2. Video clip

3. ENDOMEMBRANE SYSTEM
Definition of ENDOMEMBRANE SYSYTEM:

8. Vesicle fuses with the Golgi and protein is modified as it passes through.
Protein is packaged into transport vesicles and travels to the Golgi along the cytoskeleton “track”
Using RNA code, a protein is synthesized on a ribosome and transported in channels of the ER.

9. Completed protein is packaged into secretory vesicles for release from the cell or stored in vesicle or lysosome if used inside the cell.
Vesicle fuses with the Golgi and protein is modified as it passes through.
Protein is packaged into transport vesicles and travels to the Golgi along the cytoskeleton “track”
Using RNA code, a protein is synthesized on a ribosome and transported in channels of the ER.

10. Vesicle transport

11. Endomembrane System Phospholipid bilayer Like a bubble MOSAIC
Membranes within the eukaryotic cell that work together to modify, process and ship molecules around and out of the cell.
Semipermeable
FLUID

12. Endomembrane System All made of phospholipid bilayer Includes:
Nuclear envelope
Rough ER
Smooth ER
Transport vesicles
Golgi apparatus
Lysosomes
Secretory vesicles

13. The Endomembrane System
proteins
transport
vesicle
Golgi
apparatus
smooth ER
rough ER
nuclear pore
nucleus
ribosome
cell
membrane
protein secreted
cytoplasm

14. production of mRNA from DNA in nucleus mRNA out of nucleus
nuclear
membrane
mRNA
nuclear pore
production of mRNA from DNA in nucleus
mRNA out of nucleus
through nuclear pore

16. Endoplasmic Reticulum
Function
processes proteins
manufactures membrane
Structure
membrane connected to nuclear envelope & extends throughout cell
accounts for 50% membranes in eukaryotic cell

17. Types of ER
rough
smooth

19. INSULIN being released by pancreas cells using exocytosis

20. Origin of Eukaryotic Cells

21. Prokaryotes dominated earth for about 1by
Earth is 4.6 byo
Life originated 3.5–4.0 bya
Prokaryotes dominated earth for about 1by 21

22. Cyanobacteria
Cyanobacterium heterocyst
A type of prokaryote with much infolding of the cell membrane
Capable of performing photosynthesis, which releases oxygen into the atmosphere 22

23. Oxygen atmosphere Oxygen begins to accumulate 2.7 bya
evidence in banded iron in rocks (rusting)
makes aerobic respiration possible 23

24. Eukaryotes nearly all are aerobic,
they depend on free oxygen to carry out their metabolic processes
Accordingly, they could not have evolved before at least some free oxygen was present in the atmosphere

25. Two processes are thought to have led to the origin of eukaryotes….
Infoldings of the prokaryotic cell membrane
Endosymbiosis

26. Development of internal membranes
create internal micro-environments (“compartments”)
advantage = increase efficiency
~2 bya
nuclear envelope
*note double membrane
endoplasmic reticulum (ER)
plasma
membrane
infolding of the plasma membrane
nucleus
DNA
cell wall
plasma
membrane
Prokaryotic
cell
Prokaryotic ancestor of eukaryotic cells
Eukaryotic
cell

27. Membrane infolding
Endosymbiotic theory

28. Given what you know about in folding and the cell membrane as a phospholipid bilayer:
Why is the nuclear membrane a DOUBLE membrane (two layers of bilayer)

31. Bozeman Originally proposed in early 1900’s
Endosymbiotic Theory
Bozeman
Originally proposed in early 1900’s
Idea reintroduced in 1963 by Lynn Margulis
Suggests that engulfed prokaryotes shared symbiotic relationship with host cell
Advantages for both: ~ one supplies energy ~ other raw materials & protection

32. Endosymbiosis
In this relationship one cell lived within the other, which is a special type of symbiosis called endosymbiosis
in some cases of a symbiotic relationship, one symbiont cannot live independently of the other
This may have been the case early symbiotic prokaryotes that became increasingly interdependent until the unit could exist only as a whole

33. Endosymbiosis FIRST early eukaryotic cells engulfed aerobic bacteria
but did not digest them
Led to the origin of mitochondria
Mutually beneficial relationship
internal membrane system
aerobic bacterium
mitochondrion
Endosymbiosis
Ancestral
eukaryotic cell
Eukaryotic cell
with mitochondrion

34. Endosymbiosis photosynthetic bacteria but did not digest them
Eukaryotic
cell with
mitochondrion
THEN eEarly eukaryotic cells engulfed
photosynthetic bacteria
but did not digest them
Led to origin of chloroplasts
mutually beneficial relationship
chloroplast
mitochondrion
Endosymbiosis
Eukaryotic cell with
chloroplast & mitochondrion

35. A model of the origin of eukaryotes

36. Resemble bacterial structure
Structural Evidence
Both mitochondria & chloroplasts
Resemble bacterial structure
Are found in membranous envelopes (like a cell membrane)
are the same approximate size as prokaryotes
have 70s ribosomes

37. have circular naked DNA
Genetic Evidence
Both mitochondria & chloroplasts
have circular naked DNA
DNA shares common sequences with modern prokaryotes

38. move freely within the cell
Functional Evidence
Both mitochondria & chloroplasts
move freely within the cell
reproduce independently from the cell through binary fission
are inhibited by antibiotics

39. Where Did Organelles Come From ?
Membranous infoldings
Nucleus ER
Golgi
Lysosomes
Vesicles
Endosymbiosis
Mitochondria
Chloroplasts

40. Theory of Endosymbiosis
Lynn Margulis
How is the word “theory” in science different than the use of the word theory in every day language?