Cell Types

1. Cell Types

2. Cell Theory • Every living organism is made of one or more cells • The smallest organisms are made of single cells while multicellular organisms are made of many cells • All cells arise from pre-existing cells

3. Cell Function Limits Cell Size • most cells are small, ranging from 1 to 100 micrometers in diameter • cells need to exchange nutrients and wastes with the environment • no part of the cell can be far away from the external environment • surface area to volume ratios must be kept rather large

4. All Cells Share Common Features • a plasma membrane encloses all cells and regulates material flow in and out of the cell • cytoplasm is the fluid interior where a cell’s metabolic reactions occur (cytosol) • DNA(deoxyribonucleic acid) is the hereditary blueprint and RNA (ribonucleic acid) copies DNA for protein production (universal genetic code)

5. Two Basic Cell Types Prokaryotic Cells (bacteria) • DNA is in the form of circular loops and is free in the cytoplasm • cells contain no internal membranes and no organelles except for ribosomes Eukaryotic Cells (protists, fungi, animals, plants) • DNA is linear, bound with histone proteins in structures called chromosomes and housed in a central structure called a nucleus • cells contain complex internal membrane systems and specialized organelles

6. ‘Naked ring of DNA’X

7. 2 µm 5 µm 1 µm Spiral Rod-shaped (bacilli) Spherical (cocci)

11. Making Scientific Illustrations • Draw only on white, unlined paper. • One drawing per page. Draw large – but not off the edge of the page. • Draw only in pencil. • Do not shade or color your drawings. Stay focused on FORM. • Use clean, unbroken lines. No artsy sketching. • Have a title, magnification, and appropriate labeling on each drawing. • Draw only biological structures! Do not draw air bubbles, dust, debris, and other irrelevant objects just because you see them. • Pay attention to detail. Draw less, draw big (fill the space), draw carefully.