3.1 Cell Theory These are some things that you may think of when you think of a cell: Cell phone jail cell monk’s cell cell They have/are: structure, small, things inside, matter, mass, made of atoms, used by humans…

3.1 Cell Theory Main Ideas Early studies led to the development of the cell theory Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells.

3.1 Cell Theory The cell theory grew out of the work of many scientists and improvements in the microscope. Many scientists contributed to the cell theory. First to identify cells and named them Made better lenses for microscopes First to note that plants are made of cells Concluded that ALL living things are made of cells Proposed that all cells come from other cells

3.1 Cell Theory Robert Hooke In 1665 he used the three-lens compound microscope to examine thin slices of cork He observed that cork is made of tiny, hallow compartments These compartments reminded Hooke of small rooms found in monasteries (where monks live), so he named them cells.

3.1 Cell Theory More was learned about cells as microscopes improved.

3.1 Cell Theory Cells cork Red blood cells

3.1 Cell Theory How does the size of a cell in a blue whale compare to the size of the cell in a tadpole?

3.1 Cell Theory How does the size of a cell in a blue whale compare to the size of the cell in a tadpole? A: Most cells in a whale are the same size as in a tadpole! So what makes a blue whale so much bigger? A whale has far more cells.

3.1 Cell Theory The Cell theory has three principles. 1. All living things are composed of cells.

3.1 Cell Theory 2. Cells are the basic units of structure and function in living things.

3.1 Cell Theory 3. All cells are produced from other cells.

3.1 Cell Theory One of the 3 principles of cell theory is that ALL existing cells are produced by other existing cells. Apply this principle to a cut on your arm. (Explain what is happening throughout the healing process)

3.1 Cell Theory One of the 3 principles of cell theory is that ALL existing cells are produced by other existing cells. Apply this principle to a cut on your arm. Answer You get a cut You start to bleed You form a scab Messages are sent to skin cells to replicate Skin cells replicate through mitosis New skin cells are created Scab falls off You are healed!

3.1 Cell Theory All cells share certain characteristics:

3.1 Cell Theory All cells share certain characteristics: – –Cells tend to be microscopic. Bacterium (colored SEM; magnification 8800x)

3.1 Cell Theory All cells share certain characteristics: – –Cells tend to be microscopic. – –All cells are enclosed by a membrane. Bacterium (colored SEM; magnification 8800x) cell membrane

3.1 Cell Theory All cells share certain characteristics – –Cells tend to be microscopic. – –All cells are enclosed by a membrane. – –All cells are filled with cytoplasm. Bacterium (colored SEM; magnification 8800x) cell membrane cytoplasm

3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells. Eukaryotic cells have a nucleus. – –The nucleus holds the DNA Have membrane-bound organelles May be multi-cellular or single-celled organisms nucleus cell membrane organelles Draw and label picture on top of p. 24

3.1 Cell Theory Organelles: structures that are specialized to perform distinct processes within a cell. The nucleus is usually the largest and most visible organelle.

3.1 Cell Theory Things that have Eukaryotic Cells: PLANTS ANIMALS FUNGI

3.1 Cell Theory Cytoplasm: is a jellylike substance that contains dissolved molecular building blocks- such as proteins, nucleic acids, minerals, and ions Bacterium (colored SEM; magnification 8800x)

3.1 Cell Theory Prokaryotic cells do not have a nucleus. do not have membrane- bound organelles DNA is in the cytoplasm All are microscopic, single-celled organisms cell membrane cytoplasm Draw and label picture on top of p. 24

3.1 Cell Theory Things that have prokaryotic cells Bacteria Archaea