Questions and Answers
Protein phosphorylation is commonly involved with all of the following EXCEPT _____.
The toxin of Vibrio cholerae causes profuse diarrhea because it _____.
modifies a G protein involved in regulating salt and water secretion
Which of the following poses the best evidence that cell-signaling pathways evolved early in the history of life?
Signal transduction molecules found in the distantly related organisms are similar
Which of the following statements is true of signal molecules?
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Magnesium has an atomic number of 12. What is the most stable charge for a magnesium ion?
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What results from an unequal sharing of electrons between atoms?
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How many electrons are involved in a double covalent bond?
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What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms?
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What is the difference between covalent bonds and ionic bonds?
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Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers from 92-100. Therefore, which of the following can be true?
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In what way are elements in the same column of the periodic table the same? They have the same number of _____.
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What do you predict to be the charge on ammonium?
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If you change the number of neutrons in an atom, you create ____.
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Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?
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How many electron pairs are shared between carbon atoms in a molecule that has the formula C2H4?
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When are atoms most stable?
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What is true for the reaction 3H2 + N2 = 2NH3?
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What correctly describes all chemical equilibrium?
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What is the atomic mass of an oxygen atom?
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Bonds between two atoms that are equally electronegative are _____.
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How many electrons are involved in a single covalent bond?
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Which bond or interaction would be difficult to disrupt when compounds are put into water?
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What describes a reaction that has reached chemical equilibrium?
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Why are lipids and proteins free to move laterally in membranes?
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The voltage across a membrane is called the _____
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In what way do the membranes of a eukaryotic cell vary?
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What determines whether a drug molecule selectively enters target cells?
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Define diffusion.
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What happens to the membrane's permeability to glucose when increasing the proportion of unsaturated phospholipids?
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Why do unsaturated fatty acids help keep a membrane more fluid at lower temperatures?
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According to the fluid mosaic model of cell membranes, phospholipids can _____.
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Why are cell membranes asymmetrical?
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Which proteins are NOT embedded in the hydrophobic portion of the lipid bilayer?
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How is lactose classified?
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Define a lipid.
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What are nucleic acids made of?
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How many molecules of water are used to completely hydrolyze a polymer that is 11 monomers long?
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The polypeptide sequence of hemoglobin from a new organism has many differences. This suggests the new organism is more closely related to _____
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Which polysaccharide is an important component in the structure of many animals and fungi?
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Normal hemoglobin is a tetramer. In sickle-cell disease, hemoglobin exhibits what?
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What is the major ingredient of margarine?
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What is a protein molecule that assists in the proper folding of other proteins called?
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Why can humans digest starch but not cellulose?
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Which one of the following is NOT a component of each monomer used to make proteins?
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Why does ice float in liquid water?
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What is the predicted outcome when NaCl crystals are added to pure water and pure methanol?
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What is the rarest property among compounds regarding water?
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The partial negative charge in a molecule of water occurs because _____
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Why do Portland and Minneapolis have different climates despite their similar latitudes?
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Which of the following is true of carbon?
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Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, what happens with chains that have double bonds?
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What kind of bond(s) is a carbon atom most likely to form with other atoms?
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Which two functional groups are always found in amino acids?
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Stanley Miller's 1953 experiments supported which hypothesis?
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Which amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?
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What is characteristic of a steroid hormone action?
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What would be inhibited by a drug that blocks the addition of phosphate groups to proteins?
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Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions?
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What do phosphatases do in signal transduction?
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What is true during a typical cAMP-type signal transduction event?
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Why do molecules involved in hydrogen bonding almost always contain either oxygen or nitrogen or both?
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In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by _____
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Rank, from low to high, the pH of blood, stomach acid, and urine.
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An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?
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What digests a bacterium engulfed by a white blood cell through phagocytosis?
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How do the membranes of winter wheat remain fluid in extremely cold temperatures?
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What is a characteristic feature of a carrier protein in a plasma membrane?
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What does the use of proton pumps imply about the common ancestor of all three domains of life?
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What is the difference between pinocytosis and receptor-mediated endocytosis?
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Which membrane activity requires energy from ATP?
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Where do receptor molecules end up after endocytosis?
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Why is the sodium-potassium pump called an electrogenic pump?
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What describes the movement of phospholipids in a membrane according to the fluid mosaic model?
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How do starch and cellulose compare?
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What best fits the class of molecules known as nucleotides?
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Why are steroids considered lipids?
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What happens when a single amino acid in a protein consisting of 325 amino acids is changed?
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Which polysaccharide is an important component in the structure of many animals and fungi?
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Which of the following contain amino acids?
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What best summarizes the relationship between dehydration reactions and hydrolysis?
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What is the highest level of structure found in proteorhodopsin, a light-sensitive molecule?
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What are saturated fatty acids characterized by?
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Why is carbon so important in biology?
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What can organic molecules with only hydrogens and five carbon atoms not do?
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Compared to a hydrocarbon chain with only single bonds, a hydrocarbon chain with double bonds will _____.
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Why are hydrocarbons insoluble in water?
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In the formation of biofilms, what function does cell signaling serve?
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What is programmed cell death called?
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Describing apoptosis, what happens during this event?
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Study Notes
Trace Elements
- Iodine is a trace element required by humans and other vertebrates but not by bacteria or plants.
Chemical Bonds
- In a molecule with the formula C2H4, carbon atoms share 2 electron pairs.
- Atoms achieve stability by satisfying the octet rule, needing eight valence electrons for a full outer shell.
- Nonpolar covalent bonds exist between two atoms of equal electronegativity.
- A single covalent bond involves two electrons.
Reactions and Chemical Equilibrium
- Ammonia (NH3) formation occurs simultaneously with decomposition in the reaction 3H2 + N2 ↔ 2NH3.
- In chemical equilibrium, forward and reverse reactions occur without net change in reactant and product concentrations.
Atomic Structure and Mass
- Oxygen has an atomic number of 8 and a mass number of approximately 16 daltons.
Membrane Dynamics
- Lipids and proteins in membranes can move laterally due to weak hydrophobic interactions.
- Membrane potential refers to the voltage across a cellular membrane.
- The unique proteins in each eukaryotic membrane contribute to membrane variation.
- Increased unsaturated phospholipids raise membrane permeability to glucose.
Fluid Mosaic Model
- Phospholipids can laterally move within the membrane, making cell membranes fluid.
- The asymmetrical nature of membranes facilitates differing functions on either side.
Biological Molecules
- Lactose is classified as a disaccharide, composed of glucose and galactose.
- Lipids are composed of glycerol and three fatty acid chains.
- Nucleic acids consist of nucleotide monomers.
Hydrolysis and Dehydration Reactions
- Hydrolyzing a polymer of 11 monomers requires 10 molecules of water.
- Dehydration reactions build polymers, while hydrolysis reactions break them down.
Protein Structure
- Hemoglobin is a tetramer that can have altered structures in sickle-cell disease.
- Chaperonins assist in the proper folding of proteins.
Enzyme Activity
- Humans have enzymes for digesting starch but not cellulose, due to differences in glycosidic linkages.
Carbon Chemistry
- Carbon can form polar and nonpolar bonds, making it versatile in biological systems.
- Hydrocarbons are generally insoluble in water due to their nonpolar covalent links.
Signal Transduction
- Phosphorylation is essential in protein signaling pathways, affecting receptor functions.
- Ligand-gated ion channels alter ion distributions across membranes upon signaling molecule binding.
Properties of Water
- Ice floats on liquid water due to lower density as a solid, allowing for environmental sustainability.
- Water molecules' partial negative charge arises from unequal electron sharing between oxygen and hydrogen.
Cellular Processes
- Apoptosis is programmed cell death involving DNA and organelle fragmentation.
- In receptor-mediated endocytosis, receptors end up on the vesicle's inside surface after internalization.
ATP and Cellular Energy
- Active transport, like the sodium-potassium pump, requires ATP to move ions against their concentration gradient.
Atomic Number and Isotopes
- Magnesium's stable ion charge is +2.
- Molybdenum can have 50-58 neutrons due to its isotopes with varying mass numbers.
Summary of Compounds
- Starch and cellulose are both glucose polymers.
- Nucleotides consist of nitrogenous bases, phosphate groups, and sugars.
General Chemistry
- Covalent bonds involve electron sharing, while ionic bonds arise from electrical attraction between charged atoms.
- Elements in the same periodic table column share the same number of valence electrons, influencing reactivity and properties.
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Test your knowledge of essential biology concepts with this set of flashcards. Covering trace elements, molecular structures, and atomic stability, this quiz is perfect for students seeking to reinforce their understanding of biological principles. Challenge yourself and improve your retention of key terms in biology.