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AP Biology Test: Unit 1
The Chemistry of Life
What are the most common elements in humans?
Oxygen, Carbon, Hydrogen, and Nitrogen
a substance that cannot be broken down to other substances by chemical means
a substance consisting of two or more different elements combined in a fixed ratio
anything that takes up space and has mass
elements required by an organism in minute quantities
smallest unit of matter that still retains the properties of an element
particles that compose an atom
a subatomic particle with a neutral charge, weighs 1 dalton/amu, and is found in the nucleus
a subatomic particle with a positive charge, weighs 1 dalton/amu, and is found in the nucleus
a subatomic particle with a negative charge, weighs 0 dalton/amu, and is found orbiting the nucleus
the dense core of an atom packed with neutrons and protons
the number of protons in an atom of an element
the sum of the protons and neutrons in the nucleus of an atom
the total mass of an atom
one of the atomic forms of an element, with each form varying in neutron amount and atomic numbers
an isotope in which the nucleus decay spontaneously
the capacity to cause change
the energy that matter possesses because of its location or structure
the different states of potential energy that electrons have in an atom
the average distances of electrons from the nucleus, which correlates to electrons' energy levels
the outermost electrons of an atom
the outermost electron shell
the attractive forces that hold atoms together
the sharing of a pair of valence electrons by two atoms
two or more atoms held closely together by covalent bonds
the attraction of an atom for the electrons of a covalent bond
nonpolar covalent bond
a covalent bond where the electrons are shared equally
polar covalent bond
a covalent bond where the electrons are not shared equally; on atom is more electronegative than the other
a charged atom
a positively charged atom
a negatively charged atom
the attraction between cations and anions
compounds formed by ionic bonds; aka salts
a weak bond formed when a hydrogen atom covalently bonded to on electronegative atom is also attracted to another electronegative atom
van der Waals interactions
weak attractions between molecules or parts of molecules that are brought about by localized charge fluctuations
the binding together of like molecules, often by hydrogen bonding
the clinging of one substance to another
a measure go how difficult it is to stretch or break the surface of a liquid
the energy of motion
a measure of the total amount of kinetic energy due to molecular motion in a body of motion
the intensity of heat due to the average kinetic energy of the molecules
the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C
Heat of vaporization
the quantity of heat a liquid must absorb for 1 g of it to be converted from liquid to gas
when liquid evaporates, and the surface of the liquid than remains behind cools down
a liquid that is completely homogenous mixture of two or more substances
the dissolving agent of a solution
the substance that is dissolved
a solution where water is the solvent
any substance that has an affinity for water
substances that do not have an affinity for water
the sphere of water molecules around each dissolved ion
a stable suspension of fine particles in a liquid
the number of moles of solute per liter in a solution
a substance that increases the hydrogen ion concentration of a solution
a substance that reduces the hydrogen ion concentration of a solution
a single proton with a charge of 1+
How are isotopes used in biology?
Radioactive isotopes are used to date fossils and label chemical substances in metabolic processes
What happens when electrons change levels?
Electrons absorb or lose energy when they change energy levels.
What is the significance of valence numbers?
Valence numbers determine the chemical behavior of an atom.
Why is H bonding so important to water's properties?
Properties such as cohesion, adhesion, surface tension, and high specific heat would onto exist without hydrogen bonding.
Why is cohesion important to living things?
Cohesion helps to transport water and nutrients to plants.
Why is moderation of temperature important to living things?
Moderation of temperature prevents living organisms from overheating and stabilizes temperature in bodies of water.
Why is expansion when freezing important to living things?
Expansion when freezing prevents large bodies of water from completely freezing over, thus protecting underwater sea life.
Why is versatile solvent important to living things?
Versatile solvent means water is strong enough to dissolve necessary enzymes into bodily fluids, such as blood and saliva, without dissolving cell membranes.
What happens when hydrogen bonds break?
Heat is absorbed when hydrogen bonds break.
What happens when hydrogen bonds form?
Heat is released when hydrogen bonds break.
shape of a molecule
very important to its function, depends on the shape of the valence shells
the branch of chemistry that specializes in carbon compounds
organic molecules consisting only of carbon and hydrogen
compounds that have the same numbers of atoms of the same elements, but different structures and properities
isomers that differ in the covalent arrangements of their atoms
isomers with the same covalent partnerships, but they differ in their spatial arrangements
molecules that are mirror images of each other
the components of organic molecules most commonly involved in chemical reactions
-OH; hydrogen atom bonded to oxygen atom, which is bonded to the carbon skeleton; alcohols
>CO; carbon atom joined to an oxygen atom by a double bond; Ketones if carbonyl is within a carbon skeleton, Aldehydes if the carbonyl is at the end of the carbon skeleton
-COOH; oxygen atom double bonded to a carbon atom that is bonded to a hydroxyl group; carboxylic acids
-NH₂; nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton; amines
-SH; sulfur atom bonded to a hydrogen atom; thiols
-OPO₃²⁻; phosphorus atom bonded to four oxygen atoms, one oxygen is bonded to the carbon skeleton, two oxygen carry negative charges; organic phosphates
adenosine triphosphate; primary energy-transferring molecule in the cell
condensation reaction/dehydration reaction
two molecules are covalently bonded together through the loss of a water molecule
the reverse of a dehydration reation
simple sugars with molecular formulas with a multiple of CH₂O
two monosaccharides joined by a glycosidic linkage
a covalent bond formed between two monosaccharides by a dehydration reaction
polymers made up of multiple monosaccharides
a storage polysaccharide of plants, entirely glucose monomers, helical, alpha
a storage polysaccharide of animals, entirely glucose monomers, helical, alpha
a structural polysaccharide of plants, straight, entirely glucose, beta
a structural polysaccharide of arthropods to build their exoskeletons
constructed from glycerol and fatty acids
a long carbon skeleton
three fatty acids linked to one glycerol molecule
an alcohol with three carbons, each with a hydroxyl group
saturated fatty acid
a fatty acid with no double bonds between carbons, solid at room temperature
unsaturated fatty acid
a fatty acid with one or more double bonds between carbons, liquid at room temperature
a lipid with only two fatty acids attached to glycerol, with the third hydroxyl group joined to a phosphate group
lipids characterized by a carbon skeleton consisting of four fused rings
a common component of animal cell membranes and is the precursor for which other steroids are synthesized
polymers of amino acids
one or more polypeptides folded and coiled into specific conformations
organic molecules possessing both carboxyl and amino groups
the resulting covalent bond between the carboxyl group of one amino acid to the amino group of another, with the removal of a water molecule
What are the general roles of carbohydrates?
The two roles are to supply energy and help form cell structures.
a disaccharide composed of glucose and glucose
a disaccharide composed of fructose and glucose
a disaccharide composed of galactose and glucose
How does the alpha differ from the beta form of glucose?
In the alpha version, the hydroxyl group is attached to the carbon-1 in the same manner as the hydroxyl group attached to the carbon04. In the betas version, the hydroxyl group is switched.
a unit of inheritance
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
polymers of nucleic acids
monomers of nuclide acids composed of a nitrogenous base, a pentose (five-carbon sugar), and a phosphate group.
a nitrogenous base with a six-membered ring of carbon and nitrogen atoms; cytosine, thymine, and uracil.
a larger nitrogenous base with six-membered ring fused to a five-membered ring; adenine and guanine
What types of nitrogenous bases belong to DNA or RNA?
Thymine is only found in DNA and uracil is only found in RNA. Adenine, cytosine, and guanine are found in both.
What's the difference between DNA and RNA?
DNA lacks a oxygen atom on the second carbon in its ring.
What makes fats hydrophobic?
The non-polar C-H bonds in the hydrocarbon chains of the fatty acids make fats hydrophobic.
How do phospholipids interact in an aqueous solution?
The hydrophilic heads stay on the outside of the bilayer, facing the water. The hydrophobic tails stay in the interior of the bilayer, away from the water.
List the several functions of proteins.
Proteins preform several functions including transport, storage, structural support, speeding up chemical retains, cellular communications, movement, and defense against foreign substances.
What are the three properties used to classify amino acids?
Nonpolar, polar, and electrically charged are the three properties of side chains used to classify amino acids.
What determines the primary structure of a protein?
Primary structure is determined by inherited by genetic information.
Describe the "Primary" level of protein structure.
The unique sequence of amino acids in a protein.
Describe the "Secondary" level of protein structure.
The coils and folds formed by the hydrogen bonds between repeating sections of the polypeptide backbone.
Describe the "Tertiary" level of protein structure.
Overall shape of a polypeptide, resulting from interactions between side chains.
Describe the "Quaternary" level of protein structure.
Overall protein structure that results from aggregation of the polypeptide subunits.
Describe the two functions of DNA in a cell.
DNA provides directions for its own replication and it directs RNA synthesis.
a chemical agent that speeds up the rate of a chemical reaction, without being consumed by the reaction
protein that acts as a biological catalyst
activation energy, Eₐ
the initial investment of energy for starting a reaction
the reactant an enzyme acts upon
the restricted region of the enzyme that binds to the substrate
The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate.
How is the substrate held in the active site?
The substrate is held by weak interactions, such as hydrogen and ionic bonds.
What are the effects of temperature and pH on enzyme activity?
Each type of enzyme as an optimal temperature and pH level. If they reach too far from its optimal environment, the enzyme will denature.
non-protien helpers for catalytic activity
cofactors that are organic molecules
mimics that reduce the productivity of enzymes by blocking substrates from the active sites
mimics that do not directly compete with the substrate to bind to the enzyme at the active site