Physiology Wescott Chapter 2

What is matter?

Matter is anything that has mass and occupies space. It exists in different states, primarily solid, liquid, and gas.

What is an ionic bond?

An ionic bond is a type of chemical bond formed through the transfer of electrons from one atom to another, resulting in the attraction between positively and negatively charged ions.

What is a covalent bond?

A bond formed when atoms share electrons.

What is a hydrogen bond?

A weak bond that occurs between a hydrogen atom and a more electronegative atom, typically involving polar molecules.

Nonpolar

Molecules have equal sharing of electrons, leading to no charge separation.

Polar

Molecules have unequal sharing of electrons, resulting in a charge separation.

Mass number

sum of the number of protons and neutrons in the nucleus of an atom

Element

subatomic particle having a negative charge and nearly no mass; found orbiting the atom’s nucleus

Compound

substance composed of two or more different elements joined by chemical bonds.

What is an atom?

smallest unit of an element that retains the unique properties of that element

What are the three subatomic particles and their charges?

Proton (+), neutron (0), electron (–).

Proton

heavy subatomic particle having a positive charge and found in the atom’s nucleus.

Atomic number

number of protons in the nucleus of an atom

What is mass number?

Protons + neutrons.

What is an isotope?

one of the variations of an element in which the number of neutrons differ from each other

Radioactive isotope

unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes.

• An isotope whose nucleus decays and emits particles/energy. (“A radioactive isotope is an isotope whose nucleus readily decays, giving off subatomic particles and electromagnetic energy.”)

Electron Shell

area of space a given distance from an atom’s nucleus in which electrons are grouped

Valence Shell

outermost electron shell of an atom

What makes an atom stable vs reactive?

Full valence shell = stable; incomplete = reactive.

Why do atoms form bonds?

To fill their valence shells and become stable.

Molecule

two or more atoms covalently bonded together

Ion

Atom with an overall positive or negative charge

Cation

atom with a positive charge

Anion

atom with a negative charge

Why do water molecules stick together?

Hydrogen bonds form between the slightly positive H and slightly negative O of different water molecules.

Why does salt dissolve in water?

Water’s polarity attracts and separates ions.

Why don’t oil and water mix?

Water repels nonpolar molecules.

Kinetic energy

Energy of motion.

Potential energy

stored energy matter possesses because of the positioning or structure of its components

Chemical energy

is the form of potential energy in which energy is stored in chemical bonds. When those bonds are formed, chemical energy is invested, and when they break, chemical energy is released.

Exergonic reactions

Chemical reactions that release energy.

Endergonic reactions

Chemical reactions that absorb energy.

Mechanical energy

is the sum of potential and kinetic energy in a system used to do work. For example, mechanical energy is what powers machines and bodily movements.

Radiant energy

is energy that travels in waves, such as light, heat, and electromagnetic radiation. It is essential for processes like photosynthesis and vision.

Electrical energy

supplied by electrolytes in cells and body fluids, contributes to the voltage changes that help transmit impulses in nerve and muscle cells.

Reactant

one or more substances that enter into the reaction

Product

One or more substances produced by a chemical reaction

Synthesis reaction

type of anabolic reaction in which two or more atoms or molecules bond, resulting in the formation of a larger molecule

Decomposition reaction

type of catabolic reaction in which one or more bonds within a larger molecule are broken, resulting in the release of smaller molecules or atoms

Exchange reaction

type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components

What does a reversible reaction look like?

A reaction shown with a double arrow (⇄).

How does surface area affect reaction rate?

More surface area → faster reaction.

How does temperature affect reaction rate?

Higher temperature → faster reaction.

How does concentration/pressure affect reaction rate?

More particles or higher pressure → more collisions → faster reaction.

What is a catalyst?

substance that increases the rate of a chemical reaction without itself being changed in the process

What is an enzyme?

protein or RNA that catalyzes chemical reactions

What is activation energy?

The energy needed to start a reaction.

Threshold

The minimum level of stimulus required to trigger a response in a cell or organism.

Inorganic compound

substance that does not contain both carbon and hydrogen

Organic compound

substance that contains both carbon and hydrogen

Solution

homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent

Homogeneous

having a uniform composition throughout

Colloid

liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light

Suspension

liquid mixture in which particles distributed in the liquid settle out over time

What is dehydration synthesis?

Two molecules join and release water.

Hydrolysis

Water is added to break a bond.

What is an acid?

compound that releases hydrogen ions (H⁺) in solution

Base

compound that accepts hydrogen ions (H⁺) in solution

What is pH?

negative logarithm of the hydrogen ion (H⁺) concentration of a solution

Buffer

solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids.

What does a low pH mean?

More acidic, more H⁺.

What does a high pH mean?

More basic, fewer H⁺.

A functional group

group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms

macromolecule

large molecule formed by covalent bonding

carbohydrate

class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio

monosaccharide

monomer of carbohydrate; also known as a simple sugar

disaccharide

pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond

Polysaccharides

compound consisting of more than two carbohydrate monomers bonded by dehydration synthesis via glycosidic bonds

Adenosine triphosphate (ATP) is

is composed of a ribose sugar, an adenine base, and three phosphate groups. ATP releases free energy when its phosphate bonds are broken, and thus supplies ready energy to the cell. More ATP is produced in the presence of oxygen (O₂) than in pathways that do not use oxygen.

lipid

class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water

triglyceride

lipid compound composed of a glycerol molecule bonded with three fatty acid chains

Saturated Fatty Acids

fatty acids are a type of lipid that contain no double bonds between carbon atoms in their fatty acid chains, which means they are saturated with hydrogen atoms. This results in a solid state at room temperature.

Unsaturated fatty acids

fatty acids that contain one or more double bonds between carbon atoms in their chains, resulting in a liquid state at room temperature.

phospholipid

a lipid compound in which a phosphate group is combined with a diglyceride

steroid

(also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules

prostaglandin

lipid compound derived from fatty acid chains and important in regulating several body processes

protein

class of organic compounds that are composed of many amino acids linked together by peptide bonds

amino acid

building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain

peptide bond

covalent bond formed by dehydration synthesis between two amino acids

disulfide bond

covalent bond formed within a polypeptide between sulfide groups of sulfur-containing amino acids, for example, cysteine

Denaturation

change in the structure of a molecule through physical or chemical means

substrate

reactant in an enzymatic reaction

nucleotide

class of organic compounds composed of one or more phosphate groups, a pentose sugar, and a base

Deoxyribonucleic acid (DNA)

deoxyribose-containing nucleotide that stores genetic information

Ribonucleic acid (RNA)

ribose-containing nucleotide that helps manifest the genetic code as protein

purine

nitrogen-containing base with a double ring structure; adenine and guanine

pyramidine

nitrogen-containing base with a single ring structure; cytosine, thiamine, and uracil

Phosphorylation

addition of one or more phosphate groups to an organic compound.