Bio Ch 16
Terms
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- Replication Fork
- Y-shaped region at the end of each replication bubble.
- Nucleosome
- Basic unit of DNA packing; the string betwên the beads is called linker DNA.
- Errors in completed DNA
- 1 in 10 billion. 1 in 100,000 for incoming nucleotide pairing.
- Pyrimidines
- Cytosine and Thymine. Single rings
- Rosalin Franklin and Maurice Wilkins
- Franklin's X-ray was used by Watson to determine the DNA structure. Maurice Wilkins received noble prize with Watson and Crick.
- Conservative and Dispersive Models
- Parent somehow re-forms. Dispersive - all four strands of DNA have a mixture of old and new DNA.
- Radioactive sulfur
- T2 is tagged with radioactive sulfur because protein contains sulfur.
- Synthesis of lagging strand
- Okazaki fragments must be primed separately. DNA polymerase I replaces the RNA nucleotides of the primers with DNA versions, ađing them 1 by 1 to the end of the Okazaki fragments.
- Purines
- Adenine and Guanine. Two organic rings
- Nucleases
- DNA cutting enzyme that cuts out the damaged segment of DNA strand. DNA pol and ligase repair the gap. DNA repair of this type = nucleotide excision repair.
- Radioactive phosphorus
- All of the phage
- Phospho-diester bond
- p-sugar-p between 5' and 3' end
- Measurement of helix
- Helix makes one full turn every 3.4nm. Bases are stacked .34nm apart. Diameter of helix is 2nm.
- Leading and Lagging Elongation
- 5' to 3' direction always. Opposite direction for the lagging strand. Synthesized in a series of fragments called Okazaki fragments. Sugar-phosphate backbones joined by DNA ligase.
- Helicase, topoisomerase, single-strand binding
- Helicase unwinds the parental strands to be template strands. Topoisomerase relieves the strain from the helicase unwinding, and also corrects overwinding by breaking, swiveling, and rejoining DNA strands. Single-strand binding proteins bind to unpaired DNA strans to stabilize them.
- Oswald Avery, Maclyn McCarty, Colin MacLeod
- Declared the transforming agent was DNA. Purified various types of molecules from heat killed pathogenic bacteria, then tried to transform live nonpathogenic. Only DNA worked.
- Telomeres
- Multiple repetitions of one short nucleotide sequence. Telomeric DNA protects the organism's genes from being eroded through replication. Postpones the erosion.
- Polymerization reaction
- Hydrolysis of the pyrophosphate to two molecules of inorganic phosphate is exorgonic. Drives DNA polymerization reaction.
- Potential Harmful Chem and Phys Agents
- Reactive chemicals, radioactive emissions, X-rays, and UV(thymine dimer) light can change nucleotides in ways that can affect encoded genetic information. Spontaneous chemical change.
- Origin of Replication
- Eukaryotes have many. Prokaryotes have one.
- DNA bonds
- Hydrogen bonds hold the nitrogenous bases. Van der Wăls attractions betwên stacked pairs play a major role in holding the molecule together.
- Primase and Primer
- Primase enzyme joins RNA nucleotides together to make a primer complementary to the template strand. DNA pol III will then ađ DNA nucleotides to the 3' end of the RNA primer.
- Mismatch repair
- Cells use special enzymes to fix incorrectly paired nucleotides.
- Frederick Griffith
- Declared phenomenon transformation. A change in genotype and phenotype due to the assimilation of external DNA by a cell.
- Telomerase
- Enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells, restoring their original length. Made possible by a short molecule of RNA that serves as template for a new telomere segment.
- Erwin Chargarff
- Chargaff's rules - equal amount of A-T and C-G
- Hydrogen bonds. A-T
- Adenine can form two hydrogen bonds with thymine
- Blend and Centrifuge
- Cultures are whirled in a blender to shake lơse any parts of the phages that remained outside the bacterial cells. Then the mixtures were spun in a centrifuge, forcing bacterial cells to form a pellet at the bottom of the centrifuge tubes, but allowing frêphages and parts of phages, to remain suspended in the supernatant. Then they measured the radioactivity in the pellet and in the supernatant. Nucleic acids are hereditary material for viruses.
- Alfred Hershey and Martha Chase
- DNA is the genetic material of a phage as T2. Tơk bacteria and isolated proteins. Destroyed proteins and realized DNA transformation still happened.
- Semiconservative Model
- Double helix replicates, resulting in one old strand derived from the parent molecule, and one newly made strand.
- Nucleoside Triphosphate
- Nucleoside. A sugar and a base. Adenine has deoxyribose whereas ATP has ribose only.
- Hydrogen bonds. G-C
- Guanine forms three hydrogen bonds with cytosine
- Deamination
- C changes to U (remove NH2) this is a type of damage to DNA strand
- DNA polymerase
- Enzyme that catalyzes DNA replication. Poly I and poly III are involved in replication for E. Coli.
- Reactivity of triphosphate DNA monomers
- Triphosphate tails have an unstable cluster of negative charge. Loses two phosphate groups as a molecule of pyrophosphate when joining the growing end of a DNA strand.