Cell Theory

Cells

Biology I

Unit 3

Mrs. Abbott

The History of the Cell

●Cell - the basic unit of living organisms

●4 Major Scientists:

○Leeuwenhoek (1674) - described cells as seen through a simple microscope.

○Robert Hooke (1665) - used a crude compound microscope to examine cork cells from the back of oak trees.

○Matthias Schleiden (1830s) - observed plants and concluded that all plants are composed of cells.

○Theodor Schwann (1830’s) - made observations concerning animal cells.

Multiple Choice

How many scientists made contributions to cell theory?

• 2
• 4
• 5
• 3

Multiple Choice

Which scientist made contributions to cell theory regarding animal cells?

• Theodor Schwann
• Louis Pasteur
• Robert Hooke
• Rudolf Virchow

Multiple Choice

Who was credited with making observations regarding cork cells?

• Anton van Leeuwenhoek
• Louis Pasteur
• Gregor Mendel
• Robert Hooke

Multiple Choice

What scientist first saw cells through a simple microscope?

• Robert Hooke
• Anton van Leeuwenhoek
• Charles Darwin
• Louis Pasteur

Multiple Choice

Name the scientist that made observations regarding plant cells.

• Robert Hooke
• Gregor Mendel
• Louis Pasteur
• Matthias Schleiden

Cell Theory

●The observations and conclusions from these and other scientists from the late 17th century to the time of Schleiden and Schwann are summarized into the Cell Theory.

●The Cell Theory is made up of 3 main ideas:

○All organisms are composed of one or more cells.

■Can be single celled or multicellular.

○The cell is the basic unit of organization of organisms (life)

○All cells come from pre-existing cells.

Multiple Choice

What portion of cell theory makes it a theory?

• All organisms are made up of one or more cells.

• The cell is the basic unit of life.

• Cells can be unicellular or multicellular.

• All cells come from pre-existing cells.

Multiple Choice

True or False: All cells are either unicellular or multicellular.

• True

• False

Basic Types of Cells

●2 types of cells:

○Prokaryote - an organism with a cell that lacks internal structures surrounded by membranes.

■Single Celled Organisms.

○Eukaryote - an organism that has cells containing internal, membrane bound structures.

■These structures are called organelles.

■These organelles have a membrane surrounding it, isolating it from the rest of the cell.

■Largest organelle in the cell is the nucleus - contains the cell’s DNA and controls the cell’s
functions.

Multiple Choice

What are the two basic cell types?

• Multicellular cells and Unicellular cells
• Prokaryotic cells and Eukaryotic cells
• Animal cells and Plant cells
• Bacterial cells and Viral cells

Multiple Choice

What is the difference between a prokaryote and a eukaryote?

• Prokaryotes have a nucleus; eukaryotes do not.
• Eukaryotes are always unicellular; prokaryotes are multicellular.
• Prokaryotes are larger than eukaryotes in size.
• Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

Multiple Choice

What is a cell organelle?

• A cell organelle is a type of protein that helps in cell division.
• A cell organelle is a specialized structure within a cell that performs a specific function.
• A cell organelle is a liquid found in the cytoplasm.
• A cell organelle is a type of virus that infects cells.

Poll

What is the largest organelle in the cell?

• Cell Membrane

• Mitochondria

• Nucleus

• Nucleolus