Introduction to Cells

The Discovery of Cells Cells are too small to see! So how were they discovered? In 1665 Robert Hooke, an English scientist, used a crude microscope to look at the cells of a piece of cork. Anton van Leeuwenhoek, from 1665-1675 , studied pond water and called what he saw “animalcules”.

Cell Theory It took over 150 years for scientists to understand the importance of this discovery and to develop the concept of Cell Theory. All living things are made of one or more cells Cells are the basic units in organisms All cells arise from existing cells

Levels of Organization

Looking at Cells A cells shape and size reflects the cell’s function. Cell Size The larger the cell the harder it is for the cell to exchange nutrients and waste. These substances must move farther to reach where they need to go. Cell Shape Larger cells often have shapes to reduce the cells surface area-to-volume ratio How does a cell’s size affect the cell’s function?

Cell Features Cell membrane: the cell’s outer boundary, acts as a barrier. Cytoplasm: includes the fluid inside the cell and many of the structures like ribosomes. Ribosomes: structure that assembles the 20 amino acids of which proteins are made.

Prokaryotic Cells Include bacteria and archaea. They do not have a nucleus, mitochondria, or any other membrane-bound organelles. Evolved before Eukaryotes.

Eukaryotic Cells Eukaryotic cells have a more complex organization with a nucleus and membrane-bound organelles. They are also bigger than prokaryotes. The nucleus is where genetic material is stored.

Introduction to Cells: Review List the three parts of the cell theory. Describe the importance of a cell’s surface area-to-volume ratio. Compare the structure of a eukaryotic cell with that of a prokaryotic cell.

Inside the Eukaryotic Cell Framework Direction of Cellular Activity Protein Processing Storage and Maintenance Energy Production

The Framework of the Cell Much like we have bones, a cell has a web of protein fibers called the cytoskeleton. The cytoskeleton helps the cell: -move -keep its shape -organize its parts

Directing Cellular Activity Almost all cellular activity depends on the proteins that the cell makes. Instructions for making proteins are stored in DNA. What type of Biomolecule is DNA?

Directing Cellular Activity Nucleus DNA is stored in the nucleus. DNA instructions are copied as RNA messages which leave the nucleus which go to …..

Directing Cellular Activity …the Ribosomes…. In the cytoplasm, ribosomes use the RNA message to assemble proteins. They are the factories of proteins!

Protein Processing Some proteins are exported outside the cell. There are two main organelles responsible for this: Endoplasmic Reticulum (ER) two types, smooth ER and rough ER. Ribosomes are attached to the rough ER. Golgi Apparatus This organelle helps make and Package materials to be Transported out of the cell

Storage and Maintenance Vesicles are small membrane enclosed sacs that store and transport materials within a cell. There are several kinds of vesicles. Lysosomes These vesicles contain enzymes that Break down food for the cell and Also digest old organelles. They are made In the Golgi Apparatus. Vacuoles There are many kinds of vacuoles. Some store water , nutrients, and wastes. First pic is animal cell, second is plant. Plants have larger vacuoles for water storage.

Energy Production Cells need a constant source of energy.

Chloroplasts Chloroplasts are organelles that use light energy to make sugar from carbon dioxide and water. Found in plants and plant-like protists (seaweed)

Mitochondria Mitochondria are organelles that use energy from organic compounds to make ATP. What kind of biomolecule is ATP? Why do muscle cells have a lot of mitochondria?

Inside the Eukaryotic Cell: Review 1.Where is DNA stored in a Eukaryotic Cell? 2.What do ribosomes make and what two places will you find them in a cell? 3. Compare the role of mitochondria and chloroplasts.