DNA Replication Flashcards
what were the experimental organisms that enabled scientists to learn about DNA?
bacteria and viruses
what did Griffith work with in 1928?
bacteria that causes pneumonia
what 2 strains did Griffith work with?
S (smooth) Strain - encased in a capsule and pathogenic
R (rough) Strain - lacked a capsule and could be destroyed by the host’s immune/lymphatic system
What happened in the experiment where heat killed S cells were mixed with R cells?
DNA from the heat killed S was picked up by the living R and they “transformed” into pathogenic S cells
what did Griffith’s experiment show?
transformation - when DNA from one source assimilates into another source, causing a change/ “transformation” in genotype and phenotype
who was the first to suggest that DNA was the agent being transferred between bacteria cells?
Oswald Avery
what did most scientists think were the agents?
proteins
what are phages?
viruses that infect bacteria
who proved that it was DNA and not proteins that were responsible for transferring genetic info ? through what work?
Hershey and Chase; through their work with bacteriophages
what are bacteriophages?
viruses that infect bacteria
at minimum, what is a virus?
DNA/RNA in a protein coat called a capsid
protein contain what elements?
CHON
what is different between proteins and DNA?
protein - S
DNA -P
what did batch 1 have?
radioactive S (protein)
what did batch 2 have?
radioactive P (DNA)
what was incorporated in T2 bacteriophages that infect E coli bacteria?
2 different radioactive tags - S and P
what was the result of Hershey and Chase’s experiment?
P appeared in E coli and S didnt, so DNA was being transferred
who noticed the percentages of A,T,C,G in DNA?
Chargaff
A and T ~ 30%
C and G ~ 20%
A=T and C=G equalities are known as
Chargaff’s Rule
the race to discover DNA’s true shape was won by?
Watson and Crick
(Maurice Wilkins also won Nobel Prize)
how was DNA’s shape found?
Rosalind Franklin took X-ray crystallography images taken, and Watson and Crick saw that it was a double helix
the correct model of DNA consists of
sugars (deoxyribose) and phosphates along the sides of the ladder and the N bases along the rungs
bonds between phosphate group and sugar?
covalent phosphodiester
bonds between complementary n bases?
H bonds