APHY 201 Ch 1, 2: Homeostasis, Chemistry Ivy Tech

explain why chemistry is an important part of the study of physiology

all the cells in your organs are composed of chemicals and chemical reactions are involved in all of your body's movements and cycles

matter

Anything that occupies space and has mass; the physical material of the universe

element

a pure substance that cannot be created or broken down by ordinary chemical means

most abundant elements in humans

oxygen (O), carbon (C), hydrogen (H), nitrogen (N)

compound

substance composed of two or more elements joined by chemical bonds

proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

electron

A subatomic particle that has a negative charge and found outside the nucleus

nucleus

center of an atom, contains protons and neutrons

atomic number

the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table

valence electrons

The electrons in the outermost shell (main energy level) of an atom; these are the electrons involved in forming bonds.

bond

a weak or strong electrical attraction that holds atoms in the same vicinity

molecule

atoms bonded together

ionic bond

Formed when one or more electrons are transferred from one atom to another

cation

A positively charged ion

anion

A negatively charged ion

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

polar covalent bond

A covalent bond in which electrons are not shared equally

nonpolar covalent bond

a covalent bond in which the electrons are shared equally by the two atoms

hydrogen bonds

Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic atom in another molecule

reactant

A chemical substance that is present at the start of a chemical reaction

product

A substance produced in a chemical reaction

synthesis reaction

a reaction in which two or more substances combine to form a new compound

anabolism

Energy requiring phase of metabolism, in which atoms or molecules combine to form a larger, more complex molecule; A + B -> AB (synthesis reaction); always involves bond formation and storing energy

decomposition reaction

a reaction in which a single compound breaks down to form two or more simpler substances

catabolism

Energy releasing phase of metabolism in which a molecule is broken down into smaller molecules; AB -> A + B (reverse of synthesis reactions); always involves breaking of bonds and releasing energy

exchange reaction

Parts of the reacting molecules are shuffled around to produce new products

chemical equilibrium

In a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time.

Why are biological reactions sometimes irreversible?

Energy requirements to go backward are too high or products have been removed

The rate of a chemical reaction depends on

temperature, concentration (collision frequency), particle size and properties, and the use of a catalyst

organic

contains carbon; unique to living systems

inorganic

Water, salts, bases and acids

water

most abundant and important inorganic compound (60-80% volume of living cells)

properties of water

absorb and release heat slowly, participates in chemical reactions, and cushions body organs.

Hydrophilic

"water-loving"; pertaining to polar or charged molecules (or parts of molecules) that are soluble in water

Hydrophobic

water hating; nonpolar substances that will not mix with water.

Polar

has an uneven distribution of elctron density

Solvent

the component of a solution that is present in greatest amount; Ex: the ___ for seawater is water and the solute is salt

Solute

the minor component in a solution, dissolved in the solvent; Ex: The solvent for lemonade is water and the _________(s) are sugar and lemon juice

Solution

homogeneous mixture composed of a solute and a solvent; Ex: the solvent for air is nitrogen (78.09% ) and the solutes include oxygen (20.95%), water (1%), and carbon dioxide (0.039%)

Salt

ionic compounds that dissolve in water

Common identifiers: NaCl, CaCo3, KCl

Electrolyte

ions that conduct ELECTRICAL currents in a solution

Acids and Bases

-Both are electrolytes

-Ionize and dissociate in water

Acids

Proton donors- release H+ in a solution

Bases

Proton acceptors (OH-) that take up a H+ from a solution

how are acids and bases represented on the pH scale?

As free (H+) increases, then pH decreases (acidity)

As free (H+) decreases, then pH increases (alkalinity, base)

Normal pH of human blood

7.35-7.45 (slightly alkaline)

why is pH homeostasis important?

pH influences every physiological activity in the body;

pH change interferes with cell function and may damage living tissue; pH affects speed of all biological and electrical reactions; even slight change in pH can be fatal

buffer

molecules that resist abrupt and large swings in pH

how does a buffer prevent abrupt changes in pH?

by converting strong acids into weak acids and strong bases into weak bases

polymer

large molecule consisting of similar subunits called monomers

dehydration synthesis

water is removed to form a bond. Polymers are synthesized this way.

hydrolysis

water is added to break a bond. Polymers are broken down this way.

carbohydrates

sugars and starches; contain C, H, and O [(CH20)n]

what are the classes of carbohydrates?

monosacchrides, disaccharides, and polysaccharides

monosaccharides

glucose, fructose, galactose; building blocks of polysaccharides

disaccharides

sucrose, maltose, lactose; two monosaccharides bonded together

major source of cellular fuel (Ex: glucose) and structural molecules (Ex: ribose of RNA)

functions of carbohydrates

storage forms of carbohydrates

glycogen (animals), starch and cellulose/fiber (plants)

glycogen

polysacchrides that animal cells use to store sugar

starch

storage polysacchrides used by plants (Potatoes, rice)

fiber (cellulose)

polysaccharide found in all plants that are undigestible for humans but necessary for a healthy dietary tract

lipids

insoluble in water but dissolve in other lipids; all lipids are non-polar

types of lipids

triglycerides, neutral fats, phospholipids, steriods (cholestrol), and eicosanoids

triglycerides

neutral fats; composed of three fatty acids bonded to a glycerol molecule

main functions of lipids

Energy storage, insulation, protection

phospholipids

head (polar/hydrophilic) and tail (nonpolar/hydrophobic) regions that have different properties making the molecule amphiphilic; major component of cell membranes

steroids

An interlocking 4 ring structure including cholestrol, vitamin D, steriod hormones (estrogen, testosterone, cortisol) and bile salts.

cholesterol

most important steriod; basis for all steriods formed in the body.

proteins

polymers of amino acids

amino acids

monomers of proteins; joined by covalent peptide bonds

saturated fatty acids

single covalent bonds between C atoms; max number of H atoms; solid animal fats (butter)

unsaturated fatty acids

one or more double bonds between C atoms; reduced # of H atoms; heart healthy; plant oils (olive oil)

levels of protein structure (4)

Primary, Secondary, Tertiary, and Quaternary.

primary structure

sequence of amino acids forms the polypeptide chain

secondary structure

primary chain forms spirals (a-helices) and (beta) sheets

tertiary structure

superimposed on secondary structure.

-Helices and/or -sheets are folded up

to form a compact globular molecule

held together by intramolecular bonds

quaternary structure

two or more polypeptide chains,

each with its own tertiary structure,

combine to form a functional

protein

Protein denaturation

proteins unfold and lose functional 3-D shape; active sites destroyed (cannot function); usually reversible if normal conditions restored

what causes protein denaturation?

can be caused by decreased pH or increased temperature

cofactor/coenzyme

component required to make certain enzymes functional; metal ion (cofactor) - organic molecule often a vitamin (coenzyme)

enzymes

proteins that act as biological catalysts (regulate and increase speed of chemical reactions by lowering activation energy)

enzyme characteristics

some functional enzymes consist of two parts (protein and cofactor/coenzyme); enzymes are specific; usually end in -ase; often named for the reaction they catalyze (Ex: hydrolase, sucrase)

nucleic acids

ribonucleic acid (RNA) and deoxyribnucleic acid (DNA); largest molecules in the body

deoxyribonucleic acid (DNA)

double-stranded helical molecules (double helix) located in the cell nucleus; provides instructions for protein synthesis

ribonucleic acid (RNA)

single-stranded molecule mostly active outside the nucleus; carry out the DNA orders for protein synthesis

adenosine triphosphate (ATP)

directly powers chemical reactions in cells; energy form immediately useable by all body cells

where does the cell get the energy that is stored in ATP?

breaking the chemical energy in bonds of fuels (carbohydrates, proteins, fats) then storing the energy in ATP

what are some examples of cellular work driven by ATP?

transport work, mechanical work, chemical work