BIOLOGY CHAPTER 14,15,21

• DNA is the blueprint; what makes you different from everyone else.
• James Watson and Francis Crick discovered in April 1953 that DNA is an elegant double-helical model for deoxyribonucleic acid (DNA) structure.
• Genetic Endowment is contained in the 46 chromosomes inherited from your parent and the mitochondria inherited from your mother.
• Nucleic Acid is unique because it can direct their replication.
• The resemblance of offspring to their parents is dependent on the precise replication of DNA and its transmission from one generation to the next.
• Genetic Program is a DNA sequence that every cell has that will direct the development of your biochemical, anatomical, physiological, and (to some extent) behavioral traits.
• Environmental factors are also important in determining your traits.
• DNA is the Genetic material.
• T.H Morgan showed that genes existed apart of chromosomes.
• DNA damage constantly occurs in somatic adult cells, with errors due to replication and mutagens increasing the number of mutations above the background level.
• DNA polymerases have proofreading ability, back up, cut out, and reinsert correct base pairs.
• Photolyase is a repair mechanism that undoes covalent bonds created so that hydrogen bonds can revert, requiring energy.
• Excision repair is a nonspecific repair mechanism that cuts out and replaces the incorrect base.
• Mismatch repair removes incorrect bases incorporated during DNA replication, usually done by polymerases.
• Mutagens are any agent that increases the number of mutations above the background level, including radiation and chemicals.
• The law in somatic adult cells, except for hair cells, tends to contribute to cancer.
• There are two categories of DNA repair: specific repair, which targets a single kind of lesion and only repairs that kind of damage, and nonspecific repair, which repairs multiple kinds of lesions in DNA.
• Photorepair is a mechanism that repairs UV light damage by creating a covalent bond between two bases.
• Chromosomes are made of chromatid, which consists of DNA and proteins; DNA is wrapped around protein, which allows the DNA to condense and fit inside of the nucleus.
• Up until the 1940s, scientists believed that proteins seemed to indicate that proteins were genetic material.
• DNA is made up of 20 amino acids (proteins) and 4 nucleic acids.
• Federick Griffith studied Streptococcus pneumoniae, a pathogenic bacterium causing pneumonia.
• Streptococcus pneumoniae has two strains: S strain, which is pathogenic, and R strain, which is nonpathogenic (harmless).
• Federick Griffith infected mice with each strain to understand the difference between strains.
• Prokaryotic replication involves one circular chromosome with one origin of replication.
• DNA replication begins at particular sites around the DNA strands called origins of replication.
• Each nucleotide that is added to a growing DNA strand is a nucleoside triphosphate.
• The DNA sample was a mixture of Heavy/ Light & Light.
• Mosiac Matthew Meselson and Franklin Stahl: Batch 1 cultured in medium with N15 (heavy isotope) and Batch 2 bacteria transferred to medium with N14 (lightly isotope).
• Elongation involves DNA polymerase adding matching bases and phosphate backbone, taking monomers → polymers, and continuing until it bumps into another RNA primer or it falls off of the template strand for DNA.
• Dispersive: Copy parts and divide it in half: 50% old and 50% new, dispersed.
• When adding nucleoside triphosphate, we cut off 2 phosphates, releasing tons of energy to catalyze the formation of covalent bonds from the 3’ to the new 5’.
• Replication proceeds from both directions, proceeds until it completely unwinds two companies from the DNA.
• Replication ignition at the end of the replication bubble involves unwinding of double-stranded DNA by helicase, stabilization of single-stranded DNA by single-stranded binding protein, and creation of a cut in the phosphate backbone of the DNA by topoisomerase/ gyrase.
• The DNA sample was centrifuged after the first and second replication, separating them by densities.
• DNA replication requires 3 things: 1 parental DNA molecule, something to do the copying (enzymes), and building locks to make copy (Nucleotide triphosphate: A-T, C-G).
• Semi-conservative replication model was consistent with all observations: 1 band after round 1 and 2 bands after round 2.
• Mice infected with S strain died (pathogenic), while mice infected with the R strain recovered and were fine (nonpathogenic).
• Federick Griffith concluded that the reason the mouse died was due to transformation.
• Transformation: a change in the genotype and phenotype due to the assimilation.