Quiz 2 Flashcards
What is the central dogma?
flow of genetic information from DNA to RNA, to protein
What did Fredrick Griffin do to show DNA is the genetic material?
Discovered “transforming factor”; Studied smooth and rough strain in mice cells and found that some factor in S cell (that kills) transformed living R cells into S cells
How did Avery, MacLead, and McCarthy show that DNA is a hereditary material
Took s cells, spun them in centrifuges, heat killed them; took out constituents through filtrate and extracted it to that of a complex mixture; treated with individual enzymes but when done failed to recover just R cells; so degraded complex mixture till only DNA was left and found that it destroyed the transforming principle
People worried if contents in DNA were pure
How did Alfred Hershey and Martha Chase contribute to the finding of DNA as a use of genetic material
infected T2 bacteriophage into E. coli growing in the presence of either 35S to label the protein or in the presence of 32P to label the DNA.
incubated the labelled phage with the E. coli for 20 minutes to allow the genetic material to enter the E. coli.
blended to cell/phage mixture at high speed to knock the phage ghosts off the E. coli.
purified the phage ghosts and the E. coli cells and showed that when the protein was labelled with S35 the label remained outside the E. coli but when the DNA was labelled with P32 the label entered the bacterial cells
labelled DNA but not labelled protein could be recovered in the progeny phage showing DNA and not protein entered the cells
What are the steps for bacteria cell to infect DNA
- Phage attaches to bacterial cell
- Phage injects DNA
- Phage DNA directs host cell to make more phage DNA and protein parts so new phages can form
- Cell lyses and releases new phages (whole process takes a good 20 min)
What do nucleotides contain
Nitrogenous base, 5 carbon sugar, phosphate group
What are purines
Adenine and Guanine
What are Pyrimidine
Cytosine, Uracil, Thymine
What was Chargaff’s Rule
Nitrogenous bases occur in definite ratios; a+g = c+t
Complement base form hydrogen bonds; AT = double bond; GC = triple bond
Who deduced the secondary structure of DNA and how
James Watson and Francis Creek; used Wilkins and Franklins x-ray diffraction (beam directed at molecule in form of solid; positions of atoms are deduced from diffraction patterns produced by film)… but it. was rlly Franklin that determined that the DNA was a helix shape
What is the process of DNA replication
process of two strands unwinding, separating, then acting as a template for new strand to be made through synthesis
What is DNA transcription
- Creates an RNA copy of one strand of DNA
- RNA made in 5’ to 3’ direction using 3’ to 5’ as a template
- Results in RNA that will translated into a protein
Carried out by RNA polymerase; There are specific nucleotide sequences that hint when to start and stop; only introns (protein coding genes for mRNA are translated) exons are removed through splicing
Why are nucleic acids are synthesized 5’ to 3’
This is because the energy to catalyze to formation of the new phosphodiester bond is provided by the hydrolysis of the phosphodiester bonds in ATP, GTP, CTP, and TTP. If we are adding on the nucleotide phosphate, we must be adding that 5’phosphate to the 3’hydroxyl of the chain we are elongating. We synthesize 5’ to 3’, always elongating at the 3’ hydroxyl.
What is DNA translation
Polypeptide synthesis with the use of a ribosome in order to assemble amino acids
What are the characteristics of genetic code
Codon is three nucleotides
AUG - start
UAA, UAG, UGA, - stop
