1. Unit 2: Cells
Objective 1: Describe the fundamental chemistry of living cells
Objective 2: Describe the flow of energy and matter in cellular function
Objective 3: investigate the structure and function of cells and cell parts

2. Intro to Cells
Cells are the basic units that make up every type of organism.
Cells are very small, thus we need a microscope to see them.
Robert Hooke created a primitive light microscope in 1665 and observed cells for the very first time.
How do fats/lipids, carbohydrates, proteins, and nucleic acids come together to form a living organism? By forming a cell. These organic compounds are the raw materials needed for life, and a cell is the smallest unit of an organism that is still considered living. Some organisms, like bacteria, consist of only one cell. Other organisms, like humans, consist of trillions of specialized cells working together. Even if organisms look very different from each other, if you look close enough you’ll see that their cells have much in common.

3. Cell Theory The Cell Theory states:
All organisms are made of cells
Cells are alive and the basic living units of all organisms
New cells come from other cells
Three scientists credited with developing the cell theory are:
Theodor Schwann
Matthias Jakob Schleiden
Rudolf Virchow
In 1858, after microscopes had become much more sophisticated than Hooke’s first microscope, Rudolf Virchow proposed that cells only came from other cells. For example, bacteria are composed of only one cell (Figure below) and divide in half to replicate themselves. In the same way, your body makes new cells by the division of cells you already have. In all cases, cells only come from pre-existing cells.
Credit for developing cell theory is usually given to three scientists: Theodor Schwann, who stated all animals are made of cells, Matthias Jakob Schleiden who stated all plants are made of cells, and Rudolf Virchow who observed cells dividing. In 1839, Schwann and Schleiden suggested that cells were the basic unit of life. Their theory accepted the first two tenets of modern cell theory. In 1855, Rudolf Virchow concluded that all cells come from pre-existing cells. Since 1855 when Virchow introduced the ideas, the cell theory has been supported by thousands of experiments and no evidence has ever contradicted it.

4. Cell Structure: What are Cells Made of?
Cell membrane
Nucleus and chromosomes
Other organelles
Prokaryotic and Eukaryotic Cells
Understanding the structure and function of cells is essential to understanding how living organisms work. Cell biology is central to all other fields of biology, including medicine. Many human diseases and disorders are caused by the malfunction of people’s cells. Furthermore, toxins in the environment often impact specific cellular processes. The healthy functioning of the body and its organs is dependent on its smallest unit - the cell. To better understand the biology of the cell, you will first learn to distinguish the two basic categories of all cells: prokaryotic and eukaryotic cells. You will also learn what makes a cell specialized; there are major differences between a “simple” cell, like bacteria, and a “complex” cell, like a cell in your brain. To understand these differences, you need to first understand the basic components of the cell, which include the:
 Cell membrane
 Nucleus and chromosomes
 Other organelles
 Prokaryotic and Eukaryotic Cells

5. Prokaryotic Vs Eukaryotic Cells
Prokaryotic Cells
Eukaryotic Cells
Include bacteria & archaea
Small & simple; usually microorganisms
Surrounded by cell wall (supports & protects the cell)
MAIN DIFFERENCE: The DNA (genetic material) forms a single large circle that coils up on itself; do not have a nucleus
Contain extra small circles of DNA, known as plasmids
Organelles are absent
Include all other cells
Larger and more complex; specialized
MAIN DIFFERENCE: Contain a nucleus (where the DNA “lives” and surrounded by a membrane)
Contains organelles

6. Prokaryotic vs Eukaryotic Cells

7. Plasma Membrane (both)
The plasma membrane is a double layer of specialized lipids, known as phospholipids, along with many special proteins. It is used to control what goes in and out of the cell.
It is semipermeable because it is selective of what enters and leaves.
The cell membrane gives the cell an inside that is separate from the outside world, without it, the prats of a cell would just float away.
Without a cell membrane, a cell would be unable to maintain a stable internal environment separate from the external environment (homeostasis).
Plasma Membrane (both)

8. Cytosol (both) An internal fluid-like substance.
Composed of water and other molecules, including enzymes that speed up the cell’s chemical reactions.

9. Organelles in Eukaryotic Cells
Ribosomes
Involved in making proteins
Golgi apparatus (golgi bodies)
Packages proteins and some polysaccharides
Mitochondria
Makes ATP (energy)
Smooth Endoplasmic Reticulum (ER)
Makes lipids, transports
Rough Endoplasmic Reticulum (ER)
Makes proteins, transports
Lysosomes
Digests macromolecules
Cell Membrane
Regulates input and output; semipermeable

10. Organelles in Eukaryotic Cells
Vacuole
Storage of water, nutrients and wastes
Cytoplasm
Nucleus
Controls functions of the cell, contains DNA
Nucleolus
Where ribosomes are made
*Chloroplast
Makes sugar (photosynthesis; plant)
*Cell Wall
Support, structure (plant)
^Centriole
Aids in cell division (animal)

11. Nucleus Found exclusively in eukaryotic cells.
Membrane-enclosed structure contains most of the genetic material.
Holds vital information, mainly detailed instructions for building proteins.

12. Nucleus
Nuclear envelope – a double membrane that surrounds the nucleus; controls which molecules go in and out of the nucleus.

13. CHromosomes Chromosomes are the DNA all wrapped in special proteins.
The genetic information on the chromosomes is stored, made available to the cell when necessary, and also duplicated when it is time to pass the genetic information on when a cell divides.
All the cells of a species carry the same number of chromosomes. Human cells each have 23 pairs of chromosomes.
Chromosomes carry hundreds or thousands of genes that help determine traits.

14. The Cell Factory
Mitochondria – powerhouse of cell; generates ATP (cellular respiration)
Chloroplasts – capture sunlight energy; make glucose (photosynthesis)
Vacuoles – storage centers
Cytoskeleton – internal skeleton
Lysosomes – recycling trucks; break down old molecules
Ribosomes – make proteins
Rough Endoplasmic Reticulum – covered with ribosomes; make and transport proteins
Smooth Endoplasmic Reticulum – makes lipids and transports them
Golgi Apparatus – receives products from ER and ships them where they need to go

15. Plant Cells Plant cells differ from animal cells. Plant cells have:
A large central vacuole
A cell wall (gives the plant cell strength, rigidity, and protection)
Chloroplasts (carry out photosynthesis)