Week 2 Homework Flashcards
What is a covalent bond?
A covalent bond is one in which electron pairs are shared, which is represented in the image by overlapping circles.
A ___ refers to two or more atoms held togther by covalent bonds
Molecule
In a 2D image showing a chemical molecule, what is the most common way to represent a covalent bond?
A solid line
What is the difference between covalent and non-covalent bonds?
Atoms in covalent bonds always share electrons, but atoms in non-covalent bonds do not
What are the two possible hydrogen bonding interactions between two molecules?
Between an H atom of an amine group and a O atom
Between an H atom of an amine group and a N atom
How can you tell if an atom is a hydrogen bond donor?
The atom to which the hydrogen is covalent bonded to
How can you tell if an atom is a hydrogen bond acceptor?
The atom which has a pair of non bonded electrons
True or false? All noncovalent bond interactions result from attractions between atoms with opposite charges.
True
True or false? Noncovalent interactions can be intramolecular - between atoms in the same molecule.
True
True or false? In a protein, ionic interactions are the weakest and dispersion forces are the strongest.
False
True or false? The strength of a noncovalent interaction depends on the magnitude of any charge on an atom and whether the charge is permanent or temporary.
True
Water molecules clustered around nonpolar molecules contribute to hydrophobic interactions because ________.
order of nonpolar molecules increases the total entropy of water
True or false? Carbon’s electronegativity is too low to participate in hydrogen bonding.
True
Are covalent bonds or hydrogen bonds weaker?
Hydrogen bonds
The aggregation of nonpolar molecules or groups in water occurs because of?
increased entropy in the aqueous environment, and therefore, the total system.
Much is made of water’s ability to dissolve a wide variety of molecules and yet, one of its most important characteristics is its effect on nonpolar, uncharged molecules. Select the TRUE statement(s) about the hydrophobic effect.
I. The hydrophobic effect plays an important role in the assembly of lipid bilayers (membranes).
II. The amount of entropy (disorder) in water molecules is lowest when hydrophobic molecules aggregate.
III. Hydrophobic molecules clump together largely because of forces of attraction between them.
1 only
True or false? All proteins possess aldehyde and thiol (sulfhydryl) functional groups.
False
True or false? Proteins are composed of amino acids and these amino acids are all amphipathic.
False
True or false? All proteins are polymers.
True
True or false? Proteins carry out a wide variety of functions in cells.
True
Which factors help explain this rich diversity in protein structure and function.
I. Proteins are composed of sequences of 20 different amino acids that vary in their order in a polypeptide chain.
II. Proteins can have one or more polypeptide chains.
III. Polypeptide chains vary widely in length.
I, II, and III
Why would an animo acid be classified as nonpolar.
Because the atoms in the R group all have similar electronegativities, which makes the covalent bonds nonpolar and the overall R group hydrophobic.
