1. Cell Organelles Chapter 7, page 174
Use this presentation in conjunction with the Cell Organelle note-taking worksheet. Run through the entire presentation before using it in class so that you know what’s coming next! It helps to print the outline and notes to have with you while presenting so that there are no surprises. –JessB.org
Modified from an original PPT of Beauchemin 2006

2. Introduction to Cells

3. Inside a Cell

4. What is a cell?
A cell is a collection of living matter enclosed by a barrier that separates the cell from its surroundings. The cell is the basic unit of all forms of life.

5. (An organism is a living thing.)
Remember the three parts to cell theory:
All living organisms are composed of one or more cells.
The cell is the basic unit of structure, function in all organisms.
All cells come from preexisting, living cells.
(An organism is a living thing.)

6. There are two main categories of cells:
Prokaryote (prokaryotic cells)
Bacteria
Have no membrane-bound nucleus
Nucleic acid is usually found in “loops” in the cytoplasm
Usually smaller than eukaryotes
Have fewer organelles than eukaryotes

7. Eukaryotes (eukaryotic cells)
Larger
Have a membrane-bound nucleus where DNA is located
More organelles
All organisms except bacteria are eukaryotes

8. Homework Read pages 174 to 181 Answer questions 1 to 4 on page 181
Be able to label both a plant and an animal cell
(use your handouts for practice)

9. Cell Organelles in Eukaryotes
Organelle means
“little organ”
Cytoplasm is everything inside the cell membrane, except the nucleus
You may or may not wish to distinguish between cytosol and cytoplasm. The correct use of each term is shown here. Most high school textbooks, however, use the word “cytoplasm” to mean “cytosol.”

10. Cytosol or the intracellular fluid is the liquid found inside cells.

11. Cell Membrane The boundary of the cell Emphasize word parts here:
phospho= phosphate head; lipid= fatty acid tail
bi= 2

12. Cell Membrane Surrounds the cytoplasm and holds the shape of the cell
Protects the cell
Allows certain material to pass through
(selectively permeable)

14. Phospholipid Bilayer

15. For more information on the cell membrane, please refer to your handout.

16. Cell Wall
A tough, flexible but sometimes fairly rigid layer that surrounds some types of cells.
Located outside the cell membrane

17. Provides structural support and protection, sometimes preventing the cell from bursting from water entering the cell.
Found in plants, some bacteria, fungi, and algae.

18. Nucleus Control center of the cell
Contains DNA which contains the coded instructions for making proteins which are the molecules that do “everything”.
Cells with more than one nucleus include muscle cells and liver cells, largely because of the massive volume of cytoplasm and number of organelles that need controlling.

19. Nucleus continued
Surrounded by a double membrane called the nuclear membrane or nuclear envelope.
Nuclear envelope has thousands of pores which allow material to move into and out of the nucleus.

20. (red blood cells do not have nuclei.)
Usually one per cell
(red blood cells do not have nuclei.)
Usually the easiest organelle to see under a microscope

21. Chromatin in the Nucleus
The thread-like material in the nucleus is called chromatin which is DNA wrapped around protein.
Usually looks like this but as a cell prepares to divide, chromatin condenses to form chromosomes.

22. Chromosomes

23. Nucleolus Small dense region within the nucleus
The assembly of ribosomes begins here

24. Ribosome
Proteins are assembled by ribosomes, following instructions from DNA.
Ribosomes are found attached to rough endoplasmic reticulum or floating free in cytoplasm
Produced in a part of the nucleus called the nucleolus
A polypeptide is a chain of amino acids. In this diagram, you can see the ribosome is making a polypeptide, also known as a protein.

25. Endoplasmic Reticulum (ER)
The internal membrane system of the cell
Connected to the nuclear membrane
Assembles lipid components of the cell membrane, proteins and other materials for export from the cell.
It’s not necessary that the students can read the labels here; just point out the black dots are ribosomes.

26. Rough Endoplasmic Reticulum
Studded with ribosomes
Proteins that are being synthesized for export from the cell and proteins that are to be used in the cell membrane are made on the these ribosomes.

27. Proteins synthesized on the ribosomes on the RER enter the RER where they may be chemically modified.

28. Smooth Endoplasmic Reticulum
No ribosomes
Synthesizes lipids
Contains many enzymes which have specialized jobs
Makes membrane lipids; carries proteins; detoxifies drugs

29. Golgi Apparatus Looks like a stack of plates
Modifies, sorts, and packages proteins and other materials made in the ER for storage in the cell or secretion from the cell.
AKA Golgi Complex. It is not necessary that the students read the labels, this diagram gives them a general idea of the Golgi’s shape.

30. Golgi Apparatus (continued)
Vesicles which contain the materials modified by the Golgi Apparatus pinch off the ends.

31. Which organelles do lysosomes work with?
Clean-up crew (sometimes called cannibals)
Membrane-bound sacks filled with enzymes that break down lipids, carbohydrates and proteins from food into smaller molecules that the cell can use.
Students should recognize the shapes of the Golgi and ER even if they cannot read the captions.
Which organelles do lysosomes work with?

32. Lysosomes (continued)
Also break down organelles that have outlived their usefulness for disposal.

33. What type of microscope may have been used to take this picture?
Vacuoles
Storage container for water, food, enzymes, wastes, pigments, etc.
Large central vacuole in plant cells
Many small vacuoles in animal cells
The image is 2D, so it must have been a light microscope or TEM. If the cell is very tiny, then a TEM was used. Otherwise, a strong light microscope could have captured this image.
What type of microscope may have been used to take this picture?

34. Contractile Vacuole

35. Mitochondria (singular = mitochondrion)
“Powerhouse of the cell”
Convert the chemical energy from food into energy that can be used by the cell.
Enclosed by two membranes---an outer one and another that is folded up inside the mitochondrion
Explain that this diagram shows the mitochondria cut open to reveal the internal membranes.

36. Mitochondria (continued)
Cellular respiration occurs here to release energy for the cell to use
Has its own strand of DNA
Our mitochondria are inherited from our mothers via the eggs cell.

37. Chloroplast Found in plant cells
Contains the green pigment chlorophyll which captures the sun’s energy and converts it into chemical energy (glucose) in a process called photosynthesis.
Chloroplasts absorb light, which is the catalyst for photosynthesis.

38. Cytoskeleton
A network of protein filaments/tubes that helps the cell maintain its shape and which helps move materials around the cell.
Actin, also found in muscle cells, mainly help maintain cell shape in their cytoskeletal role. Microtubules mostly move organelles around the cell. Intermediate filaments also provide structural support.

39. Cytoskeleton (cont’d)
Acts as skeleton and muscle
Provides shape and structure

40. Microfilaments (1 type of cytskeleton)
Thread-like structures
Made of a protein called actin
Make a tough, flexible framework that supports the cell
May also help the cell move by assembling and disassembling

41. Microtubules (another type ofmicroskeleton)
Hollow structures made of proteins known as tubulins
Perform different functions in different cells:
Critical to maintaining shape of some cells
Form spindles in mitosis

42. Form centrioles (animal cells only)
Build projections from cell’s surface such as flagella and cilia that enable some cells to “swim”
Some cells have them arranged so that they can be used to produce controlled movements of the cell.

43. Centrioles Aid in cell division Found in pairs in animal cells
Made of microtubules
Microtubules are also part of the cytoskeleton.

44. Cell Wall Found in plant and bacterial cells Rigid, protective barrier
Located outside of the cell membran
Made of cellulose (sugar/fiber)
This is an actual microscopic image. Explain that the colors are added digitally to enhance the different parts.

45. Quick Review Which organelle is the control center of the cell?
Nucleus
Which organelle holds the cell together?
Cell membrane
Which organelles are not found in animal cells?
Cell wall, central vacuole, chloroplasts
Which organelle helps plant cells make food?
Chloroplasts
What does E.R. stand for?
Endoplasmic reticulum
You may choose to delete the answers from the PowerPoint or change the animation so that they come in after all 5 questions are asked in case you want to quiz students individually at the end.