13.1: Expression Flashcards
components of chromosomes
proteins and DNA
what was initial thought about genetic material?
it was initially thought proteins were the molecule of inheritance since it was bigger than DNA, it was soon proved otherwise through studying bacteria and the viruses that infect them
Fredrick Griffith
while working with pathogenic and nonpathogenic bacteria trying to find a vaccine to pneumonia, he found- after heat killing the pathogenic bacteria and mixing it in with the nonpathogenic- the living bacterium became pathogenic, the substance that did this was still not found( Oswald Avery later found it)
transformation
found by Griffith, change in genotype and phenotype due to assimilation of DNA from other cells
bacteria(phages)
studied to prove inheritance molecules like DNA, viruses that infect bacteria
virus
DNA coated by proteins, must infect machinery of Cell in order to replicate
Alfred Hershey and Martha Chase
experimented on phages(T2) to show that DNA was the genetic material
T2
was said to be able to turn an E. Colli cell quickly into a replicating machine and was composed of proteins and DNA(phage)
What did the T2 infected Cell do?
The infected cell started producing the tagged DNA, this provided evidence to the fact that DNA is the genetic material and not proteins
Erwin Chargaff
analyzed the base composition of DNA and reported that base composition of DNA varies from one species to another, proved that molecular diversity among species is due to DNA, also found that number of A = T and number of G = C
Chargaff’s rule
(1)DNA base composition varies between species and for each species. (2)The percentages of A and T are equal, same for G and C
What was trying to be found after genetic material was found? Who helped?
After establishing DNA as genetic material, Maurice Wilkins, Rosalind Franklin, and Linus Pauling started to try to find the structure(3d)
James Watson and Francis Crick confirmed
Story of how model was made (1)
Watson traveled to Cambridge and met up with Crick, while there, Watson saw an X-ray image of DNA at the lab of Wilkins. These X-ray images were produced by Franklin. Wilkins showed Watson and he confirmed that DNA was helical. More information by Franklin let them deduce a 2 stranded molecule/double helix
What can happen to DNA ?
DNA is a linear sequence of nucleotides and can be transcribed into mRNA and translated into a polypeptide
Story of how model was made (2)
Watson and Crick started building models of the double helix, using chargaff’s rule and Franklin had already deduced the sugar-phosphate back ones were on the outside of the DNA molecule. Watson used this info to make a model with antiparallel sugar-phosphate backbones(2), using chargaff’s rule they paired the purines and pyrimidines
Watson and Crick had made a perfect DNA model and both of them and Maurice Wilkins received Nobel Prize, sadly Franklin did not due to her passing
