DNA

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DNA
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DNA Packaging Inside Nucleus
Nucleosome
Supercoil
Protein Scaffold
Chromosome
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First Base in Codon
Third Base in Codon
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CELL MEMBRANE

• Controlling what goes in and out of the cell.
• Anchoring of the cytoskeleton to provide shape to
  the cell
• Attaching to the extracellular matrix to help
  group cells together in the formation of tissues
• Transportation of particles by way of ion pumps,
  ion channels, and carrier proteins
• Containing receptors that allow chemical messages
  to pass between cells and systems
• Participation in enzyme activity important in
  such things as metabolism and immunity

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CELL MEMBRANE The cell mem consists of three
classes of amphipathic lipids PHOSPOLIPIDS,
GLYCOLIPIDS, STEROIDS Membrane is held together
via weak non-covalent interaction of hydrophobic
tails Structure is
fluid and not fixed rigidly in place.
Phospholipid molecules are fluid free to
diffuse and exhibit rapid lateral diffusion along
the layer they are present in.
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The FATTY ACID chains in phospholipids and
glycolipids usually contain an even number of
carbon atoms, typically between 14 and 24. The
16- and 18-carbon fatty acids are the most
common. In animal cells, cholesterol is found
dispersed in varying degrees throughout cell
membranes, where it confers a stiffening and
strengthening effect on the membrane. It resides
in the irregular spaces between the hydrophobic
tails of the membrane lipids.
polar, hydrophilic heads
7nm
hydrophobic tails
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SELECTIVE TRANSPORT OF MOLECULES ACROSS
MEMBRANE Nutrients in Waste
out Gate Keepers Transmembrane
PROTEINS Create ion channels, proton pumps,
etc. Extremely important to cell e.g. a third
of the genes in yeast code specifically for
them Again chicken and egg Need DNA to code for
membrane proteins but Need membrane proteins
to create selective membrane to allow cell to
exist.
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