{ Cell Structure Chantel

 Cells are the fundamental units of all plant and animal tissues.  Cells are produced by the division of preexisting cells.  Cells are the smallest units that perform all vital physiological functions.  Each cell maintains homeostasis at a cellular level. Cell Theory

 Intracellular fluids  Cytoplasm  Cytosol  Organelles Fluids Fluids Extracellular Fluids What the cell floats in.

 The cell membrane (plasma membrane) forms the outer boundary of the cell.  Major components  Phospholipids  Proteins  Glycolipids  Cholesterol  Function  Isolation  Protection  Sensitivity  Organization Cell Membrane

Physical isolation Physical isolation The cell membrane is a physical barrier that separates the inside of the of the cell from the surrounding extracellular fluid. Importance The cell membrane is responsible for letting in molecules or letting them out. Structure The cell membrane is extremely thin and delicate. It ranges from 6 to 10nm in thickness. For the most part it is a very complex structure. Cell Membrane….

 Most of the communication involves the cell membrane.  The cell membrane regulates the dynamic exchange between intracellular and extracellular fluids. These environments are quite different and they must be maintained to preserve homeostasis. Communication Through The Cells

Doesn’t have a membrane 1. Cytoskeleton- Strength, movement of cellular structures and materials 2. Microvilli- Absorption of extracellular materials. 3. Centrioles- Movement of chromosomes during cell division 4. Cilia- Movement of materials over surface 5. Ribosomes- Protein synthesis Structure and Function Has a membrane 1.Mitochondria- Energy source 2.Nucleus- Control of metabolism; storage and processing of genetic information. 3.Endoplasmic Reticulum- Synthesis of secretory products; in tracellular storage and transport. 4.Golgi Apparatus- Storage, alteration, and packaging or secretory products and lysosomes. 5.Lysosomes- Intracellular removal of damaged organelles or of pathogens. 6.Peroxisomes- Neutralization of toxic compounds.

 The Mitochondria is the main energy source. They provide energy to cellular functions from their metabolic enzymes. Mitochondria contains DNA, RNA, and the enzymes needed to synthesize proteins. This synthetic capability enable mitochondria to control their own maintenance, growth, and reproduction. Energy

The nucleus is the control center for the whole cell. It Controls cellular operations through its regulation of protein synthesis. cellular operations through its regulation of protein synthesis. Metabolism Metabolism Storage Storage Processing of genetic information Processing of genetic information Nucleus

 In order to have a cell cycle, a single cell must divide. Cellular division occurs when one cell divides into two daughter cells. Both of them are then half the size of the original cell. After a cell divides, the two daughter cells may last from hours to decades it just depends on the environment. Most cells don’t last longer than a human being. Therefore, the life cycle repeats itself by dividing again into two daughter cells.  Cells go into different phases which are broken up into different parts. Cell Life Cycle

 Interphase  Stage One  Prophase  Stage Two  Metaphase  Stage Three  Anaphase  Stage Four  Telophase Cell Life Cycle… These are the most common stages of the life cycle. Mitosis involves Prophase, Metaphase, Anaphase, and Telophase.

 The transmembrane potential is characteristic of all living cells because it results from the active and passive properties of their cell membranes.  The transmembrane potential is just as important as any structural characteristic or organelle. Many cell functions that involve the cell membrane, such as secretion or ciliary movement, involve changes in the transmembrane potential. But it has significant functions.  Transmembrane Potential

 Two factors, one passive and one active, interact to create and maintain the transmembrane potential. Transmembrane Potential... The passive factor is that the membrane permeabilities for sodium and potassium are quite different. Potassium ions can diffuse out of the cell through potassium channels faster than sodium ions can enter the cell through sodium channels. The cell therefore loses positive charges faster than it gains them. The interior of the cell develops excess of negative charges. The active factor is the presence of the sodium potassium exchange pump in the membrane surface. At a transmembrane potential of 0 mV, potassium ions enter it, and the exchange pump cannot prevent the net loss of positive charges.

 Attachments occur at cell junctions that are not involved in membrane flow. There are four different types  Gap junctions  Tight junctions  Intermediate junctions  desmosomes  Gap Junctions- two cells are held together by an interlocking of membrane proteins.  Tight Junctions- the strongest intercellular connections.  Intermediate Junctions-held together by a thick layer of proteoglycans.  Desmosomes- very thin proteoglycan layer between the opposing cell membranes, reinforced by a network of intermediate filaments that lock the two cells together.  Desmosomes are very strong, and the connection can resist stretching and twisting. Cell Attachment Gap Junctions are found mostly in the muscle tissue, smooth muscle tissue, and sometimes nerve cells.