Molecular Biology Flashcards
Griffith and his experiment
He discovered that genetic information could be transferred from dead bacteria to live bacteria (injecting mice w live vs dead vs noninfectey + dead)
Watson, Crick, Wilkins, and Franklin and their experiments
They discovered the structure of DNA
Semiconservative Replication
DNA replication where one double helix is unzipped, and then a correspondey strand is woven for each side. One part of each new helix was conserved, but one part of it is new
Which enzyme unwinds the DNA helix?
Helicase
Which proteins attach to each strand of uncoiled DNA to keep them seperate?
single-strand-binding-proteins
Which direction does DNA polymerase move?
3 prime 5 prime. DNA polymerase tags on the corresponding bases, which go in the 5 prime 3 prime direction. This strand (the corresponding one) is the leading strand
Which way does the lagging strand go?
the 3 prime 5 prime direction, but it’s corresponding section of old DNA goes in the 5 prime 3 prime direction.
How does DNA polymerase assemble DNA in the 5 prime 3 prime DNA strand?
It goes back then forwards then back creating little fragments of complementary DNA called Okazaki fragments. These fragments are connected by DNA ligase. This is the lagging strand
Explain how RNA primers work and why they exist
DNA polymerase can only attach nucleotides to an already existing complementary strand. This means that for the creation of the lagging strand an enzyme called primase has to create fake little strands of RNA to make the DNA polymerase work and make okazaki fragments. These strands of RNA are called RNA primers.
How are prokaryotes and eukaryotes different in terms of DNA replication?
Prokaryotes have circular chromosomes (euks have linear ones), and they only have one origin of replication (euks have many)
What are telomeres?
Basically, aglets for our chromosomes
What does the enzyme telomerase do?
It makes sure that telomeres exist on the ends of the lagging strand (since DNA polymerase can only function in the 3 prime 5 prime direction).
DNA repair methods
Proofreading: DNA polymerase proofreads.
Mismatch repair proteins repair stuff that DNA polymerase doesn’t catch
Excision repair proteins repair nucleotides that change because of external factors like radiation
What are the three steps of protein synthesis?
transcription (think music), RNA processing, translation
Messenger RNA
A single strand of RNA that provides the information for which amino acids to assemble and in what order. Each three-base codon codes for one or more amino acids
Transfer RNA
RNA dedicated to transporting amino acids to the ribosomes where they are assembled into proteins. They contain anticodons, which is what the strands from mRNA actually bond to.
Ribosomal RNA
These molecules are transcribed in the nucleus. Make up ribosomes, which coordinate the activities of mRNA and tRNA.
Three stages of transcription
initiation, elongation, termination
Initiation (transcription)
An RNA polymerase attaches to a promoter region (for RNA, often includes TATA) on the DNA and begins to unzip it.
Elongation (transcription)
mRNA is transcribed. The RNA strand goes in the 5 prime 3 prime direction
Termination (transcription)
When the RNA polymerase reaches a termination point (a “stop” set of nucleotides)
mRNA processing
Introns are cut away, and exons are left. Exons are sequences that EXpress a code for a polypeptide, while introns are INtervening, non-coding sequences. snRNPs are the ones that do this cutting
Translation
mRNA attaches to the ribosome, where tRNAs bring amino acids to the ribosome such that their codon-anticodon things match. The new amino acids is then attached to other amino acids that are already present with a peptide bond. This process is repeated until a “stop” codon is reached.
Mutagens
A chemical or radiation that causes mutation. Carcinogens are chemicals that cause uncontrolled cell growth (cancer)