Page #DescriptionDatePoints What are cells? Presentation11/ Cells a look inside presentation11/610

Chapter Five: Cell Structure and Function 5.1 What are Cells? 5.2 Cells: A Look Inside

5.1 What are cells? A cell is the basic unit of structure and function in a living thing. Your body is composed of trillions of cells. Trillion = 1,000,000,000,000

5.1 What are cells? You have nerve cells, skin cells, muscle cells, blood cells, and many other types as well. These are some of the types of cells found in your blood.

5.1 What are cells? Each cell in your body shares the characteristics of all living things.

5.1 Finding out about cells English scientist Robert Hooke (1635–1703) was the first to record his observations of cells. In 1663, he took a thin slice of cork and placed it under a microscope that he built himself.

5.1 Finding out about cells As microscopes improved, scientists made many discoveries. A modern fluorescent microscope enables scientists to use glowing proteins to see tiny cell parts as DNA in these mouse cells.

5.1 The cell theory Later, the observations of Matthias Schleiden and Theodore Schwann (1830’s) lead to the cell theory: –All organisms are made of one or more cells –The cell is the basic unit of structure and organization in living things –All cells come from pre-existing cells The cell theory explains the relationship between cells and living things.

Review What is the name of the tool that allows people to see small things? What was the name of the man that named cells? All organisms are made up of one or more cells is part of what theory?

Review How has cell theory evolved from what Schleiden and Schwann first came up with and what we know today? –Hint how many criteria did they originally write and how many do we know today.

5.1 Similarities among cells In many-celled organisms like you, there are many different specialized cells. All cells share certain common characteristics.

5.1 Similarities among cells There are 4 common parts of all cells: 1.Cell Membrane – a barrier that controls movement of materials into and out of cells 2.Cytoplasm – a fluid mixture that contains the organelles and the compounds the cell needs 3.Organelles – a structure inside of a cell that helps it perform its functions Like mini-organs for the cell 4.DNA – the instructions for the cell either floating in the cell (prokaryotes) or found in the nucleus (eukaryotes)

Review What are the 4 things that all cells have in common? Where are the two locations that genetic material can be found in cells?

5.1 Classifying cells Prokaryotic (before core) do not have a nucleus. Scientists believe that all life on Earth came from ancient cells of this type. Only bacteria have this type of cell.

5.1 Classifying cells Eukaryotic (true core) have a nucleus and membrane- covered organelles. They tend to be about ten times larger than prokaryotic cells. Animals, plants, fungi, and protists all have eukaryotic cells.

5.1 Comparing cell types

Types of cells There are 3 different types of cells: –Animal - lack chloroplasts and cell wall –Humans, Cats, Dogs –Plant - contain photosynthetic chloroplasts and cell walls –Trees, Grass –Bacteria - Some have cell walls and chloroplasts, but all lack nucleus