Chapter 3 Flashcards
(15 cards)
How would you summarize the chemical evolution hypothesis?
Proteins on early Earth were enveloped in a lipid membrane.
The first membrane-enclosed structure divided to form two structures.
Complex organic compounds formed from water and atmospheric gases present on early Earth.
Iron oxides formed on early Earth
’
s rock surfaces.
Complex organic compounds formed from water and atmospheric gases present on early Earth.
At which step of chemical evolution did life become possible?
creation of carbon-containing compounds from chemicals present in the atmosphere and oceans of ancient Earth
production of small molecules containing reduced carbon
polymerization of building-block molecules into larger organic molecules
evolution of an information-containing, self-replicating molecule
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?
Proteins transmit information from one generation to the next.
They are a major energy source for all living organisms.
They impart mobility to cells and entire organisms.
They are self-replicating molecules.
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?
catalysts
heat
electricity
light
electricity
What class of macromolecules is made up of amino acids?
carbohydrates
nucleic acids
lipids
proteins
proteins
What two functional groups are present in every amino acid?
a hydroxyl group and a carboxyl group
an amino group and a sulfhydryl group
an amino group and a carboxyl group
an amino group and a hydroxyl group
an amino group and a carboxyl group
Which statement best describes the R-groups or side chains of amino acids?
The chemical behavior of an amino acid is always determined by the reactivity of its R-group.
The reactivity of side chains arises from the presence of the amino functional group NH3.
The polarity of each amino acid is determined by the placement of COOH in each side chain.
The nature of side chains determines how soluble each amino acid is in water.
The nature of side chains determines how soluble each amino acid is in water
Monomers join to form polymers under what chemical conditions?
hydrolysis
adding water
catabolism
condensation
condensation
The _____ structure of a protein is the sequence of amino acids.
primary
secondary
tertiary
quaternary
primary
What types of interactions are responsible for the secondary structure of a protein?
van der Waals forces
covalent
hydrogen
ionic
hydrogen
Sickle-cell anemia results when valine replaces glutamate at position 6 of the b-globin subunit of hemoglobin. The sickling seen in red blood cells with the defective hemoglobin subunit affects the _____.
structure of the heme group found in hemoglobin
ability of oxygen and hydrogen to form hydrogen bonds
need for dietary iron
primary structure of hemoglobin
primary structure of hemoglobin
How do prions cause disease?
They are chaperones that cause proteins to unfold.
They cause changes in the shape of normal protein molecules that lead to disintegration of mammalian brains.
They cause changes in a protein
’
s primary structure so that the protein is nonfunctional.
They are alternate but functional forms of normal proteins.
They cause changes in the shape of normal protein molecules that lead to disintegration of mammalian brains.
The lowering of activation energy during the transition step of enzyme catalysis depends on _____ at the enzyme’s active site.
reactants orienting precisely
products being released
interactions with R-groups
temperatures rising
interactions with R-groups
In what important way does competitive inhibition differ from allosteric regulation?
They are two different terms that mean the same thing.
During competitive inhibition, a regulatory molecule binds to a site other than the active site.
During competitive inhibition, a regulatory molecule binds to the active site, whereas during allosteric regulation, a regulatory molecule binds to a site other than the active site.
Allosteric regulation is important in maintaining homeostasis, whereas competitive inhibition is not.
During competitive inhibition, a regulatory molecule binds to the active site, whereas during allosteric regulation, a regulatory molecule binds to a site other than the active site.
From the list below, choose the most likely enzyme to be present in a bacterium found in a hot water vent in an acidic current.
Enzyme B-functions best at a pH of 3 and a temperature of 90°C
Enzyme D-functions best at a pH of 7 and a temperature of 50°C
Enzyme C-functions best at a pH of 10 and a temperature of 30°C
Enzyme A-functions best at a pH of 10 and a temperature of 90°C
Enzyme B-functions best at a pH of 3 and a temperature of 90°C
