What is the relationship between Bacteria, Archaea, and Eukarya?
These groups are descendants of a single common ancestor cell.
Energy that is stored in the chemical bonds
Which of the following properties of water come about because of water's polar bonds and bent structure?
Where on the phylogenetic tree should the origin of a nuclear envelope appear?
at the base of all Eukaryotes
The oxygen revolution, which resulted in the accumulation of oxygen in Earth's atmosphere, was the direct result of which process?
In the same portion of rRNA, you find the following sequences: Land Plants: AUAUCGAG Green Algae: AUAUGGAG Fungi: AUAUGGAC Based on these data, which statement most accurately summarizes the evolutionary relationships of these three types of organisms?
Fungi are more closely related to green algae than to land plants.
Peroxisomes are centers for oxidation reactions, including those that render certain toxins harmless.)
Which of the following factors affect(s) the process of a chemical reaction?
A functional group
a carbon-containing (organic) or inorganic (without carbon) chemical group that contains H, N, or O
Substance that gives up a proton during a chemical reaction, raising the hydrogen ion concentration of water
A prokaryotic cell is distinct from a eukaryotic cell because a prokaryotic cell lacks______?
a membrane-bound nucleus
If water were a linear (not bent) molecule, electrostatic interactions between water molecules would be much weaker. Why?
The partial negative charge on oxygen would stick out less and be less able to participate in hydrogen bonding.
Cells cannot stay alive without inputs of energy. Why not?
Cells are composed of highly ordered molecules that contain high-energy bonds.
Which statement best explains the physical basis for why oil and water don't mix?
Oils are nonpolar molecules that cannot interact with water molecules via hydrogen bonding.
Which evidence supports the endosymbiotic hypothesis for the origin of the mitochondrion?
Mitochondria have their own ribosomes and manufacture their own proteins.
The eukaryotic cell overcomes the problem of its larger size by _____.
compartmentalizing cellular functions into various organelles
n plant cells, why are toxins such as nicotine, cocaine, and caffeine found in vacuoles instead of the cytosol?
Toxins in vacuoles are sequestered from the rest of the cell, where they could do harm.( Vacuoles serve as storage depots that keep noxious compounds such as toxins separate from the rest of the cell. If released into the cytosol, toxins would poison the cell.)
A chemical bond that results from sharing electrons between two elements with very similar electronegativity would best be termed _____.
Aerobic respiration is more efficient than anaerobic respiration because of what property of oxygen?
It is highly electronegative.
Primary production by photosynthetic protists is considered "primary" because _____.
these protists produce chemical energy by fixing CO2
Darwin described the process of "descent with modification." What is this process?
The characteristics of a species change from generation to generation.
Cells in a live organism differ from cells in a dead organism. Why?
Live cells replicate by division, dead cells do not,Live cells process genetic information, dead cells do not,Live cells acquire energy, dead cells do not.
What evidence supports the hypothesis that the nuclear envelope of eukaryotes arose from infolding of the plasma membrane?
The nuclear membrane and endoplasmic reticulum of modern eukaryotes are continuous.
The cell wall found in bacterial cells functions to _____.
protect the cell and provide shape and rigidity
Polymers are composed of amino acids
Proteins. They are are composed of amino acids joined together.
What is the central atom in an amino acid bonded to?
The central carbon atom in an amino acid is bonded to an amino functional group, a carboxyl functional group, a side chain, and hydrogen.
Which part of an amino acid is always acidic?
The carboxyl group (COOH) contains two oxygen atoms that tend to pull electrons away from the hydrogen atom, so this group tends to lose a proton and is acidic.
Describe the formation of polypeptides from amino acids.
A hydroxyl group is removed from the carboxyl group of one amino acid and hydrogen is removed from the amino group of the other amino acid, allowing a bond to form between the two groups.
How do enzymes in the digestive tract break down food molecules?
Enzymes in the digestive tract catalyze hydrolysis reactions (which is a process that occurs by hydrolysis)
The final three-dimensional folding of protein molecules (tertiary structure) can result from which types of chemical interactions?
covalent bonding, hydrophobic interactions, hydrogen bonding, ionic bonds
Enzyme inhibitor that is roughly the same shape as the substrate and binds at the active site
Term for the process of forming covalent bonds between amino acids during protein synthesis
How does allosteric regulation can change an enzyme's activity?
In allosteric activation a regulatory molecule binds to a site other than the active site, resulting in a change in enzyme shape that allows the active site to bind substrate.
An amino acids possess side chains that would be unable to form hydrogen bonds with water
amino acids with nonpolar side chains
Under otherwise equivalent conditions, do more chemical reactions occur with a catalyst than without one? Why or why not?
Yes. Because catalysts lower the activation energy, a greater number of reactant molecules will have enough kinetic energy to complete the reaction.
The secondary structure of proteins results because of _____ bonding between molecules in the protein molecules' backbone.
Why does an enzyme alter the activation energy for a reaction but not the overall free-energy change?
An enzyme brings reactants together in precise orientations and reduces the free energy of the transition state; it does not change the free energies of the reactants or products.