1. Cells: The Basic Units of Life
Chapter 2
Cells: The Basic Units of Life

2. Section 1: Objectives State the parts of the Cell Theory.
Explain why cells are so small.
Describe the parts of a cell.
Describe how Eubacteria are different from Archaebacteria.
Explain the difference between prokaryotic cells and eukaryotic cells.

3. The Diversity of Cells All living things are made up of cells.
Cell: smallest unit that can perform all life processes
Because of their size, cells weren’t discovered until the mid-1600s.

4. The Diversity of Cells
Robert Hooke was the first person to discover cells.
He examined cork (from the bark of trees).
The cork looked like it was made of little boxes (cells).

5. The Diversity of Cells
In 1863, Anton van Leeuwenhoek made his own microscopes.
He examined organisms in pond water.
“Animalcules” = little animals

6. The Diversity of Cells Today we call these protists.
He also examined animal blood.
Leeuwenhook was the first person to examine bacteria.

7. The Diversity of Cells
Almost 200 years passed before scientists concluded that cells are present in living things.
As years passed many more scientists contributed to the examination of cells.
2 of these scientists were Schleiden and Schwann.
Schleiden studied plants and Schwann studied animals.
They concluded that plants and animals were made of cells.

8. The Diversity of Cells The Cell Theory:
Schwann wrote the first 2 parts:
All organisms are made up of one or more cells
The cell is the basic unit of all living things
Virchow wrote the third part:
All cells come from existing cells

9. The Diversity of Cells All cells are surrounded by a cell membrane.
Cell membrane: protective layer that covers the cell’s surface and acts as a barrier (separates cell from environment)
The cytoplasm is the fluid inside the cell and all of its contents.

10. The Diversity of Cells
Organelles are structures that perform specific functions within the cell
Different types of cells have different organelles.
Most organelles are surrounded by membranes.

11. The Diversity of Cells All cells contain DNA.
DNA is the genetic material that carries information needed to make new cells and new organisms.

12. The Diversity of Cells
In most cells, the DNA is located in the nucleus.
Bacterial cells do not have a nucleus.
Does this mean bacterial cells do not have DNA?

13. The Diversity of Cells There are 2 kinds of cells:
Prokaryotic: single cell with no nucleus
Eukaryotic: more than one cell with a nucleus

14. The Diversity of Cells
Prokaryotes: Single-celled organisms with no nucleus or membrane-bound organelles
Example: Bacteria
Prokaryotes include:
Eubacteria
Archaebacteria

15. The Diversity of Cells Eubacteria: Most common prokaryotes (bacteria)
Bacteria are the world’s smallest cells.
Do not have a nucleus, but do have DNA (long, circular molecule)
Have no membrane-bound organelles.
Do have ribosomes (round organelles made of protein)

16. The Diversity of Cells Eubacteria:
Bacteria have a strong, web-like exterior cell wall.
Has a cell wall and a cell membrane.
Bacteria live in:
Soil
Water
In/on organisms

17. The Diversity of Cells Archaebacteria: “Ancient bacteria”
Not as common as Eubacteria but similar.
Has DNA, cell wall, cell membrane, and ribosomes.
Its ribosomes are different than the ribosomes of Eubacteria.

18. The Diversity of Cells Archaebacteria: There are 3 types:
Thermophiles: heat-loving
Halophiles: salt-loving
Methanogens: Methane-makers
Extremophiles: live in places where conditions are extreme

19. The Diversity of Cells Eukaryotes:
The largest cells (10 X larger than bacterial cells)
Have a nucleus and membrane-bound organelles.
Nucleus contains DNA.
Multicellular (more than 1 cell)
Examples: Humans, animals, plants

20. Chapter 2 Sec. 1 Recap
1) List any 2 scientists that we discussed this section and describe their contribution to the discovery of cells.
2) List the 3 parts to the Cell Theory.
3) What is the cytoplasm?
4) List 3 places bacteria can live.
5) List and describe 3 types of Archaebacteria.

21. Chapter 2 Sec. 1 Recap
6) Describe some key differences between Eubacteria and Archaebacteria.
7) What are most cells surrounded by?
8) Explain the difference between eukaryotes and prokaryotes.
9) T/F Not all cells contain DNA.
10) List 2 examples of prokaryotes.

22. Section 2: Eukaryotic Cell Organelles
Objectives:
Identify the different parts of a eukaryotic cell
Explain the function of each part of a eukaryotic cell

23. Eukaryotic Cell Organelles
1. Cell wall: rigid structure that gives support to a cell
Plants and algae have a cell wall made of cellulose: complex sugar
Fungi also have cell walls made of chitin: chemical in fungi

24. Eukaryotic Cell Organelles
2. Cell Membrane
All cells have a cell membrane.
Protective barrier that encloses the cell
Outermost structure for cells with no cell wall.
Contains lipids (fats), proteins, and phospholipids.
What is the unique quality of lipids?

25. Eukaryotic Cell Organelles
3. Cytoskeleton:
Web of proteins in the cytoplasm.
Acts as a muscle and a skeleton.
Keeps cell membrane from collapsing.
Also helps cells move.
“Backbone of the cell”

26. Eukaryotic Cell Organelles
4. Nucleus:
Large organelle that contains DNA.
DNA contains information for how to make proteins.
Proteins control the chemical reactions in a cell and provide structural support.

27. Eukaryotic Cell Organelles
5. Nucleolus: dark area inside the nucleus where ribosomes are made
The nucleus also has a double membrane.

28. Eukaryotic Cell Organelles
5. Ribosomes:
Organelles that make proteins
Smallest of the organelles.
Most abundant organelle.
Not covered by a membrane.

29. Eukaryotic Cell Organelles
6. Endoplasmic Reticulum (ER):
Site of many chemical reactions.
System of folded membranes.
Produces proteins and lipids.
Part of the internal delivery system of the cell.
Substances move through the ER to different parts of a cell.

30. Chapter 3 Sec. 1-2 Review Questions
1) What is an extremophile?
2) Where is DNA located in most cell?
3) What is a prokaryote?
4) What is a eukaryote?
5) ____ ____ is a protective membrane that encloses a cell.
6) What do ribosomes produce?

31. Eukaryotic Cell Organelles
7.Endoplasmic Reticulum:
There are 2 types:
A) Smooth ER: ER that lacks ribosomes
Makes lipids
Breaks down materials that could harm the cell
B) Rough ER: contains ribosomes
Found near the nucleus
Makes proteins

32. Eukaryotic Cell Organelles
8. Mitochondria:
Main power source of the cell.
Have their own DNA.
Breaks sugar down to produce energy.
Energy released by mitochondria is turned into ATP.
Most of a cell’s ATP is produced in the mitochondria.

33. Eukaryotic Cell Organelles
9. Chloroplasts:
Organelles in plants/algae where photosynthesis takes place.
They are green because they contains chlorophyll, a green pigment.
This absorbs sunlight and uses it to make sugar.
What is the sugar used for in the cell?

34. Eukaryotic Cell Organelles
10. Golgi Complex:
Packages and distributes proteins.
Looks like smooth ER.
Lipids and proteins from the ER are sent to the Golgi Complex.
After being modified, they are enclosed in a membrane which pinches off to form a small bubble and then transported to other parts of the cell or out of the cell.

35. Eukaryotic Cell Organelles
11. Cell Compartments:
The bubble that forms the Golgi complex’s membrane is a vesicle (small sac that surrounds material to be moved into or out of the cell)
Vesicles also move materials around the cell.

36. Eukaryotic Cell Organelles
12. Lysosomes
Responsible for cellular digestion.
Have the following functions:
Destroy damaged organelles
Gets rid of waste materials
Protects cell from foreign invaders

37. Eukaryotic Cell Organelles
13. Vacuoles:
Large vesicle
In plant and fungal cells, some act like large lysosomes.
Some store digestive enzymes while others store water.
What happens to a plant when its vacuoles lose water?

38. Chapter 2 Sec. 2 Pop Quiz
What is the difference between a prokaryote and a eukaryote?
What does the mitochondria do for the cell?
What cells are chloroplasts located in and what takes place there?
The Golgi complex ____ and _____ proteins.
List 2 of the 3 functions of lysosomes.

39. Cell Organelle Review 1) Cell membrane 2) Nucleus 3) Chloroplast
4) Ribosomes
5) Endoplasmic Reticulum
6) Golgi complex
7) Mitochondria

40. Section 3: Objectives
List the three advantages of being multi-cellular.
Describe the four levels of organization in living things.
Explain the relationship between the structure and function of a part of an organism.

41. Organization of Living Things
In some ways, organisms are like machines.
Some machines have just one part but most machines have many parts that work together to achieve a common goal.
The same concept is true for organisms and cells.

42. Organization of Living Things
Most cells are smaller than the period at the end of this sentence.
Every cell in an organism performs all life processes.
Are there advantages to having more than one cell?

43. Organization of Living Things
Mutli-cellular organisms contain many cells.
What kinds of organisms are multi-cellular?
There are 3 benefits to being multicellular:
Larger size
Longer life
Specialization

44. Organization of Living Things
Multicellular organisms are usually larger than unicellular organisms.
Larger organisms are prey for fewer organisms.
Larger predators can eat a wider variety of prey.
What are some large predators?
What are some predators that are restricted by their size?

45. Organization of Living Things
The life span of a multicellular organism is longer than that of a unicellular organism.
Why is this generally
true?

46. Organization of Living Things
Multi-cellular organisms are specialized.
This (specialization) means that each type of cell has a particular job.
Specialization makes organisms more efficient.
Heart muscles are an example. They contract and help the heart pump blood.

47. Chapter 2 Sec. 2 Recap
1) T/F In some ways, organisms are like machines.
2) List 3 benefits to being multi-cellular.
3) Describe what happens in interphase of the cell cycle.
4) _____ is the step that follows Metaphase in the Cell Cycle.
5) In which phase of mitosis does the nuclear membrane begin to disappear?

48. Organization of Living Things
A tissue is a group of cells that work together to perform/complete a specific task.
Plants and animals have different types of tissues.
Why would plants and animals have different types of tissues?
Hint: Do they have different types of cells?

49. Organization of Living Things
A structure made up of 2 or more tissues working together is an organ.
An example of an organ would be the heart or the brain.
What are some other examples of organs?

50. Organization of Living Things
A group of organs working together to perform a particular function is called an organ system.
The digestive system is an example.

51. Organization of Living Things
Anything that can perform life processes by itself is an organism.
Some organisms live in colonies where they depend on each other to survive.
Bacteria

52. Organization of Living Things
In organisms, structure and function are related.
Structure is the arrangement of parts in an organism
Function is the job each part does

53. Organization of Living Things
An example of this would be the respiratory system:
The structure of the lungs is a large, spongy sac. There are millions of tiny sacs here called alveoli. Blood vessels wrap around the alveoli. Oxygen from the air enters the blood and blood brings oxygen to the tissues.

54. Chapter 2 Sec. 2 Recap
1) ____ is a group of tissues that work together.
2) List 1 example of an organ.
3) T/F Structure and function are related. Explain your answer.
4) T/F Plants and animals have identical tissues and cells.
5) List 1 example of an organism that lives in colonies.

55. Chapter 2 Vocabulary Review
_______: the process by which cells become different types of cells
_______: groups of similar types of cells that work together to carry out specific tasks
_______: the period during the cell cycle of a cell’s growth and development
_______: two identical chromosomes that make up a duplicated chromosome
_______: the phase of the cell cycle in which the cytoplasm and its contents divide

56. Chapter 2 Vocabulary Review
6) ______: unspecialized cells that are able to develop into many different cell types 7) ______: the stage of the cell cycle in which the nucleus and its contents divide 8) ______: a structure that holds sister chromatids together 9) ______: the two new cells that result from mitosis and cytokinesis

57. Chapter 2 Vocabulary Review
10) _______: groups of different tissues that work together to perform a particular job 11) _______: groups of different organs that work together to complete a series of tasks 12) _______: a cycle of growth, development, and division that most cells in an organism go through