Lec 11: Special synthesis (unrelated topic) Flashcards
When was penicillin discovered?
1928
What are the two classes of antibiotics?
Bacteriostatic agents, bactericidal agents
What is a bacteriostatic agents?
restrict growth and reproduction
What is a bactericidal agent?
Causes bacterial cell death
What are the primary components of neosporin?
Bacitracin, neomycin and polymyxin B.
What does Bacitracin do?
Cell wall inhibitor good against Gram+ bac
What does Neomycin do?
Attack ribosome
What does Polymyxin B do?
punch holes in cell membrane, best for gram negative bacteria.
What do antibiotics that target the ribosome do?
They slow down the ribosome thus making the fidelity low. Making more mistakes. Slower the ribosome the more chance our RNA is discovered and chewed up.
What does Puromycin do?
Causes the premature release of nascent polypeptide chains by its addition to the growing chain end. (looks like a release factor just not as specific)
Since ribosomes of euk mitchondria often resemble those of bacteria in their sensitivity to inhibitors, what happens?
Some of these antibiotics can have a deleterious effect on human mitochondria
What is the paradox pertaining to DNA or protein?
DNA is the genetic material but it is reliant of proteins to do replication, proteins catalyze chemical reactions bbut nucleic acids code for proteins, so which came first? DNA or Protein?
What was one plausible solution to the paradox?
It was RNA.
What does the RNA world hypothesis state?
Made by Orgel, Crick, Woese (1960s) states that RNA not DNA is the original genetic material, Watson-crick base pairing rules have always been used. RNA not protein catalyzed the first chemical rxns needed to create life
What are some supporting evidence the RNA world hypothesis?
1.Ribosomes: RNA evolution is rapid due to the reactive nature of its structure. Ribozymes can pretty much do anything. 2. Evolutionary relics still persist in our cells: DNA is just a specialized variation of RNA that is better suited for storage of info. Vitamin and cofactors (GTP/ATP) are based on nucleotides all use ribose as the sugar. When synthesizing new nucleotdies we make the ribose based nucleotides first then we go to deoxyribose version.
What are some flaws to the RNA world hypothesis?
- This current complexity couldnt have risen from just one type of marcromolecule the RNA. 2. Introns early vs introns late debate.
What is the introns early vs introns late debate?
Introns early: introns promote recomination in trans of proteins. Prok lost their introns due to purifying selection when genome were streamlined to permit rapid replication.
Introns late: Introns are an invetion of euk. Introns are present in mitochondrial and chloroplast genomes, reinforcing that introns evolved simultaneously with eukaryotes
Which is the result of the introns early vs introns late debate?
No conclusion but introns late is more plausible
