1. The Path to the Cell Theory
1500’s
First magnifying lenses used in Europe to look at the quality of cloth
1600’s
- First telescope and microscope constructed in Holland -

2. 1665
Robert Hook – used a microscope to look at a thin slice of cork (bark from an oak tree) and saw what looked like small boxes
- First to name them cells (because they looked like the small rooms that monks lived in called “cells”)
1674
Anton van Leeuwenhoek – First to view organisms using a microscope from pond water

3. Advancements in Cell Biology and Imaging Quality

4. Cofounders of the Cell Theory
1838
Matthias Schleiden – concluded that all plants were made of cells
1839
Theodore Schwann – concluded that animals were made of cells
1858
Rudolf Vichow –
Cells come from
pre-existing cells.
German botanist
German zoologist

5. The Cell Theory All living things are composed of cells.
Cells are the basic units of structure and function in living things.
New cells are produced from existing cells.

6. Discoveries since the Cell Theory
Endosymbiotic Theory
In 1970, American biologist, Lynn Margulis, provided evidence that some organelles within cells were at one time free living cells themselves
Supporting evidence included organelles with their own DNA
Chloroplast and Mitochondria

8. Modern Cell Theory
With advancements and more studies in science the following additions have been added onto the Cell Theory:
Energy Flow occurs within cells.
Metabolism
Cells contain hereditary information that is passed on from cell to cell during cell division
DNA
All cells are basically the same in chemical composition in organisms of similar species.

9. Cell Types Cells Basic units that make up organisms
Can only be observed under a microscope
Three Basic Types:
Animal Cell
Plant Cell
Bacterial Cell

10. Cell Sizes _________ > _____________ > ___________ Plant cell
Animal cell
bacteria

11. Typical cells range from 5 – 50 micrometers (microns) in diameter
CELL SIZE
Typical cells range from 5 – 50 micrometers (microns) in diameter

12. How Big is a Micron ( µ ) ?
1 cm = 10,000 microns 1” = 25,000 microns

13. Number of Cells
Although ALL living things are made of cells, organisms may be:
Unicellular – composed of one cell
Multicellular- composed of many cells that may organize into tissues, etc.

14. Multicellular Organisms
Cells in multicellular organisms often specialize (take on different shapes & functions)

15. Cell Specialization
Cells in a multi-cellular organism become specialized by turning different genes on and off
This is known as DIFFERENTIATION

16. Specialized Animal Cells
Muscle cells
Red blood cells
Cheek cells

17. Specialized Plant cells
Guard Cells
Pollen
Xylem cells

18. Biologists divide cells into two main categories:
Prokaryotes
Eukaryotes

19. Prokaryotes Simplest type of cell Cells Bacteria
Lack a nucleus or membrane bound organelles
Have single, circular chromosomes
Bacteria
Still carry out all life processes – grow, reproduce, move, respond to changes in their environments
Generally smaller and simpler than eukaryotes

20. Prokaryotes Cell surrounded by cell membrane & cell wall
Nucleoid region (center) contains the DNA
Contain ribosomes (no membrane) in their cytoplasm to make proteins
Flagella – long tail like structure that aids in movement

21. Eukaryotes More complex type of cells Cells
Have a nucleus and membrane-bound organelles
Includes single cell and multi cellular organisms like protists, fungi, plants, and animals

22. Eukaryotic Cell Contain 3 basic cell structures: Nucleus Cell Membrane
Cytoplasm with organelles

23. Two Main Types of Eukaryotic Cells
Animal Cell
Plant Cell

24. Cell Organelles (Cell Structures)
Parts and Structures inside of the cell
Very small (microscopic)
Perform various and sometimes specialized functions for the cell
Found in the cytoplasm
May or may not be membrane bound
Like a factory

25. Animal Cell Organelles
Nucleolus
Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

26. Plant Cell Organelles

27. Nucleolus
Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

28. Cell Membrane Plasma Membrane Function:
Surrounds the outside of all cells
Controls what enters and leaves the cell
Takes in food and water
Eliminates wastes
Protects and supports the cell
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

29. Cell Membrane Made up of a phospholipid bilayer Double layered sheet
Tough, flexible structure that forms a strong barrier between the cell and its surroundings
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

30. Cell Membrane Tails (Made of fatty acids)
Heads (Made of gylcerol and phosphate)
Tails (Made of fatty acids)
Hydrophobic
Hydrophilic
Repel water
Attract water
Point inward
Point outward
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

31. The Cell Membrane is Fluid
Molecules in cell membranes are constantly moving and changing

32. Cytoplasm Ribosome (attached) Nucleolus Ribosome (free) Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles
Cytoplasm

33. Cytoplasm Jelly like substance that fills the cell
Enclosed by the cell membrane
Function:
Contains the organelles to carry out specific functions
Found in all cells

34. Nucleus Ribosome (attached) Nucleolus Ribosome (free) Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

35. Nucleus Usually the largest organelle Function:
Controls the normal activities of the cell

36. Nucleus Function: Contains DNA in chromosomes
Each cell has a fixed number of chromosomes that carry genes
Genes control the cell’s characteristics

37. DNA is the hereditary material of the cell.
DNA contains the code and instructions to make different proteins.

38. Nuclear Envelope Nuclear Membrane
A double membrane that surrounds the nucleus
Connected to the rough ER
Function:
Has pores that allow materials to enter and leave the nucleus

39. Nucleolus Inside nucleus May have multiple
Disappears when cell divides
Function:
Makes ribosomes that make proteins

40. Cytoskeleton Made of proteins Function:
Helps the cell maintain its shape
Can also help move organelles around

41. Cytoskeleton Microtubules – tubelike structures made of tubulin
Microfilaments – threadlike structures made of actin
MICROTUBULES
MICROFILAMENTS
Cell Membrane
Endoplasmic Reticulum
Mitochondrion
Ribosomes

42. Centrioles Ribosome (attached) Nucleolus Ribosome (free) Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

43. Centrioles Found only in animal cells Made of bundles of microtubules
Appear during cell division and form the mitotic spindle
Function: Help to pull chromosome pairs apart to opposite ends of the cell

44. Mitochondrion Ribosome (attached) Nucleolus Ribosome (free) Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

45. Mitochondria Function: In both plant and animal cells
Powerhouse of the cell
Cellular Respiration (burning of glucose)
Generates ATP (cellular energy)
In both plant and animal cells
The more active the cell (muscle cells) the more mitochondria they have

46. Mitochondria Surrounded by a double membrane Has its own DNA
Cristae - folded inner membrane (increases surface area for chemical reactions)

47. Interesting Fact ---
Mitochondria Come from cytoplasm in the EGG cell during fertilization
Therefore …
You inherit your mitochondria from your mother!

48. Endoplasmic Reticulum
Nucleolus
Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
Endoplasmic
Reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

49. Endoplasmic Reticulum (ER)
Network of hollow membrane tubules
Connects to nuclear envelope and cell membrane
Functions in synthesis of cell products and transport

50. Rough Endoplasmic Reticulum
Has ribosomes on its surface
Function:
Ribosomes on the Rough ER make proteins for:
Cell Membrane
Export out of the cell
Proteins move to the inside the Rough ER and are modified and transported

51. Smooth Endoplasmic Reticulum
Does not have ribosomes on its surface
Attached to the end of the Rough ER
Function:
Makes cell products that are used inside of the cell
Membrane lipids (steriods)
Regulates calcium (muscle cells)
Destroys toxic substances (liver cells)

52. Endomembrane System
Includes nuclear membrane connected to ER connected to cell membrane (transport)

53. Ribosomes Ribosome (attached) Nucleolus Ribosome (free) Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

54. Ribosomes Made of proteins and rRNA
Can be free or attached to another organelle
Functions:
Protein Synthesis
Protein Factories - Make proteins for the cell
Join Amino Acids together to make proteins

55. Golgi Apparatus Ribosome (attached) Nucleolus Ribosome (free) Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
Centrioles

56. Golgi Apparatus Stacks of flattened stacks
Looks like a stack of pancakes
Has a shipping side and a receiving side
Functions:
Modify, sort, and package molecules from the ER for storage or transport out of the cell

57. Golgi Apparatus

58. Golgi Animation
Materials are transported from Rough ER to Golgi to the cell membrane by VESICLES

59. Lysosomes

60. Lysosomes Contain digestive enzymes Function:
Break down food, bacteria, and worn out cell parts for cells

61. Lysosome Digestion Cells take in food by phagocytosis
Lysosomes digest the food & get rid of wastes

62. Cilia and Flagella Made of protein tubes called microtubules Function:
Move cells
Cilia – shorter and more of them on the cell
Flagella – longer and fewer of them on the cell

63. Cell Wall

64. Cell Wall Surrounds the plant cell Found outside of the cell membrane
Made of cellulose in plants
Made of peptidoglycan in bacteria
Made of chitin in Fungi
Function:
Supports and protects the cell

65. Cell Membrane

66. Cell Membrane Lies immediately against the cell wall in plant cells
Function:
Pushes out against the cell wall to maintain the cell shape

67. Vacuoles

68. Vacuoles Fluid filled sacs Function: Large in plant cells
Storage of sugars, proteins, minerals, lipids, wastes, salts, water, enzymes, etc.
Large in plant cells
Small or absent in animal cells

69. Chloroplasts

70. Chloroplasts Found only in plants Function:
Specifically only in producers that have chlorophyll
Function:
Photosynthesis
Uses energy from the sun and makes own food (glucose)
Energy stored in the chemical bonds of sugar.

71. Chloroplasts Contains its own DNA Surrounded by a double membrane
Outer membrane smooth
Inner membrane has sacs called Thylakoids
Thylakoids in stacks call Grana
Interconnected
Stroma – gel like material surrounding thylakoids

72. Factors Affecting Cell Size
Surface area (plasma membrane surface) is determined by multiplying length times width (L x W)
Volume of a cell is determined by multiplying length times width times height (L x W x H)
Therefore, Volume increases FASTER than the surface area

73. Cell Size
As cells increase in size the surface area to volume ratios decrease
Makes cells unable to obtain nutrients or remove wastes
Too big
Because of this cells divide to stay small or change shape to increase surface area or reduce volume

74. Cell Size
Question: Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?

75. About the same size, but …
Cell Size
Question: Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?
About the same size, but …
The elephant has MANY MORE cells than a mouse!