Lesson Overview 7.1 Life is Cellular

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.

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.

Early Microscopes and the Cell Theory 1665 – Robert Hooke – Compound Microscope First to identify cells Same time period – Anton van Leeuwenhoek First to observe living microorganisms 1838 – Matthias Schleiden (German botanist) Plants are made of cells 1839 – Theodor Schwann (German biologist) All animals are made of cells 1855 – Rudolf Virchow (German physician) New cells only from division of existing cells (Lorenz Oken 50 years earlier)

Virchow contribution to the cell theory had to do with Cell structure Cell membranes Cell reproduction Cell size of 26 45 Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Who stated that all animals are made of cells Robert Hooke Matthias Schleiden Rudolf Virchow Theodor Schwann of 26 45 Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Cell Theory So once again, 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.

Which of the following is not part of the cell theory? All living things are made of cells Basic units of structure and function Plants and animals are made of cells Cells come from existing cells of 26 45 Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Cells are the basic units of life. True False of 26 45 Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Prokaryotes and Eukaryotes How are prokaryotic and eukaryotic cells different? Prokaryotic cells do not separate their genetic material within a nucleus. In eukaryotic cells, the nucleus separates the genetic material from the rest of the cell.

Prokaryotes and Eukaryotes Cells are amazingly diverse. Size varies (typically 5-50 micrometers) 0.2 microns – 1000 microns All Cells have DNA All Cells have a cell membrane (thin flexible barrier) Cells may or may not have a nucleus (nuclei) Contains genetic material, has membrane Whether or not they have a nucleus determines whether they are prokaryotes or eukaryotes.

In many cells the structure that controls the cell is the…. Cell membrane Nucleolus Nucleus Cytoplasm of 26 45 Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Prokaryotes and Eukaryotes Eukaryotes are cells that enclose their DNA in nuclei. Prokaryotes are cells that do not enclose DNA in nuclei.

Prokaryotes Prokaryotic cells are generally smaller and simpler than eukaryotic cells. Despite their simplicity, prokaryotes grow, reproduce, and respond to the environment, and some can even move by gliding along surfaces or swimming through liquids. The organisms we call bacteria are prokaryotes.

Eukaryotes Eukaryotic cells are generally larger and more complex. Most eukaryotic cells contain dozens of structures and internal membranes. Many eukaryotes are highly specialized. There are many types of eukaryotes: plants, animals, fungi, and organisms commonly called “protists.”

Which of the following is true of a eukaryote but not a prokaryote? Genetic material is in a nucleus It has genetic material Generally smaller and simpler Carries out all activities of living things of 26 45 Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Even though cells are different sizes and shapes they all have DNA and A nucleus A cell membrane A cell wall Ribosome of 26 45 Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26