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BS 161 Exam 1 2017

Terms in this set (79)

Dehydration
synthesis of a polypeptide
Hydrolysis
breaking of a polypeptide
Distinguish between a protein and a polypeptide.
Polypeptide refers to a polymer of amino acids linked by peptide bonds. Quaternary structure of a protein represents many polypeptides together folded exactly into the shape of a functioning unit. Some proteins may only have 1 polypeptide.
Explain how a peptide bond forms between two amino acids.
A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the molecule, releasing a molecule of water.
List and describe the four major components of an amino acid.
Amino group-
Carboxyl group-
R group-
Hydrogen group-
Explain how amino acids may be grouped according to the physical and chemical properties of the R group.
A variable side chain; confers the unique physical and chemical properties of each amino acid. Side chains may be either nonpolar and hydrophobic, or polar or charged (acidic or basic) and thus hydrophilic.
Describe the 4 levels of protein structure.
Primary structure: can fold into a pleated sheet or a helix
Secondary structure: pleated sheet/ a helix. (Rounded or zigzag)
Tertiary structure: interactions between R groups. Three dimensional structure resulting from folding and covalent cross linking of a protein.
Quaternary structure: Protein quaternary structure is the number and arrangement of multiple folded protein subunits in a multi-subunit complex.
Explain how the primary structure of a protein is determined.
The structure of a protein is determined by the shape which is determined by how the amino acid functional groups interact.
Name two types of secondary protein structure. Explain the role of hydrogen bonds in maintaining secondary structure.
α-helix and the ß-sheet. When they are in a polar environment (water) allows it to coil up also in the a-helix they interact with themselves (the hydrogen bonds) and it helps them coil better.
Explain how weak interactions and disulfide bridges contribute to tertiary protein structure.
Weak interactions and disulfide bridges contribute to tertiary protein structure the disulfide bridge makes the shape of the polymer. Weak interactions contribute to tertiary structure
Discuss conditions under which proteins may be denatured
Denaturation of proteins involves the disruption and possible destruction of both the secondary and tertiary structures. Since denaturation reactions are not strong enough to break the peptide bonds, the primary structure remains the same after a denaturation process.
Relate the structure of proteins to their functions.
The function of a protein is determined by its shape. The shape of a protein is determined by its primary structure (sequence of amino acids). The sequence of amino acids in a protein is determined by the sequence of nucleotides in the gene (DNA) encoding it.
Identify the molecules that comprise a lipid.
a lipid is any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents. They include many natural oils, waxes, and steroids. Each lipid is comprised of a glycerol, ester linkage, & fatty acid chain
Explain the molecular difference between solid fats and liquid oils.
Solid fats at room temperature are usually composed of mostly saturated fats which condensed structure stacks & forms a rigid structure.
Liquid fats at room temperature are usually composed of mostly unsaturated fats that have more "kinked" structures allowing less compact structure and more spreading ability.
Sketch the difference between saturated and unsaturated fats and explain how and why these structural differences impact the fluidity of fats and membranes.
The double bonds present in unsaturated fats acount for "kinking" which makes them unable to stack into solids at room temperature and therefore be more fluid than saturated fats. This is also why they are considered the "healthier" fats becuase they do not clog up our organs as badly as saturated fats tend to.
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