Chapter 7.2 Notes

Biology

1. Cell Structure Section 2
Section 2: Inside the Eukaryotic Cell
Preview
•Bellringer
•Key Ideas
•The Framework of the Cell
•Directing Cellular Activity
•Protein Processing
•Storage and Maintenance
•Energy Production
•Summary

2. Cell Structure Section 2
Bellringer
Use a light microscope to view a slide of a eukaryotic cell.
Try to find the nucleus of the cell and give your reason why
you identified the structure as the nucleus.

3. Cell Structure Section 2
Key Ideas
•What does the cytoskeleton do?
•How does DNA direct activity in the cytoplasm?
•What organelles are involved in protein production?
•What are vesicles and vacuoles?
•How does the cell get energy?

4. Cell Structure Section 2
The Framework of the Cell
•The cytoskeleton helps the cell move, keep its shape, and
organize its parts.
–Like a human’s skeleton
•There are three different kinds of cytoskeleton fibers:
microfilaments, microtubules, and intermediate fibers.

5. Cell Structure Section 2
Directing Cellular Activity
•DNA contains instructions for making proteins which
control most of the activity of the cell.
•The DNA of eukaryotic cells is stored in the nucleus.

6. Cell Structure Section 2
Directing Cellular Activity, continued
Nucleus
•The nuclear envelope surrounds the nucleus.
•Nuclear pores located on the nuclear envelope act as
channels to allow certain molecules to move in and out of
the nucleus.
•The nucleolus is a structure within the nucleus where
ribosomes are made.

7. Cell Structure Section 2
The Nucleus
A
B
C
D
Click to animate the image.

8. Cell Structure Section 2
Directing Cellular Activity, continued
Ribosomes
•Each ribosome in a cell is made of RNA and many
different proteins.
•Free ribosomes make proteins that remain inside the cell.

9. Cell Structure Section 2
Protein Processing
•Proteins that are sent outside the cell are packaged in
vesicles. Vesicles are small, membrane-bound sacs that
enclose the proteins.
–Like sending mail (need to put mail in an envelope)
•The endoplasmic reticulum and Golgi apparatus are
organelles involved in preparing proteins for extracellular
export.

10. Cell Structure Section 2
Protein Processing, continued
Endoplasmic Reticulum
•The endoplasmic reticulum, or ER, is a system of internal
membranes that moves proteins and other substances
through the cell.
•The endoplasmic reticulum is divided into two portions:
rough ER and smooth ER.

11. Cell Structure Section 2
Endoplasmic Reticulum (ER)

12. Cell Structure Section 2
Protein Processing, continued
Endoplasmic Reticulum
•The portion of the ER with attached ribosomes is called
rough ER because it has a rough appearance
•The portion of the ER with no attached ribosomes is called
smooth ER because it has a smooth appearance

13. Cell Structure Section 2
Visual Concept: Endoplasmic Reticulum
(ER) and Ribosomes

14. Cell Structure Section 2
Protein Processing, continued
Golgi Apparatus
•The Golgi apparatus is a set of flattened, membrane-
bound sacs.
•The Golgi apparatus helps modify, sort, and package cell
products for distribution.

15. Cell Structure Section 2
Golgi apparatus

16. Cell Structure Section 2

17. Cell Structure Section 2
Storage and Maintenance
Lysosomes
•A lysosome is a vesicle produced by the Golgi apparatus
that contains enzymes that break down large molecules.
•Lysosomes recycle old or damaged organelles and digest
food particles to provide nutrients for the cell.
(the “stomach” of a cell)

18. Cell Structure Section 2
Visual Concept: Lysosomes

19. Cell Structure Section 2
Storage and Maintenance, continued
Vacuoles
•A vacuole is a fluid-filled vesicle found in the cytoplasm of
many plant cells.
•Plant cells contain a large compartment called the central
vacuole, which stores water, ions, nutrients, and wastes.
•When water fills the central vacuole, the cell becomes
rigid, allowing the plant to stand up. When the vacuole
loses water, the cell shrinks, and the plant wilts.

20. Cell Structure Section 2
Visual Concept: Vacuoles

21. Cell Structure Section 2
Energy Production, continued
Chloroplasts
•A chloroplast is an organelle found in plant and algae cells
that uses light energy to make carbohydrates from carbon
dioxide and water.

22. Cell Structure Section 2
Energy Production, continued
Mitochondria
•Mitochondria are cell organelles that use energy from
organic compounds to make ATP (Adenosine
Triphosphate – the main energy source for cells).

23. Cell Structure Section 2
Mitochondrion

24. Cell Structure Section 2
Summary
•The cytoskeleton helps the cell move, keep its shape, and
organize its parts
•In the cytoplasm, ribosomes use the RNA messages to
assemble proteins.
•The endoplasmic reticulum and Golgi apparatus are
organelles involved in preparing proteins for extracellular
export.

25. Cell Structure Section 2
Summary, continued
•Vesicles help maintain homeostasis by storing and
releasing a variety of substances as the cell needs them.
•The energy for cellular functions is produced by chemical
reactions that occur in the mitochondria and chloroplasts.