Blog 2: 10 points to know about genetics

[1] DNA and RNA grows from 5'-3'. 5' end contains a free phosphate group attached to deoxyribose while the 3' end contains a free hydroxyl group attached to deoxyribose. New nucleotides can only be added to the 3' end.

[2] Frederick Griffith showed that bacteria rendered harmless could assimilate a foreign substance (DNA) from heat-killed bacteria and become pathogenic. This proved proteins were not the genetic material as heat kills proteins. Griffith called this process transformation.

[3] Watson and Crick's model of semi conservative replication states that DNA molecules produce daughter molecules with one old strand and one newly made strand.

[4] A large team of enzymes and proteins carry out DNA replication at many sites where the DNA has been opened up into a "bubble" with replication forks at the ends.

[5] DNA replication: the leading strand is continuously elongated while the lagging strand is elongated in short pieces called Okazaki fragments.

[6] Transcription synthesizes mRNA from the template strand of a gene. It begins at the promotor region (5' TATA 3') on the template strand and endd when a terminator sequence is transcribed (AAUAA, "Arnold"). RNA polymerase II is used to synthesize the mRNA.

[7] Introns and RNA splicing are responsible for the wide range of proteins a single gene can code for.

[8] Codons are triplets of nucleotides on the mRNA that code for a specific amino acid. 5' AUG 3' starts a polypeptide chain which ends on a stop codon (UGA, UAA, UAG).

 

[9] On a 5' to 3' mRNA codon, the 3rd base can form pairs with tRNA anti codons that do not follow the Watson and Crick model. This wobble position helps to defend against point mutations (a nucleotide swapped for another). In the case a mutation occurs on the 3rd base, the codon can still be translated to the correct protein (ex. UUC and UUA both code for Phenylalanine)

[10] A gene is a region of DNA whose final product is either a polypeptide or an RNA molecule