Cytology—the study of cells.

1600’s

Anton van Leeuwenhoek—Holland inventor invented the microscope. The first to observe microorganisms in pond water.

Robert Hooke—Coined the word "cell" after observing cork under the microscope.

1800’s

Matthias Schleiden—German botanist concluded, "all plants are made up of cells".

Theodor Schwann—Another German scientist concluded, "all animals are made up of cells".

Rudolf Virchow—German physician who studied cell reproduction. Proposed the thought that all cells come from existing cells.

Over the course of 200+ years and many contributions from many scientists, the cell theory was born.

• All living things are composed of cells.
• Cells are the basic units of structure and function in living things.
• New cells are produced from existing cells.

Basic cell structures, common to most cells:

*Cell membrane

• thin, flexible barrier around the cell
• functions to hold the cell together
• also functions to regulate flow of materials in and out of the cell

• strong layer around the cell membrane
• found in plants, algae and some bacteria (not in animal cells)
• function to provide support and protection to the cell

• contains most of the cell’s genetic material
• functions to control the cell’s activities
• largest organelle of a cell

• all the fluid material inside the cell membrane, excluding the nucleus
• contains many important organelles

Cell Wall

• found in plants, algae, fungi, and almost all prokaryotes except animals
• function to provide support and protection for the cell
• made from fibers of carbohydrates and protein
• plant cell walls made of cellulose

• network of protein filaments that helps the cell maintain its shape
• provides support and aids in cell movement
• made up of microtubules and microfilaments

• hollow tubes of protein
• form tracks that are important in moving organelles around in the cell
• help cell maintain its shape
• help separate chromosomes in cell division
• in some cells, form cilia and flagella, which enable cells to move

• long thin fibers that support the cell and help the cell to move
• form tough, flexible framework that supports the cell
• smaller, narrower than microtubules

• controls most cell processes
• contains the hereditary information of DNA
• DNA holds the coded instructions for making proteins

 

Chromatin

• granular material within the nucleus
• consists of DNA bound to protein

• condensed chromatin
• threadlike structures contain the genetic information that is passed from one generation of cells to the next

• small dense region of the nucleus
• assembly of ribosomes starts here

• double membrane layer surrounding the nucleus
• contains pores which allow material to move in and out of nucleus

Ribosomes

• small particles of RNA and protein
• function to produce proteins
• site of mRNA translation
• translate mRNA into specific amino acids or polypeptide chains

• internal membrane system
• function to assemble cell membrane
• also function to modify proteins

• function to synthesize proteins
• proteins made by ribosomes are chemically modified in the rough ER
• has ribosomes on its surface

• does not contain ribosomes on its surface
• contains collections of enzymes that perform specialized tasks

Golgi Apparatus

• stack of membranes
• receive proteins made by rough ER
• function to attach carbohydrates and lipids to proteins by use of enzymes made here

• small organelles filled with enzymes
• function to break down lipids, carbohydrates, and proteins from ingested food into smaller particles that can be used by the cell
• also function to breakdown old organelles

• saclike structures
• function to store water, salts, proteins and carbohydrates
• some vacuoles are involved with transporting substances within the cell
• plant cells have single large, central vacuole which provide support for leaves and flowers

• found in plant cells and some other organisms
• never found in animal or fungal cells
• function to use energy from sunlight to make food in the process of photosynthesis
• contain the green pigment chlorophyll in photosynthetic membranes
• contain some of their own genetic information in the form of DNA

• function to release energy from stored food particles
• use energy to make high-energy compounds that the cell uses for growth, development, and movement
• known as the powerhouse of the cell
• found in most all eukaryotic cells
• contain some of their own genetic information in the form of DNA



 
 

*The cytoskeleton supports the structure of the cell.

*The nucleus controls the activities of the cell.

*The nucleus sends RNA to the rest of the cell.

*RNA carries instructions for the type of protein to be made.

*The ribosomes make the protein.

*Proteins are released to the Golgi Apparatus.

*The Golgi apparatus attaches carbohydrates and lipids to the proteins and transports them to their destination.

*The energy to accomplish all of this comes from chloroplasts and/or mitochondria.

*The chloroplasts use energy from the sun to make food molecules.

*Mitochondria use food to produce high-energy compounds that the cell will use for energy.