DNA/RNA & DNA Replication (finished)

• Prokaryotic: organisms that don't have a distinct nuclear compartment to house their DNA

  • Ex.: archaea, bacteria
• Eukaryotic: organisms that house their DNA in a distinct, subcellular compartment
• DNA: genetic material found in prokaryotes and eukaryotes

  • Deoxyribonucleic acid
  • Double stranded
  • Polymer with deoxyribose, phosphoric acid, nitrogenous bases
• RNA: performs multiple functions inside the cell

  • Ribonucleic acid
  • Polymer of ribose, phosphoric acid, nitrogenous bases
• Gene: basic unit of heredity
• Genome: combined total of all genetic information contained in an organism
• Proteome: combined total of all genetic information contained in an organism
• DNA Replication: Occurs during S phase of cell cycle where DNA is copied to produce two identical strands
• Cell Cycle: different phases in the life of a dividing cell where the cell grows and divides into daughter cell
• Mitosis: occurs during the M phase of the cell cycle where there the division of the nucleus of a eukaryotic cell

  • Involves the condensation of DNA into visible chromosomes and the separation of the duplicated chomosome to make 2 identical sets
• Gene Mutation: changes in the nucleotide sequence of DNA

  • May or may not cause disease related consequences for the organism
• DNA polymerase: enzyme that catalyzes DNA synthesis

  • Copies an original strand to make dsDNA
• DNA Ligase: enzyme that joins 2 DNA strands together
• Exonuclease: enzymatic activity that degrades DNA one base at a time
• Francis Crick & James Watson got the Nobel Prize for discoveries of DNA structure and replications
• DNA undergoes semiconservative replications
• Erwin Chargaff was known for his base composition research of DNA

  • The # of As and Ts match, and the # of Cs and Gs match
• Rosalind Franklin & Maurice Wilkins advanced studies of DNA through X-ray diffraction studies
• DNA is stable, RNA is unstable & transient
• 2 types of bases:

  • Purines
  • Pyrimidines
• DNA uses: adenine, thymine, cytosine, guanine
• RNA uses: uracil, adenine, cytosine, guanine
• The DNA double-helix has a major groove, minor groove, and is around 2 nm
• • Between C and G there are 3 hydrogen bonds
  • Between A and T there are 2 hydrogen bonds
• Nucleotide: sugar phosphate + base
• The double-helix shape of DNA is formed because of the way nucleotides bond together
• Many proteins that modulate transcription and translation bind to DNA have major and minor groove binding

  • Resembles fingers
• Prokaryotic DNA: is organized in a linear, contiguous fashion

  • Transcription of DNA -> RNA creates RNA copy that is ready for use as a template
  • Template undergoes translations and protein synthesis
  • RNA transcript can be translated into protein during transcription because there's no nucleus
• The promoter and operator are what starts RNA transcription/translation in prokaryotes
• Depending on the type of promoter and its location, you could get different proteins

  • Part of how new biologics can be made
• Inducible transcription: starts and ends on-demand by introducing a stimulus
• Because of the eukaryotes complicated structure:

  • We can make more different, complex, and variable proteins
  • Gives more control over when, how, and where genes are expressed
• Eukaryotic cell differentiation is enable by eukaryotic gene structure differences
• Coding regions (exons): DNA is segmented into blocks of sequences that give rise to a specific protein structure
• Exons are separated by noncoding introns

  • This includes the 5' and 3' end called untranslated regions (UTRs)
• After the first copy of DNA is made in a linear fashion, all the introns are removed from a process called splicing
• After splicing, the mRNA is modified into mature mRNA. Then it is transported out of the nucleus and used as a template for protein synthesis (translation)
• One gene can code for many proteins

  • This phenomenon is due to alternative splicing
• Beadle and Tatum are known for winning a Nobel Prize for their "one gene, one enzyme" hypothesis

  • Theory seemed correct because they studied only prokaryotic specimen
• Human Genome Project: A project to map the entire human genome

  • In the late 1990s, scientists assumed that once the human genome was uncovered that all genomic diseases would be understood and curable
  • Funding for the project slowed down around 2009