General Features of Cells PDF

Cell Structure & Function  The Cell A cell is the smallest unit that is capable of performing life functions. Amoeba Proteus Plant Stem Bacteria Red Blood...

Cell Structure & Function  The Cell A cell is the smallest unit that is capable of performing life functions. Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell  Microscopes and Cells 1600’s. –Anton van Leeuwenhoek first described living cells as seen through a simple microscope. Microscopes and Cells –Robert Hooke first used a compound microscope to view thinly sliced cork cells. Compound scopes use a series of lenses to magnify in steps. Hooke was the first to use the term “cell”.  Microscopes and Cells 1830’s. –Mathias Schleiden identified the first plant cells and concluded that all plants are made of cells. - Thomas Schwann made the same conclusion about animal cells.  Cell Theory 1. All living things are made up of 1 or more cells. 2. Cells are the smallest working units of all living things. 3. All cells come from pre-existing cells through cell division.  Number of Cells Organisms may be: Unicellular- composed of 1 cell OR Multicellular- made of many cells  Cells can be Eukaryotic or Prokaryotic Prokaryotes :do not have a nucleus or organelles (bacteria). Eukaryotes: have a nucleus and organelles (plants, fungi, animals, protists)  Organelles Cell structures that have a specific function and are surrounded by a membrane that are found in eukaryotes only.  Prokaryotic vs. Eukaryotic Http://micro.magnet.fsu.edu/cells.html Prokaryotic Cells Believed to be the first cells to evolve. Lack a membrane bound nucleus and organelles. Genetic material is free in the cytoplasm Ribosomes are only other cell structure.  Eukaryotic 2 major types of eukaryotic cells- Plant and Animal cells Plant Animal http://library.thinkquest.org/C004535/eukaryotic_cells.html Cell Structures & Functions Cell Wall Found outside of the cell membrane in plant cells & bacteria only Contains cellulose that provides support (rigidity) & protection Cell or Plasma Membrane Outer membrane of cells that controls movement of substances in and out of the cell Double layer (bi-layer) In plants and bacteria, this is within the cell wall.  Cytoplasm Gel-like mixture inside cells Surrounded by cell membrane Contains cell structure that carry out specific jobs ex. Mitochondrion, nucleus Provides a medium for chemical reactions to take place Nucleoid In prokaryotes. Region of the cytoplasm where chromosomal DNA is located. Singular, circular chromosome. Smaller circles of DNA called plasmids are also located in cytoplasm.  Ribosomes Each cell contains thousands Make proteins Found on endoplasmic reticulum & floating throughout the cell cytoplasm Organelles Nucleus “Control center” Directs cell activities Contains the genetic material (DNA) Separated from cytoplasm by nuclear membrane (or nuclear envelope).  Nuclear Membrane Surrounds nucleus, separates DNA from cytoplasm Made of two layers Openings called pores allow some materials to enter and leave nucleus Chromatin In nucleus Genetic material (DNA) of cell in its non-dividing state. Ie. Uncoiled chromosomes Contain instructions for traits & characteristics  Nucleolus Dark-staining structure in the nucleus Makes ribosomes that make proteins Rough Endoplasmic Reticulum Network of continuous sacs, studded with ribosomes. Internal delivery system of the cell. Manufactures, pro- cesses, and transports proteins for export from cell. Continuous with nuclear envelope. Smooth Endoplasmic Reticulum Similar in appearance to rough ER, but without the ribosomes. Produces lipids, involved in carbohydrate metabolism, and detoxification of drugs and poisons. Golgi Apparatus Protein 'packaging plant‘ Modifies proteins and lipids made by the ER and prepares them for export from the cell. Encloses digestive enyzymes into membranes to form lysosomes (transport pods). Lysosome Digestive 'plant' for proteins, fats, and carbohydrates Digestive enzymes break down cellular waste and debris Transports undigested material to cell membrane for removal Cell breaks down if lysosome explodes  Mitochondria Cell “powerhouse” Membrane bound organelles that are the site of cellular respiration (use glucose to produce cell energy, ATP) Active cells like muscles have more mitochondria  Animal Vacuole Membrane-bound sacs for storage, digestion, and waste removal Contains water solution Plant Vacuole Plants have large central vacuoles that store water and nutrients needed by the cell. Help support the shape of the cell.  Chloroplast Usually found in plant cells Contains green pigment chlorophyll Where photosynthesis takes place Produces plant food (sugars) and oxygen gas  Cilia and Flagella External appendages from the cell membrane Cilia that aid in locomotion (movement) of the Flagella cell. Cilia also help to move substance past the membrane. Centrioles Found only in animal cells. Self-replicating Made of bundles of microtubules. Help in organizing cell division. Cytoskeleton The cell’s skeleton Made of microtubules and filaments Give the cell shape, strength and ability to move