Biol 1551 Sep 20^th lecture notes

 

Chapter 4 Tour of the Cell

 

1. Overview
1. Discovery of cells

Development of microscope contributed to the discovery of cells.

 

First report of cells 17^th century

            Anton van Leeuwenhoek

               Robert Hooke

 

All living organisms are made of cells.

 

2. Cells come in different sizes and shapes (Fig 4.2, p54)

·        specific functions of cells forces cells to have specific size and shape

 

ex. egg -  very large – provide nutrients to embryos

      nerve cells – very long and thin – allows fast signal transmission

      red blood cells – small and flat – go through small vessels,

                                     allows maximum oxygen exchange efficiency

·        Sizes of cells normally falls in the range between  10 – 100 μm.

 

3. Limitation of cell size

·        The ratio of surface area to volume becomes smaller as the shape becomes bigger.

·        This ratio is a limiting factor for the sizes of cells.

- If cells are too large, they cannot receive enough nutrients to support themselves.

 

 

2. Structure of prokaryotic cells (Fig 4.4, p55)

prokaryotes – Domains Bacteria and Archaea

 

Prokaryotic cells are different from eukaryotic cells in that they have no nucleus and no organelles.

 

·        nucleoid – contain DNA

·        ribosome – site of protein synthesis

·        plasma membrane – separate cell contents from environment

·        cell walls – keeps cell shape, protect cells

·        capsule – sticky outer coat

·        pili (pilus) – helps cells to attach to other surface

·        flagella (flagellum) – propel cells

 

3. Structure of eukaryotic cells (Fig 4.5 A and B)

Eukaryotic cells contain nucleus and organelle.

Cytoplasm is everything inside the cell between plasma membrane and nucleus.

 

• structures common to plants and animals
• nucleus
• plasma membrane
• endoplasmic reticulum (ER)
• rough ER
• smooth ER
• Golgi apparutus
• mitochondrion
• peroxisome

 

• structures only found in animals
• lysosome
• centriole

 

• structures only found in plants
• cell walls
• chloroplast
• (central) vacuole