1. Chapter 7 Cellular Structure & Function
7.1 Cell Discovery & Theory
7.2 Plasma Membrane
7.4 Cellular Transport
7.3 Structures & Organelles

2. 7.1 Cellular Discovery & Theory
Main idea-The invention of the microscope led to the discovery of cells
Objectives
Relate advances in microscope technology to discoveries about cells
Compare compound light microscopes with electron microscopes
Summarize the principles of the cell theory
Differentiate between a prokaryotic cell and a eukaryotic cell.
Review Vocabulary
Organization: the orderly structure of cells in an organism

3. History of the Cell Theory
1665, Robert Hooke made a simple microscope
Cell-the basic structural and functional unit of all living organisms
Late 1600’s Anton Van Leeuwenhoek designed his own microscope

4. The Cell Theory
Fundamental idea of modern biology that includes these three principles:
All living organisms are composed of one or more cells
Cells are the basic unit of structure and organization of all living organisms
Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells

5. Microscope Technology
Compound Light Microscope
Utilizes a series of glass lenses and visible light to produce a magnified image
Maximum magnification is around 1000X.

6. Microscope Technology
Electron Microscope
Utilizes magnets to aim a beam of electrons at a cell to produce images
Specimens must be nonliving
Magnifies images up to 500,000X

7. Basic Cell Types Cells exists in various shapes and sizes
Cells differ based on their function they perform for the organism
All cells have at least one physical trait in common - the plasma membrane

8. Two Categories of Cells
Prokaryotic Cells
Cells without specialized internal structures
Unicellular
Similar to the first organisms on Earth

9. Two Categories of Cells
Eukaryotic Cells
More complex than prokaryotic cells
Contain a structure called a nucleus (a distinct central organelle that contains the cell’s genetic material in the form of DNA) and other organelles (specialized structures that carry out specific cell functions)
Generally one to one hundred times larger than prokaryotic cells

10. Origin of Cell Diversity
Why two basic cell types?
Eukaryotic cells derived from prokaryotic cells?
Endosymbiont Theory
A symbiotic mutual relationship involved one prokaryotic cell living inside the plasma membrane of another
Because eukaryotic cells are larger and have distinct organelles, these cells have developed specific functions.
Specific functions has led to cell diversity, and thus more diverse organisms that can adapt better to their environment.

11. 7.2 The Plasma Membrane
Main idea: The plasma membrane help’s to maintain a cell’s homeostasis
Objectives:
Describe how a cell’s plasma membrane functions
Identify the roles of proteins, carbohydrates, and cholesterol in the plasma membrane
Review Vocabulary
Ion: an atom or group of atoms with a positive or negative electric charge

12. Plasma Membrane Primarily responsible for homeostasis in the cell
A thin, flexible boundary between a cell and its environment that allows nutrients into the cell and allows waste and other products to leave the cell

13. Selective Permeability
A key property of the plasma membrane which allows some substances to pass through while keeping others out
Controls the substances in and out of the cell

14. Plasma Membrane Structure
The plasma membrane is composed of the phospholipid bilayer.
Phospholipid is a molecule that has a glycerol backbone, two fatty acid chains, and a phosphate-containing group
Phospholipid bilayer is two layers of phospholipids arranged tail to tail

15. Plasma Membrane Structure

16. Plasma Membrane Structure
Phosphate group makes the head polar and are hydrophillic
The two fatty acid tails are non-polar and hydrophobic
The phospholipids are arranged in such a way that the polar heads can be closest to the water molecules and the non-polar tails can be farthest away from the water molecules

17. Other Components of the Plasma Membrane
Proteins
Transmit signals inside the cells (receptor proteins)
Acts as a support structure to give the cell its shape
Provide pathways for substances to enter and leave the cell (transport proteins)

18. Proteins

19. Cholesterol
Prevents fatty acid tails of the phospholipid bilayer from sticking together
Helps maintain cell homeostasis

20. Carbohydrates
Help cells identify chemical signals

21. Fluid Mosaic Model
The components of the plasma membrane are in constant motion (fluid)
The different substances in the plasma membrane creates a pattern (mosaic) on the surface

22. 7.4 Cellular Transport
Main idea – Cellular transport moves substances within the cell and moves substances into and out of the cell
Objectives
Explain the processes of diffusion, facilitated diffusion, and active transport.
Predict the effect of a hypotonic, hypertonic, or isotonic solution on a cell
Discuss how large particles enter and exits cells.
Review Vocabulary
Homeostasis: regulation of the internal environment of a cell or organism to maintain conditions suitable for life.

23. Passive Transport
Movement of particles across the cell membrane without using energy is passive transport
Diffusion
Facilitated Diffusion
Osmosis

24. Diffusion
Movement of particles from an area of high concentration to an area of lower concentration
Diffusion Rate Factors
Concentration
Temperature
Pressure

25. Dynamic equilibrium
Reached when diffusion of material into the cell equals diffusion of material out of the cell
Molecules continue to move, but the overall concentration remains the same.

26. Diffusion in a cell

27. Facilitated Diffusion
Movement of materials across the plasma membrane using transport proteins
Channel proteins-water filled transport protein that opens and closes to allow the substance to diffuse through the plasma membrane
Carrier proteins – change shape to move particles through the membrane

28. Channel Proteins

29. Carrier Proteins

30. Osmosis Diffusion of water across a selectively permeable membrane
Three types of solutions
Isotonic – the cell is at equilibrium
Hypotonic – lower concentration of solute
Hypertonic – higher concentration of solute

31. Isotonic Solution
Water and dissolved substances diffuse into and out of the cell at the same rate.

32. Hypotonic Solution Solute concentration is higher inside the cell
Water diffuses into the cell
Cell swells and may burst

33. Hypertonic Solution Solute concentration is higher outside the cell
Water diffuses out of the cell
Cell wilts or shrinks

34. Active Transport
Requires energy to move substances against a concentration gradient or from low to high concentration
Active transport using carrier proteins or pumps to maintain cell homeostasis. Ex. Na+/K+ ATPase Pumps – moving 3 Na+ ions out of the cell and 2 K+ ions into the cell

35. Transport of Large Substances
Endocytosis - Process by which the cell surrounds and takes particles into the cell
Exocytosis - Secretion of material out of the plasma membrane

36. 7.3 Structures & Organelles
Main idea: Eukaryotic cells contain organelles that allow the specialization and the separation of functions within the cell.
Objectives
Identify the structure and function of the parts of a typical eukaryotic cell
Compare and contrast structures of plant and animal cells
Review vocabulary
Enzymes: a protein that speeds up the rate of a chemical reaction.

37. Cytoplasm and Cytoskeleton
Cytoplasm - a semi-fluid material that constitutes the environment inside the plasma membrane (Plant & Animal Cells)
Cytoskeleton - a supporting network of long, thin protein fibers that form a framework for the cell and provide an anchor for the organelles inside the cell (Plant & Animal Cells)

38. Cytoskeleton
A framework for the cell within the cytoplasm that rapidly assemble and disassemble and slide past one another. This allows cells and organelles to move.
Microtubules-long, hollow protein cylinders that form a rigid skeleton for the cell and assist in moving substances within the cell
Microfilaments-thin protein threads that help give the cell shape and enable the entire cell or parts of the cell to move

39. Cytoskeleton

40. Cell Structures
Nucleus - brain of the cell; directs the cell processes (Plant & Animal Cells)
Contains most of the cell’s DNA, which stores information used to make proteins for cell growth, function, and reproduction
Nuclear envelope - double membrane with nuclear pores that surrounds the nucleus
Nuclear pores - allow larger-sized substances to move in and out of the nucleus
Nucleolus – site of ribosome production
Chromatin – the complex DNA attached to protein; spread throughout the nucleus

41. Nucleus

42. Ribosomes
Ribosomes are the most numerous of the cell’s organelles (Plant & Animal Cells)
The ribosome is the site of protein synthesis. (Protein factories)
Composed of RNA & protein
The concentration or distribution of ribosomes in the cells depends on how the proteins they produce will be used.
Proteins used by the cells are made by free floating ribosomes.
Exported proteins are made by ribosomes that are attached to the ER.

43. Ribosomes

44. Endoplasmic Reticulum (ER)
The “ER” is a membrane system of folded sacs and tunnels (Plant & Animal Cells)
Rough ER are covered with ribosomes
Smooth ER have little or no ribosomes and function primarily as an intercellular highway, a path which molecules can move from one part of the cell to another
Also the site of carbohydrate and lipid synthesis

45. ER

46. Golgi Apparatus
The processing, packaging and secreting organelle of the cell (Plant & Animal Cells)
Notice that the Golgi Apparatus consists of a stack of membranes.
It operates like a production line in a factory, where a product is assembled at one end, then packaged, and finally shipped out.
The protein vesicle is modified as it passes from sac to sac. Finally it is released to be sent out of the cell.

47. Golgi Apparatus

48. Vacuole
A membrane-bound vessicle for the temporary storage of materials
Plant cells-one large; Animal cells-a few small

49. Lysosomes
Lysosomes are organelles that contain powerful digestive (Animal Cells Only)
They destroy foreign bodies that get into the cell
They also digest food vacuoles to help feed the cell
They destroy the cell when it is too old or damaged. This is why they are sometimes called the “suicide sacs of the cell”

50. Lysosomes

51. Centrioles
Centrioles are tiny t-shaped structures in the cell that function in helping the cell when it divides to form two new cells (Animal Cells and most Protists)

52. Mitochondria
The Mitochondria are the respiration centers of the cell (Plant and Animal Cells)
They are called the “powerhouse of the cell”
They provide energy for the cell.
Mitochondria have their own DNA.
The number of mitochondria in a cell depends on the needs of the cell.

53. Mitochondria

54. Chloroplasts
The Chloroplast is an organelle that is responsible for making food (Plants Cells Only)
This process is called photosynthesis.
They use sunlight + Water + Carbon dioxide and make glucose (sugar).
The waste product of this is oxygen and water vapor.

55. Cell Wall
A Cell Wall is the rigid covering of a plant cell that provides shape and protection (Plant Cell Only)
It is made primarily of cellulose (carbohydrate)
Pores in the cell wall allow ions and molecules to pass to and from the cell membrane.

56. Cellular Projections
The Cilia is a hair-like cellular projection that functions in movement both of an organisms and of moving particles. Like in the illustration to the right (Some Animal Cells).
The Flagella is a whip-like tail cellular projection that is long and help movement in unicellular organisms and some individual cells such as the sperm on the right (Some Animal Cells)

57. Animal Cell

58. Plant Cell