HB+Human+Cells+and+Tissues

=Cells and Tissues (ch.3 & 4)=

What is a Cell?

 * Cells are the basic units of life, and new cells only come from preexisting cells. Cells are quite small and usually seen only by microscope, (Cells are small) because it gives them a favorable surface- to volume ratio.

What does the cell theory state?

 * A cell is the basic unit of life. All living things are made up of cells, New cells arise only from preexisting cells.

Why are cells so tiny?

 * The small size of cells is explained by surface to volume ratio. Basically the Volume represents the needs of a cell but as cells get larger in volume the surface area decreases. THIS IS A PROBLEM. MORE VOLUME LESS SURFACE. SO CELLS ARE HAVE SMALL VOLUMES AND THUS A GREATER ABILITY TO GET MATERIAL IN AND OUT OF THE CELLS.

What are the three main parts of a eukaryotic cell?

 * The eukaryotic cell is made up of cytoplasm, a plasma membrane, organelles. THE MOST IMPORTANT ORGANELLE FOUND IN A EUKARYOTIC CELL IS THE NUCLEUS WHICH HOUSES THE DNA.

Which of these also occur in prokaryotes (bacteria)? Which one does not occur?

 * Both prokaryotes and eukaryotes have a plasma membrane and cytoplasm. The endomembrane system is unique to the eukaryotic cell. SO EUKARYOTIC CELLS HAVE MEMBRANE BOUND ORGANELLES NOT FOUND IN PROKARYOTES. THE MOST IMPORTANT BEING THE NUCLEUS. REMEMBER THAT PROKARYOTES HAVE DNA BUT IT IS NOT STORED IN A MEMBRANE BOUND ORGANELLE. PROKARYOTES ARE MUCH SIMPLER AND SMALLER.

What is a tissue?

 * A tissue is composed of specialized cells of the same type that perform a common function in the body.

What are the four major types of tissues found in the human body?

 * The connective tissue binds and supports body parts. The Muscular tissue can contract to move the body and its parts. Nervous tissue receives stimuli and conducts electrical (charge) impulses. Epithelial tissue covers body surfaces and lines body cavities.