1、 问题:What is the most appropriate definition of conformation?
A:The chemical formula of a molecule
B:The fixed arrangement of atoms dictated by the bonds of a molecule
C:The three dimensional structure a molecule is most likely to adopt, given its chemical formula
D:The (potentially flexible) spatial arrangement of atoms around fixed bonds in a molecule
答案: 【The (potentially flexible) spatial arrangement of atoms around fixed bonds in a molecule】
2、 问题:The following reaction: S⟶P has a ΔG of -10 kJ/mol. The reaction is:
3、 问题:Of the elements below, two are much more abundant in earth’s crust than in living organisms. What are these two elements?
1、 问题:The non-covalent intermolecular forces described in this video behave differently. How are the forces ranked in terms of their energy?
A:Van Der Waals > Ionic > Hydrogen bonds
B:Ionic > Van Der Waals > Hydrogen bonds
C:Ionic > Hydrogen bonds > Van Der Waals
D:Hydrogen bonds > Ionic > Van Der Waals
答案: 【Ionic > Hydrogen bonds > Van Der Waals 】
2、 问题:In a Ramachandran plot, what do all of the shaded areas represent?
A:The most common combinations of bond angles in proteins
B:Angles that cause the formation of beta sheets
C:Angles that cause the formation of alpha helices
D:Areas of steric clash between the R groups of adjacent amino acids
答案: 【The most common combinations of bond angles in proteins】
3、 问题:Why does proline often “break” an alpha helix?
A:It cannot adopt the psi and phi angles required to form an alpha helix.
B: often adopts the trans conformation, unlike the other amino acids.
C:It flips between the cis and trans conformations frequently.
D:It has no free hydrogen to bond with a carbonyl because of the imino ring
答案: 【It has no free hydrogen to bond with a carbonyl because of the imino ring】
4、 问题:Which statement correctly describes the structure of lipids?
A:Lipids enclose the aqueous cytosol of an animal cell in a monolayer
B:Lipids are formed by addition of repeating subunits into a polymer
C:Lipids all have a large hydrophobic region
D:Most lipids contain peptide bonds
答案: 【Lipids all have a large hydrophobic region】
5、 问题:Glycerol can form triacylglycerol when..
A:three glycerol molecules react with one another
B:the acyl groups cyclize to form a multi-ring structure
C:each ester linkage is replaced with a phosphodiester linkage