Cells
Chapter 3
Composite Cell
• The three major parts of a human cell is a nucleus,
cytoplasm, and cell membrane
• Nucleus-houses the genetic material
• Cytoplasm-surrounds the nucleus and contains all the
other organelles
• Cell Membrane-surrounds the cytoplasm and controls
what goes in and out, also communicates with other cells
• Organelles-specialized structures that perform specific
functions which divide the labor of the cell
http://images.protopage.com/view/721661/9om6i6botf38jm7zive0ddjpj.jpg
Cell membrane
• Regulates movement of substances in and out
of cell
• Molecules that are part of the membrane receive
information from outside and transmit it inward in
a process called signal transduction
• Also, helps adhere to other cells (important in
forming tissues)
• It is selectively permeable because it only lets
some substances in and out of the cell
http://upload.wikimedia.org/wikipedia/commons/e/ee/CellMembraneDrawing.jpg
Cell Membrane structure
• Composed of lipids, proteins, and carbs
• Mainly a phospholipid bilayer (two layers)
• The surface is made up of water soluble
phosphate heads (hydrophilic-water
loving) and water-insoluble fatty acid tales
make up the interior (hydrophobic-water
hating)
http://t1.gstatic.com/images?q=tbn:ANd9GcSRFknJcaIVMIHrcsa-2d6DUgwFPkxA-JqQ-NYQ2HbfY6Jz3W-8
• O, and CO2 (soluble in lipids) can pass
through easily
• Water soluble molecules like amino acids,
sugars, proteins, nucleic acids, and many
ions cannot readily pass through
• Cholesterol is also imbedded in membrane
and make it less soluble, also stabilizes
the membrane
http://www.dynamicscience.com.au/tester/solutions/biology/cell/cholesterol.jpg
• Also has proteins which:
– Are receptors (hormones, growth factors)
– Transport molecules or ions
– Support the cells interior
– Hold carbohydrates for identification and
signaling
– Determine where cells move in the body
http://img.sparknotes.com/figures/A/a981208a1abd542364d5a13c08702881/cellmembrane.gif
Cytoplasm
• Contains networks of membranes and
organelles suspended in the cytosol (clear
liquid)
• Also, contains Cytoskeleton which is a
framework of proteins
• Many types of organelles in cytoplasm
http://nursingcrib.com/wp-content/uploads/cell2.jpg?9d7bd4
Cell Nucleus
• Houses the genetic material which directs
all cell activities
• Surrounded by the nuclear envelope
which is a bilayer of phospholipids
http://library.thinkquest.org/06aug/01942/plcells/thinkquest/nucleus.jpg