FT LEC: Proteins and Enzymes Flashcards
All _________ contain the elements carbon, hydrogen, oxygen, and nitrogen; most also contain sulfur
PROTEINS
the main protein of milk, contains phosphorus
Casein
Other elements, such as phosphorus and iron, are essential constituents of certain specialized proteins
- Casein
- Hemoglobin
The presence of nitrogen sets them apart from carbohydrates and lipids, which most often do not contain nitrogen.
PROTEINS
the oxygen-transporting protein of blood, contains iron
Hemoglobin
Casein, the main protein of milk, contains ________
phosphorus
Hemoglobin, the oxygen-transporting protein of blood, contains _______
iron
Proteins are naturally occurring polymers in which the monomer units are ________
amino acids
The Building Blocks for Proteins
AMINO ACIDS
an organic compound that contains both an amino (-NH2) group and a carboxyl (-COOH) group
AMINO ACIDS
Amino acids found in proteins
α-amino acid
the amino group and the carboxyl group are attached to the α-carbon atom
α-amino acid
distinguishes α-amino acids from each other
R group
amino acid side chain
R group
STANDARD AMINO ACIDS
- Nonpolar Amino Acid
- Polar Amino Acid
has nonpolar side chain
Nonpolar Amino Acid
hydrophobic (water-fearing)
Nonpolar Amino Acid
Found in the interior of proteins, where there is limited contact with water
Nonpolar Amino Acid
R group – hydrocarbons (aliphatic or aromatic)
Nonpolar Amino Acid
has polar side chain
Polar Amino Acid
hydrophilic (water-loving)
Polar Amino Acid
Found on the surfaces of proteins
Polar Amino Acid
Subcategorized to: Polar neutral, polar acidic, and polar basic
Polar Amino Acid
Side chain of Polar neutral
has groups containing heteroatoms
TYPES OF POLAR AMINO ACIDS
- Polar Neutral
- Polar Acidic
- Polar Basic
contain polar but neutral side chain (R group)
Polar neutral
contain a carboxyl group as part of the side chains
Polar acidic
Side chain of polar acidic:
carboxylic acid
contain an amino group as part of the side chain
Polar basic
Side chain of polar basic
amine, imine
The ________ of one amino acid interacts with the amino group of the other amino acid.
carboxyl group
Amino acids are linked together by an _______
amide (peptide) bond via a condensation reaction
The four levels of protein structure are
Primary (1o)
Secondary (2o)
Tertiary (3o)
Quaternary (4o)
Amino acid sequence
Primary (1o)
Overall 3D shape of folded protein
Tertiary (3o)
H-bonds on protein backbone
Secondary (2o)
Subunit organization
Quaternary (4o)
is the order/sequence in which amino acids are linked together in a protein
PRIMARY STUCTURE (1o)
Amino acids are linked to each other by ____________
peptide bonds
Arrangement in space adopted by the hydrogen-bonded arrangement of the backbone portion of a protein
SECONDARY STRUCTURE (2o)
Common types of secondary structures
- α helix
- β pleated sheet (β-sheet)
Folding is stabilized by noncovalent interactions
SECONDARY STRUCTURE (2o)
Composed of 1 polypeptide chain
α helix
H bonds are within a single polypeptide chain (backbone only)
α helix
R-groups are outside
α helix
Right-handed or clockwise, spiral
α helix