Amino Acids

Question 1

amino acids

Answer 1

building blocks of proteins, there are 20 coded for by our DNA

Question 2

primary sequence

Answer 2

the unique sequence of a.a.’s in each protein predicts its conformation and the properties of side chains on each amino acid dictates the associations b/w them leading to the conformation of the protein

Question 3

general a.a. structure

Answer 3

all of the 20 a.a.’s have a common structure: the carbon is substituted w/ an amino group, a carboxylic acid group, a hydrogen, and an individual side chain (R)

Question 4

what do side chains determine?

Answer 4

how a protein can interact w/ other molecules

Question 5

zwitterions

Answer 5

amino acids exist in this form at physiologic pH and the amino and carboxylic groups are charged; depending on the pKa of each side chain, the group may be charged/uncharged at physiological pH

Question 6

protonation

Answer 6

occurs at very low pH

Question 7

deprotonation

Answer 7

occurs at very high pH

Question 8

peptide bond

Answer 8

chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid (condensation reaction), and the C’s and N’s of the a.a.’s form the polypeptide backbone

Question 9

amino acid side chain classifications

Answer 9

non-polar aliphatic, aromatic, polar uncharged, sulfur-containing and charged

Question 10

non-polar aliphatic amino acids properties

Answer 10

hydrophobic, electrons shared and no charges to interact w/ polar molecules

Question 11

what are the non-polar alipathic a.a.’s?

Answer 11

glycine, alanine, proline, valine, leucine, isoleucine

Question 12

aromatic amino acids properties

Answer 12

similar ring structures but each have diff. polarity

Question 13

what are the aromatic a.a’s?

Answer 13

phenylalaline (non-polar, hydrophobic), tryptophan and tyrosine (more polar; contain N and O)

Question 14

uncharged polar amino acids properties

Answer 14

contain electronegative O and N atoms and therefore polar, but side groups are not charged (allows them to interact w/ polar water molecules, increasing hydrophilicity)

Question 15

what are the uncharged polar amino acids?

Answer 15

asparagine, glutamine, serine, threonine

Question 16

disulphide bonds

Answer 16

sulfhydryl groups of 2 cysteines oxidize to form cystine; disulphide bonds are an important conformational stabilizer and often holds diff. parts of a protein molecule or 2+ chains that make up a protein molecule

Question 17

charged amino acids properties

Answer 17

carry either a negative (acidic) charge or a positive (basic) charge

Question 18

what are the charged a.a.’s?

Answer 18

aspartate, glutamate (negatively charged); arginine, lysine and histidine (+ve charge)

Question 19

side-chain interactions

Answer 19

side-chain interactions

the charged groups on a.a.’s can interact with each other and this is considered an electrostatic interaction/bond

Question 20

sickle cell anemia

Answer 20

improper protein conformation causes RBC to be sickle shaped; genetically inherited

Question 21

homologs

Answer 21

similar proteins that have arisen from a common ancestor, often by gene duplication (mutations at the variant residue are more likely to cause problems)

Question 22

polymorphisms

Answer 22

DNA variants that occur within a specific population at a frequency greater than 1%

Question 23

posttranslational modification

Answer 23

the covalent and generally enzymatic modification of proteins during or after protein synthesis

Question 24

blood coagulation

Answer 24

coagulation enzymes and substrates must assemble on a -ve surface (e.g. platelet membrane); calcium required to bridge b/w the gamma-carboxylated proteins and the membrane surface; Vitamin K is required for γ-carboxylation and this is where the drug warfarin interferes to prevent clots

Question 25

what are the sulfur containing amino acids?

Answer 25

methionine and cysteine