Chapter 2- Chemical Components of Cells Flashcards by Allie Loeffler

C, N, O, and H make up around ___% of a cell’s mass

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atomic number = # of

protons

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in living tissues, only ___ undergo rearrangements

electrons

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___ bonds stronger than ___ bonds

covalent, ionic

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when a positively charged region of one water molecule comes close to a negatively charged region of a second water molecule a ___ bond is established

hydrogen

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substances releasing protons when they dissolve in water

acids

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any molecule that accepts a proton when dissolved in water

base

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sugars are linked together by a _____ reaction

condensation

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bonds formed during condensation reactions can be broken by ____

hydrolysis

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3 fatty acid chains + glycerol

triacyglycerol

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amino acids all contain a ___ acid group, and an ___ group all linked to an ___ carbon

carboxylic, amino, alpha

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the ___ ____ distinguishes one amino acid from another

side chain

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the covalent bond between two amino acids is

peptide bond

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nucleosides with one or more phosphate groups attached to the sugar are known as

nucleotides

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C,T,U are all

pyrimidines

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A,G are

purines

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A molecule that releases a proton when dissolved in water; this dissociation generates hydronium (H 3O+) ions, thereby lowering the pH.

acid

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Small organic molecule containing both an amino group and a carboxyl group; it serves as the building block of proteins.

amino acid

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The smallest particle of an element that still retains its distinctive chemical properties; consists of a positively charged nucleus surrounded by a cloud of negatively charged electrons.

atom

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The mass of an atom expressed in daltons, the atomic mass unit that closely approximates the mass of a hydrogen atom.

atomic mass

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Molecule that serves as the principal carrier of energy in cells; this nucleoside triphosphate is composed of adenine, ribose, and three phosphate groups.

ATP

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The number of molecules in a mole, the quantity of a substance equal to its molecular weight in grams; approximately 6 × 1023.

avagadros number

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Molecule that accepts a proton when dissolved in water; also used to refer to the nitrogen-containing purines or pyrimidines in DNA and RNA.

base

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Mixture of weak acids and bases that maintains the pH of a solution by releasing and taking up protons.

buffer

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An exchange of electrons that holds two atoms together. Types found in living cells include ionic bonds, covalent bonds, and hydrogen bonds.

chemical bond

Combination of atoms, such as a hydroxyl group (–OH) or an amino group (–NH2), with distinct chemical and physical properties that influences the behavior of the molecule in which it resides.

chemical group

Chemical reaction in which a covalent bond is formed between two molecules as water is expelled; used to build polymers, such as proteins, polysaccharides, and nucleic acids.

condensation reaction

Precise, three-dimensional shape of a protein or other macromolecule, based on the spatial location of its atoms in relation to one another.

conformation

Stable chemical link between two atoms produced by sharing one or more pairs of electrons.

covalent bond

Negatively charged subatomic particle that occupies space around an atomic nucleus (e– lt;/i>).

electron

Force that draws together oppositely charged atoms. Examples include ionic bonds and the attractions between molecules containing polar covalent bonds.

electrostatic attraction

Molecule that consists of a carboxylic acid attached to a long hydrocarbon chain. Used as a major source of energy during metabolism and as a starting point for the synthesis of phospholipids.

fatty acid

A weak noncovalent interaction between a positively charged hydrogen atom in one molecule and a negatively charged atom, such as nitrogen or oxygen, in another; these interactions are key to the structure and properties of water.

hydrogen bond

Chemical reaction that involves cleavage of a covalent bond with the accompanying consumption of water (its –H being added to one product of the cleavage and its –OH to the other); the reverse of condensation.

hydrolysis reaction

The form taken by a proton (H+)) in aqueous solution.

hydronium ion

Molecule or part of a molecule that readily forms hydrogen bonds with water, allowing it to dissolve; literally, “water loving.”

hydrophilic

Nonpolar, uncharged molecule or part of a molecule that forms few or no hydrogen bonds with water molecules and therefore does not dissolve; literally, “water fearing.”

hydrophobic

Type of noncovalent bond that forces together the hydrophobic portions of dissolved molecules to minimize their disruption of the hydrogen-bonded network of water; helps push together membrane phospholipids and fold proteins into a compact, globular shape.

hydrophobic interaction

Not composed of carbon and hydrogen.

inorganic

An atom carrying an electrical charge, either positive or negative.

ion

Interaction formed when one atom donates electrons to another; this transfer of electrons causes both atoms to become electrically charged.

ionic bond

Organic molecule that is insoluble in water but dissolves readily in nonpolar organic solvents; typically contains long hydrocarbon chains or multiple rings. One class, the phospholipids, forms the structural basis of biological membranes.

lipid

Thin pair of closely juxtaposed sheets, composed mainly of phospholipid molecules, that forms the structural basis for all cell membranes.

lipid bilayer

Polymer built from covalently linked subunits; includes proteins, nucleic acids, and polysaccharides with a molecular mass greater than a few thousand daltons.

macromolecule

Sum of the atomic weights of the atoms in a molecule; as a ratio of molecular masses, it is a number without units.

molecular weight

Group of atoms joined together by covalent bonds.

molecule

Small molecule that can be linked to others of a similar type to form a larger molecule (polymer).

monomer

Chemical association that does not involve the sharing of electrons; singly are relatively weak, but can sum together to produce strong, highly specific interactions between molecules. Examples are hydrogen bonds and van der Waals attractions.

noncovalent bond

Basic building block of the nucleic acids, DNA and RNA; includes a nucleoside with a series of one or more phosphate groups linked to its sugar.

nucleotide

In chemistry, describes a molecule or bond in which electrons are distributed unevenly.

polar

Long molecule made by covalently linking multiple identical or similar subunits (monomers).

polymer

The linear order of monomers in a large molecule, for example amino acids in a protein or nucleotides in DNA; encodes information that specifies a macromolecule’s precise biological function.

sequence

A monomer that forms part of a larger molecule, such as an amino acid residue in a protein or a nucleotide residue in a nucleic acid. Can also refer to a complete molecule that forms part of a larger molecule. Many proteins, for example, are composed of multiple polypeptide chains, each of which is called a protein subunit.

subunit

A substance made of carbon, hydrogen, and oxygen with the general formula (CH2O)n. A carbohydrate or saccharide. The “sugar” of everyday use is sucrose, a sweet-tasting disaccharide made of glucose and fructose.

sugar

Weak noncovalent interaction, due to fluctuating electrical charges, that comes into play between two atoms within a short distance of each other.

van der waals

Functional group derived from a carboxylic acid.

acyl group

Organic compound containing a hydroxyl group (–OH) bound to a saturated carbon atom, for example, ethanol.

alcohol

Reactive organic compound that contains the HC=O group, for example, glyceraldehyde.

aldehyde

Functional group consisting solely of single-bonded carbon and hydrogen atoms, such as methyl (–CH3) or ethyl (–CH2CH3) groups.

alkyl groups

Molecule containing the functional group –CONH2.

amide

Molecule containing an amino group (–NH2).

amine

Functional group (–NH2) derived from ammonia. Can accept a proton and carry a positive charge in aqueous solution.

amino group

Average distance between two interacting atoms in a molecule, usually those linked covalently.

bond length

The strength of the chemical linkage between two atoms, measured by the energy in kilocalories needed to break it.

bond energy

General term for sugars and related compounds with the general formula (CH2O)n.

carbohydrate

Carbon atom linked to an oxygen atom by a double bond.

carbonyl group

Carbon atom linked to an oxygen atom by a double bond and to a hydroxyl group (–COOH). In aqueous solution, acts as a weak acid.

carboxyl group

Unit of molecular mass. Defined as one-twelfth the mass of an atom of carbon 12 (1.66 × 10-24 g); approximately equal to the mass of a hydrogen atom.

dalton

Substance that cannot be broken down to any other chemical form; composed of a single type of atom.

element

Membrane lipid molecule that has a short carbohydrate chain attached to its hydrophilic head.

glycolipid

Positively charged ion generated by the removal of an electron from a hydrogen atom; often used to refer to a proton (H+) in aqueous solution. Its presence is the basis of acidity.

hydrogen ion

Chemical group consisting of a hydrogen atom linked to an oxygen, as in an alcohol.

hydroxyl

Describes a molecule that lacks a local accumulation of positive or negative charge; generally insoluble in water.

nonpolar

Molecule made of a nitrogen-containing ring compound attached to a sugar, either ribose (in RNA) or deoxyribose (in DNA).

nucleoside

Strong covalent bond that forms the backbone of DNA and RNA molecules; links the 3′ carbon of one sugar to the 5′ carbon of another.

phosphodiester bond

A double-ringed, nitrogen-containing compound found in DNA and RNA. Examples are adenine and guanine.

purine

A nitrogen-containing, six-membered ring compound found in DNA and RNA. Examples are thymine, cytosine, and uracil.

pyrimidine

Compound made of three fatty acid tails covalently attached to glycerol. A storage form of fat, the main constituent of fat droplets in animal tissues (in which the fatty acids are saturated) and of vegetable oil from plants (in which the fatty acids are mainly unsaturated).

triacylglycerol