Cell Structure and Function
Essential Question Why is the cell considered the basic unit of all life?
Discovery of Cells It wasn’t until the 1600s that scientists were able to use microscopes to observe living things.
Cells In 1665, Robert Hooke observed cork cells under the microscope. He called them cells. This is a drawing he made of the cork cells.
More Cork Cells Here is what cork cells look like in a modern microscope with special lighting.
Leeuwenhoek’s Microscope Anton Van Leeuwenhoek used a single-lens microscope to view pond water and other things. Here is his microscope.
Cell Theory All living things are made of cells. The Cell Theory States All living things are made of cells. Cells are the basic units of structure and function in living things. New cells are produced from existing cells. It wasn’t long before scientists realized that all living things were made up of cells. This discovery brought about the formulation of the cell theory.
Types of Cells Cells are classified as prokaryotic or eukaryotic. Prokaryotic cells have genetic material that is not inside a nucleus. No nucleus. Eukaryotic cells have genetic materials in a nucleus. (“true” nucleus)
Cell Structures Cells contain small structures called organelles. Each organelle has a specific job it performs in the cell.
1.The Nucleus This is a membrane-bound structure that contains the DNA. DNA is the genetic material that is the code for making proteins. EX: Chief Executive Officer (CEO) Found: Both
2. Ribosomes EX: Workers in the assembly line Ribosomes are protein assembly organelles. Ribosomes can be “free” in the cytoplasm or on the endoplasmic reticulum. EX: Workers in the assembly line Found: Both
3. Endoplasmic Reticulum The endoplasmic reticulum is the site where lipids of the cell membrane are assembled, along with proteins and other materials. It can contain ribosomes and be Rough ER or have no ribosomes and be Smooth ER EX: Assembly line (where workers do their work) Found: Both
4. Golgi Apparatus The golgi apparatus modifies, sorts, and packages proteins and other materials from the ER. EX: Finishing / packaging department Found: Both
5. Lysosomes Lysosomes are small organelles that contain enzymes. These enzymes breakdown lipids, carbohydrates, and proteins into small molecules that can be used by the cell. Lysosomes also remove “junk and clutter” in the cell. EX: Maintenance crew
6. Vacuoles Vacuoles are storage organelles.They store water, salts, proteins, etc. Plants have a large vacuole that helps plants support leaves and stems. Example: Warehouse Found: Both
7. Mitochondria The mitochondria is the organelle that converts chemical energy from food into ATP to power cell processes. EX: Power plant Found: Both
8. Chloroplasts Chloroplasts are organelles that capture sunlight energy and convert it into chemical energy in a process known as photosynthesis. EX: Power plant Found: Plants
9. Cytoskeleton The cytoskeleton is a network of protein filaments that helps the cell maintain its shape. EX: Support beams (walls, ceilings, and floors)
10. Cell Membrane The cell or plasma membrane surrounds the cell and regulates what enters and exits the cell. Ex: shipping and receiving Found: Both
Cell Wall Found: Plants
11. Cytoplasm The cytoplasm (cytosol) is the fluid outside the nucleus. It contains the organelles. EX: factory floor where most of the products are assembled, finished, and shipped. Found: Both
12. Centrioles Centrioles are cylindrical bundles of microtubules that function in cell reproduction. Found: Animals
Division of Labor In multicellular organisms, each cell has a specialized task to keep the organism alive. Specialized cells include blood, muscle, heart cells, etc. Living things are organized into the following hierarchy. 1. Cells 2. Tissues 3. Organs 4. Organ Systems 5. Organisms
Levels of Organization This chart shows the increasing complexity of organization from tiny molecules to the whole biosphere. 1. Macromolecules 2. Organelles 3. Cells 4. Tissues 5. Organs 6. Organisms 7. Populations 8. Communities 9. Ecosystems 10. Biosphere