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Specialized Cells
• Cells can vary in the shape, size, and content.
• Each type of cell is specialized to perform a
different function.
• Structure determines function.
Nerve Cells or Neurons
• Neurons are cells of the nervous system and
are specialized to carry "messages" through an
electrochemical process.
Neurons are similar to other cells in
the body because:
• Neurons are surrounded by a cell membrane.
• Neurons have a nucleus that contains genes.
• Neurons contain cytoplasm, mitochondria and
other organelles.
• Neurons carry out basic cellular processes
such as protein synthesis and energy
production.
Neurons differ from other cells in the
body because:
• Neurons have specialize cell parts called
dendrites and axons. Dendrites bring
electrical signals to the cell body and axons
take information away from the cell body.
• Neurons communicate with each other
through an electrochemical process.
Nerve Cell
Sperm Cell
• A sperm cell is the male reproductive cell that
carries the male portion of chromosomes,
DNA or hereditary information to be fused
with the female egg, or ovum.
• The sperm cell is composed of three main
parts: the head, middle piece and tail.
Parts
• The head contains enzymes near the tip, used
to penetrate the egg; contains the nucleus and
all hereditary information needed to
successfully reproduce once the sperm cell
has fertilized an egg.
• The middle piece contains mitochondria which
provides energy to move the cell.
• The flagellating tail propels the sperm cell.
Sperm Cell
Guard Cell
• Guard cells are cells surrounding each stoma
in plants. They help to regulate the rate of
transpiration by opening and closing the
stomata.
Guard Cell
Xylem and Phloem
• Vascular tissue in plants; contain several types
of specialized cells.
• Xylem – made up of tracheid and vessel
elements, carry water from the roots to the
rest of the plant
• Phloem – made up of sieve tube elements and
companion cells; transports food
Xylem and Phloem
• Multicellular organisms begin as
undifferentiated masses of cells
• Variations in DNA expression and gene activity
determine cell specialization
• During differentiation, only specific parts of
DNA are activated which determine the
function and specialized structure of a cell
• All cells contain the same DNA; all cells have
the potential to become any type of cell
• Depends on the genetic instructions
• Stem cells – unspecialized cells which can
differentiate into other types of cells (can be
manipulated in laboratories under the right
conditions)
• Stem cells→DNA→cell differentiation→specialized
cells