Ch 13 Molecular Basis of Inheritance Flashcards
lagging strands (okazaki fragments)
- one of two strands of DNA at replication fork
- lagging strand has delay before it’s replicated and must be replicated discontinuously in small fragments
leading strand
strand that is synthesized continuously during replication
replication fork
y-shaped region in chromosome that serves as growing site for DNA replication
Codon
sequence of 3 nucleotides that together from unit genetic code in DNA/RNA
init-codon
sequence of three nucleotides forming unit of genetic code in tRNA, corresponding complementary codon in mRNA
point mutation
mutation affecting one or few nucleotides in gene sequence
central dogma
- DNA codes for RNA which codes for proteins
- DNA is molecule of heredity that passes from parents to offspring, contains instruction for building RNA and proteins
Avery, MacLeod & McCarty
Took mixture of heat killed S cells and living R cells and tested to see what caused transformation of R strand to S strand
***RNA & proteins not transforming principal DNA IS TRANSFORMING PRINCIPAL
Chargaff DNA analysis experiment
Used paper chromatography to separate DNA & UV spectrometry used to analyze amounts of bases
- **base composition of DNA varies between species
- **A&T equal to G&C
Franklin
Got best x-ray diffraction of DNA w/x-ray crystallography to learn DNA structure (photo 51)
-Wilikins hares data w/Watson and Crick
R. Griffith’s Mouse experiment
Goal:develop vaccine against pneumonia Procedure: Injected mice w/diff bacteria living S cells-->dies living R cells-->lives heat killed S cells-->lives mixture heat-killed S cells & living R cells-->dies Conclusion:living R bacteria transformed
R. Griffith’s Mouse conclusion
Conclusion: living R bacteria transformed into pathogenic S bacteria, unknown inheritable substance changed R cells- to S cells
Results: coined “transformation” now known as change in genotype and phenotype from assimilation of foreign DNA
Hersey & Chase T4 bacteriophage experiment
Procedure: took mixture of heat-killed S cells and living R cell and tested to see what cause transformation of R strand into S strand
Hersey & Chase T4 bacteriophage conclusion
RNA and proteins aren’t transforming principal DNA IS TRANSFORMING PRINCIPLE
meselson and stahl experiment
used centrifuge to separate DNA
- heavy isotopes at bottom lighter at top
- looked to see where samples where at end of replication
meselson and stahl conclusion
1st round Conservation model (incorrect) -parent at bottom daughter at top Semi conservative -sediment toward middle Dispersive -sediment toward middle
2nd round conservative (incorrect) semiconservative(correct) -bands toward top hybrid in middle Dispersive (incorrect)
Watson & Crick
Came up w/model for DNA structure
**solved structure of DNA w/franklins data
Components of nucleotide
- sugar (deoxyribose)
- phosphate (1 phosphorous atom joined to 4 oxygen)
- base (one of A,G,G,T)