Four major families of organic molecules: sugars, fatty acids, nucleotides, amino acids. About their function, structure, etc. Noncovelent bonds and how strong they are/ weak. Proteins: structures (and alpha helix and beta sheets), bonds, amino acids, 4 views, domain + domain shuffling, dimer, tetr...
Molecular biology of the cell 1
Lecture 1
Chapter 2 Cell Chemistry and Bioenergetics
Four major families of organic molecules
1) sugars
2) fatty acids (do not polymerize)
3) nucleotides
4) amino acids
SUGARS:
- in aqueous solution, the aldehyde or ketone
group of a sugar molecule tends to react with a
hydroxyl group of the same molecule, thereby
closing the molecule into a ring. (= ring
formation)
A Fischer projection is a way to show how a
compound is structured in an open-chain form.
A Haworth structure is a way to show how a
compound is structured in a closed ring form in
three dimensions.
- isomers = molecules that have the same
formula, but differ in the arrangement of groups
around one or two carbon atoms.
the differences make only minor changes in the chemical properties of the
sugars but they are recognized by enzymes and other proteins and therefore can
have major biological effects.
beta position = OH- group pointed upwards
alpha position = OH-group pointed downwards
these positions can change rapidly, but as soon as one sugar is linked to
another the alpha or beta form is frozen.
- the carbon that carries the aldehyde or ketone can also react with a second
sugar forming a disaccharide.
- oligosaccharides = short chains of repeating sugar subunits
- polysaccharides = long chains of repeating sugar subunits
condensation reaction = when you link two
molecules together and water (H2O) cleaves
off
hydrolysis reaction = reaction where water
is needed.
FATTY ACIDS:
Unsaturated = one or more double bond in
their (hydrocarbon) tail
the double bond creates a kink in the chain.
Saturated = no double bonds
, hydrophobic tail and hydrophilic head this way a phospholipid bilayer can form
in water called spherical micelles or a film can form.
- fatty acids are stored in cells as an energy reserve in the form of
triacylglycerols ( = 3 fatty acids and glycerol)
form large spherical fat droplets in the cell cytoplasm
- Phospholipids and glycolipids are the major constituents of cell membranes.
they can also form monolayers, bilayers, micelles and liposomes.
form self-sealing lipid bilayers, which are the bases for all cell membranes.
- phospholipid bilayer can also form a vesicle which is important for drug
delivery.
- Steroids = lipids that have a common multiple-ring structure and are made
from isoprene units.
- Nucleoside = base + sugar (pentose)
- Nucleotide = base + sugar (pentose) + phosphate
nucleotides are the subunits of the nucleic acids and are bound to
each other by a phosphodiester linkage.
Function of nucleotides:
- carriage of chemical energy (e.g. ATP)
- combination with other groups to form coenzymes
- used as specific signaling molecules
- sugars ribose (RNA) or deoxyribose (DNA)
ribose has an hydroxy group (OH)
deoxyribose misses the hydroxy group
ribonucleic acid = RNA
deoxyribonucleic acid = DNA
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