People Flashcards
1) Mendel
Ch. 14
- first to document particular inheritance
- disproved the “blending” hypothesis
- discovered the principles of heredity
- experiments: breeding pea plants (petal color)
- “true-breeding”
- hybridization
- “P” generation => F1 => F2
- 3:1 phenotype ratio
- 1:2:1 genotype ratio
- dominance and recessive
- Law of Segregation
- dihybrid cross: are two characters transmitted as a package?
- 9:3:3:1 phenotype ratio
- Law of Independent assortment
- PROPOSED that genes are located on chromosomes
2) Morgan
Ch. 15
- provided evidence that chromosomes are the location of genes
- Experiment: fruit flies (Drosophila)
- Wing type and eye color (red wild, white mutant)
- determined mutant allele must be on the X chromosome
- genes are linked to specific chromosomes (sex linked)?
- Linked genes
- Experiment: wild type (grey bodied, normal wing) and mutant type (black bodied, vestigial wing)
- Genes that are close together on the same chromosome are linked and do not assort independently
- Unlinked genes are either on separate chromosomes or are far apart on the same chromosome and tend to assort independently
- PROPOSED that some process must occasionally break the physical connection between genes on the same chromosome (crossing over)
3) Alfred Sturtevant
Ch. 15
- used crossing over of linked genes to develop genetic maps
- hypothesized that the frequency of recombinant offspring reflected the distance between genes on chromosomes
(the farther apart, the more likely to be separated) - genetic and linkage map
4) James Watson, Francis Crick, Rosalind Franklin, Maurice Wilkins
Ch. 16
demonstrated an elegant double-helical model for the structure of DNA
5) Fredrick Griffith
Ch. 16
- the role of DNA in heredity
- Experiment: studying a pathogenic strain (S) and a nonpathogenic strain (R) of the bacterium Streptococcus pneumonia that causes pneumonia in mammals (rats)
- S: died
- R and heat-killed S: lived
- HKS and R: died => transformation
- nonpathogenic assimilated the DNA from the pathogenic strain
6) Alfred Hershey and Martha Chase
Ch. 16
showed that DNA not protein is the genetic material
of a bacteriophage known as T2
7) Erwin Chargaff
Ch. 16
found and analyzed the base composition of DNA from a number of different organisms
8) Martha Wilkins and Rosalind Franklin
Ch. 16
- used a technique called X-ray crystallography to produce a picture of the molecular structure of a DNA molecule
Franklin: DNA was composed of 2 antiparallel sugar-phosphate backbones, with the nitrogenous bases paired in the molecule’s interior
adenine with thymine
cytosine with guanine
9) Watson and Crick
Ch. 16
- DNA was a double-helix through observations of the X-ray crystallographic images of DNA
- each base pair is complimentary and forms a different number of hydrogen bonds
AT = 2
CG = 3
10) Meselson and Stahl
Ch. 16
- Experiments demonstrated that DNA replication is semiconservative
11) Archibald Garrod
Ch. 17
first to suggest that genes dictate phenotypes through enzymes that catalyze specific chemical reactions in the cell
1909
12) Beadle and Tatum
Ch. 17
- cause breads (Neurospora crassa) to mutate with X-rays creating mutants that could not survive on minimal medium
- developed the “one gene-one enzyme hypothesis”
1930s
