1) Cell biology is the study of cells, the fundamental unit of life. Key discoveries included Hooke observing cells in 1665 and van Leeuwenhoek improving microscopy. The cell theory established that cells are the basic unit of life. 2) Microscopy revolutionized cell biology by allowing observation of subcellular structures. Light microscopes use visible light while electron microscopes use beams of electrons for higher magnification. 3) Key cellular structures include the nucleus that houses DNA, organelles like mitochondria and chloroplasts that generate energy, and the endomembrane system involved in protein transport and modification.

1. Cell Biology

2. Cells
• Cell – Smallest unit of life that can function
independently
– Discovered by Robert Hooke – 1660
– Antony van Leeuwenhoek – improved lenses,
made observing cells easier
• Cell Theory – Schleiden, Schwann
– All organisms are made of one or two cells
– Cell fundamental unit of all life

3. Surface Area/Volume

4. History of Cell Biology
Robert Hooke 1635-1703

5. History of Cell Biology
Anton von Leeuwenhoek
1673-1723
Leeuwenhoek Microscope
(circa late 1600s)

6. History of Cell Biology
Cell Theory: 1800s
Theodor Schwann Matthias Schleiden

7. Microscopes
• Microscope uses an energy source (light, electrons,
ect.) to view objects under magnification
– Can view things that you cannon view with the naked eye
– Light Microscopes – uses light to view things in real color,
item must be thin enough to get light thru.
• Compound – uses 2 or more lenses to focus visible light through
a specimen, magnify 1600 times
• Confocal – focus white or laser light through a lens to the
object.
– Electron Microscopes – MUCH higher magnification
• Transmission – Sends beam of electrons through a sample
• Scanning – Sends beam of electrons over the surface of object

8. Microscopy
Why do we need
microscopes?

9. Resolution
Resolution: ability to distinguish two points as
distinct
Picture created and printed at a
high resolution
Picture created and printed at a
low resolution

10. Microscopy
Light Microscopy
ADV: living cells
DISADV: low
resolution

11. Light Microscopy
Phase Contrast

12. Light Microscopy
Differential Interference Contrast

13. Electron Microscopy
Uses beams of electrons

14. Electron Microscopy
Scanning Electron Microscopy (SEM)
ADV: shows details of cell surfaces

15. Electron Microscopy
Transmission Electron Microscopy (TEM)

16. Cell Structures
• All cells have these structures:
– DNA
– RNA
– Ribosomes – make proteins
– Proteins
– Cytoplasm – fluid filling of the cell
– Cell Membrane – makes a boundary between
inside and outside of cell

17. Types of Cells – Prokaryotic
• Lack a true nucleus and membrane bound
organelles
• Domains Bacteria and Archaea
• Structures:
– Nucleoid – contains cells DNA, NOT bound by a
membrane
– Cell Wall – rigid, outside of cell membrane, gives
cell its shape (rod-shaped, round, spiral)
– Flagella – whip-like tail for movement

18. Types of Cells - Eukaryotic
• All other cells except for bacteria, archaea
– Plants, animals, protists, fungi
• Domain – Eukarya
• Have MEMBRANE BOUND organelles, larger
than prokaryotic
• 2 basic types of eukaryotic cells
– Animal
– Plant

21. Cell Membrane
• Function:
– Separate cell from environment
– Transport substances in and out of cell
– Receive and respond to stimuli
• Properties
– Hydrophobic and hydrophilic
– Selectively permeable
• Structure:
– Phospholipid bi-layer
– Fluid mosaic of phospholipids, sterols, proteins

22. Proteins
• Transport Proteins
• Enzymes
• Recognition Proteins
• Adhesion Proteins
• Receptor Proteins
Animal cell membrane

23. • Cell wall
– Maintain structure
– Maintain internal pressure

24. Nucleus
• Function:
– “Brain” of the cell
– Contains DNA, mRNA
• Structure
– Nucleolus – assemble ribosomes
– Nuclear envelope – separates nucleus from
cytoplasm
– Nuclear pores – holes in envelop with channels for
mRNA to leave nucleus

25. Nucleus
Nuclear envelope
Nucleolus
Nuclear pore
1) Nuclear envelope
2) Outer ring
3) Spokes
4) Plug

26. Nucleus

27. Endoplasmic Reticulum and
Ribosomes
• Rough Endoplasmic Reticulum (ER)
– Function: Help make cell membrane and secretory
proteins for various bodily functions
• In pancreas, insulin; leukocytes, antibodies
– Structure: Connected to nuclear envelop and cell
membrane with ribosomes on outside
• Smooth ER
– Function: Make and store proteins, carbohydrates, lipids
• In liver, enzymes for detox; muscle, proteins for contraction
– Structure: Same as smooth ER – ribosomes
• Ribosomes
– Function: Assemble proteins for the cell
– Structure: Large and small subunits

28. The Endomembrane System
Rough Endoplasmic Reticulum: makes secreted and
membrane proteins, and proteins destined for some organelles

29. The Endomembrane System
Smooth Endoplasmic Reticulum: synthesizes lipids,
steroids, detoxifies

30. The Endomembrane System:
Endoplasmic reticulum
Rough ER

31. The Endomembrane System:
Endoplasmic reticulum

32. Golgi Apparatus
• Function:
– Process and complete protein production
– Sorts and packages proteins to send to cell
membrane and out or as membrane proteins
• Structure:
– Stack of flat membrane enclosed sacs

33. The Endomembrane System: Golgi
Receives vesicles from RER and packages proteins for
export

34. The Endomembrane System: Golgi
Receives vesicles from RER and packages proteins for
export

35. Lysosomes
• Function:
– Digestion
– Enzymes to break down and recycle food, bacteria, old
organelles
• Structure:
– Made by Golgi Apparatus
– Fuse with vesicles that have things that need to be
digested
• Number of lysosomes depends on type of cell
– White blood cells, liver cells - lots

36. The Endomembrane System:
Lysosomes
Membranous sac of digestive enzymes

37. Vacuoles
• Function:
– Same as lysosomes
– Replace lysosomes in plant cells
– Growth
– Maintain pressure
– Holds pigments
– Contractile vacuole – protists (pump water, digest)
• Structure:
– Contains water solution of enzymes, sugars, salts,
weak acids

38. The Endomembrane System: Vacuoles
• Various Functions http://www.youtube.com/watch?v=iG6Dd3
COug4
Contractile vacuole
Central vacuole

39. Peroxisomes
• Function:
– Dispose of toxic substances
– Protect cells from toxic byproducts
• Structure:
– DIFFERENT from lysosomes that originate from ER
NOT Golgi body

40. Peroxisomes
Peroxisomes (green)

41. Cytoskeleton
• Function:
– Transportation within the cell
– Support
– Cell division
– Connectivity
– Movement – Cilia and flagella
• Structure:
– Network of protein tubules and tracks
• Microfilaments
• Intermediate filaments
• Microtubules – organized by centrosomes

42. The Cytoskeleton and Cell Surfaces
Microfilaments
Functions
(1) Structure
(2) Cell motility (muscles)

43. The Cytoskeleton and Cell Surfaces
Intermediate Filaments
Functions:
(1) Cell shape
(2) Anchor organelles
Keratin intermediate filaments (red)

44. The Cytoskeleton and Cell Surfaces
Microtubules
Functions:
(1) Support
(2) Tracks
(3) Cell division

45. The Cytoskeleton and Cell Surfaces:
Cilia and Flagella
Cilia
http://www.youtube.com/watch?v=QGAm6hMysTA
http://www.youtube.com/watch?v=7kM_kRPrcrk
http://www.youtube.com/watch?v=09kLIsNfaO8&NR=1

46. The Cytoskeleton and Cell Surfaces:
Cilia and Flagella
Structure:
9+2
Basal body
Dynein
Spokes

47. Extracellular Matrix
Glycoproteins: proteins + carbohydrates, fibers

48. Extracellular Matrix
Glycoproteins: proteins + carbohydrates, fibers
C-terminally truncated human glypican-1

49. Endosymbiotic Theory

50. Chloroplast
• Function:
– Site of photosynthesis
– Only 1 type of plastid – all have different pigments
• Structure
– Double membrane
– Stroma – inner fluid
– Thylakoid – stacked disks with grana
• Have photosynthetic pigments (chlorophyll)
– Have OWN DNA and ribosomes

51. Plastid
Chloroplast

52. Mitochondria
• Function:
– Powerhouse of the cell
– Carries out cellular respiration
• Structure:
– Double membrane
– Matrix – inner “goo”
– Crtistae – folds in inner membrane w/ enzymes for
cellular respiration
– Have OWN DNA

54. Cell Junctions
Type Function Example Location
plasmodesmata enable direct, regulated, symplastic intercellular
transport of substances between cells
plant cell walls
tight junctions hold cells together; help to maintain the polarity of
cells; prevent the passage of molecules and ions
through the space between plasma membranes of
adjacent cells
the kidney and liver
anchoring
(adhering) juctions
serve as a bridge connecting the actin cytoskeleton
of neighboring cells through direct interaction
epithelial and
endothelial tissues
gap junctions connects the cytoplasm of two cells, which allows
various molecules, ions, and electrical impluses to
directly pass through a regulated gate between cells
nerves

55. Cell Junctions: Tight Junction

56. Cell Junctions: Anchoring (Adhering) Junction

57. Cell Junctions: Gap Junction

58. Organelles Summary
Organelle Structure Function
Plant
Cells?
Animal
Cells?
Nucleus contains DNA and RNA provides a segregated site for genetic
transcription, allowing levels of gene regulation
that are not available to prokaryotes
Yes Yes
Ribosome highly complex; made up of dozens of
distinct proteins
serves as the primary site of biological protein
synthesis (translation)
Yes Yes
Rough endoplasmic
reticulum
membrane studded with ribosomes manufacture of secreted proteins; manufacture
of lysosomal enzymes
Yes Yes
Smooth endoplasmic
reticulum
membrane (smooth) synthesizes lipids, phospholipids, and steroids Yes Yes
Golgi apparatus large stacks of membrane-bound
structures
packages proteins inside the cell before they
are sent to their destination
Yes Yes
Lysosome spherical vesicles containing enzymes break down proteins, nucleic acids,
carbohydrates, lipids, and cellular debris
Rarely Yes
Central vacuole enclosed compartments filled with water isolates materials that might be harmful or a
threat to the cell; contains waste products
Yes No
Peroxisome lipid bilayer membrane; crystalloid core
(not always present)
breakdown very long chain fatty acids; detoxify
various toxic substances that enter the blood
Yes Yes
Chloroplast outer and inner membrane surrounding
thylakoid system
conduct photosynthesis Yes No
Mitochondrion Membrane surrounding cristae and
matrix (containing mitochondrial DNA)
generate most of the cell's supply of ATP, used
as a source of chemical energy
Yes Yes
Cytoskeleton network of fibers composed of proteins;
dynamic
allows cells to migrate; stabilizes tissues Yes Yes
Cell wall tough, flexible layer surrounding cells protection and filtering Yes No