1. Biomolecules and Water

Question 1

trace element

Answer 1

element present in small quantities in a living organism

Question 2

amino acid

Answer 2

a compound consisting of a carbon atom to which are attached to a primary amino group, a carboxylate group, a side chain (R group), and an H atom

Question 3

carbohydrate

Answer 3

a compound with the formula (CH2O)n where n is greater or equal to 3
- a saccharide

Question 4

monosaccharide

Answer 4

carbohydrate consisting of a single sugar molecule

Question 5

nucleotide

Answer 5

• monomeric units of nucleic acids
• one nucleoside esterified to one or more phosphate groups

Question 6

nucleoside

Answer 6

a nitrogenous base linked to either ribose or deoxyribose

Question 7

lipid

Answer 7

class of molecules that is largely and mostly hydrophobic, insoluble in water but soluble in organic solvents, non-polar (but may contain one polar aspect, -OH)

Question 8

monomer

Answer 8

structural units that add together to form a polymer

Question 9

explain what is meant by ‘directionality’

Answer 9

• asymmetric bond connection between monomers
• attachment of monomers in which the points of connections are distinct from one another

Question 10

residue

Answer 10

term for what remains of a monomeric unit after it has been incorporated into a polymer

Question 11

peptide bond

Answer 11

what links the amino acid residues in a polypeptide.
an amide linkage between the alpha-amino group of one amino acid and the alpha-carboxylate group of another.

Question 12

phosphodiester bond

Answer 12

a phosphate group esterified to two alcohol groups

Question 13

glycosidic bond

Answer 13

covalent linkage b/w two monosaccaride units in a polysaccaride, or the linkage b/w the anomeric carbon of a saccharide and an alcohol or amine

Question 14

list the most abundant elements in biological molecules

Answer 14

hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur

Question 15

list the major classes of biological molecules and biological polymers

Answer 15

major molecules:
1. amino acids
2. carbohydrates
3. nucleotides
4. lipids

major polymers:
1. proteins
2. nucleic acids
3. polysaccharides

Question 16

what are each of the biological polymers composed of? what is the major function of each?

Answer 16

proteins
- made of amino acids connected by peptide bonds
- carry out metabolic reactions and support cellular structures

nucleic acids
- made from nucleotides connected by phosphodiester bonds
- encodes information

polysaccharides
- made from monosaccharides connected by glycosidic bonds
- stores energy and supports cellular structures

Question 17

List the 3 major types of electrostatic forces that act on biological molecules and explain the nature of them

Answer 17

1. ionic interactions +/-
   - the non covalent interaction of oppositely electrically charged atoms.
   - limited amount in molecules, strong force
2. hydrogen bonds
   - where a hydrogen is shared between two electronegative atoms
3. van der waals forces
   - dipole-dipole: between polar non-charged groups
   - london dispersion: between nonpolar molecules

Question 18

How many hydrogen bonds can water make?

Answer 18

typical: 3
maximum: 4 (2 as donor, 2 as acceptor)

Question 19

how does water solubility relate to hydrogen bonding

Answer 19

with increasing numbers of potential hydrogen bonding groups, water solubility for a molecule will increase

Question 20

list the types biological molecule bonding in order of decreasing strength

Answer 20

covalent bond > ionic bonds > hydrogen bonds > van der waals

Question 21

explain the term ‘hydrophobic effect’ and outline the role that entropy plays in the process

Answer 21

• the hydrophobic effect occurs when the hydrogen bonding pattern of water is disrupted by the non-polar molecules; non-polar compounds tend to associate more with each other in water

entropy: reflects the degree of chaos or uncertainty within a set of conditions
- the clustering/association of nonpolar molecules in water reduces the amount of surface area that is exposed to water ~ increasing the entropy of water