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Chapter 3
CELLS
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:
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Centrosome
Centrioles
Endoplasmic Reticulum
Mitochondria
Golgi Apparatus
- Lysosomes
- Perioxisomes
- Cytoskeleton
- Pinocytic Vesicles
© 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
• Anaphase
• Metaphase
• 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
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.