1. The Cellular Level of Organization
Living things are constructed of cells.
Living things may be unicellular or multicellular.
Cell structure is diverse but all cells share common characteristics.

2. The cell theory states:
All organisms are composed of one or more cells.
Cells are the basic unit of structure and function in organisms.
All cells come only from other cells.
Cell Theory came about through the work of seventeenth century scientists who had invented fairly primitive microscopes. Antonie van Leeuwenhoek made his own microscopes and observed many types of tiny things. Englishman Robert Hooke was the first to use the term “cell” and confirmed Leeuwenhoek’s findings. During the 1830s, German microscopist Matthias Scheiden found that plants were composed of cells, and Theodore Schwann found that animals were composed of cells. Rudulf Virchow of Germany came to the conclusion that cells come only from preexisting cells. All of these scientists contributed to the Cell Theory. Modern scanning and transmission electron microscopes have allowed scientists to determine the structure of cells at the level of the organelle.
The cell theory also provides us with an operational definition of "life."

3. Cells are small so they can exchange materials with their surroundings.
Surface area relative to the volume decreases as size of cell increases.
- limits the size of cells

4. The different microscopes:
Light microscope - resolving power is limited by the wavelengths of light.
Specimen should be stained, but can be alive
Compound microscope
stereomicroscope
Electron microscope - resolving power is greater since wavelengths of electrons is smaller than those of light.
SEM - 3D image
TEM - flat image
electron microscopes cannot use live specimens

5. 10 must see electron micrograph images!

7. Prokaryotic vs. Eukaryotic Cells
Prokaytotic cells:
Bacteria
genetic material not in a nucleus
no membrane bound organelles
Eukaryotic cells:
Protists, Plants, Fungi and Animals
true nucleus with genetic material
has membrane bound organelles

8. Eukaryotic Cells
All cells are surrounded by a plasma membrane made of phospholipids and proteins.
Eukaryotic cells have membrane bound intracellular organelles.
The most prominent is the nucleus that controls the workings of the cell.
INSIDE A CELL (click here)

9. …SAME IN PROKARYOTE AND EUKARYOTE

10. The plasma membrane regulates what enters and exits the cell.
What is the space between the cell membrane and the nucleus called?
Inside the plasma membrane, the nucleus is surrounded by cytoplasm. This includes the organelles and the cytosol.
The cytosol is the fluid medium found in the cytoplasm
Plant cells have a cell wall in addition to the plasma membrane.
Cytoplasm is a semi-fluid medium.
Primary cell walls are made from cellulose. The secondary cell wall, which forms inside the primary wall, is formed from lignin. Its purpose is to give strength to the cell.

11. Animal and plant cells have organelles.
Organelles compartmentalize functions within the cell.
The organelles of animal and plant cells are similar to each other except that centrioles are present only in animal cells, and chloroplasts are present only in plant cells.

12. Animal cell anatomy

13. Plant cell anatomy

14. Structure of the Nucleus
Chromatin: DNA and protein complex of threadlike fibers that make up the eukaryotic chromosome.
Chromosome : Chromatin fibers condense into visible chromosomes during cell division.
Nucleolus: Chromatin and ribosomal subunits
Nuclear envelope: Double membrane with pores
Nucleoplasm: semifluid medium inside the nucleus.

15. CELLS/NUCLEUS

16. The nucleus and the nuclear envelope

17. Ribosomes
Protein synthesis occurs at tiny organelles called ribosomes.
Ribosomes are composed of a large subunit and a small subunit.
Ribosomes can be found alone in the cytoplasm, in groups called polyribosomes, or attached to the endoplasmic reticulum.

18. The endomembrane system consists of:
Nuclear envelope
Rough Endoplasmic reticulum
Smooth Endoplasmic reticulum
Golgi apparatus
Vesicles
MOVEMENT OF MATERIAL INSIDE the CELL
The membranes that make up the endomembrane system are connected by direct physical contact and/or by the transfer of vesicles from one part to the other.

20. Vesicles
A vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. Vesicles store, transport, or digest cellular products and waste

21. Vesicles and the Rough ER

22. The endoplasmic reticulum
The endoplasmic reticulum (ER) is a system of membranous channels and saccules.
Rough ER is studded with ribosomes and is the site of protein synthesis and processing. Also will store inactive proteins
Smooth ER lacks ribosomes and is the site of synthesis of phospholipids and the packaging of proteins into vesicles, among other functions.
Saccules are flattened vesicles.

25. The Golgi apparatus
The Golgi apparatus consists of a stack of curved saccules.
Process proteins from inactive to active
Formation of Lysosomes
The Golgi apparatus receives protein and also lipid-filled vesicles from the ER, packages, processes, and distributes them within the cell.
This organelle may also be involved in secretion.

27. Lysosomes and vacuoles
Lysosomes are vesicles produced by the Golgi apparatus.
Lysosomes contain hydrolytic enzymes and are involved in intracellular digestion.
Vacuoles (large) and vesicles (small) are membranous sacs in the cell that store substances.
Digestion within the cell disposes of worn-out cell parts and is necessary for cell rejuvenation.
Vacuoles and vesicles can store a variety of substances for the cell. Anything from water to plant pigments and toxic substances are stored in these membranous sacs.

31. Vacuoles Larger than vessicles food vacuoles = formed by phagocytosis
contractile vacuole = found in fresh water protozoans, keep water balance
central vacuole = found in most plant cells stores organic compounds, has enzymes to break macromolecules, has poisonous and unpalatable compounds,etc...

32. Peroxisomes Peroxisomes are vesicles than contain enzymes.
Contains enzymes that transfer hydrogen from substrates to oxygen, producing hydrogen peroxide.
Peroxisomes are abundant in the liver where they produce bile salts and cholesterol and break down fats.
In liver they detoxify alcohol and other poisons, by transferring hydrogen from poison to oxygen
Hydrogen peroxide is toxic, what enzyme can be used to break this down?

33. Energy-Related Organelles
The two energy-related organelles of eukaryotes are chloroplasts and mitochondria.
Both organelles house energy in the form of ATP.

34. Mitochondria and Chloroplasts
Not part of endomembrane system
their membrane proteinsare made by free ribosomes and their own ribosomes
Both have small amount of DNA
Grow and reproduce on their own within the cell
Involved in Energy transformation

35. Chloroplasts
A chloroplast is bounded by two membranes enclosing a fluid-filled stroma that contains enzymes.
Membranes inside the stroma are organized into thylakoids that house chlorophyll.
Chlorophyll absorbs solar energy and carbohydrates are made in the stroma.

37. Mitochondria Also Known as the ‘Power House’ of the cell
Mitochondria are found in plant and animal cells.
Mitochondria are bounded by a double membrane surrounding fluid-filled matrix.
The inner membranes of mitochondria are cristae.
The matrix contains enzymes that break down carbohydrates and the cristae house protein complexes that produce ATP.

39. The Cytoskeleton Actin filaments
The eukaryotic cytoskeleton is a network of filaments and tubules that extends from the nucleus to the plasma membrane.
The Cytoskeleton is a network of protein fibers in the cytoplasm that gives shape to a cell, holds and moves organelles, and is typically involved in cell movement
The cytoskeleton contains three types of elements responsible for cell shape, movement within the cell, and movement of the cell:
Actin filaments
Microtubules
Intermediate filaments

40. Cytoskeleton

42. Microtubules are shown in green, actin is shown in red and DNA is in blue.

43. Actin filaments occur in bundles or mesh-like networks.
Actin filaments play a structural role in intestinal microvilli and also interact with motor molecules, such as myosin.

44. Microtubles are small hollow cylinders made of the globular protein tubulin.
Microtubules are tubes made up of spiraling, two-part subunits.  It aids in chromosome movement, movement of organelles, and the movement of cilia and flagella.
Microtubules help maintain the shape of the cell and act as tracks along which organelles can move.

46. Centrioles
Centrioles are short cylinders with a pattern of microtubule triplets.
Centrioles may be involved in microtubule formation and disassembly during cell division and in the organization of cilia and flagella.

47. Prokaryotic Cells Prokaryotic cells include the bacteria and archaea.
Bacterial cells have these constant features:
Outer Boundary: Cell wall
Plasma membrane
Cytoplasm: Ribosomes
Thylakoids (Nucleoid: Chromosome (DNA only)

48. Bacterial cells may have plasmids, small accessory rings of DNA.
Some bacteria have a capsule or a slime layer.
Most bacteria have flagella.
Some also have fimbriae that help cells attach to surfaces.
Bacteria have a great metabolic diversity!

49. THE FIGHT OR FLIGHT RESPONSE
CELLS COMMUNICATE Cells communicate through signals, aided by pathways made mostly of proteins. A cell's response depends on the signal itself, as well as the cell type.
THE FIGHT OR FLIGHT RESPONSE

50. Evolution of the Eukaryotic Cell
Endosymbiotic hypothesis
Eukaryotes arose from a symbiotic relationship between various prokaryotes.
Heterotrophic bacteria became mitochondria.
Cyanobacteria became chloroplasts.
Host cell was a large eukaryotic cell.
Evidence for the endosymbiotic hypothesis is the following:
Mitochondria and chloroplasts are similar to bacteria in both size and structure.
Both organelles are bounded by a double membrane – the outer membrane may represent the engulfing vesicle, and the inner membrane from the prokaryote.
Mitochondria and chloroplasts each contain a limited amount of genetic material and divide by splitting. The DNA is a circular loop like that of prokaryotes.
Most proteins of mitochondria and chloroplasts are now produced by the host cell, but these organelles do have their own ribosomes and do produce some proteins. Their ribosomes resemble those of prokaryotes.
The RNA base sequence of the ribosomes in chloroplasts and mitochondria suggests a prokaryotic origin.
Lynn Margulis proposed endosymbiont hypothesis: that organelles derived from ancient colonization of large bacteria (became the eucaryotic cell) by smaller bacteria (became the mitochondria, chloroplast, etc.) Symbiosis = "living together". Eventually, organelles lost ability to exist as separate organisms, cannot be separated from cell. Recent evolutionary taxonomy by comparing ribosomal RNA shows that this idea has lots of merit.

51. Some of the oldest cells on Earth are single-cell organisms called bacteria. Fossil records indicate that mounds of bacteria once covered young Earth. Some began making their own food using carbon dioxide in the atmosphere and energy they harvested from the sun. This process (called photosynthesis) produced enough oxygen to change Earth's atmosphere. Soon afterward, new oxygen-breathing life forms came onto the scene. With a population of increasingly diverse bacterial life, the stage was set for some amazing things to happen.
THE EVOLUTION OF THE CELL
                                                                                              
Click on picture.

52. Evolution of the eukaryotic cell

53. Name the cell structure and its function.
Let’s Review:
Name the cell structure and its function.
Be able to tell if this structure is found in prokaryote, eukaryote, plant and/or animal cells.
And…
Or…