1. Chapter 3 Cells
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2. Chapter 3 The Cell: Module Hyperlinks
3.1 Cells are the fundamental units of life
3.2 Plant vs. animal cells
3.3 Membranes: structure
3.4 Membranes: function
3.5 The nucleus
3.6 Organelles in protein production
3.7 Chloroplasts and mitochondria
3.8 Other organelles
The Cell: The Fundamental Unit of Life
Cells are the fundamental unit of life.
Plant and animal cells have common and unique structures.
Membranes are made from two layers of lipids.
Membranes regulate the passage of materials.
The nucleus houses DNA packaged as chromosomes.
Several organelles participate in the production of proteins.
Chloroplasts and mitochondria provide energy to the cell.
Other organelles provide cell shape, movement, storage, and recycling.
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3. 3.1 Opening Questions: Are all living things made of cells?
What are at least five things you know about cells?
Active Learning: Opening questions can be done as a 1-minute THINK-PAIR-SHARE activity. The opening questions are designed as a set of engagement questions to get students thinking about cells and linking their prior knowledge.
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4. 3.1 All living organisms consist of cells.
Some living organisms have just one cell.
Some living organisms have trillions of cells.
Cells are the fundamental units of life
Figure 1.1-2b A Virus is Not Alive - 2 of 4
Figure 1.2-1e The Levels of Biological Organization - 5 of 11
Cells are the fundamental units of life.
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5. 3.1 Cells can be grouped into two categories.
Prokaryotic cells
Small, simple cells
No organelles
First appeared 3.5 BYA
Unicellular
Eukaryotic cells
Larger, complex cells
Membrane-enclosed organelles
First appeared 2.1 BYA
Unicellular or multicellular
Are you a prokaryote or a eukaryote?
Figure 3.1-1a Prokaryotic Cells - 1 of 2
Figure 3.1-2a Eukaryotic Cells - 1 of 2
Active Learning: The mini-question can be done as a short ASK-YOUR-NEIGHBOR activity.
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6. 3.1 Cells can be grouped into two categories
All cells on Earth can be classified into two general kinds:
Prokaryotic cells
Bacteria
Small, simple cells
Single celled
Eukaryotic cells
Plants, animals, fungi and protists
Larger, more complex cells
Single celled or multicellular
Are Homo sapiens (humans) a prokaryote or a eukaryote? .

7. 3.1 Cells can be grouped into two categories.
Prokaryotic cells
Bacteria and Archaea
Eukaryotic cells
Plants, Animals, Fungi, and Protists
Figure 3.1-1b Prokaryotic Cells - 2 of 2
Figure 3.1-2b Eukaryotic Cells - 2 of 2
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8. 3.1 All prokaryotes are relatively simple single-celled organisms.
There are two domains of prokaryotes: Bacteria and Archaea.
Prokaryotic fossils date back at least 3.5 billion years.
Figure 3.1-3a Prokaryotic Cells - 1 of 2
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9. 3.1 Bacteria have some unique features and some features common to all cells.
Figure 3.1-3b Prokaryotic Cells - 2 of 2
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10. 3.1 Bacteria have common and some unique features
Common features
Cell wall
Plasma membrane
Cytoplasm
Ribosomes
Nucleoid region with DNA
Unique features
Capsule
Flagellum
Plasmids
Pili

11. 3.2 Opening Questions: What are you really made of?
Did you know that scientists estimate that only maybe one in 10 of the cells in your body are actually human! The rest are largely prokaryote cells. These good bacteria help us digest food, synthesize vitamins, and protect against disease.
How is it possible to have more bacteria cells than human cells?
Does knowing the above change your view of bacteria?
Active Learning: Opening questions can be done as a 1-minute THINK-PAIR-SHARE or ASK-YOUR-NEIGHBOR activity. The opening questions are designed as a set of engagement questions to get students thinking about the size differences between prokaryotes and eukaryotes.
Background: Instructor may want to include a video that introduces the importance of the human microbiota.
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12. 3.2 Animals and Plants are made of eukaryotic cells that contain organelles.
Compared to prokaryotic cells, eukaryotic cells are relatively large (10-fold bigger) and more complex.
Eukaryotic cells contain organelles, which are membrane-enclosed structures that perform specific functions.
Figure 1.2-1i The Levels of Biological Organization - 9 of 11
Compared to prokaryotic cells, eukaryotic cells are relatively large (about 10-fold bigger) and more complex. Eukaryotic cells contain organelles (“little organs”), membrane-enclosed structures that perform specific functions. Eukaryotes evolved from prokaryotes around 2 billion years ago.
Prokaryotes do not contain organelles!
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13. 3.1 Eukaryotic cells are bigger and more complex
Animals, fungi, plants, and protists are all eukaryotes.
Eukaryotes evolved from prokaryotes around 2 billion years ago.
Compared to prokaryotic cells, eukaryotic cells are relatively large (about 10-fold bigger) and more complex. Eukaryotic cells contain organelles (“little organs”), membrane-enclosed structures that perform specific functions. Eukaryotes evolved from prokaryotes around 2 billion years ago.
Figure 3.1-2a Eukaryotic Cells–1 of 2

14. 3.2 Plant and animal cells have many organelles in common.
All eukaryotic cells are fundamentally alike.
All eukaryotic cells have:
Plasma membrane
Nucleus
Mitochondria
Ribosomes
Cytoplasm
Endoplasmic reticulum
Golgi
Figure 3.2-1a Structure of an Idealized Animal Cell - 1 of 2
Figure Structure of an Idealized Plant Cell
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15. 3.2 Structure of an idealized animal cell
Figure 3.2-1a Structure of an Idealized Animal Cell - 1 of 2
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16. 3.2 Structure of an idealized plant cell
Figure Structure of an Idealized Plant Cell
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17. 3.2 Animal and plant cells have some unique organelles.
Animal cells have lysosomes.
Plant cells have chloroplasts, cell walls, and central vacuoles.
Looking at cells under a microscope, you see cell walls and chloroplasts. What type of cells are these?
Figure 3.1-2a Eukaryotic Cells – 1 of 2
Active Learning: The mini-question can be done as a 1-minute THINK-PAIR-SHARE activity. These questions are designed to engage students in the process of cell division and start considering its importance for everyday life.
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18. 3.2 Some cells have unique organelles
Only animal cells have lysosomes.
Only plant cells have chloroplasts, cellulose cell walls, and central vacuoles.
Some animal cells, protists and prokaryotic cells have flagella and/or cilia
Plant cells do not
Bacteria have
Peptidoglycan cell wall, plasma membrane, cytoplasm, ribosomes, DNA
Some bacteria have capsule, flagellum, cilia, thylakoid membranes .

19. 3.3 Every cell is surrounded by a plasma membrane.
All cells are surrounded by a plasma membrane.
Membranes regulate the passage of materials.
Figure Structure of a Plasma Membrane
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20. 3.3 Membranes are made of lipids
Plasma membranes are made from two layers of phospholipids and integrated proteins.
Figure Phospholipids
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21. 3.3 Structure of a plasma membrane
Figure The Cytoplasm
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22. 3.4 Membranes regulate the passage of materials.
Cells are surrounded by a plasma membrane.
Organelles may have their own outer and internal membranes.
The most important function of any membrane is to regulate the flow of materials.
Figure 1.1-2b A Virus is Not Alive - 2 of 4
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23. 3.4 Membranes regulate what substances can enter and leave the cell.
Every membrane is selectively permeable.
Some substances flow freely.
Others pass under certain circumstances.
Some cannot pass. GO
YIELD
STOP
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24. 3.4 Transport across membranes can be passive or active.
Passive transport requires no energy.
Substances move along a concentration gradient from high to low.
Active transport requires energy.
Substances move against a concentration gradient from low to high.
Active transport is like trying to get into a crowded club!
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25. 3.4 Passive transport: Diffusion
Higher concentration
Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration.
Figure 3.4-1b Passive Transport - 2 of 6
Lower concentration
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26. 3.4 Passive transport: Osmosis
aquaporins
Lower concentration
The diffusion of water is called osmosis.
Water will always flow from an area of higher water concentration to an area of lower water concentration.
Aquaporins are proteins in the plasma membrane for osmosis
Figure 3.4-1c Passive Transport – 3 of 6
Higher concentration
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27. 3.4 Passive transport: Facilitated diffusion
Higher concentration
Large molecules can move through embedded transport proteins via facilitated diffusion.
Substances still move from an area of higher concentration to an area of lower concentration.
Figure 3.4-1d Passive Transport – 4 of 6
Lower concentration
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28. 3.4 Active transport requires energy to move substances.
Lower concentration
Active transport involves moving a substance from an area of lower concentration to an area of higher concentration.
Moving a substance against its concentration gradient always requires an expenditure of energy.
Higher concentration
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29. 3.4 Active transport is usually driven by a protein that sits within the membrane.
Figure 3.4-2a Active Transport - 1 of 2
Here, you can see a protein called the sodium-potassium (Na+/K+) pump moving three sodium ions into the cell.
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30. 3.4 Active transport is usually driven by a protein that sits within the membrane
the sodium-potassium (Na+/K+) pump moves three sodium ions out of the cell and two potassium ions into the cell. This membrane protein uses the energy from ATP hydrolysis

31. Exocytosis is the export from the cell.
3.4 Cells can also transport substances by fusing a portion of the cell membrane.
Exocytosis is the export from the cell.
Endocytosis is the import into the cell.
Figure 3.4-2b Active Transport - 2 of 2
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32. 3.5 Opening Questions: Where did you get your chromosomes from?
Human cells contain 46 chromosomes.
What are at least three things that you know about chromosomes?
Can you draw a chromosome?
What is it made of?
Active Learning: Opening questions can be done as a 1-minute THINK-PAIR-SHARE or ASK-YOUR-NEIGHBOR activity. The opening questions are designed as a set of engagement questions to get students thinking.
Background: The nucleus, surrounded by an envelope and containing DNA, directs the activities of the cell. Materials, such as RNA, can pass out of the nucleus via protein-lined pores.
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33. 3.5 Only eukaryotic cells contain organelles surrounded by membranes.
The most prominent membrane-enclosed organelle is the nucleus.
Every eukaryotic cell (including plant and animal cells) contains a nucleus.
Figure 3.5-1a The Nucleus - 1 of 3
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34. 3.5 The nucleus contains most of the cell’s DNA stored in chromosomes.
The nucleus, surrounded by an envelope and containing DNA, directs the activities of the cell.
Figure 3.5-1c The Nucleus - 3 of 3
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35. 3.5 The nucleus is surrounded by a double membrane called the nuclear envelope.
Protein-lined nuclear pores in the nuclear envelope allow certain molecules, such as RNA, to pass through.
Figure 3.5-1b The Nucleus - 2 of 3
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36. 3.5 The nucleus houses the chromosomes.
DNA molecules are wrapped around proteins to form fibers called chromatin.
Each very long chromatin fiber twists and folds to form a chromosome.
Figure 3.5-3c Chromosomes - 3 of 3
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37. 3.5 The nucleus contains a darker area called a nucleolus.
The nucleolus is a particular location within the nucleus.
This area produces ribosomal RNA (rRNA), an important component of a ribosome.
Figure Nucleolus
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38. 3.6 Opening Questions: Who’s in charge?
Think of the cell as analogous to a factory. However, instead of producing widgets, the cellular factory produces proteins.
What roles might the following organelles play in the cell factory?
Plasma membrane
Nucleus
Ribosomes
Mitochondria
Active Learning: Opening questions can be done as a 1-minute THINK-PAIR-SHARE or ASK-YOUR-NEIGHBOR activity. The opening questions are designed as a set of engagement questions to get students thinking.
Background: DNA directs a cell’s activities through the production of proteins. RNA made in the nucleus travels to the ER and the ribosomes, where it is translated into proteins, which are finalized in the Golgi.
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39. 3.6 DNA directs a cell’s activities through the production of proteins.
DNA in the nucleus contains the instructions for making proteins.
Proteins are very important molecules in our cells. They are involved in virtually all cell functions.
DNA
RNA
Protein
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40. 3.6 Several organelles are involved in protein manufacture.
Endoplasmic Reticulum (ER)
Ribosomes floating or attached to ER
Figure 3.2-1b Structure of an Idealized Animal Cell - 2 of 2
Golgi Apparatus
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41. 3.6 Protein production involves two steps:
Figure 3.6-1a-6 An Overview of Protein Production - 6 of 6 (Step 6)
Transcription in the nucleus results in the production of RNA from DNA.
Translation at the ribosomes results in the production of proteins.
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42. 3.6 After transcription, RNA travels from the nucleus to a ribosome.
Ribosomes are where proteins are made.
Some ribosomes are bound to the membrane of the rough ER.
Other ribosomes float freely in the cytoplasm.
Figure Ribosomes
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43. 3.6 The endoplasmic reticulum (ER) is filled with membranes.
The smooth ER contains enzymes that produce lipids (such as steroid hormones).
The rough ER contains ribosomes that produce many kinds of proteins.
Figure Endoplasmic Reticulum
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44. 3.6 Proteins are finalized and packaged in the Golgi apparatus.
The Golgi apparatus finishes, sorts, and ships cell products.
The Golgi apparatus finishes cell products in vesicles, small bubbles made of membrane.
Figure Golgi Apparatus
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45. 3.6 Lysosomes are a type of vesicle that contains digestive enzymes.
Lysosomes can dissolve large food molecules, old cellular components, or invasive organisms such as bacteria.
Figure Vesicles
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46. 3.7 Opening Questions: What if your organelles went missing?
What would happen if all the ribosomes in your cells disappeared?
What would happen if half of the mitochondria in your cells disappeared?
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47. 3.7 Two organelles help provide energy for the cell.
Chloroplasts are found in all plant cells and the cells of some algae.
Mitochondria are found in both plant and animal cells (mitochondrion is singular).
Figure 3.7-1a Chloroplasts and Chlorophyll - 1 of 2
Figure 3.7-2a Mitochondria - 1 of 2
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48. 3.7 Chloroplasts are the organelle of photosynthesis.
In photosynthesis, the energy of sunlight is used to create molecules of sugar.
Chloroplasts require a supply of water and carbon dioxide (CO2).
The sugars produced by photosynthesis provide the energy to power the cell.
Figure 3.8-3b Cell Walls - 2 of 4
Within a cell, chloroplasts are visible as green blobs.
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49. 3.7 The chloroplast
Figure 3.7-1b Chloroplasts and Chlorophyll - 2 of 2
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50. 3.7 Mitochondria are the organelle of cellular respiration.
Cellular respiration uses oxygen (O2) to harvest energy from molecules of sugar.
The harvested energy is stored as chemical energy in molecules of ATP, which can then be used to power many other cellular processes.
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51. 3.7 The mitochondrion Figure 3.7-2b Mitochondria - 2 of 2
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52. 3.8 Opening Questions: Plant cells vs. animal cells
List three structures in the plant cell that are not found in animal cells.
For each of these structures, explain why it is useful for plant cells, but not for animal cells.
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53. 3.8 Vacuoles function in the general maintenance of the cell.
Vacuoles are intracellular sacs.
Some are for storage, such as for food, nutrients, or pigments.
Some pump water out of a cell.
Many plant cells have a very large central vacuole.
Figure 3.8-1a Vacuoles - 1 of 4
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54. 3.8 Some cells have moving appendages.
Flagella propel the cell through their whip-like motion.
Cilia move in a coordinated back-and-forth motion.
Figure 3.8-2c Cilia and Flagella - 3 of 3
Figure 3.8-2a Cilia and Flagella - 1 of 3
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55. Plant, fungus, and some prokaryotic cells have a rigid cell wall.
3.8 Some cells are supported by a rigid cell wall surrounding the membrane.
Plant, fungus, and some prokaryotic cells have a rigid cell wall.
Plants can stand upright in part because their rigid cell walls are made of cellulose.
Figure 3.8-3a Cell Walls - 1 of 4
Note: Animal cells do not have a cell wall!
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56. 3.8 Animal cells maintain their shape with an internal cytoskeleton.
The cytoskeleton is a network of protein fibers that provides mechanical support, anchorage, and reinforcement.
The cytoskeleton network can be
quickly dismantled and reassembled,
providing flexibility.
Figure Cytoskeleton
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57. 3.8 Animal cells stick together.
Animal cells produce a sticky extracellular matrix that helps hold cells together.
Cells are held together into a
tissue by the extracellular matrix.
Figure Extracellular Matrix
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