Cells
CELLS
• All cells no matter what kind, have a Plasma membrane.
• They also possess a genome made up of DNA.
Plasma membrane
• Serves as a boundary for the cell, separating it from its
surrounding.
DNA
• Encodes the information for making the proteins required by
the cell.
• To translate the information in the DNA and make the
proteins it encodes, all cells have the machinery for protein
synthesis, namely, ribosomes and tRNAs.
Source of energy
• Phototrophs
– are organisms that obtain metabolic energy from light.
• Chemotrophs
– Get their energy from the oxidation of chemical fuels.
• Autotrophs
– Organisms that cab capture energy from light or from
chemical sources.
• Heterotrophs
– Which use, as their energy source, the organic
compounds made by other organisms.
Plants are autotrophs while animals are heterotrophs.
Cells may be aerobic or anaerobic.
• Cells may be aerobic (i.e., use of oxygen)
• Anaerobic (able to live without oxygen)
Prokaryotic and Eukaryotic cells
• Prokaryotes
– Unicellular and generally considerably smaller than their
eukaryotic cousins.
o With the sizes ranging from 0.5-5 µm in
diameter.
– Typically have circular chromosomes.
– may sometimes contain extra-chromosomal DNA
elements called plasmids.
– The DNA-protein complexes in prokaryotes create a
structure called a nucleoid.
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