BIOL 1090 Lecture Notes - Lecture 16: Lynn Margulis, Endoplasmic Reticulum, Endomembrane System
16 Dec 2017
School
Department
Course
Professor
March 8, 2017 – L16: Endomembrane
•How did the cell become compartmentalized?
The origin of eukaryotic cells – endosymbiont theory
•Lynn Margulis is a major proponent of this theory
•“certain organelles of the eukaryotic cell have evolved from smaller prokaryotic cells
that have taken up residence within the cytoplasm of a larger host cell”
oCan be proven bc the DNA, mitochondria, and ribosomes in the organelles/
prokaryotes are the same as the eukaryotes
Overview of endomembrane system
•Endomembrane system is a series of sheets connected by tubes
•Membranous vesicles
•Extensive network of membranous canals and stacks of “sacs”
•Endoplasmic reticulum (ER)
•Golgi complex
•Lysosomes/vacuoles
•Vesicles
find more resources at oneclass.com
find more resources at oneclass.com
•The combined surface area of cytoplasmic membranes is many times greater than the
area enclosed by the plasma membrane
•Endomembrane organelles are part of a dynamic system in which material are shuttled
back and forth from one part of the cell to another
•The organelles of the endo-membrane system are functionally distinct from one
another
oContain a particular set of proteins
oPerform a unique set of activities
oProvides compartmentation and functional diversity
oConserved in eukaryotes
oDynamic structures
Cells utilize several membrane trafficking pathways
•Transport of macromolecule s
oSecretion and uptake
•2 main secretory (biosynthetic) pathways
oConstitutive – materials transported in secretory vesicles and
continuously discharged into extracellular space
oModified – materials are stored as membrane-bound pakcages that
are discharged only in response to a specific stimulus
•Endocytic pathway
oUptake/recycling – works in inward direction
oMaterials move from outer cell surface to the cytoplasm
Intracellular protein transport
•Ability to transport a synthesized protein to a specific
destination within the cell
•Destinations include organelles and a sub-cellular regions
•Sense of polarity/directionality within cell essential
•Different organelles contain different integral proteins
•‘sorting signals’ encoded in amino acid codes are involved
•Both targeting (directed) and recruiting are involved
•Motor proteins and cytoskeletal elements are involved
•Vesicles (membrane-bound) w/contents flow and fuse
•How have the connections been made b/w sites of synthesis, the transport route, and
final target sites for a particular protein?
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The origin of eukaryotic cells endosymbiont theory. Lynn margulis is a major proponent of this theory. Endomembrane system is a series of sheets connected by tubes: membranous vesicles. Extensive network of membranous canals and stacks of sacs . The combined surface area of cytoplasmic membranes is many times greater than the area enclosed by the plasma membrane. Endomembrane organelles are part of a dynamic system in which material are shuttled back and forth from one part of the cell to another. The organelles of the endo-membrane system are functionally distinct from one another: contain a particular set of proteins, perform a unique set of activities, provides compartmentation and functional diversity, conserved in eukaryotes, dynamic structures. 2 main secretory (biosynthetic) pathways: constitutive materials transported in secretory vesicles and continuously discharged into extracellular space, modified materials are stored as membrane-bound pakcages that are discharged only in response to a specific stimulus.
