1. Microscopes and the Cell
Thursday, October 17th

2. What is “cell theory”?

3. Who helped developed the cell theory?
1665
Robert Hooke
Observed cork under a primitive microscope
Coined the term “cell”
Looked like monks cells

5. Who helped developed the cell theory?
1674
Antonie van Leeuwenhoek
Observed and described the first microscopic organisms
Father of microbiology
Improved the light microscope
Made more than 25 different types

6. Who helped developed the cell theory?
1830’s
Schleiden (PLANTS) & Schwann (ANIMALS)
Worked independently but upon meeting, made important connections in regards to the cell nucleus
Summarized many observations into what is now know as the cell theory
1840’s
Virchow
Studied bacteria and disease
Claimed that bacteria was also made of cells

7. What is “cell theory”? Cell Theory (3 parts)
All living things are made of cells. (Hooke)
Cells are the basic unit of structure and function in organisms. (Schleiden & Schwann)
All cells come from other cells. (Virchow)

8. UNAIDED EYES
LIGHT MICROSCOPE
ELECTRON MICROSCOPES

9. What are the different types of microscopes?
Light (or Optical)Microscope
Light passes through one or more lenses to enlarge
Magnification = the ability to make things larger
Resolution = the measure of clarity of an image
Can magnify images:
40x - 100x - 400x

10. Light Microscope

11. What are the different types of microscopes?
Electron Microscopes (EMs)
Allows scientists to view a universe too small to be seen with a light microscope
Forms an image using a beam of electrons
Focus a beam of electrons through a specimen (TEM) or onto its surface (SEM)

12. What are the different types of microscopes?
Scanning Electron Microscope (SEM)
Provides for detailed study of the surface of a specimen
Creates a 3D image
Cannot view living specimens

18. Surface of Tongue

19. Head louse clinging to a human hair

20. Eyelash hairs growing from the surface of human skin

21. The surface of a strawberry

22. Cut human hairs and shaving foam between two razor blades

23. Household dust – pollen, human hair, pet dander, leaf litter

24. Toothbrush
bristle

25. Snowflake

26. What are the different types of microscopes?
Transmission electron microscope (TEM)
Provides for detailed study of the internal structure of cells
Electrons are passed through thin specimens
2 dimensional

27. TEM vs. SEM
Viruses leaving a cell

28. Cell Structure and Function

29. What are the common features of ALL cells?
Cell Membrane: AKA plasma membrane
Encloses the cell
Separates the inside from the outside
Regulates what goes in & out of cell
DNA
Genetic code
Cytoplasm: the “fluid” inside of the cell
Provide support of internal structures
Site of cellular reactions

30. What are prokaryotes? Single celled organism that lack nuclei
More primitive; appeared first in the geologic record
Many have flagella, that help them move
Bacteria

31. What are eukaryotes? Have a nucleus Compartment that houses the DNA
Controls all functions of the cell
Have organelles
structures that carries out specific jobs in the cell

32. What’s found in the nucleus?
Nuclear envelope
A double membrane which encloses the nucleus
Has pores that regulate molecular traffic in and out of the nucleus
Chromosomes
Condensed and coiled DNA
Each species has characteristic chromosome number

33. What is the cytoskeleton?
Skeletal system of the cell membrane
Gives the cell its shape & structure
Involved with transport AND cell division
Microtubules
Long hollow cylinders
Movement of chromosomes during cell division

34. Cytoskeleton Cell membrane Endoplasmic reticulum Microtubule
Microfilament
Ribosomes
Michondrion
Go to Section:

35. What organelles are found within eukaryotes?
Endoplasmic Reticulum (ER)
Moves proteins/other substances through the cell
Makes proteins from the ribosomes
Rough ER is covered with ribosomes
Connected to the nucleus
Smooth ER makes lipids (fats)
Ribosomes: structures that make proteins

37. What organelles are found within eukaryotes?
Golgi Apparatus/ Golgi Body
Packaging and distribution center
Modifies lipids and proteins from the ER
Ships out the new products to their final destinations
Vacuoles: Storage containers that can also provide structure

38. What organelles are found within eukaryotes?
Mitochondria
Organelle that takes energy from sugar and turns it into ATP (energy) that the cell can use
Has its own DNA

39. What are the organelles found only in plant cells?
Cell wall
Made of proteins & carbohydrates
Helps keep the cell’s shape
Provides rigid support
Protects from cell damage
Connects the cell with adjacent cells
Chloroplasts
Organelle that uses light energy to make carbohydrates through photosynthesis

40. What are the organelles found only in plant cells?
Central Vacuole
Large membrane covered space that stores water and other substances

41. Plant Cell

42. ENDOPLASMIC RETICULUM (ER)
An Animal Cell
ENDOPLASMIC RETICULUM (ER)
Nucleolus
DNA
Nuclear envelope
NUCLEUS
Rough ER
Smooth ER
Flagella
Plasma membrane
Centrioles
CYTOSKELETON
Microfilaments
Microtubules
Ribosomes
Golgi apparatus
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
Lysosome
Mitochondrion

43. A Plant Cell Rough endoplasmic reticulum Smooth endoplasmic reticulum
Nuclear envelope
Nucleolus
NUCLEUS
DNA
Ribosomes
(small brown dots)
Central vacuole
Golgi
Micro-
filaments
CYTO-
SKELETON
Micro-
tubules
Mitochondrion
Plasma membrane
Chloroplast
In plant cells but
not animal cells:
Chloroplasts
Central vacuole
Cell wall
Cell wall

44. What are the 2 different cell types?
Prokaryotic vs Eukaryotic
YOU are eukaryotic
Larger cells
Found in all other kingdoms
Often multicellular
Nucleus
Contains membrane bound organelles
Linear DNA
Asexual OR sexual reproduction
Small cells
Bacteria types
ALWAYS unicellular
No nucleus
No membrane bound organelles
Circular DNA
Asexual reproduction
Eukaryotic
Prokaryotic

45. The Cell Membrane

46. What is the cell membrane made of?
Provides protection and support for cells
Separates the cell from the outside environment
Phospholipid
Molecule that allows the CM to be selectively permeable
Certain substances can pass in and out of the cell
Lipid Bilayer (2 layers)
Phospholipids - phosphate and 2 fatty acids

47. Cell Membrane

48. What is the cell membrane made of?
They are SELECTIVELY impermeable
Some substances (not all) can pass across the membrane
Hydrophobic tails…
Water HATING
Fats & oils
Hydrophilic heads...
Water LOVING

49. What is the cell membrane made of?
Protein channels
Allow nutrients (sugars or amino acids) to enter the cell
Allow products of metabolism to leave (waste products)
These channels are quite specific
Recognize only a limited group of chemical substances to pass through the membrane

50. What is the function of the cell membrane?
Gives the cell a flexible structure
Forms a barrier between the cell and its environment
Anchors the cytoskeleton to provide shape to the cell
Attaches to the extracellular matrix to help group cells together (tissues)

51. What is the Structure of the Cell Membrane?
Outside
of cell
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains
Inside
of cell
(cytoplasm)

52. What is the Structure of the Cell Membrane?
Carbohydrates
Act like chemical ID cards
Allows individual cells to identify one another
Membrane allows the following materials in and out of the cell:
Water, Glucose (sugars), Oxygen, chemical compounds & wastes

53. How do things pass in and out of the cell?
Concentration
# of molecules present
Diffusion
Spreading of molecules OUT into available space
From MORE concentrated to LESS concentrated

54. How do things pass in and out of the cell?
DRAW THIS!
Concentration
# of molecules present
DIFFUSION
Spreading out of molecules into available space
From MORE concentrated to LESS concentrated

55. How do things pass in and out of the cell?
DRAW THIS!
Notice it’s not the MOLECULES THAT MOVE
IT’S THE WATER/LIQUID SOLUTION
Passive transport clip

56. How do things pass in and out of the cell?
Diffusion depends on random particle movements
Doesn’t require cellular ENERGY
Called PASSIVE TRANSPORT
Equilibrium

57. How do things pass in and out of the cell?
Osmosis
The diffusion of WATER through a cell membrane

58. How do things pass in and out of the cell?
Isotonic = Same strength
Concentrations are the same on either side of the membrane
Hypertonic = Above strength
More concentrated solution OUTSIDE of cell membrane
Hypotonic = Below strength
Less concentrated solution OUTSIDE of cell membrane

59. DRAW THIS DIAGRAM

61. Osmosis Video Higher Concentration of Water Water molecules Cell
membrane
Sugar molecules
Lower Concentration
of Water

63. Needs water for movement
Osmosis vs Diffusion
Diffusion
Osmosis
Water?
Doesn’t need
Needs water for movement
What it is
Spontaneous movement of molecules from high to low concentration
Spontaneous movement of WATER across a semipermeable mebrane, from high to low conc.
Process
Mainly occurs in gases and liquids
Occurs when the medium (liquid) around a cell has a higher WATER concentration than the cell

64. What is another example of passive transport?
Facilitated Diffusion
Passage of molecules with transport proteins across a membrane
Uses channels
Does NOT require ENERGY

65. What is Active Transport?
Movement of a substance against its concentration gradient with the use of ENERGY
Moving in the OPPOSITE direction
From LOW to HIGH concentration
Active transport uses MOST of the energy a cell has for daily activities
Active transport clip

66. What is Active Transport?
Cells try to accumulate high concentrations of molecules they need:
Ions
Glucose (sugar)
Amino acids (proteins)
Carried out by protein channels

67. What are the types of Active Transport?
Exocytosis
Molecules EXIT through the cell membrane
Endocytosis
Molecules ENTERING the cell through the membrane
VIDEO

68. How is Passive different from Active Transport?
Does not use any type of energy
Uses energy (Active)
Examples:
Diffusion
Exocytosis
Osmosis
Endocytosis

69. Specialization vs Differentiation
SPECIALIZATION - Multicellular organisms have cells that perform SPECIFIC jobs
Ex – blood cells carry nutrients, skin cells protect the interior of the body
Cells work together to perform a specific function for TISSUES
Similar tissue types make up ORGANS
Organs function together make up ORGAN SYSTEMS
Cells  Tissues  Organs  Organ Systems  Organisms

71. Specialization vs Differentiation
Normal process where less specialized cells develop to perform a function
A fertilized egg (zygote) will develop into an adult human being
Stem cells will develop into neurons, somatic cells and germ cells