It was assumed that genes would be composed of ______?
Amino acids (because at that time they appeared to be the only biomolecules with sufficient complexity).
Research on the mold neurospora was done by who?
Beadle and Tatum.
Beadle and Tatum supported what hypothesis?
They supported Archibald Garrod's hypothesis that genes work by controlling the synthesis of specific enzymes.
Recap: Genes work by _______ the synthesis of ______ _______.
controlling; specific enzymes.
The idea of DNA being genetic material emerged from?
Frederick Griffith in 1928 from studies on a pneumonia cuasing bacterium.
Pathogenicity reflected the action of what gene?
The capsule gene which coded for a key enzyme involved in the synthesis of the carbohydrate-containing capsule that surrounds most pneumonia casuing bacteria.
The capsule gene (s gene) coded for an enzyme involved in?
The synthesis of carbohydrate capsule.
What did Frederick Griffith do?
He basically "transformed" the R strain with the S strain. The s cell was heated to kill... The S gene was released and recombined in the R cell (non pathogenic).
Griffith's experiment was done with what bacteria?
In 1944, after 10 years of research ____ showed that transforming agent was ______.
Oswald Avery, Colin MacLeod, and Maclyn McCarthy; DNA.
Oswald basically isolated and purified DNA from s strains and added to R cells to tranform them T/F?
The transforming ability of purified active fractions was destroyed by addition of?
Did the addition of either ribonuclease or proteases have an effect on transforming ability?
No it did not.
Hershey Chase experiment involved what?
Involved a T2 phage or bacteriophage.
What did Hershey and Chase lable radioactively?
35-S (protein) and 32-P (DNA).
What did Hershey and Chase's experiment do?
They took the phage and introduced it to a host cell in which it infected. After agitation, the "ghost" protein coat fell off and the DNA material was inside the host cell which then replicated and formed new phages.
What did Hershey and Chase's experiment prove?
It proved that the protein coat only served to protect the genetic material and transport it. After violent agitation it simply fell off. (VIRAL GENES ARE NUCLEIC ACIDS).
What are the steps of infection?
1. Adsorption 2. Penetration 3. Replication 4. Release of virions.
In 1938 Astbury first _______.
X-ray diffraction of DNA.
1950s Wilkins and Franklin confirmed?
DNA was helical shaped and composed of more than one polynucleotide chain.
1952 Alexander Todd lab showed?
DNA chains were held together by 3' --> 5' phosphodiester bonds.
Erwin Chargaff proved what?
A = T C = G and purines = pryimidines.
The new DNA strand grows from _' to _'.
5' to 3'.
The 3' OH is linked to the _' ______.
Is the strand anti parallel?
Yes it is antiparallel.
The 3' strand has the __ group and the 5' stand has the __ group.
What did Meselsohn and Stahl do?
They tested the replication of DNA by doing a CsCl density gradient centrifugation to show the separation of complementary strands during DNA replication.
In M and S experiment after one generation of growth the strands are?
A hybrid of one heavy and one light.
After two generations of growth what happened?
Half the DNA molecules were light and half hybrid.
M and S used what isotopes?
14 N and 15 N.
DNA models: semi, cons, and disp
Semi: each of the two daughter DNAs should be of hybrid density (one original and only newly synthesized strand).
Cons: one daughter DNA is heavy (both original strands) and the other daughter DNA is light (both newly synthesized strans).
Disp: DNA strands proposed to be broken as frequently as every 10 bp & used to prime synthesis.
Protein synthesis in all eukaryotic cells occurs in?
DNA cannot be the template that directly orders amino acids during protein synthesis T/F?
A typical gene has how many base pairs?
1000 number of potential genes in that size? 4^1000 much greater than the # of genes in any organism.
What did Torbjorn Caspersson & Jean Brachet find?
RNA is in the same cellular compartment where protein synthesis occurs (mostly in cytoplasm).
What two things distinguish RNA from DNA?
1. Sugar (deoxyribose vs ribose). 2. No thymine but uracil.
RNA is usually found ___ stranded but _______.
Single stranded; double stranded can form but each strand is the same.
Francis Crick called it the _________ which stated DNA -> RNA -> Protein
Central Dogma. DNA ----transcription---- RNA ----translation---- Protein.
Crick proposed that the amino acids were first attached ______.
To specific adapter molecules.
Zamecnik and Hoagland proposed _______.
transfer RNA molecule (Crick's adapter molecule).
tRNA accounts for __ of all RNA.
About __ of all cellular RNA is found ____.
85 percent in ribosomes.
The amino acid attaches to which end on the tRNA?
The 3' end on the tRNA.
About __ of total cellular RNA is mRNA.
Because only a small segment of mRNA is attached at a given moment to a ribosome, a single mRNA molecule can simultaneously be read by several ribosomes. T/F?
True this is called polyribosomes in this case.
What enzyme actually transcribed RNA from DNA templates?
These RNA Polymerases were found by?
Jerard Hurwitz and Sam B. Weiss.
These RNA Polymerases required what substrates (4)?
ATP, GTP, CTP, & UTP.
The new RNA strand from the DNA template grew from _' to _'.
5' to 3'.
What is degeneracy?
When more than one codon codes for the same amino acid.
What are the initiator codons in prokaryotes and eukaryotes?
AUG, GUG; AUG.