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MMG Macromolecules


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Briefly recap covalent bonding
-sharing of a pair of electrons
-strongest bond
-requires energy (releases it when broken; needs enzymes)
-can be polar or nonpolar
What is the definition of electronegativity?
-attraction of atom for electrons; the more electronegative, the greater the pull its nucleus exerts on electrons
What are nonpolar covalent bonds?
-atoms with similar electronegativities; electrons are equally shared
What are polar covalent bonds?
-unequal sharing of electrons due to dignificantly different electronegativities
What are ionic bonds?
-electrons donated/accepted to give full charges and outer shells
-important in osmotic changes
-easily broken in water and reforming the ions again
What are Hydrogen bonds?
-electrical attraction between partially charge H and full or partial neg charge on another (or same) molecule
-weakest of bonds
-hold DNA strands together
-in protein molecules, responsible for 2, 3, and quaternary structures
What are macromolecules made up of? And what makes these up?
What are some examples of macromolecues?
-nucleic acids
What are lipids known as and what are they composed of?
-fatty acids bonded to C3 (tertiary carbon) alcohol glycerol
-saturated means no c=c
-unsaturated means one or more c=c
What does amphipathic mean?
-hydrophilic and phobic
-important for cellular membranes
Describe Steroids (make-up and use).
-consist of four rings (5 or 6 C's) fused together and used as hormones in mammalian cells (testosterone, estradiol, progesterone)
Describe Sterols (make-up only)
-basically, steroids with an -OH functional group
-found in eukaryotic membranes
-rigid, planar molecules that provide rigidity to membranes
What is ergosterol?
-a sterol found in fungal membranes; target of many anti-fungal drugs
What are 6 functions of polysaccharides?
-long-term storage of chemical energy
-readily available energy source
-part of backbones of nucleic acids
-converted to amino acids
-form cell wall
-involved in intracellular interactions between animal cells
What are polysaccharides sometimes coupled with?
-with proteins= glycoproteins
-with lipids= glycolipids
What is responsible for forming the bonds in macromolecules?
What do starch, glycogen, and cellulose have in common?
-all composed of glucose
What does the stereochemistry of bonds determine in polysaccharides?
-whether poly-glucose becomes starch, glycogen or cellulose
What elements make up polypeptides and proteins?
-enzymatic catalysis
What functional groups make up amino acids?
What affects molecule interaction?
-amino group
-carboxyl group
-functional R group
*R groups affect how amino acids interact with one another and how protein interacts with other molecules
What are the 21 common amino acids?
-glycine -alanine
-valine -leucine
-isoleucine -serine
-threonine -aspartate
-asparagine -glutamate
-glutamine -cysteine
-selenocysteine -tyrosine
-methionine -phenylalanine
-tryptophan -lysine
-arginine -histidine
What are the two forms amino acids and sugars can exist in?
-optical isomers
*same chemical formula
What forms are synthesized and utilized amino acids in?
How about sugars?
-L form
-D form
*enzymes must be able to discriminate one form from another
How are peptide bonds formed?
-amino acids are polymerized into a polypeptide through the loss of a water molecule (dehydration)
What are the four structures of polypeptides and how are they held together?
-primary; peptide bonds
-secondary; folding and then held with H-bonds
-tertiary; folding and held with H-bonds, covalent S-S bond between cysteine AA, and interactions between R groups
-quaternary; interactions between 2 or more polypeptides and the same as 3' (no cysteine?)
What are the two structures of secondary structures?
Which one is strongest/rigid?
-alpha-helix structure (more flexible)
-beta-sheet structure (more rigid)
What can cause a protein to denature?
-extreme pH
-high temperature
What does denaturing do to proteins?
-causes loss of protein function by affecting sexondary, tertiary, and quaternary structures (NOT primary structure) of protein
*depending on harshness of denaturation, proteins can renature
What is so important about denaturing proteins since it is normally thought of as bad?
-important in destroying microbes
What and where are nucleic acids?
-information carriers of the cell
-found as polynucleotides of either DNA or RNA
What are nucleotids composed of?
-sugars, nitrogen bases, and phosphates
Besides DNA/RNA, what are nucleotides important for?
-important energy sources
-metabolic regulatory molecules
In DNA, does it exist as a single or double strand?
-How is it held together?
-base pairing between purines and pyrimidines by H-bonding hold it together
*A with T and G with C
RNA is single stranded, but was can lead to a secondary RNA structure?
-intrastrand base pairing
(A with U, G with C)
What does A, T, G, C, U stand for?

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