https://padlet.com/christina_m_baldwin/p9zddrx8zdcm Made with charisma en-us 2019-03-06 17:10:04 UTC 2024-10-16 00:16:42 UTC hello@padlet.com https://padlet-assets.s3.amazonaws.com/icons/Dartstarget.png https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371080 -The Griffith Transformation provide strong evidence that genes are made of DNA. Found that enzymes that destroy proteins and RNA did not affect the ability of the extract to transform bacteria, while enzymes that destroy DNA inactivated it. 

-Fredrick Griffith conducted experiments using Streptococcus pneumoniae bacteria and mice. He was trying to develop a vaccine against pneumonia using two related strains of bacteria known as R and S strains. 

R strain: When grown in a petri dish, the R bacteria formed colonies, or clumps of related bacteria, that had well-defined edges and a rough appearance (hence the abbreviation "R"). The R bacteria were nonvirulent, meaning that they did not cause sickness when injected into a mouse.

S strain: S bacteria formed colonies that were rounded and smooth (hence the abbreviation "S"). The smooth appearance was due to a polysaccharide, or sugar-based, coat produced by the bacteria. This coat protected the S bacteria from the mouse immune system, making them virulent (capable of causing disease). Mice injected with live S bacteria developed pneumonia and died.

When harmless R strain bacteria is combined with heat killed S strain bacteria, and injected into the mouse, the mouse was killed by pneumonia. When checking the blood sample of the mouse afterwards, it was found to contain living S strain bacteria. 

]]> 2019-10-30 11:57:31 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371080 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371144 (Carson, Delaney, Eve, Maria, Melissa)

Watson & Crick:
- in 1953, they published a two-page paper revealing the structure of DNA
- they proposed the idea of complementary bases (thymine and adenine, and guanine and cytosine) which connect in the center to form the double helix


Franklin & Wilkins:
-Rosalind Franklin got images of her DNA through DNA crystallography
-DNA crystallography was an idea first pioneered by Maurice Wilkins

Watson and Crick retrieved Franklin's DNA x-ray without permission, and with this, they were able to discover the structure of DNA-a double helix

Watson, Crick, and Wilkins all received a Nobel Prize for their work, but Franklin was not honored for her work.


]]> 2019-10-30 11:57:42 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371144 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371254 Devon Gratz, Alex Bacon

The researchers prepared an extract from the disease-causing S strain of pneumococci and showed that the "transforming principle" that would permanently change the harmless R-strain pneumococci into the pathogenic S strain is DNA. This was the first evidence that DNA could serve as genetic material.]]> 2019-10-30 11:58:01 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371254 368123 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371515 Cracking the code

In the 1960's scientist struggled to figure out which amino acid of the 64 nucleotide triplets designates.

Faking the Message (Katie McDonald)
Nirenberg decided to use polynucleotide phosphorylase, an enzyme that would that would join ribonucleictides together in the absence of a template. First he tried a mRNA completely made out of uracil.  He then gave this to a free translation system and in return it synthesized a poly peptide made of just phenyalanine. Unfortunately, there is only so much information you can get from pumping the translation system full of one nucleotide and he needed to make more complex mRNA. Gobind Khorana, a bio chemist researching synthetic DNA, found out about Nirenberg's research and assisted letting them create more complex mRNA. It was much harder to decode but gave them a lot of information. Unfortunately, when there were two alternating bases like UGU and GUG they could tell which coded for which amino acid.

Trapping the Triplets
Nirenberg  and Phil Leder discovered that RNA fragments that were only three nucleotides in length  could bind to a ribosome and attract the appropriate amino acid containing tRNA molecule. 


]]> 2019-10-30 11:58:34 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404371515 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404372129 Meselson And Stahl
all are bacteria grown in different mediums and the results came out looking so clean with discrete bands forming at the expected positions for newly replicated hybrid molecules
-The experiment done by Meselson and stahl demonstrated that DNA replicated semi-conservatively, meaning that each strand in a DNA molecule serves as a template for synthesis of a new, complementary strand.
-The Meselson–Stahl experiment is an experiment by Matthew Meselson and Franklin Stahl in 1958 which supported Watson and Crick's hypothesis that DNA replication was semi conservative.]]> 2019-10-30 11:59:53 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404372129 366389 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404372651 Hershey and Chase (page 195)
-1952 experiment which helped to confirm that DNA is a genetic material
-They worked with T2 viruses made entirely of protein and DNA, they placed a batch of DNA in radioactive phosphorus and one in radioactive sulfur. DNA lacks sulfur while protein lacks phosphorus meaning the radioactive isotopes allowed the researchers to differentiate the two types of molecules. ]]> 2019-10-30 12:01:13 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404372651 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375056 2019-10-30 12:07:43 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375056 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375353 2019-10-30 12:08:26 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375353 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375507 2019-10-30 12:08:49 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375507 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375512 Founded in 1954 by American biologist James D. Watson and Russian–American physicist George Gamow to "solve the riddle of the RNA structure and to understand how it built proteins" and with the motto "do or die; or don't try", the club consisted of 20 members, each of whom corresponded to an amino acid, and an additional four honorary members (S. Brenner, VAL. F. Lipmann, A. Szent-Gyorgyi, and another individual), one for each nucleotide. Also, each member received a woolen necktie with an embroidered helix on them, hence the name "RNA Tie Club".

Meetings of the RNA Tie Club were friendly, cordial affairs involving cigars and alcohol. This time allowed for bonding and close friendships among this scientific elite, and it turned out to be a breeding ground for creative ideas. While meetings were held twice a year, between meetings the members mailed letters and preprints of articles suggesting new concepts and ideas.

Gamow postulated that a nucleotide code consisting of three letters would be enough to define all of the amino acids.
Sydney Brenner proposed the concept of a codon, the idea that three nucleotides could code for one amino acid.
Francis Crick proposed the "adaptive hypothesis" suggesting that some molecule ferried the amino acids around, and put them in the correct order corresponding to the nucleic acid sequence.

Unfortunately, the goal of understanding and deciphering the code link between nucleic acids and amino acids was achieved by Marshall Nirenberg, who was not a member of the RNA Tie Club.]]> 2019-10-30 12:08:50 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404375512 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404376103 2019-10-30 12:10:24 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404376103 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404376222 2019-10-30 12:10:39 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404376222 https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404377298 2019-10-30 12:13:16 UTC https://padlet.com/christina_m_baldwin/p9zddrx8zdcm/wish/404377298