1. Notes on Cells

2. Cell Theory
1665: Hooke: British, first to look at magnified plant tissue (cork); named cells = basic unit of all life forms
1674: Leuwenhoek: Dutch, first to magnify “nature” with a lens
1838: Schleiden: German, (botanist) said all plants were made of cells
1839: Schwann: German, (zoologist) said all animals were made of cells
1855: Virchow: Stated that all cells come from other cells

3. Robert Hooke
Hooke’s sketch of the cork cells he observed under his microscope.

4. Cell Theory: summary of these discoveries
a. All living things are made up of cells
b. Cells are the basic unit of structure and function in living things
c. New cells are produced from existing cells

5. Prokaryotic Cells No true nucleus No membrane-bound organelles
Single-cell
No Mitochondria
Have cell wall and cell membrane
Grow, reproduce, respond to changes in the environment
Do contain ribosomes
DNA is circular (Plasmid)
Belong to the Kingdoms: Archaebacteria and Eubacteria & Cyanobacteria
Much smaller than Eukaryotic cells

6. Eukaryotic Cells Do have a nucleus Eu= true
Do contain a nucleus: a structure that contains genetic information and controls cell functions
Have cell membrane: thin, flexible barrier around cell
Have cytoplasm: material inside cell membrane but not including organelles
ex. Belong to the Kingdoms:
Protista, Fungi, Plantae, Animalia

7. Cell Structures
Cytoplasm
Structure:
Jelly-like material inside the cell membrane which contains water, salts, and organic molecules
Function: In constant movement Cytoplasmic streaming Surrounds organelles

8. Organelles – specialized structures that perform important cellular functions

9. Mitochondria “Powerhouse”
Function: Respiration centers for the release of energy
Use energy from food to make high-energy compounds that the cell can use to power growth, development, Movement
(ATP -adenosine triphosphate) - Most numerous organelle in cells that use a lot of energy (muscles)
Enclosed by 2 membranes
outer – smooth, forms boundary
inner – long folds (cristae) increase surface area
Has its own DNA and ribosomes!
evidence that the mitochondria evolved from a heterotrophic prokaryote

10. Mitochondria

11. 2. Endoplasmic reticulum (ER)
Membrane system of sacs and tunnels
covered with ribosomes- rough ER, place where proteins are modified
few or no ribosomes – smooth ER, contains enzymes that perform specialized tasks, like production of lipids
“intracellular highway”

12. Smooth and Rough ER

13. 3. ribosomes
“protein factories”
made of RNA and proteins
where proteins are made (most numerous organelle) – produces proteins following encoded instructions that come from the nucleus
granulated, attached to ER or float in cytoplasm

14. Ribosomes

15. 4. Golgi apparatus
processing, packaging, and secreting organelle
stack of membranes or sacs which package proteins produced by rough ER
“protein packagers”

16. contain digestive enzymes
5. lysosomes
contain digestive enzymes
breakdown carbohydrates, lipids, and proteins into particles that can be used by the cell
breakdown of organelles that are no longer useful
remove debris that otherwise accumulate/clutters the cell
in animal cells and fungi
“suicide sacs”
lysis = breakdown
soma = body

17. Lysosomes “suicide sacs”

18. 6. centrioles
rod-shaped bodies close to the nucleus which guide the cell during division
animals cells only

19. 7. Vacuoles
cavities (containers) which store enzymes, waste products, water, salts, proteins, and carbohydrates
mainly in plant cells – plants have a large central vacuole filled with liquid
in mature plants – the vacuole takes up 90% of volume of the cell
smaller vacuoles are called vesicles

20. chemical factories to store food only in plants can contain pigments
8. plastids
chemical factories to store food
only in plants
can contain pigments
example: chloroplasts

21. Cytoskeleton: framework of cell (supports the cells)
network of protein filaments
used in cell movement
9. Microtubules
small hollow tubes of protein; maintains cell shape, forms tracks along which organelles are moved
assembled and broken down as needed (during cell division)
in some cells they form cilia and flagella that aid in movement
act as the “bones” in the cell

22. Flagella and Cilia

23. 10. microfilaments
protein threads of actin for cytoplasmic streaming
smaller than microtubules
act as “muscles” in the cell

24. Nucleus – identified in 1831
control center of the cell
site of nucleic acid synthesis

25. Nucleus nuclear envelope (membrane)
double membrane (phospholipids and proteins)
nuclear pores allow substances to enter and leave

26. Nucleus 2. nucleoplasm protoplasm within the nucleus
dense, protein rich

27. Nucleus 3. nucleolus (singular), nucleoli (plural) form ribosomes
composed of RNA

28. Nucleus 4. chromatin fine strands of DNA and proteins genetic material
chromosomes – coiled up chromatin when the cell is dividing

29. Differences in Plant Cells
a. Cell wall – provides support and protection for plant cell
contain pores which allow H2O, CO2, and O2 to pass through
made from fibers of carbohydrates and proteins (cellulose)
cellulose – tough carbohydrate fibers, makes up wood and paper

30. Differences in Plant Cells:
b. vacuoles – one large central vacuole
- 90% of cell’s volume

31. Differences in Plant Cells:
c. Plastids
Plastid
Pigment
Function
Chloroplast
Chlorophyll
Absorb sun’s energy
Chromoplast
Carotene (orange)
Xanthophyll
(pale yellow)
Store pigments
Leucoplast
N/A
Store food as starches, lipids, or proteins

32. Cell Membrane

33. Cell Membrane
forms outer boundary and separates the cell from its surroundings and other cells
composed of two layers of phospholipids and proteins – both move like a liquid called “fluid mosaic model”

34. Fluid Mosaic Model
Phospholipid molecule
(2-layers)

35. contains protein molecules that provide attachment points for carbohydrate molecules to form chains
some proteins in cell membrane form channels and pumps to help move materials
regulates what enters and leaves the cell – selectively permeable (semi-permeable) (Keeps out some molecules but allows others to enter)

36. Evolution of Cells Present day bacteria are divided into two groups
Archaebacteria and Eubacteria
Diverged early in evolutionary history

37. Endosymbiosis created Eukaryotic cells
Symbiotic association with prokaryotes
Mitochondria and chloroplasts evolved from prokaryotic organisms living inside larger cells

38. Evidence of Endosymbiosis
Chloroplasts and mitochondria have their own unique DNA that replicates independently
Chloroplasts and mitochondria are similar in size to bacteria (prokaryotes)
The ribosomes of chloroplasts and mitochondria are more closely related to bacterial ribosomes than those of eukaryotes

39. Evolution of Cells into Multicellular Organisms
Evolved from unicellular eukaryotes
Colonies of algae are precursors to present day multicellular plants
Increasing specialization led to the transition from colonies to multicellular organisms