Midterm 1 Flashcards
Ernst Hackel (embryologist)
nucleus has to take care of the inheritance of the heritable traits
cytoplasm is concerned with accommodation of adaptation to the environment (sperm cells have very little cytoplasm)
Friederich Miescher
isolated nuclein or DNA, studying leukocytes collected from pus on fresh surgical bandages
Nuclein from pus: does not contain protein, since it did not contain any sulfur (found in proteins)
Nuclein from salmon sperm: the ideal source for isolating large quantities of pure nuclein
He found that nuclein contained mostly C,N,H,O,P
Albrecht Kossel (chemist)
nuclein consisted of protein component (histone) and non protein component (nucleic acids- CTAG)
protein made of 20 aa
nucleic acids has 4 diff bases
Walter Flemming
found a basophilic dye that specifically stained material inside cell nucleus (chromatin)
coined the term MITOSIS: each individual chromosome break into two, doubling the number of chromosomes (has genes: genotypes and phenotypes)
William Bateson, William Johannsen
Bateson coined the term genetics to describe study of inheritance
genes: units of hereditary information
genotype: genetic constitution of organism
phenotype: organisms totality of inherited characteristics
Thomas Hunt Morgan
proposed that association of eye color and sex in fruit flies had a physical and mechanistic basis in chromosomes
discovered sex-linked genes; developed concept of genetic linkage (ie. genes that are close together on the chromosomes are often inherited together during meoisis)
Herman Muller
worked with Morgan to use Xrays to induce mutations in Drosophilia genome
found that genes can be mutated by chemical or radiological insults (mutated genes can be passed on from one generation to the next)
George Beadle, Edward Tatum
used bread mold, Neurospora crassa to determine if and how genes control known biochemical rxns
Neurospora
easy to grow and reproduce by crossing
easy to produce mutation effects (since haploid state only has one set of unpaired chromosomes)
biochemistry of amino acid was already known
Wildtype spores
can synthesize all amino acids
can grow on complete medium or minimal medium
mutant spores
select for strains that have mutations that disrupted AA biosynthesis pathway
cannot grow in minimum medium unless supplemented with AA in growth medium
George Beadle, Edward Tatum experiment
mutate genome and screen for specific phenotype- loss of ability to synthesize a specific amino acid
isolated 4 strains of Neurospora that only grew on minimal medium if supplemented with arginine
suggested that loss of multiple genes resulted in same phenotype - loss of production of single AA
Forward genetic screening
starting with an observed trait and finding the gene responsible by inducing random mutations
Reverse genetic mutations
starting with a known gene and understanding its function by manipulating or altering its observed effects
Transforming principle
heat killed S strain (causes pneumonia) can transform R to S- strain
non-virulent strain transformed into virulent strain
