1. Membrane-Bound Organelles
Section 4.5

2. Learning Objectives
Distinguish between smooth and rough endoplasmic reticulum in terms of structure and function
Trace the path of protein synthesis in rough ER from creation to delivery to final destination
Compare the functions of lysosomes, vacuoles, and peroxisomes
Contrast the functions of mitochondria & chloroplasts & compare their structure

3. Endomembrane System
A series of interacting organelles that exchange materials through small membrane-enclosed containers
Involved in making & modifying lipids & proteins for the cell
Made up of all organelles found in the cytoplasm except mitochondria and chloroplasts

4. Interactions among organelles keep the cell alive

5. Endoplasmic Reticulum (ER)
ER = a complex network of membranes expanding from the nuclear envelope that has various functions and structures
2 main types: Rough ER and Smooth ER
One function in both types is storage of calcium ions for cell signaling

6. Rough Endoplasmic Reticulum
Also called Rough ER
An extension of the nuclear envelope
Has ribosomes attached to it
Makes it look bumpy or rough
Function is making proteins

7. Smooth Endoplasmic Reticulum
Also called Smooth ER
An extension of the nuclear envelope
Has no ribosomes on it
Functions:
Makes lipids
Makes hormones
Breaks down drugs and toxins
Can cause cells to make more smooth ER so they can break it down faster

8. Golgi Complex Also called Golgi apparatus or Golgi body
Makes changes to proteins and lipids received from other parts of the cell
Finished lipids & proteins are then sorted & packaged for delivery by vesicles to other parts of the cell
Makes lysosomes

9. Vesicles Vesicle = Membrane bound sac or container
Transport materials around the cell
Move along cytoskeleton tracks or “roads”

10. Lysosomes Lysosomes are made in the Golgi apparatus
Contain enzymes that break down organic molecules
Also breaks down worn out or damaged cell parts
Only found in animal cells

11. If lysosomes are missing an enzyme then materials can build up in the cells
Eventually causes the cell to die
Cause of some diseases (ex. Tay-Sachs Disease)

12. Vacuoles Vacuoles are larger than vesicles
Can form when vesicles fuse together
Function in the storage of materials
Store water, waste, sugars, toxins, etc.
Some protists have contractile vacuoles
Helps remove extra water from the cell

13. Plants have a very large Central Vacuole
Filled with stored food, salts, pigments, wastes, and lots of water
Pushes on the cell wall to give the cell strength

14. Peroxisomes Peroxisomes are created in the Smooth ER
Breaks down fatty acids & toxins
Contains the enzyme catalase
Changes hydrogen peroxide (which is toxic to cells) into water and oxygen
Found in both plant & animal cells

15. Cells Store Energy as ATP
Energy enters cells as chemical energy stored in food molecules or as light energy
Must be converted into a form of energy the cell easily use and store (such as ATP)
Organelles involved in energy conversion
Mitochondria
Chloroplasts

16. Mitochondria Mitochondria are organelles with: Function is making ATP
Double-membrane
Inner membrane has many folds called cristae
Its own DNA & ribosomes
Function is making ATP
Break down glucose
Also involved in apoptosis
Programmed cell death

17. Plastids Plastids have a double membrane
Function in producing and storing food materials
Found in plant & algal cells
3 common types:
Amyloplasts
Chromoplasts
Chloroplasts

18. Plastids Amyloplasts – store starch
Have no pigment (color)
Chromoplasts – make and store pigments that are not chlorophyll
Attracts animals to act as pollinators or seed dispersers

19. Chloroplast Chloroplast = plastid specialized for photosynthesis
Has a double membrane (outer membranes)
Have their own DNA & ribosomes
Third highly folded inner membrane called the thylakoid membrane
Fluid filled space surrounding thylakoid membrane is the stroma
Function is to capture light energy to make sugars from water and CO2

20. Parts of a Chloroplast

21. Theory of Endosymbiosis
Why do mitochondria & chloroplasts have their own DNA & ribosomes?
They are very similar to certain species of bacteria
Scientists think their ancestors were free-living bacteria that were ingested by eukaryotic cells
The bacteria were then allowed to live within the cell & produce sugar or ATP for it