cell structuresection 1 section 1: introduction to cells preview bellringer key ideas the discovery...
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Cell Structure Section 1
Section 1: Introduction to Cells
Preview• Bellringer• Key Ideas• The Discovery of Cells• Looking at Cells• Cell Features• Summary
Cell Structure Section 1
Bellringer
After viewing the list of items on the board, work with a partner and make two new lists: those items on the list comprised of cells and those items not comprised of cells.
Give a rationale for each answer.
Cell Structure Section 1
Key Ideas
• How were cells discovered?
• Why does cell shape vary?
• What enables eukaryotes to perform more specialized functions than prokaryotes?
Cell Structure Section 1
The Discovery of Cells
• Microscope observations of organisms led to the discovery of the basic characteristics common to all living things.
• Scientists first discovered cells in the 1600s using crude microscopes.
• Observations made by scientists using more powerful microscopes in the 1800s led to the formation of the cell theory.
Cell Structure Section 1
Visual Concept: Cell Theory
Cell Structure Section 1
Looking at Cells
• Cells vary greatly in their size and shape.
• A cell’s shape reflects its function. Cell size is limited by a cell’s surface area-to-volume ratio.
• Cells can be branched, flat, round, or rectangular.
Cell Structure Section 1
Looking at Cells, continued
• All substances that enter or leave a cell must cross the surface of the cell.
• A cell’s ability to move substances across its surface can be estimated by finding its surface area-to-volume ratio.
• Cells with greater surface area-to-volume ratios can exchange substances more efficiently.
Cell Structure Section 1
Relationship between Surface Area and Volume
Cell Structure Section 1
Looking at Cells, continued
• When comparing cells of the same shape, small cells have greater surface area-to-volume ratios than large cells.
• So, small cells function more efficiently than large cells.
Cell Structure Section 1
Cell Features
• All cells share common structural features, including a cell membrane, cytoplasm, ribosomes, and DNA.
• The cell membrane is the outer layer that covers a cell’s surface and acts as a barrier between the outside environment and the inside of the cell.
• The cytoplasm is the region of the cell within the cell membrane. The cytoplasm includes the fluid inside the cell called the cytosol.
Cell Structure Section 1
Cell Features, continued
• A ribosome is a cellular structure that makes proteins.
• The DNA of a cell provides instructions for making proteins, regulates cellular activities, and enables cells to reproduce.
Cell Structure Section 1
Features of Prokaryotic and Eukaryotic Cells
Cell Structure Section 1
Cell Features, continued
Features of Prokaryotic Cells
• A prokaryote is an organism made of a single prokaryotic cell.
• Prokaryotic cells do not have a nucleus or other internal compartments. The genetic material of a prokaryotic cell is a single loop of DNA.
• For millions of years, prokaryotes were the only organisms on Earth.
Cell Structure Section 1
Cell Features, continued
Features of Eukaryotic Cells
• A eukaryote is an organism made up of one or more eukaryotic cells. All multicellular organisms are made of eukaryotic cells.
• The DNA of a eukaryotic cell is found in an internal compartment of the cell called the nucleus.
• All eukaryotic cells have membrane-bound organelles. An organelle is a small structure found in the cytoplasm that carries out specific activities inside the cell.
Cell Structure Section 1
Cell Features, continued
• Each organelle in a eukaryotic cell performs distinct functions.
• The complex organization of eukaryotic cells enables them to carry out more specialized functions than prokaryotic cells.
Cell Structure Section 1
Visual Concept: Comparing Prokaryotes and Eukaryotes
Cell Structure Section 1
Comparing Prokaryotes and Eukaryotes
Cell Structure Section 1
Summary
• Microscope observations of organisms led to the discovery of the basic characteristics common to all living things.
• A cell’s shape reflects its function. Cell size is limited by a cell’s surface area-to-volume ratio.
• The complex organization of eukaryotic cells enable them to carry out more specialized functions than prokaryotic cells.