1. Chapter 7 Cell Structure & Function

2. 7-1: Life is Cellular OBJECTIVES: What is the cell theory?
What are the characteristics of prokaryotes and eukaryotes?
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There is a common structure that makes up every living thing - the cell

3. The Discovery of the Cell
In 1665, Robert Hooke used a microscope and saw chamber in cork that he called cells
Anton van Leeuwenhoek also observed tiny organisms in water
Contributions to the cell theory:
Schleiden - all plants are made of cells
Schwann - all animals are made of cells
Virchow - new cells could only come from the division of existing cells
The Cell Theory:
All living things are composed of cells
Cells are the basic units of structure & function
New cells are produced from existing cells

4. CORK CELLS

5. White Boards
Who was the first scientists to see living cells?

6. White Boards
Which scientist determined that all animals are made of cells?

7. White Boards The cell theory says:
All living things are composed of cells
New cells are produced from existing cells
Cells are the basic units of _____?_____

8. Exploring the Cell
Light microscopes are limited in detail (resolution) because light is easily scattered as it passes through air
Electron microscopes (TEM’s and SEM’s) can view things 1000x smaller than light microscopes
Scanning probe microscopes can operate in ordinary air and can even show samples in solution (DNA, protein, and other biomolecules)

9. SEM

10. IMAGES

11. Prokaryotes and Eukaryotes
All cells have two things in common
Surrounded by a barrier (membrane)
Contain DNA
The nucleus is a membrane-enclosed structure that contains the cell’s genetic material in the form of DNA
Prokaryotic cells have no nucleus
Eukaryotic cells have a nucleus

12. Prokaryotes and Eukaryotes

13. Prokaryotes and Eukaryotes
Nucleus NO
YES
Size
Generally Smaller
Generally Larger
Specialized Structures
Not Usually
Number of Cells
Unicellular
Unicellular or Multicellular

14. White Boards
What two features do all cells share?

15. Which type of organism has cells that contain a nucleus?
White Boards
Which type of organism has cells that contain a nucleus?
PROKARYOTIC or EUKARYOTIC

16. 7-1 Section Assessment What three statements describe the cell theory?
What are the differences between prokaryotic cells and eukaryotic cells?
Compare the processes used to create a TEM and an SEM.
What structures do all cells have?
How did the invention of the microscope help the cell theory?

17. 7-2: Eukaryotic Cell Structure
What are the functions of the major cell structures?
OBJECTIVES

19. Comparing the Cell to a Factory
At first, cells look impossibly complex, but patterns eventually emerge
Many structures are common to eukaryotic cells
These structures act as specialized organs and are called organelles
Eukaryotic cells are divided into two parts: The nucleus and the cytoplasm

20. White Boards
Eukaryotic cells are divided into two parts: the ________ and the ________.

21. Nucleus The nucleus is the control center
The nucleus contains nearly all the cell’s DNA: Coded instructions for making proteins and other molecules
It is surrounded by a nuclear envelope which has pores to let materials in and out
Chromatin is granular material in the nucleus which is made of DNA bound to protein
Chromatin condenses to form chromosomes when the cell divides
The dark region in the nucleus is the nucleolus: The location of ribosome construction

24. White Boards
________ is made of DNA bound to protein.

25. White Boards
When a cell divides, chromatin condenses to form ________.

26. Ribosomes Proteins are assembled on ribosomes
Ribosomes are small particles of RNA and protein and are found throughout the cytoplasm
They produce proteins by following coded instructions that come from the nucleus

28. White Boards
Where do the instructions for making proteins come from?

29. White Boards
Proteins can be found throughout the ________ and are sometimes attached to the ________.

30. Endoplasmic Reticulum
The endoplasmic reticulum (ER) is the site where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell
Rough ER is covered with ribosomes and is involved in the synthesis of proteins
Smooth ER does not contain ribosomes and contains collections of enzymes that perform specialized tasks (synthesis of lipids, detoxification, etc.)

32. White Boards
Rough ER is involved with the synthesis of ________.

33. Golgi Apparatus
The function of the golgi apparatus is to modify, sort, and package proteins and other materials from the ER for storage in the cell or secretion outside the cell
The golgi ships proteins to their final destinations throughout the cell or outside of the cell

35. Lysosomes Lysosomes are small organelles filled with enzymes
Lysosomes digest (break down) lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell
Lysosomes also break down unuseful organelles and other “junk” in the cell

37. Vacuoles
Vacuoles are saclike structures used for storage of materials such as water, salts, proteins, and carbohydrates
Plant cells have a large central vacuole used for support
Vacuoles can also be found in some single-celled organisms and some animals

39. Mitochondria & Chloroplasts
Mitochondria are organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use
Nearly all mitochondria in humans come from the cytoplasm of the mother’s egg cell
Chloroplasts are organelles that capture energy from sunlight and convert it into chemical energy in a process called photosynthesis
Chloroplasts and mitochondria contain their own DNA
Lyn Margulis developed the endosymbiotic theory: Prokaryotic ancestors of mitochondria and chloroplasts developed symbiotic relationships with early eukaryotes

42. White Boards
Organelles that capture energy from sunlight and convert it to chemical energy are called ________.

43. Cytoskeleton
The cytoskeleton is a network of protein filaments that help the cell to maintain its shape
The cytoskeleton is also involved in movement
Microfilaments are threadlike structures made of actin that:
Support the cell
Assist with movement
Microtubules are hollow structures made of proteins called tubulins that:
Maintain shape
Form centrioles during cell division (Animal cells only)
Form cilia and flagella

45. 7-2 Section Assessment
Describe the functions of the endoplasmic reticulum, Golgi apparatus, chloroplast, and mitochondrion.
Describe the role of the nucleus in the cell.
What are two functions of the cytoskeleton?
How is a cell like a factory?
You examine an unknown cell under the microscope and discover the cell contains chloroplasts. What type of organism could you infer that the cell came from?

46. 7-3: Cell Boundaries OBJECTIVES Cell membrane: thin, flexible barrier
Cell Wall: Strong supporting layer around the membrane of some cells
What are the main functions of the cell membrane and the cell wall?
What happens during diffusion?
What is osmosis?
OBJECTIVES

47. Cell Membrane
The cell membrane regulates what enters and leaves the cell and also provides protection and support
Composed of a lipid bilayer with embedded protein molecules and carbohydrates attached to some of the proteins
Often described as a mosaic
The proteins form channels and pumps to move materials
The carbohydrates act like chemical identification cards

50. White Boards
The cell membrane is composed of a ________ ________ with embedded protein molecules and carbohydrates attached to some of the proteins.

51. White Boards
What is the role of the protein in the cell membrane?

52. Cell Walls Plants, algae, fungi, and many prokaryotes have cell walls
The main function of the cell wall is to provide support and protection for the cell
Made from fibers of carbohydrate and protein
Plant cell walls are made of cellulose: the principal component of wood and paper

54. White Boards
What types of organisms have cell walls?

55. Diffusion Through Cell Boundaries
The concentration of a solution is the mass of solute in a given volume of a solution (mass/volume)
Particles in a solution are in constant motion
The particles tend to spread out from areas of higher concentration to areas of lower concentration: diffusion
Diffusion occurs until equilibrium is reached
Diffusion does not require the cell to use energy

56. White Boards
___________ is when particles spread out from areas of high concentration to areas of low concentration.

57. White Boards
Diffusion occurs until _______ is reached.

58. Osmosis Permeable: substances can pass through
Impermeable: substances cannot pass through
Selectively Permeable: Some can, some can’t
Osmosis is the diffusion of water through a selectively permeable membrane
Isotonic = same strength, Hypertonic = above strength, Hypotonic = below strength
Osmosis exerts a pressure known as osmotic pressure on the hypertonic side of a selectively permeable membrane
Cells do not fill with water and burst because they are surrounded by isotonic fluids or a cell wall

60. Diffusion & Osmosis

61. Diffusion & Osmosis

62. White Boards
The diffusion of water through a selectively permeable membrane is called ________.

63. Facilitated Diffusion
Cell membranes have protein channels that make it easy for some molecules to cross
Example: red blood cells have a channel that allows only glucose to cross
These cell membrane proteins are said to facilitate, or help, diffusion: known as facilitated diffusion
Facilitated diffusion depends on concentrations for movement and does not require use of the cell’s energy

65. Active Transport
Active transport moves materials against the concentration difference and requires energy
Carried out by transport proteins: “pumps,” or by endocytosis or exocytosis (for large molecules)
Active transport can concentrate materials even when diffusion tries to move them apart
Endocytosis takes materials into the cell with infoldings, or “pockets”
Exocytosis is the process of releasing large amounts of material from the cell

67. Endocytosis

68. Exocytosis

69. Active Transport

70. Active Transport

71. 7-3 Section Assessment
Describe the functions of the cell membrane and cell wall.
What happens during diffusion?
Describe how water moves during osmosis.
What is the basic structure of a cell membrane?
What is the difference between phagocytosis and pinocytosis?
What id the main way that active transport differs from diffusion?

72. 7-4:Diversity of Cellular Life
All living things are:
Composed of cells
Use the same basic chemistry
Follow the same genetic code
Contain the same kinds of organelles
What is cell specialization?
What are the four levels of organization in multicellular organisms?
OBJECTIVES

73. Unicellular Organisms
A single-celled organism is also called a unicellular organism
Unicellular organisms do everything you would expect any cell to do:
Grow, respond, use energy, reproduce, etc.
In terms of their numbers, unicellular organisms dominate life on earth

75. Multicellular Organisms
Cells can develop in different ways to perform different tasks: Cell Specialization
Specialized animal cells:
Red blood cells transport oxygen
Pancreas cells produce protein for digestion
Muscle cells use actin and myosin for movement
Specialized plant cells:
Stomata are holes in the underside of leaves use for gas exchange – surrounded by guard cells

76. Red Blood Cells
Pancreas Cells
Muscle Cells

77. Stomata & Guard Cells

78. Levels of Organization
Levels of organization in a multicellular organism are: individual cells, tissues, organs, and organ systems
TISSUE: Group of similar cells that perform a particular function
Muscle, epithelial, nervous, connective
ORGAN: Groups of tissues working together
ORGAN SYSTEM: A group of organs that work together

80. 7-4 Section Assessment
In what kinds of organisms is cell specialization a characteristic?
List the levels of biological organization in multicellular organisms from most simple to most complex.
How are unicellular organisms similar to multicellular organisms?
Using what you know about the ways muscles move, predict which organelles would be most common in muscle cells.