lecture 2 - chemical basis of life

Question 1

why are ionic bonds rare in cells?

Answer 1

they dissolve in water and are not thermodynamically favored b/c cells are 70% water

Question 2

4 types of macromolecules

Answer 2

1. proteins
2. nucleic acids
3. lipids
4. carbohydrates

Question 3

what type of reaction occurs in the formation of covalent bond between two monomers?

Answer 3

dehydration rxn; loss of H from one monomer and loss of OH from other monomer

Question 4

amino acids with nonpolar side chains

Answer 4

hydrophobic

Question 5

amino acids with polar side chains

Answer 5

hydrophilic

Question 6

3 part structure of nucleotides

Answer 6

phosphate group, pentose, nitrogenous base

Question 7

purines

Answer 7

adenine and guanine - pair of fused rings

Question 8

pyrimidines

Answer 8

cytosine, thymine, uracil - single ring

Question 9

due to phosphate group, nucleotides are…

Answer 9

acidic; releases protons (H+) and becomes negatively charged

Question 10

nucleosides

Answer 10

located in extracellular fluid; consists of a nitrogenous base and sugar (no phosphate group)

Question 11

monosaccharides

Answer 11

made up of carbohydrates

Question 12

carbohydrates

Answer 12

covalently bonded combinations of carbon atoms and water molecules

Question 13

3 functions of polysaccharides

Answer 13

reservoirs for glucose, structural components, adhesives

Question 14

glycogen

Answer 14

polymer of glucose; storage carbohydrate in animal cells

Question 15

what type of bond links monosaccharides into polysaccharides?

Answer 15

glycosidic bonds

Question 16

building blocks of biomembranes

Answer 16

phospholipids

Question 17

how do phospholipids associate?

Answer 17

noncovalently

Question 18

what does a phospholipid molecule consist of?

Answer 18

two long-chain, nonpolar fatty acid groups to a small, highly polar group

Question 19

what type of bond links phospholipid molecule parts?

Answer 19

ester bond

Question 20

what do fatty acids consist of?

Answer 20

hydrocarbon chain attached to a carboxyl group

Question 21

function of fatty acids?

Answer 21

energy source for cells

Question 22

most common phospholipid?

Answer 22

phosphoglycerides

Question 23

primary structure

Answer 23

linear covalent sequence of amino acids

Question 24

what bonds hold together secondary structures?

Answer 24

hydrogen bonds between backbone amide and carbonyl groups

Question 25

2 most common types of secondary structures

Answer 25

alpha helix and beta pleated sheet

Question 26

alpha helix

Answer 26

backbone of polypeptide forms spiral in which carbonyl oxygen (oxygen that is double bonded to carbon) atom of each peptide bond is hydrogen bonded to amide hydrogen atom of amino acid residue 4 residues along chain

Question 27

beta-pleated sheet

Answer 27

hydrogen bonds form between carbonyl oxygen atom of each residue in one strand and the amide hydrogen atom of an adjacent strand

Question 28

tertiary structure

Answer 28

the three dimensional arrangement of amino acid residues

Question 29

tertiary structure is stabilized by

Answer 29

hydrophobic interactions between nonpolar side chains, van der Waals interactions, and hydrogen bonds between polar side chains AND amino and carbonyl groups