1. LIFE IS CELLULAR

2. THINK ABOUT IT
What’s the smallest part of any living thing that still counts as being “alive?”
Can we just keep dividing living things into smaller and smaller parts, or is there a point at which what’s left is no longer alive?
As you will see, there is such a limit. The smallest living unit of any organism is the cell.

3. The Discovery of the Cell
What is the cell theory?
The cell theory states:
- All living things are made up of cells.
- Cells are the basic units of structure and function in living things.
- New cells are produced from existing cells.

4. Early Microscopes Early Microscopes date back to the mid-1600s
In 1665, Englishman Robert Hooke used an early compound microscope to look at cork.
Saw tiny, empty chambers that Hooke called “cells”.

6. In Holland, Anton van Leeuwenhoek examined pond water and mouth swabs.
Saw bacteria.

7. The Cell Theory
Soon after Leeuwenhoek, observations made by other scientists made it clear that cells were the basic units of life.

8. In 1838, German botanist Matthias Schleiden concluded that all plants are made of cells.

9. The next year, German biologist Theodor Schwann stated that all animals were made of cells.

10. In 1855, German physician Rudolf Virchow concluded that new cells could be produced only from the division of existing cells.
Confirming a suggestion made by German Lorenz Oken 50 years earlier.

11. The cell theory states:
-All living things are made up of cells.
-Cells are the basic units of structure and function in living things.
-New cells are produced from existing cells.

12. Light Microscopes
Can study living specimens.

13. A problem with light microscopy is that most living cells are nearly transparent.
Hard to see
Use stains or dyes (but kills the organism)

14. Electron Microscopes
Electron microscopes use beams of electrons, not light.
Much higher resolution than light microscopes.
Study non-living things.

15. TEM – Inner Structures
Transmission electron microscopes make it possible to explore cell structures and the insides of cells.

16. SEM – Surface Only
In scanning electron microscopes, a pencil-like beam of electrons is scanned over the surface of a specimen.

17. Eukaryotic vs. Prokaryotic
How are prokaryotic and eukaryotic cells different?
Prokaryotic cells
– No Nucleus
Eukaryotic cells
– Has a Nucleus

19. Prokaryotes Prokaryotic cells - Small - Simple - No Nucleus
Bacteria are prokaryotes.

20. Eukaryotes - Large - More complex and more advanced
Eukaryotic cells
- Large
- More complex and more advanced
- Lot of Compartments
- Highly Specialized
Eukaryotes:
- plants, animals, fungi, protists.

21. What is the role of the cell nucleus?
Cell Organization
What is the role of the cell nucleus?
The nucleus contains nearly all the cell’s DNA and, with it, the coded instructions for making proteins and other important molecules.

22. The cytoplasm is the fluid portion of the cell outside the nucleus.
Cell Organization
The eukaryotic cell can be divided into two major parts: the nucleus and the cytoplasm.
The cytoplasm is the fluid portion of the cell outside the nucleus.

23. The nucleus = control center. DNA is here.
Surrounded by a nuclear envelope – has 1000s of pores. Why?
Proteins, RNA move in and out of nucleus
Nucleus contains the nucleolus.
Ribosomes are made in nucleolus.

26. Organelles That Store, Clean Up, and Support
What are the functions of vacuoles, lysosomes, and the cytoskeleton?
“Vac” = Vaccuum
Vacuoles store materials like water, salts, proteins, and carbohydrates.

27. “Lys” = Slice
Lysosomes break down (slice) lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell.
They are also involved in breaking down pathogens.

28. The cytoskeleton helps the cell maintain its shape and is also involved in movement.

30. Make up the cytoskeleton
Microfilaments
Microfilaments are threadlike structures made up of a protein called actin.
Make up the cytoskeleton

31. They are also components of flagella.
Microtubules
Microtubules are important in cell division, form the mitotic spindle, which separates chromosomes.
They are also components of flagella.

32. Organelles That Build Proteins
What organelles help make and transport proteins Ribosomes

33. Endoplasmic Reticulum
The endoplasmic reticulum is where lipid components of the cell membrane are assembled.

34. Rough Endoplasmic Reticulum
The portion of the ER involved in the synthesis of proteins.
Ribosomes found on its surface.

35. Endoplasmic Reticulum
Rough ER has ribosomes
NO RIBOSOMES on smooth ER

36. Golgi Apparatus
Proteins produced in the rough ER move to the Golgi apparatus, which appears as a stack of flattened membranes.

37. Golgi Apparatus – UPS of the cell
The Golgi apparatus modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or release outside the cell.

38. Organelles That Capture and Release Energy
Chloroplasts (plants) capture the energy from sunlight and convert it into useable energy.
Mitochondria (animals) convert the chemical energy stored in food into compounds that are more convenient for the cells to use.

39. You get your mitochondria from Mom!
In humans, all or nearly all of our mitochondria come from the cytoplasm of the ovum, or egg cell.
You get your mitochondria from Mom!

40. Cellular Boundaries
What is the function of the cell membrane?
The cell membrane regulates what enters and leaves the cell and also protects and supports the cell.

41. Cellular Boundaries
Similarly, cells are surrounded by a barrier known as the cell membrane.
Most prokaryotes and plants, also produce a strong supporting layer around the membrane known as a cell wall.

42. Cell Membranes
All cells contain a cell membrane that regulates what enters and leaves the cell and also protects and supports the cell.

43. Cell Membranes
Double-layered sheet called a lipid bilayer.

44. The Properties of Lipids
The fatty acid portions of such a lipid are hydrophobic, or “water-hating,”
While the opposite end of the molecule is hydrophilic, or “water-loving.”

45. The Properties of Lipids
The head groups of lipids in a bilayer are exposed to water, while the fatty acid tails form an oily layer inside the membrane from which water is excluded.

46. The Fluid Mosaic Model
Because the proteins embedded in the lipid bilayer can move around and “float” among the lipids, and because so many different kinds of molecules make up the cell membrane, scientists describe the cell membrane as a “fluid mosaic.”

47. The Fluid Mosaic Model
Most biological membranes are selectively permeable, meaning that some substances can pass across them and others cannot. Selectively permeable membranes are also called semipermeable membranes.

49. Passive Transport What is passive transport?
The movement of materials across the cell membrane without using cellular energy is called passive transport.

50. One Type of Passive Transport - Diffusion
The process by which particles move from an area of high concentration to an area of lower concentration is known as diffusion.

52. 2nd Type of Passive Transport - Facilitated Diffusion
Molecules that cannot directly diffuse across the membrane pass through special protein channels in a process known as facilitated diffusion.
The movement of molecules by facilitated diffusion does not require any additional use of the cell’s energy.

54. Osmosis: An Example of Facilitated Diffusion
Osmosis is the diffusion of water through a selectively permeable membrane.
Osmosis involves the movement of water molecules from an area of higher concentration to an area of lower concentration.

55. Osmosis- The diffusion of water through a membrane
Osmosis- The diffusion of water through a membrane. Membranes prevent most solutes from crossing; however, water may move freely
1. The concentration of dissolved solutes and water is inversely proportional. Therefore, diffusion and osmosis are opposites.
2. Cells may be in One of Three Conditions…

56. Water will move equally in and out of the cell
A. Isotonic Environment- equal amount of solute and water on both sides of a membrane
Cell
5% solute
95% H2O
Beaker with 5% solute and 95% water
Water will move equally in and out of the cell

57. Water will move out of the cell
B. Hypertonic Environment- more solute outside the cell and more water in the cell
Beaker with 10% solute and 90% water
Cell
5% solute
95% H2O
Shriveled
Water will move out of the cell

58. C. Hypotonic Environment- less solute and more water outside the cell.
Beaker with 0% solute and 100% water
Cell
5% solute
95% H2O
Cells with no cell wall Burst!
Water will move into the cell

60. Active Transport – Requires Energy
What is active transport?
The movement of materials against a concentration difference is known as
active transport. Active transport requires energy.

61. Endocytosis
In phagocytosis, extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then engulfs it.
Amoebas use this method for taking in food.
Engulfing material in this way requires a considerable amount of energy and, therefore, is a form of active transport.

62. Endocytosis
In pinocytosis, cells take up liquid from the surrounding environment by forming tiny pockets along the cell membrane.
The pockets fill with liquid and pinch off to form vacuoles within the cell.

63. Exocytosis
Many cells also release large amounts of material from the cell, a process known as exocytosis.

64. Levels of Organization
Cells make up tissues…
A tissue is a group of similar cells that performs a particular function.

65. Levels of Organization
To perform complicated tasks, many groups of tissues work together as an organ.

66. Levels of Organization
A group of organs that work together to perform a specific function is called an organ system.
For example, the stomach, pancreas, and intestines work together as the digestive system.