BIOL239 Trouble Area

consensus sequence for shine dalgarno is

AGGAGG

purpose of shine dalgarno

during translation anchors the 30S ribosomal subunit at the correct location on the mRNA template.

where is TSS located

upstream of coding region but downstream of promoter

meselson stal discovered what

proved that DNA replicates using a semiconservative model

meselson stahl how did they do it

• Step 1: They grew bacteria in a food mix with heavy nitrogen (15N) for many generations. This made all the bacterial DNA heavy.

• Step 2: They moved the bacteria to a normal food mix with light nitrogen (14N).

• Step 3: They took samples after one and two rounds of cell division.

• Step 4: They spun the DNA in a cesium chloride tube. Heavy DNA and light DNA settle at different heights based on their weight.

Results and Conclusion

• After Generation 1: The DNA formed a single band of medium (hybrid) weight. This proved the conservative model wrong because it ruled out separate heavy and light bands.

• After Generation 2: The DNA formed two distinct bands: one medium-weight band and one light-weight band. This proved the semiconservative model was correct and ruled out the dispersive model.

watson and crick discovered what

that DNA has a double helix shape

sutton and boveri discovered what

coined the chromosomal theory of inheritance

griffith discovered what

bacterial transformation—proving that non-virulent bacteria could become deadly by acquiring a mysterious "transforming principle" from dead bacteria

avery discovered what

DNA is the "transforming principle" and the carrier of genetic information. Their experiments proved that DNA—not proteins, as most scientists then believed—manages heredity and transfers traits from one generation of bacteria to the next

hershey and chase proved what

DNA is the genetic material; confirmed Oswald Avery's results in 1952 by using radioactive isotopes to track bacteriophage components. They showed that viral DNA, and not protein, enters bacterial cells during infection to direct reproduction, providing independent proof that DNA is the genetic material

aminoacyl synthetase

attach the amino acid to the 3'-OH group of the terminal tRNA nucleotide.

morgan proved what

experimentally proved chromosomal theory of inheritance theory using fruit flies (Drosophila melanogaster) and discovered gene linkage and crossing over