phage
Only DNA got inside bacteria
DNA is responsible for transformation of bacteria
DNA is genetic macterial
DNA not protein is the genetic material
When did Watson and Crick’s experiment/ discovery occur?
1953
When did Meselson and Stahl’s experiment occur?
in 1957
What was the purpose of Meselson and Stahl’s experiment?
determine the type of replication: dispersive replication, conservative replication, semi-conservative replication
What was the general protocol for Meselson and Stahl’s experiment?
used two nonradioactive isotopes of nitrogen and would ananlyze the arrangement of them after replications and hypothesize how each replication would look like with each type of replication
conclusions of Meselson and Stahl’s experiment
got a result of G3 that 75% of DNA is 14N14N and 25% of DNA is 15N14N
shows that this is semi-conservative replication
What is the Chargaff rule?
Equal percentage of A and T; C and G in a given species
What were the contributions of Rosalind Franklin and Maurice Wilkins?
Rosalind Franklin found DNA picture in Wilkins lab
What were the contributions for Watson and Crick?
formulate an accurate description of the structure of DNA- double helix
What is DNAs structure?
double stranded; contains nitrogenous bases and sugar phosphate backbone
strands run in antiparallel direction
5’🡪 3’ runs antiparallel to 3’🡪5’