Chapter 3: Protein Structure and Function Flashcards
How would you summarize the chemical evolution hypothesis?
A) Proteins on early Earth were enveloped in a lipid membrane.
B) The first membrane-enclosed structure divided to form two structures.
C) Iron oxides formed on early Earth’s rock surfaces.
D) Complex organic compounds formed from water and atmospheric gases present on early Earth.
D) Complex organic compounds formed from water and atmospheric gases present on early Earth.
At which step of chemical evolution did life become possible?
a) polymerization of building-block molecules into larger organic molecules
b) evolution of an information-containing, self-replicating molecule
c) creation of carbon-containing compounds from chemicals present in the atmosphere and oceans of ancient Earth
d) production of small molecules containing reduced carbon
b) evolution of an information-containing, self-replicating molecule
Proteins are critical in living organisms. What is one example of the many important functions of proteins in organisms?
a) They impart mobility to cells and entire organisms.
b) Proteins transmit information from one generation to the next.
c) They are a major energy source for all living organisms.
d) They are self-replicating molecules.
a) They impart mobility to cells and entire organisms.
Stanley Miller set up a laboratory simulation of conditions suspected of having been prevalent on early Earth in order to ascertain whether chemical evolution was possible. Based on his experiments, what was the energy source identified as most likely responsible for the formation of complex carbon-containing compounds from simple molecules present on early Earth?
a) catalysts
b) light
c) heat
d) electricity
d) electricity
What class of macromolecules is made up of amino acids?
a) carbohydrates
b) lipids
c) nucleic acids
d) proteins
d) proteins
What two functional groups are present in every amino acid?
a) an amino group and a sulfhydryl group
b) an amino group and a carboxyl group
c) a hydroxyl group and a carboxyl group
d) an amino group and a hydroxyl group
b) an amino group and a carboxyl group
Which statement best describes the R-groups or side chains of amino acids?
a) The chemical behaviour of an amino acid is always determined by the reactivity of its R-group.
b) The reactivity of side chains arises from the presence of the amino functional group NH3.
c) The nature of side chains determines how soluble each amino acid is in water.
d) The polarity of each amino acid is determined by the placement of COOH in each side chain.
c) The nature of side chains determines how soluble each amino acid is in water.
Monomers join to form polymers under what chemical conditions?
a) condensation
b) catabolism
c) hydrolysis
d) adding water
a) condensation
The _____ structure of a protein is the sequence of amino acids.
a) primary
b) secondary
c) quaternary
d) tertiary
a) primary
What types of interactions are responsible for the secondary structure of a protein?
a) covalent
b) ionic
c) van der Waals forces
d) hydrogen
d) hydrogen
Sickle-cell disease results when valine replaces glutamate at position 6 of the β-globin subunit of hemoglobin. The sickling seen in red blood cells with the defective hemoglobin subunit affects the _____.
a) structure of the heme group found in hemoglobin
b) need for dietary iron
c) primary structure of hemoglobin
d) ability of oxygen and hydrogen to form hydrogen bonds
c) primary structure of hemoglobin
How do prions cause disease?
a) They are alternate but functional forms of normal proteins.
b) They cause changes in a protein’s primary structure so that the protein is nonfunctional.
c) They cause changes in the shape of normal protein molecules that lead to disintegration of mammalian brains.
d) They are chaperones that cause proteins to unfold.
c) They cause changes in the shape of normal protein molecules that lead to disintegration of mammalian brains.
Many proteins fold spontaneously because _____.
a) only the correctly folded protein is functional
b) the folded protein has higher entropy (more disorder)
c) The above statement is false; proteins cannot fold spontaneously.
c) the bonds that form secondary and tertiary structure are energetically favourable
c) the bonds that form secondary and tertiary structure are energetically favourable
The linear order of amino acids in a protein helps determine which level of protein structure?
a) the primary structure only
b) the secondary structure only
c) the tertiary structure only
d) all the levels of protein structure
d) all the levels of protein structure
A chemical that breaks disulfide bonds might destroy which level of protein structure?
a) the primary structure
b) the secondary structure
c) the tertiary structure
d) all the levels of protein structure
c) the tertiary structure
