CELL SPECIALIZATION Sections 2.3/2.4

SPECIALIZED CELLS Cells are specialized to carry out specific functions Cells are generally more efficient when they work together to perform a specific function

SPECIALIZED ANIMAL CELLS nerve cells: conduct electrical signals, long and thin respiratory cells: thin to allow gases to exchange between air and blood; coated in mucus and/or cilia to help remove harmful particles red blood cells: carry oxygen in hemoglobin (a protein) white blood cells: engulf invaders and digest them or kill them with antibodies stomach cells: have many Golgi apparatuses; produce and store proteins that break down food; protected from stomach acid by mucus fat cells: store extra body nutrients in vacuoles by converting them to fat small intestine cells: absorb essential nutrients from food by means of villi (finger-like projections that increase the surface area of the cell)

red and white blood cells SMALLER VERSUS LARGER The bigger the cell is, the longer messages take to reach the nucleus and the slower the cell will react Larger the ratio of cell membrane area to cell volume, the more efficient it can be in absorbing nutrients and eliminating wastes i.e. many small cells are more efficient at getting nutrients in and wastes out than one large cell

What is larger, muscle cell or fat cell? Muscle cells are more active cell, thus the need for more nutrients and produces more waste The more active the cell, usually the smaller it is.

SPECIAIZED CELLS (SKIN CELLS AND SUNLIGHT) Skin cells must be small so that the chemical message triggered by sunlight can reach the nucleus quickly. This message tells ribosomes to make melanin, which protects the skin cells by blocking sunlight and also causes the skin to darken.

SPECIALIZED PLANT CELLS Different types of cells are designed to carry out special functions thin-walled plant cells: found in flexible tissue or leaves, flowers, roots thick-walled plant cells: specialized for support; are stretchable and flexible very thick-walled plant cells: provide rigid support Cell walls can get so thick that nutrients will eventually have trouble entering the cell  usually die leaving empty chambers surrounded by hardened thick cell walls Example: tree trunks