1. Cell: Endomembrane System. Endoplasmic Reticulum,
Cell: Endomembrane System Endoplasmic Reticulum, Golgi Apparatus, Lysosomes, Peroxisomes, Vacuoles, Vesicles

2. Why organelles? Special structures with special functions
mitochondria
Why organelles?
Special structures with special functions
Containers with different local environments (pH, ionic conditions, etc)
Ex: lysosome & its digestive enzymes
Sites for chemical reactions
Ex: chloroplasts & mitochondria
chloroplast
Golgi
Why organelles?
There are several reasons why cells evolved organelles. First, organelles can perform specialized functions. Second, membrane bound organelles can act as containers, separating parts of the cell from other parts of the cell. Third, the membranes of organelles can act as sites for chemical reactions.
Organelles as specialized structures
An example of the first type of organelle is cilia, these short filaments act as "paddles" to help some cells move.
Organelles as Containers
Nothing ever invented by man is as complex as a living cell. At any one time hundreds of incompatible chemical reactions may be occurring in a cell. If the cell contained a uniform mixture of all the chemicals it would not be able to survive. Organelles surrounded by membranes act as individual compartments for these chemical reactions. An example of the second type of organelle is the lysosome. This structure contains digestive enzymes, these enzymes if allowed to float free in the cell would kill it.
Organelle membranes as sites for chemical reactions
An example of the third type of organelle is the chloroplast. The molecules that conduct the light reactions of photosynthesis are found embedded in the membranes of the chloroplast. ER

3. Endoplasmic Reticulum
Function
Many building functions (like membranes)
Structure
Extends from nuclear membrane throughout cell
rough ER = bound ribosomes
smooth ER = no ribosomes

4. Smooth ER function Metabolic processing factory
Synthesis (build) & hydrolysis (break)
enzymes …
build lipids, oils, phospholipids, steroids
In liver  breakdown of glycogen into glucose
In liver  detoxify drugs & poison

5. Rough ER function Build proteins for export out of cell
protein secreting cells
packaged into transport vesicles for export
Which cells have a lot of ER?
protein production cells like pancreas = production of digestive enzymes (rough endoplasmic reticulum from a cell of exocrine pancreas (88000X))

6. Golgi Apparatus Function Finishes, sorts, ships cell products
extensive in cells specialized for secretion
Cells specialized for secretion?
endocrine glands: produce hormones
pituitary, pancreas, adrenal, testes, ovaries
exocrine glands: produce digestive enzymes& other products
pancreas, mammary glands, sweat glands

7. Golgi Apparatus Structure
flattened membrane sacs = cisternae
2 sides = 2 functions
cis = receives material by fusing with vesicles = “receiving”
trans buds off vesicles that travel to other sites = “shipping” (transport)
cis
trans

8. Golgi processing
While moving from cis to trans, products from ER are modified into final form
tags, sorts, & packages materials into transport vesicles
Golgi = “UPS headquarters”
Transport vesicles = “UPS trucks”

9. Lysosomes  cell digestion and recycling
Structure
sacs of enzymes that hydrolyze/digest macromolecules
enzymes made by rough ER
only in
animal cells

10. Cell digestion Lysosomes fuse with food vacuoles
Polymers digested into monomers

11. Where old organelles go to die!
1960 |
Lysosomes
little “stomach”
lyso– = breaking things apart
–some = body
digests macromolecules
“clean up crew”
cleans up broken down organelles
Nobel Prize1974
Where old organelles go to die!
only in animal cells

12. Lysosome enzymes work best at pH 5 organelle creates custom pH how?
proteins in lysosomal membrane pump in H+ ions from the cytosol
adaptation:
digestive enzymes from lysosomes won’t work if they leak into cytosol = don’t want to digest yourself!
lysosomes create a space where cell can digest macromolecules safely
rupturing a few lysosomes has little impact on a cell (pH of cytosol affects functionality of the lysosomal enzymes), but massive leakage from lysosomes can destroy cell
why evolve digestive enzymes which function at pH so different from cytosol?
digestive enzymes won’t function well if leak into cytosol = most times don’t want to digest yourself!
low pH = acid environment cause oxidation (removing electrons) & promotes hydrolysis

13. But sometimes cells need to die…
Lysosomes can kill cells when they need to die  for proper development
apoptosis
“self-destruct”
lysosomes break open & kill cell
ex: tadpole tail gets re-absorbed when it turns into a frog
ex: loss of webbing between fingers during fetal development
Feedback mechanism
There are sensors in the cell that monitor growth. They trigger self-destruct when they sense processes.
Brown spots on leaves too.
Virus infected plant cell auto-destructs and even cells around it to wall off virus.

14. syndactyly
Fetal development
6 weeks
15 weeks

15. Peroxisomes Other digestive enzyme sacs in both animals & plants
breakdown fatty acids to sugars
Why? Sugars are easier energy source
detoxify cell  alcohol/poisons
produce peroxide (H2O2)
must breakdown H2O2  H2O + O (bubbles)

16. Vacuoles & Vesicles
Vesicles store, transport, or digest cellular products and waste.
Vacuoles contain water
Food vacuoles
phagocytosis, fuse with lysosomes
Contractile vacuoles
pump excess H2O out of cell in protists
Central vacuole in plants
Stockpile byproducts