CELLS Chapter 3

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. CELL MEMBRANE Every cell is surrounded by a cell membrane The cell membrane separates the cell from its external environment and neighboring cells The cell membrane regulates the transport of molecules into and out of the cell

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. NUCLEUS The nucleus is the most important organelle within the body The nucleus contains DNA and protein arranged in a loose state called chromatin Located within the nucleus are nucleoli which contain ribosomes and protein

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. CYTOPLASM Cytoplasm is the semifluid material in which life functions take place Organelles within the cytoplasm: –Centrosome- Lysosomes –Centrioles- Perioxisomes –Endoplasmic Reticulum- Cytoskeleton –Mitochondria- Pinocytic Vesicles –Golgi Apparatus

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. CELL DIVISION Cells divide for two purposes: –Meiosis is the division of the sex cell or gamete –Mitosis is the division of the nucleus and the cytoplasm Interphase Metaphase Anaphase Telophase Prophase

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. PROTEIN SYNTHESIS Cells produce proteins essential to life through protein synthesis Within each cell the DNA determines the kinds of proteins that are produced

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MOVEMENT OF MATERIALS ACROSS CELL MEMBRANES Diffusion is the process whereby substances pass across a membrane generally from an area of greater concentration to one of lesser concentration Osmosis is diffusion through a selective permeable membrane in which some materials can diffuse while others can’t

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MOVEMENT OF MATERIALS ACROSS CELL MEMBRANES Filtration - solutes move across a semipermeable membrane from high pressure to lower pressure Active transport - molecules move across membrane from low to high concentration

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MOVEMENT OF MATERIALS ACROSS CELL MEMBRANES Phagocytosis is “cell eating” of substances within particles Pinocytosis is “cell eating” of substances within solution

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. SPECIALIZATION Specialized cells may lose the ability to perform some of the other life functions Nerve and heart muscle cells cannot normally be replaced

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. DISORDERS OF CELL STRUCTURE Tumors result when cell division is abnormal –Benign tumors are composed of cells confined to a local area –Malignant tumors continue to grow and crowd out healthy cells –Malignant tumors spread through the body by a process called metastasis