1. The Endoplasmic System
Chapter 4.5
The Endoplasmic System
AP Biology
Fall 2010

2. Endoplasmic Reticulum
Endoplasmic Retculum (ER): collection of interconnected tubes and flattened sacs that begin at the nucleus and ramble throughout the cytoplasm
Flattened channel, starts at nuclear envelope and folds back on itself repeatedly in cytoplasm

3. Endoplasmic Reticulum

4. Endoplasmic Reticulum
Inside the channel polypeptide chains become modified into final proteins and lipids are assembled
Two types distinguished by presence or absence of ribosomes:
Smooth ER
Rough ER

5. Endoplasmic Reticulum
Rough ER
Consists of stacked, flattened sacs with many ribosomes attached
Oligosaccharide groups are attached to polypeptides as they pass through on their way to other organelles or to secretary vesicles
Cells that make, store and secrete proteins have a lot of rough ER
Ex. Pancreas

6. Rough Endoplasmic Reticulum

7. Endoplasmic Reticulum
Smooth ER
Has no ribosomes
Is the area from which vesicles carrying proteins and lipids are budded
Inactivates harmful chemicals and breaks down fatty acids
Makes lipid molecules that become part of cell membrane

8. Smooth Endoplasmic Reticulum

9. Golgi Bodies
Golgi Bodies: proteins and lipids undergo final processing, sorting, and packaging
Attach sugar side chains to proteins and lipids they received from the ER
Finished products are packaged in vesicles

10. Golgi Bodies
Membranes of Golgi are arranged in flattened sacs whose edges break away as vesicles

11. Vesicles
Vesicles: commonly used by the cell as transporters to and from plasma membrane
Tiny sacs that form as buds from ER, Golgi bodies, and plasma membrane
Some transport substances to or from other organelles
Fuse and form larger membranous sac, or vacuoles

13. Lysosomes Lysosomes: vesicles that bud from Golgi
Carry powerful enzymes that can digest contents of other vesicles, worn out cell part, or bacteria and foreign particles
Enzymes activated when another vesicle moves through the cytoplasm and fuses with the lysosomes
Contents are digested into bits

14. Lysosomes

15. Peroxisomes
Peroxisomes: hold enzymes that digest fatty acids, amino acids, and hydrogen peroxide (a toxic metabolic product)
Convert H2O2 to water and oxygen or use it in reactions that degrade alcohol and other toxins

16. Review What are the main differences between the rough and smooth ER?
What is the function of the golgi body?
Distinguish between a lysosome, peroxisome, and vesicle.

17. Answers
Rough ER has ribosomes and smooth ER does not. Rough ER is where oligosaccharide groups are attached to polypeptides. Smooth ER is the area from which vesicles carrying proteins and lipids are budded, inactivates harmful chemicals and breaks down fatty acids.
The golgi bodies are where proteins and lipids undergo final processing, sorting, and packaging, they attach sugar side chains to proteins and lipids they received from the ER.
Vesicles are commonly used by the cell as transporters to and from plasma membrane. Lysosomes are vesicles that bud from Golgi, contain digestive enzymes. Peroxisomes hold enzymes that digest fatty acids, amino acids, and hydrogen peroxide (a toxic metabolic product) .