R groups (side chains) Flashcards
What amino acids have R groups that are nonpolar aliphatic groups
- Alanine
- Valine
- Leucine
- Isoleucine
- Glycine
- Methionine
- Proline
The side chains that are nonpolar aliphatic R groups like to do what?
Like to cluster together with proteins & stabilize proteins structure through the hydrophobic effect
________ has the simplest form & doesn’t contribute to interactions driven by the hydrophobic effect
Glycine
Methionine
One of the two sulfur-containing amino acids has slightly nonpolar thioether groups in its side chain
Proline
Has an aliphatic side chain (R group) with a distinctive cyclic structure
What amino acids have aromatic R groups as their side chain?
- Phenylalanine
- Tyrosine
- Trytophan
________ & _________ can absorb UV light
Tryptophan, tyrosine (& phenylalanie)
What amino acids have polar uncharged R groups?
- Serine
- Threonine
- Cystenine
- Asparagine
- Glutamine
Amino acids that have polar uncharged R groups are more _______ in water
Soluble (hydrophillic)
The polarity of ________ & _______ is contributed by their hydroxyl group
Serine, Threonine
The polarity of __________ & __________ is contributed by their amide groups
Asparagine & glutamine
_______ polarity is contributed by its sulfhydryl group
Cysteine
Cysteine is oxidized to form covalently linked dimeric amino acids called _________ where two cystine molecules are joined by a disulfide bond
Cystine
The most hydrophilic R groups are those that are either __________ or ________ charged
Positively charged or negatively
What amino acids have a positive chare at pH=7?
- Lysine
- Arginine
- Histidine
What amino acids have negative charged R groups?
- Aspartate
- Glutamate
Aspartate & glutamate both have 2nd __________ group
Carboxyl
Nonpolar (alphatic & aromatic) R groups are what?
Hydrophobic and bury away from water
Polar uncharged R groups are what?
Hydrogen bonds acceptors & donors, and interact with water
Polar charged R groups are what?
Cationic and anionic groups at pH = 7
Glycine is considered ________ because of its hydrogen side group
Nonpolar
Both
Polar side chain (Polar R groups) are both hydrogen acceptor & donors & are often found at the ________ of proteins to interact with water & polar groups ( have hydroxyl & amide as their side chain)
Surface
Hydroxyl make a strong ______ when ionidize
Nucleophile
What amino acid within the polar uncharged R groups has hydroxyl as their R group?
- Serine
- Threonine
- Tyrosine
What amino acid within the polar uncharged R groups has amide as their R group?
- Glutamine (amide is not basic)
- Asparagine
Cystenine is a strong nucleophile when deprotonated & its side chains can be cross-linked if oxidized to form a __________ that stabilize the 3D structure of proteins
Disulfide bridge
Histidine
- Has an aromatic ring
- Acid or base near pH= 7.4 (common proton donor/acceptor inenzyme active)
- Signfanct fraction protonated (+) charge at pH=7.4
Lysine
- Has an alkylamino group (NH3+)
Has a long flexibile chain
Arginine
- Has a guanidino group (highly basic)
- Charge stbalizied by resonance
- Has a long flexible side chain
_________ & _______ side chains are nitrogenous bases with positive charge at pH = 7
Lysine, Arginine
Charged R gorup have ________ side chain (-)
Acidic
Aspartate & Glutamate
- Both dicarboxylic acids with ionized form stabilized at pH=7 (both have 2 carboxyl groups)
- Full negative charge at pH= 7
- Form ionic bonds with basic an=mino acids & other charged groups
- Are hydrogen acceptors & donors
- Can act as a base to affect ionization s
