Unit 1 Cells, Exchange and Structure

Light

Dead or Alive Specimens, Lowest resolution, Colour 2D image.

TEM

Dead specimens, Highest resolution, black and white, 2D image, thin specimens, Electrons Penetrate.

SEM

Dead Specimens, Black and white, Electrons scan.

The number of times larger an image is compared with the real size of the object.

Eukaryotic Cells                                               Prokaryotic Cells

Larger Cells                                                       Extremely Small Cells

Dna is Linear                                                     DNA is circular

Nucleas Present                                                No nucleus (DNA free in Cytoplasm)

No cell wall, Cellulose cell wall in plants            Cell wall made of a polysacharide

Many organells Mitochondria present                Few organelles, NO mitochondria

Larger Ribosomes                                            Small ribosomes

E.g Human Liver Cell                                        E.g E-coli bacterium

• Maintains Cell Structure
• Protects the Cell
• Enables some cell movement (using structures such as flagella and cilia)
• Plays important roles in intra-cellular transport(the movement of vesicles and organelles)