Protien Structure And Function Flashcards
What is the positively charged region of an amino acid?
Amino group, NH3+
What is the negatively charged part of an amino acid?
Carboxyl group, COO-
At physiological pH, amino acids are _____. The carboxylic acid ionizes above pH 2. The amino group ionizes below pH9.
Zwitterions
The ____ is the pH at which half the functional groups (R groups) are protonated and half are un-protonated
pK
When the pH = pK, a _____ region is formed.
Buffering region
The _____ ____ is the pH at which the molecule has a neutral charge.
Isoelectric point (pI)
Some amino acids have side chains with dissociable protons, the pK of their R groups are near physiological pH. These amino acids often participate in _____.
Catalysis
When and amine group of one amino acid bonds with the carboxylic acid of another amino acid, a ____ _____ is formed. This is a _____ reaction.
Peptide bond
Dehydration
What type of bond is shown in the picture
Peptide bond
The 6 Aliphatic (nonpolar) amino acids are _________.
Glycine, alanine, proline, valine, leucine, and isoleucine
The 3 aromatic amino acids are ______.
Phenylalanine, tyrosine, and tryptophan
The 4 polar, uncharged amino acids include:
Asparagine, glutamine, serine, and threonine
Polar amino acids are often found on the _____ of proteins. They all have _____ hydropathy indices.
Surface
Negative
The 2 sulfur containing amino acids are:
Methionine, cysteine
The 5 charged amino acids are _______ . They have a charge at near physiological pH and promote protein folding.
Aspartate, glutamate (negative)
Arginine, lysine, histidine (positive)
_____ structure refers to the linear sequence of amino acids that make up a protein.
Primary
In proteins amino acids are _____ attached to one another through peptide bonds.
Covalently
The alpha helix is a common ____ structure.
Secondary
Beta sheets are a type of ____ structure.
Secondary
The ____ ____ is a tertiary structure domain that forms a valley that binds and hydrolyzes ATP
Actin cleft
Amino acids in the interior are hydrophobic such as ____, _____ , ____. Amino acids at the surface are polar such as ____, ____ , ____.
Isoleucine, valine, phenylalanine
Serine, threonine, and tyrosine
One or more addition of ______ protects amino acids from degradation. This is common on extra cellular domains of trans membrane proteins.
Carbohydrates (sugars)
The covalent attachment of _____ to amino acids helps to anchor them to membranes
Lipids
Serine, threonine, and tyrosine side chains can be _______. Enzymes called _____ hydrolyze ATP and transfer a phosphate to the hydroxyl group of the amino acid.
Phosphorylated
Kinases
Cysteine can form a covalent ______ bond that maintains the folded shape. This is a type of ____ modification.
Disulfide
Post-translational
The interactive surfaces of proteins often have _____ amino acids in the quaternary structure
Hydrophobic 
Transient changes in quaternary structure of the ____ ____ _____ mediates, beta adrenergic receptor signaling.
G Protein complex
Which of the amino acids below would most likely be located at the solvent exposed surface of an enzyme?
Isoleucine, threonine, valine, phenylalanine or alanine
Threonine
At physiological pH what is glycine’s net charge?
Zero
The pH at which 50% of molecules with an ionizable group are protonated and 50% are on protonated is the:
pKa
Which of the amino acids below form covalent bonds through their side chains that stabilize proteins folded structures?
Histidine, glutamine, glutamate, tyrosine, or cysteine?
Cysteine
In and amphipathic, alpha helix, which amino acids side chain would project out towards a nonpolar solvent, such as a lipid membrane?
Glutamate, arginine, proline, isoleucine, or serine?
Isoleucine
In a amphipathic alpha helix, which amino acid side chains would project out towards a polar solvent?
Valine, proline isoleucine, methionine, or serine
Serine
Which of the amino acids can be modified by phosphorylation after a protein is translated?
Serine, tyrosine, and threonine
Which post translational modification is most likely to anchor a protein in a membrane?
Palmitoylation of a cysteine
Which of the phrases below best describes the quaternary structure of adult hemoglobin?
Heterotetramer
