Exam 1 ( Ppt 2) Flashcards
Mendel’s Laws
Law of
1) Segregation: Alleles of the same gene separate during replication
2) Independent assortment: Alleles of different genes do not segregate dependent on each other
3) Dominance : An allele that masks the phenotype of recessive alleles
Which Mendel Law affects phenotype or genotype
Law of
1) Segregation: Phenotype
2) Independent assortment: Genotype
3) Dominance: Phenotype
What was the implication of Mendel’s laws
Mendelian laws showed a model for inheritance that is the foundation for genetics today.
“These rules still form the foundation of our understanding of inheritance—that is, how traits are passed on and how an organism’s genotype (set of alleles) determines its phenotype (observable features)” - Khan Academy
Gregor Mendel
Published his paper in 1865 but it wasnt approved of until 1900 because 3 scientists cosign each law independently
Responsible for Mendelian laws ( laws of inheritance)
Thomas H Morgan
Responsible for genetic mapping
“developed three two-factor crosses to identify the relative positions of individual genes—Chromosome Mapping” - Prof Ye
1933 Nobel Prize Recipient
Genetic Mapping
“Assignment of the [relative] order of three genes on the basis of three two-factors crosses” - Prof Ye
Centimorgan (cM): measured distance based on offspring frequency
What was the EARLY SPECULATION of What kinds of factor(s)/materials determine traits transfer from one generation to the next?
Nucleic Acid (RNA) or Protein
What was a fruitful hypothesis before DNA was discovered
*Gene must be duplicated in order to see them in the next generation
What experiments helped identify DNA as heredity material instead of protein and RNA
Griffiths Transformation Experiment (1928)
Avery, McCleod, McCarty Exclusion Experiment (1944)
Isotopically Labeled Phage Experiments (1950)
Griffiths Transformation Experiment (1928)
Showed that a transforming principle can induce hereditary transformations by removing the pathogenic smooth cell gene from the S cell and introducing that gene fragment into a rough cell without capsule inducing it to transform into a smooth cell with a capsule.
*Did not prove it was not RNA or Proteins responsible
Avery, McCleod, McCarty Exclusion Experiment (1944)
Proved that DNA…
1) Could induce heritable transformations
2) DNA could be degraded by Dnase
By heat killing S strain cells and removing capsule components, then testing whether DNA, RNA, or Protein were hereditary materials. Only Deoxyribonuclease prevented the R strain w/o the capsule from transforming into the S strain with the capsule because DNA was degraded ( the heritable material)
Isotopically Labeled Phage Experiments (1950)
Further Proved DNA was the heritable material
2 sets of phages were isotopically labeled with either 32 phosphorus for DNA or 35 sulfur for protein. These phages were then allowed to infect bacteria cells which showed that only the 32 P labeled DNA produced 32 P labeled phages. The 35 S labeled DNA produced unlabeled phages.
Major Players in the Race for The DNA Structure
Watson and Crick, and Wilkins (Nobel Prize 1962)
Franklin
Chargaff
Important parts of a DNA molecule
1) H bonds
2) Bases (Purines= AG and Pyrimidines = CT)
3) Sugar + Phosphate backbone
Chargaff’s rules
A=T, C=G, Purines = Pyrimidines => b/c they exclusively pair to each other
Relative amounts of bases vary between species
