1. Cells
Ms. Tardalo
8/31/15

2. What is a cell? A cell is the basic unit of life.
This means that a single cell is the smallest living thing.

3. How were cells discovered?
Hooke: Robert Hooke coined the term cells, after observing the cell walls of cork under a primitive microscope in 1665.

4. How were cells discovered?
Leeuwenhoek: constructed microscopes that furthered the study of cells
Observed bacteria (single-celled organisms in pond water) and human blood cells
Schleiden: plant tissue is composed of cells
Schwann: animal tissue is composed of cells
Virchow: all cells are derived from other pre-existing cells

5. The Spontaneous Generation Myth:
Spontaneous generation, the hypothetical process by which living organisms develop from nonliving matter; also, the archaic theory that utilized this process to explain the origin of life.
It explained such occurrences as the appearance of maggots on decaying meat.
Redi and Pasteur debunk the myth:

6. The cell Theory
All living organisms are composed of cells. They may be unicellular or multicellular.
The cell is the basic unit of life.
Cells arise from pre-existing cells.

7. Cells can only grow to a certain size
Why do cells stop growing at a certain point?
Each internal region of the cell has to be served by part of the cell surface. As a cell grows bigger, its internal volume enlarges and the cell membrane expands. Unfortunately, the volume increases more rapidly than does the surface area, and so the relative amount of surface area available to pass materials to a unit volume of the cell steadily decreases.
Finally, at some point, there is just enough surface available to service all the interior; if it is to survive, the cell must stop growing.

8. Types of Cells
Prokaryotic (“Before nucleus”): oldest and simplest cell type, single –celled/ unicellular organisms, DO NOT contain membrane bound organelles (DO NOT contain a nucleus)
Examples: Bacteria
Eukaryotic (“True nucleus”): more complex cell type, majority are multi-cellular organisms, contain membrane-bound organelles, such as a nucleus.
Examples: Plants and Animals

9. Comparing Prokaryotic and Eukaryotic Cells
cytoskeleton

10. What does Membrane-Bound mean?
What is an organelle?
Organelle (“tiny organ”): specialized, membrane-bound structures within eukaryotic cells
It means the organelle is completely surrounded by a membrane.
Organelles exist to provide specialized environments for each of the cellular processes
This allows the cell to carry out multiple, conflicting processes all at the same time
This makes eukaryotic cells more complex
What does Membrane-Bound mean?
WhY Organelles?

11. Organelles
Nucleus: Contains hereditary information (DNA), where transcription, the process of creating mRNA from a DNA template, takes place
Nuclear envelope: membrane that surrounds the nucleus, it contains nuclear pores that allow for transport into and out of the nucleus.
Nucleolus: nuclear subdomain that assembles ribosomes.

12. Organelles
Mitchondria: Produces energy for the cell in the form of ATP (adenosine triphosphate) through the process of cellular respiration
Outer Membrane: outermost membrane
Inner membrane: Innermost membrane
Intermembrane space: space between the outer and inner membrane
Cristae: folds of the inner membrane that serve to increase surface area
Matrix: space inside the inner membrane

13. Organelles
Endoplasmic Reticulum (ER): The endoplasmic reticulum is a network of tubules and flattened sacs that serve a variety of functions in the cell.
There are two regions of the ER that differ in both structure and function:
rough ER because it has ribosomes attached to the cytoplasmic side of the membrane: manufactures membranes and secretory proteins
smooth ER because it lacks attached ribosomes: carbohydrate (sugars) and lipid (fats) synthesis

14. Organelles
Golgi Apparatus: packages things for transport within or out of the cell
Vesicle: membrane-bound compartment for transportation

15. Organelles
Peroxisome: Small vesicles found around the cell that have a single membrane and contain digestive enzymes for breaking down toxic materials in the cell. 
They have an enzyme that cleaves hydrogen peroxide into water

16. Organelles
Vacuole: usually smaller and for storage in animals, usually larger and for storage and digestion in plants. The vacuole of a plant cell will grow as the plant matures.

17. Not technically Organelles:
Cytoplasm:  a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins. In eukaryotic cells, the cytoplasm includes all of the material inside the cell and outside of the nucleus.
Plasma Membrane: boundary that keeps the cells internal environment separate from
Its external environment, selectively transports materials into and out of cell
Cytoskeleton: network of fibrous proteins that extend throughout the cells cytoplasm. They have a role in movement within the cell and supporting cellular structure.
Ribosomes (see next slide)

18. Not an Organelle
Ribosomes: produce proteins for cell via translation, the process of creating a protein from a strand of mRNA
Consist of two units: a large subunit and a small subunit
There are also two types:
Bound Ribosomes: attached to rough endoplasmic reticulum
Free Ribosomes: free in cytoplasm

19. Organelles that are specific to Plant or Animal Cells:
Plants: cell wall, chloroplasts, large vacuole Animals: lysosomes, centrioles

20. Organelles: Plant
Cell Wall: A rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria. Function is structural support and maintaining water balance within cells.

21. Organelles: Plant
Chloroplast: (plants only!!!) convert energy from the sun into usable energy for the plant via the process photosynthesis.
Outer Membrane: outermost membrane
Inner Membrane: innermost membrane
Thylakoid: A sac-like membrane that contains the chlorophyll (green pigment that captures sunlight)
Stroma: colorless fluid surrounding the grana

22. Organelles: Animal
Lysosome: digestive function in animal cells, contains enzymes that breakdown large molecules for use within the cell or dispose of retired cell parts or waste.

23. Organelles: Animal
Centriole: composed of microtubules (fibrous proteins), have a function in spindle formation during cellular division

24. Comparing Plant and Animal cells
Plants
Both
Animals
Cell wall
Nucleus
Lysosomes
Chloroplasts
Mitochondria
Centrioles
Large Vacuole
Plasma Membrane
Small Vacuoles
Shape: rectangular
Cytoplasm
Shape: round, irregular
Golgi Apparatus
Cytoskeleton
Endoplasmic Reticulum
Ribosomes