2. Macromolecules Flashcards
Macromolecules
Huge, highly organized molecules that form the structure and carry out the activities of cells
Macromolecules can be divided into four major categories
- lipids
- carbohydrates
- nucleic acids
- proteins
Carbohydrates, nucleic acids, and proteins are ______
polymers
polymers
composed of a large number of low-molecular-weight building blocks, or monomers
Lipids
a. small, diverse organic molecules that are insoluble in
H2O (polar) but soluble in nonpolar organic liquids
b.hydrophobic (water fearing) or contain significant hydrophobic regions
polar
different parts of the molecule have net negative or positive charge
micelle
an arrangement of lipids in water
soluble
able to be dissolved, especially in water
Biological roles of lips (4)
a) source of NRG in the diet and serve to store NRG in the body
(eg. fats [solid] and oils [liquid])
b) some hormones (chemical messengers) are lipids
(eg. steroids and prostaglandins)
c) many vitamins
(eg. A, D, E)
d) the basic structural elements of biological membranes
(eg. phospholipids-lipid layer on outside, membrane bound)
Lipids:
FATTY ACIDS
- unbranched hydrocarbon chains with a carboxyl group at one end
- chains are typically 14 to 20 carbons
- chain is hydrophobic
- saturated(no double bonds)
- unsaturated(double bonds)
- carboxyl group is hydrophilic
- fatty acids are amphipathic
- they can form micelles in water- note how water is ordered around micelles (all in same orientation)
amphipathic
both hydrophobic and hydrophilic
Carbohydrates
- have general formula (CH2O)n
* includes simple sugars (monosaccharides) and all larger molecules constructed of sugar building blocks
monosaccharides
simple sugars
energy source and source of carbon
polysaccharides definition
very long chains of monosaccharide units
a) energy-storing molecules:
- glycogen in animals cells (usually stored in liver and muscle cells)
- every time a branch breaks off, that is a little bit of energy
- starch in plant cells - non branched
Structural polysaccharides:
Cellulose
- linear polymer of several 100-1000 glucose units
- an insoluble, rigid structural polymer
- makes up cell wall of plants
- plants have cellulase to break down cell wall in order to expand
- we cannot digest links between monomers of cellulose (the bonds differ from those of starch)
- we get no NRG from cellulose
- healthy fiber which helps move things along
glycogen carbon chain is ______
branched
starch carbon chain is ______
spiral
What species can digest cellulose?
cows and termites don’t actually have cellulase (the enzyme that digest cellulose); it is their symbiotic bacteria and protozoa that digest cellulose
Nucleic acids
polymers of nucleotides
nucleotides consist of three units:
- nitrogenous base (ringed structured with N)
- pentose sugar (5 C sugar)
- phosphate group (PO4)