1. Section 7-1
Are All Cells Alike?
All living things are made up of cells. Some organisms are composed of only one cell. Other organisms are made up of many cells.
1. What are the advantages of a one-celled organism?
2. What are the advantages of an organism that is made up of many cells?

2. A. The Discovery of the Cell 1. Microscopes 2. The Cell Theory
Section Outline
Section 7-1
7–1 Life Is Cellular
A. The Discovery of the Cell
1. Microscopes
2. The Cell Theory
B. Exploring the Cell
C. Prokaryotes and Eukaryotes
1. Prokaryotes
2. Eukaryotes

3. Robert Hooke – 1665 – named cell
Section 7-1
Discovery of the Cell
Robert Hooke – 1665 – named cell
Leeuwenhoek – 1674 – observed living microorganisms
Schleiden – 1838 – all plants made of cells
Schwann – 1839 – all animals made of cells
Virchow – all cells come from cells

4. Light microscopes - pass light through the specimen
Section 7-1
Exploring the Cell
Microscopy
- the history of cytology is tied to the development of the microscope.
Light microscopes - pass light through the specimen
- can magnify up to about 1200x
- easy to prepare specimens and can look at living specimens.

5. 2. Transmission Electron Microscope
Section 7-1
2. Transmission Electron Microscope
- send a beam of electrons through the specimen
- focused with magnets
- resolving power up to 100,000(+)x
- specimens have to be prepared and can’t be alive

6. 3. Scanning Electron Microscope
Section 7-1
3. Scanning Electron Microscope
- bounce electrons off the surface of the specimen
- gives detailed three-dimensional images of the surface of the specimen

7. Section 7-1
Cell Theory
Cells are the basic structural and functional units of life
Under the conditions present on Earth today all cells come from other cells.
All living things are composed of cells

8. Bacteria are prokaryotes.
Section 7-1
Prokaryotes-cells that have genetic material that is not contained in the nucleus. Generally smaller and more simple than eukaryotes.
Bacteria are prokaryotes.
Eukaryotes-contains a nucleus in which their genetic material is separated from the rest of the cell. Plants, animals, fungi, and protists are Eukaryotes.

9. Prokaryotic and Eukaryotic Cells
Section 7-1
Cell membrane
Cytoplasm
Prokaryotic Cell
Nucleus
Eukaryotic Cell
Organelles

10. Endoplasmic reticulum
Venn Diagram
Section 7-1
Prokaryotes
Eukaryotes
Cell membrane
Contain DNA
Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Mitochondria
Cytoskeleton

11. Section 7-2
Division of Labor
A cell is made up of many parts with different functions that work together. Similarly, the parts of a computer work together to carry out different functions.
Working with a partner, answer the following questions.
1. What are some of the different parts of a computer? What are the functions of these computer parts?
2. How do the functions of these computer parts correspond to the functions of certain cell parts?

12. 7–2 Eukaryotic Cell Structure
Section Outline
Section 7-2
7–2 Eukaryotic Cell Structure
A. Comparing the Cell to a Factory
B. Nucleus
C. Ribosomes
D. Endoplasmic Reticulum
E. Golgi Apparatus
F. Lysosomes
G. Vacuoles
H. Mitochondria and Chloroplasts
1. Mitochondria
2. Chloroplasts
3. Organelle DNA
I. Cytoskeleton

13. Nucleus “control center” of the cell
Section 7-2
Nucleus
“control center” of the cell
Contains the chromosomes on which the genes are located
Fine threads called chromatin in nondividing cells
Condense into visible chromosomes during cell division
Nuclear membrane has two parallel membranes with nuclear pores penetrating them
Nuclear pores allow mRNA to leave the nucleus to go to the cytoplasm
Also contains the nucleolus where ribosomal subunits are produced

14. - many are attached to Rough ER; others are free in the cytoplasm
Section 7-2
Ribosomes
- sites of protein synthesis – where amino acids are joined
- many are attached to Rough ER; others are free in the cytoplasm
- composed of RNA and protein
- attached ribosomes make proteins for export
- free ribosomes make proteins for intracellular use

15. Endoplasmic Reticulum
Section 7-2
Endoplasmic Reticulum
- membranous-walled canals and flat sacs that extend from the plasma membrane to the nucleus
- important in the synthesis, modification, and movement of materials within the cell
A. Rough Endoplasmic Reticulum
- has ribosomes attached to its’ surface
- ribosomes make proteins which move into the cisternae of the ER and are transported toward the Golgi apparatus

16. B. Smooth Endoplasmic Reticulum - lacks ribosomes
Section 7-2
B. Smooth Endoplasmic Reticulum
- lacks ribosomes
- transports, synthesizes, and chemically modifies small molecules
- synthesizes certain lipids and carbohydrates and creates membranes for use throughout the cell

17. - some of these vesicles remain in the cell as lysosomes
Section 7-2
Golgi Apparatus
- series of flattened membranous sacs that modify protein products of the rough endoplasmic reticulum
- final products are packaged in vesicles which can then be moved to the cell membrane for export
- some of these vesicles remain in the cell as lysosomes
- can also give rise to new membrane structures for the cell

18. - digestive system of the cell
Section 7-2
Lysosomes
- digestive system of the cell
- membranous sacs which pinch off the Golgi apparatus
- contain hydrolytic enzymes which digest particles or large molecules that enter them
- also responsible for digesting unneeded or unhealthy cells and cell parts

19. Section 7-2

20. - saclike structures used for storage within the cell
Section 7-2
Vacuoles
- saclike structures used for storage within the cell
- stores water, salts, proteins, and carbohydrates
- discerning feature in many plant cells that is
large and liquid filled
makes possible for plants to support heavy
structures such as leaves and flowers
- in many cases the vacuole is controls the water content of the cell which maintains homeostasis

21. - “power plants” of cells
Section 7-2
Mitochondria
- “power plants” of cells
- double membraned organelle with fluid between the membranes
- lots of enzymes attached to both membranes
- enzymes catalyze oxidation reactions of cellular respiration and capture the energy of sugars in the bonds of ATP
- provide 95% of the cell’s energy
- contain their own ribosomes and DNA and can replicate themselves

22. - double membraned organelle like mitochondria
Section 7-2
Chloroplasts
- capture the energy of the sunlight and convert it into the chemical energy of sugar in a process called photosynthesis
- double membraned organelle like mitochondria
- also contain their own DNA
- contain large stacks of membranes containing chlorophyll

23. Acts as both muscle and skeleton for cell Cell Fibers
Section 7-2
Cytoskeleton
Internal support framework made up of rigid, rodlike proteins that support the cell and allow movement and mechanisms that can move the cell or its parts
Acts as both muscle and skeleton for cell
Cell Fibers
- form a three-dimensional support framework
- support endoplasmic reticulum, mitochondria, and free ribosomes

24. 1. Microfilaments – smallest fibers
Section 7-2
1. Microfilaments – smallest fibers
- cellular muscles that provide for movement
2. Intermediate filaments – form much of the support network of the cell
3. Microtubules – maintain cell shape and move things within the cell made up of proteins known as tublin
4. Tubulin is also used to make structures in animal cells known as the centrioles. These aid in organization during cell division

25. Figure 7-11 Cytoskeleton Cell membrane Endoplasmic reticulum
Section 7-2
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Mitochondrion

26. Figure 7-5 Plant and Animal Cells
Section 7-2
Nuclear
envelope
Ribosome
(attached)
(free)
Smooth endoplasmic
reticulum
Nucleus
Rough endoplasmic reticulum
Nucleolus
Golgi apparatus
Mitochondrion
Cell wall
Cell
Membrane
Chloroplast
Vacuole
Plant Cell

27. Figure 7-5 Plant and Animal Cells
Section 7-2
Centrioles
Nucleolus
Nucleus
Nuclear
envelope
Rough
endoplasmic
reticulum
Golgi apparatus
Smooth
Mitochondrion
Cell
Membrane
Ribosome
(free)
(attached)
Animal Cell

28. Endoplasmic reticulum
Venn Diagram
Section 7-2
Animal Cells
Plant Cells
Centrioles
Cell membrane
Ribosomes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Mitochondria
Cytoskeleton
Cell Wall
Chloroplasts

29. Section 7-3
In or Out?
How is a window screen similar to a cell membrane? Read on to find out.
1. What are some things that can pass through a window screen?
2. What are some things that cannot pass through a window screen? Why is it important to keep these things from moving through the screen?
3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?

30. 7–3 Cell Boundaries Section Outline A. Cell Membrane B. Cell Walls
C. Diffusion Through Cell Boundaries
1. Measuring Concentration
2. Diffusion
D. Osmosis
1. How Osmosis Works
2. Osmotic Pressure
E. Facilitated Diffusion
F. Active Transport
1. Molecular Transport
2. Endocytosis and Exocytosis

31. Cell Membrane Plasma Membrane
Section 7-3
Cell Membrane
All of the membranes of the cell have similar structure.
Plasma Membrane
-Fluid Mosaic Model – developed by Singer and Nicolson
-Molecules are arranged in a sheet
-Molecules are held together by chemical attractions between them and their interactions with water.
-Primary structure is a double layer of phospholipid molecules
Phosphate heads are hydrophilic; tails are hydrophobic

32. Section 7-3
Cell Membrane-cont.
-Cholesterol molecules within the membrane help it function at body temperatures.
-Because the hydrophobic tails make-up most of the membrane, water soluble materials can’t pass through the membrane.
-Channel proteins which are embedded in the membrane help control movement of materials into and out of the cell
-Glycoproteins have carbohydrates attached and serve as cell surface identifiers
-Receptor proteins react to specific chemicals and cause changes within the cell.
-Overall, the plasma membrane is selectively permeable.

33. Figure 7-12 The Structure of the Cell Membrane
Section 7-3
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

34. -Most are composed of fibers of carbohydrate and protein
Section 7-3
Cell Walls
-Provide support and protection for the cell.
-Most are composed of fibers of carbohydrate and protein
-Plant cell walls are mostly cellulose

35. Passive and Active Transport
Section 7-3

36. Movement Through the Cell Boundaries
Section 7-3
Movement Through the Cell Boundaries
Passive Transport Processes
-Do not require energy expenditure by the cell
-Second Law of Thermodynamics
Diffusion
- movement of particles from an area of high concentration to an area of low concentration down a concentration gradient.
- continues until equilibrium is reached
- membrane channels are pores through which specific ions or small water-soluble molecules can pass
- gases also move by diffusion

37. Diffusion and Osmosis Video
Section 7-3

38. Passive Transport Processes cont. Osmosis
Section 7-3
Passive Transport Processes cont.
Osmosis
- diffusion of water through a selectively permeable membrane
- water moves down it’s concentration gradient – this often means it is moving toward higher salt concentrations
- Osmotic Pressure – water pressure that develops as a result of osmosis
- healthy cells are normally in an environment where the net movement of water is 0.

39. Passive Transport Processes cont. Osmosis cont.
Section 7-3
Passive Transport Processes cont.
Osmosis cont.
- Tonicity – ability of a solution to move water in/out of a cell and change its shape
a. Isotonic – osmotic pressure is = inside and outside
b. Hypertonic – osmotic pressure is greater than within the cell – water moves out of cell causing crenation
c. Hypotonic – osmotic pressure is less than within the cell – water moves into the cell causing lysis.

40. Figure 7-15 Osmosis
Section 7-3

41. Figure Osmosis
Section 7-3

42. Osmosis Video
Section 7-3

43. Facilitated Diffusion
Section 7-3
High
Concentration
Low
Cell
Membrane
Glucose
molecules
Protein
channel
Facilitated Diffusion
- movement through carrier proteins along the concentration gradient
- rate is dependent on concentration gradient and availability of carrier molecules

44. Active Transport -cell uses metabolic energy to move materials
Section 7-3
Active Transport
Molecule to
be carried
Molecule
being carried
Energy
-cell uses metabolic energy to move materials
1. Molecular Transport
- carrier-mediated process that moves substances against their concentration gradients
- opposite of diffusion
- substances are moved by pumps which use ATP to change shape and move their cargos
- carrier proteins bind to cargo, change shape, and release the cargo

45. Active Transport
Section 7-3
Video 4

46. Active Transport (cont.)
Section 7-3
Active Transport (cont.)
2. Endocytosis and Exocytosis
- allow things to enter and leave a cell without actually passing through the plasma membrane.
A. Endocytosis – plasma membrane traps some extracellular material and moves it to the interior in a vesicle.
- Phagocytosis – large particles are engulfed within a vesicle that then fuses with lysosomes to digest particles
- Pinocytosis – fluid and the substances dissolved in it enter the cell

47. Endocytosis and Exocytosis
Section 7-3

48. From Simple to More Complex
Section 7-4
From Simple to More Complex
Many multicellular organisms have structures called organs that have a specific function and work with other organs. Working together, these organs carry out the life processes of the entire organism.

49. 2. What do you think are some characteristics of a successful team?
Section 7-4
1. Some activities cannot be performed by only one person, but need a team of people. What type of activity requires a team of people to work together in order to complete a task?
2. What do you think are some characteristics of a successful team?
3. How is a multicellular organism similar to a successful team?

50. 7–4 The Diversity of Cellular Life
Section Outline
Section 7-4
7–4 The Diversity of Cellular Life
A. Unicellular Organisms
B. Multicellular Organisms
1. Specialized Animal Cells
2. Specialized Plant Cells
C. Levels of Organization
1. Tissues
2. Organs
3. Organ Systems

51. Unicellular Organisms
Section 7-4
Unicellular Organisms
Single-celled organisms that grow, respond to the environment, transform energy, and reproduce
Multicellular Organisms
Organisms that are made up of many cells that are developed for different tasks through a process called cell specialization

52. Levels of Organization 1. Cells 2. Tissues 3. Organs 4. Organ Systems
Section 7-4
Muscle cell
Smooth muscle tissue
Stomach
Digestive system
Levels of Organization
1. Cells
2. Tissues
3. Organs
4. Organ Systems

53. Interest Grabber Answers
1. What are the advantages of a one-celled organism?
A one-celled organism has simpler needs and can respond immediately to its environment because its entire cell is immersed in its environment.
2. What are the advantages of an organism that is made up of many cells?
In a multicellular organism, different jobs are divided among different groups of cells that work together. Also, a multicellular organism can continue to survive even if it loses some of its cells.
Section 1 Answers

54. Interest Grabber Answers
Working with a partner, answer the following questions.
1. What are some of the different parts of a computer? What are the functions of these computer parts?
Answers may include: monitor (interfaces with the computer’s environment), software (instructions for how to carry out different jobs), CPU (directs the computer's activities), recycle bin or trash can (storage area for wastes), and so on.
2. How do the functions of these computer parts correspond to the functions of certain cell parts?
Students should try to link the functions they described in question 1 to the functions of the different cell structures. The cell needs a way to interface with its environment (cell membrane), instructions for carrying out different jobs (DNA), and a CPU to direct the cell’s activities (nucleus).
Section 2 Answers

55. Interest Grabber Answers
1. What are some things that can pass through a window screen?
Answers may include air, fine dust, and rainwater.
2. What are some things that cannot pass through a window screen? Why is it important to keep these things from moving through the screen?
Insects, leaves, and other matter that may fall from trees. The screen keeps out annoying insects and objects that may bring dirt into the home.
3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?
Materials such as oxygen and food that are needed by the cell have to be able to get inside the cell. At the same time, excess materials have to leave the cell.
Section 3 Answers

56. Interest Grabber Answers
1. Some activities cannot be performed by only one person, but need a team of people. What type of activity requires a team of people to work together in order to complete a task?
Answers might include building a human pyramid or constructing an arch out of blocks.
2. What do you think are some characteristics of a successful team?
Divide up jobs and cooperate well with one another.
3. How is a multicellular organism similar to a successful team?
The functions of the organism are divided up among its parts (organs and organ systems). All the parts cooperate to carry out all the functions of the whole organism.
Section 4 Answers

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