Ch. 3 Chemical Basis of Information Molecules Flashcards
What are nucleic acids?
Polymers of nucleotides that are linked together by phosphodiester bonds (covalent bonds).
What is a nucleotide?
A base, a sugar, and phosphate group(s).
What is a nucleoside?
A base and a sugar. NO phosphate group(s).
How are nucleic acids (strands) labeled?
They have a 5’ termini and a 3’ termini.
How are the RNA and DNA sugars different?
Ribonucleotides have ribose which has a 2’ OH group. Deoxyrobonucleotides have deoxyribose which has a 2’ H.
What are the RNA bases?
adenine, cytosine, guanine, and uracil
What are the DNA bases?
adenine, cytosine, guanine, and thymine
Could RNA have thymine and DNA have uracil?
Yes. It would be abnormal, but it is possible.
What are polypeptides?
Polymers of amino acids that are linked together by peptide bonds (covalent bonds).
What is the structure of an amino acid?
There is an ɑ carbon bonded to four chemical groups… amino group, carboxyl group, hydrogen, and an R group that varies.
How does the composition of a polymer affect structure?
The composition (sequence) of a polymer (nucleic acids, proteins, etc.) contributes to its structure, and structure influences function.
What does a polymer need to perform its fuction?
It must take on structure to perform its function!
What does DNA form in the cell and why?
DNA forms a double helix in the cell due to bond angles in the backbone.
What does DNA form out of the cell and why?
DNA may not form a helix because the new environment might favor different non-covalent interactions/structures.
What does RNA form in the cell and why?
RNA typically DOESN’T exist in a double stranded form because single strands allow for H-bonding into a variety of structures, which allows for a variety of functions.
What allows proteins to have various functions?
The variety of aa patterns, and hence folding of aa’s, gives proteins their various functions.
How can monomers of nucleic acids and polypeptides be modified?
Monomers can be modified by small chemical groups like phosphates, methyl groups, amine groups, etc.
What do monomer modifications do (3)?
These modifications can change gene expression, protein activity, and other molecular processes.
Why are phosphodiester bonds and peptide bonds covalent and not ionic?
Ionic bonds in a biological system are relatively weak because of the prevalence of water.
What are the weaker bonds/interactions involved in macromolecule structure and function (4)?
- ionic bonds (“+” and “-“)
- hydrogen bonds (O, N, and H)
- VDWs forces
- hydrophobic interactions
Why are these weaker bonds able to maintain structure?
While they are individually weak, their strength is additive. The more bonds present, the stronger they are.
What is steriochemistry?
The spacial arrangement of molecules
What stereochemical property do biological molecules have?
Biological molecules are chiral, so they cannot be superimposed on their mirror image.
Why do biological systems only use one enantiomer of a molecule?
Proteins are chiral, so they can only interact with one enantiomer?
