Endomembrane System

Question 1

Subcellular Fractionation

Answer 1

Isolates specific organelles
Homogenize cell and then refuse to form microsomes (small, spherical vesicles)

Microsomes possess different physical properties based on which organelle they are derived from

Centrifuges microsomes and determine biochemical composition

Question 2

Cell Free Systems

Answer 2

Biochemical approach
Characterization of the functions of specific endomembrane protein components in vitro

Incubate liposomes with isolated microsomal proteins

i.e. liposomes + coat proteins causes budding= that protein is responsible for vesicle formation

Question 3

Mutant Phenotype Analysis

Answer 3

• Genetic approach

Identify genes/proteins involved in the endomembrane system by screening for mutant phenotypes

Question 4

Sec mutants

Answer 4

Secretory mutants

Possess visible defects in endomembrane organelle morphology and distribution

Know the sequence of yeast cells, can go back and see where the mistake is, and figure out which gene is responsible for the mutation

Question 5

Sec 12

Answer 5

Involved in ER vesicle formation

Sec12 mutant yeast cells possess large, expanded ER because vesicle budding from the ER is disrupted

Question 6

Sec 17

Answer 6

Involved in Golgi vesicle fusion

ER derived vesicles in sec17 mutant yeast cells accumulate in the cytosol because they do not fuse to the Golgi