Section 5:Cell Chemistry

Element

substances that cannot be broken down or transformed chemically into other substances

Atom

the smallest component of an element that retains all of the chemical properties of that element.

Proton

is a positively charged particle that resides in the *nucleus* (the core of the atom) of an atom and has a mass of 1 and a charge of +1.

Neutron

resides in the nucleus of an atom. They have a mass of 1 and no charge

Electron

is a negatively charged particle that travels in the space around the nucleus

Atomic Number

of an element is equal to the number of protons that element contains.

Isotope

Different forms of the same element that have the same number of protons, but a different number of neutrons

Electron Shells

an electron shell may be thought of as an orbit followed by electrons around an atom's nucleus

Chemical Bond

interactions between two or more of the same or different elements that result in the formation of molecules

Ionic Bond

a chemical bond that forms between ions of opposite charges. Formed by

* by the complete transfer of some electrons from one atom to another.

Covalent Bond

A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms.

Electronegtitvity

symbolized as χ, is the tendency for an atom of a given chemical element to attract shared electrons when forming a chemical bond

Non-Polar Covalent Bond

form between two atoms of the same element or between different elements that share the electrons equally.

Polar Covalent Bond

the electrons shared by the atoms spend more time closer to one nucleus than to the other nucleus.

Ion

When an atom does not contain equal numbers of protons and electrons

Hydrogen Bond

a primarily electrostatic force of attraction between a hydrogen atom which is covalently bound to a more electronegative "donor" atom or group, and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor.

Cohesion

the attraction of molecules for other molecules of the same kind

Adhesion

 the attraction between water molecules and other molecules.

Surface Tension

the capacity of a substance to withstand rupture when placed under tension or stress.

Solvent

substance capable of dissolving another substance.

Acid

ubstances that provide hydrogen ions (H+) and lower pH

Buffer

readily absorb excess H+ or OH–, keeping the pH of the body carefully maintained in the aforementioned narrow range.

provide hydroxide ions (OH–) and raise pH

Hydrophilic

When a substance readily forms hydrogen bonds with water, it can dissolve in water 

Hydrophobic

Hydrogen bonds are not readily formed with nonpolar substances like oils and fats.These nonpolar compounds are (“water-fearing”) and will not dissolve in water.

Macromolecules

The large molecules necessary for life that are built from smaller organic molecules

Carbohydrates

any of a large group of organic compounds that includes sugars, starch, and cellulose, containing hydrogen and oxygen in the same ratio as water (2:1) and used as structural materials and for energy storage within living tissues.

Monosaccharide

 also called simple sugars, are the simplest forms of sugar and the most basic units from which all carbohydrates are built. They are usually colorless, water-soluble, and crystalline solids

Glucose

a simple sugar which is an important energy source in living organisms and is a component of many

Disaccharide

any of a class of sugars whose molecules contain two monosaccharide residues.

• Surcrose

• lactose

• maltose

Polysaccharide

a carbohydrate (e.g. starch, cellulose, or glycogen) whose molecules consist of a number of sugar molecules bonded together.

Starch

or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by α--D glycosidic bonds. This polysaccharide is produced by most green plants for energy storage

Glycogen

a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. It is the main storage form of glucose in the human body

Celluslose

is an organic compound with the formula ₙ, a polysaccharide consisting of a linear chain of several hundred to many thousands of β linked D-glucose units

Lipids

 are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids, and others

Fats

any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. 

Phospholipid

are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue. 

Steroid

have a ring structure. Although they do not resemble other lipids, they are grouped with them because they are also hydrophobic.

Saturated Fatty Acid

are saturated with hydrogen; in other words, the number of hydrogen atoms attached to the carbon skeleton is maximized.

Unsaturated Fatty Acid

are a component of the phospholipids in cell membranes and help maintain membrane fluidity but not all of these can be synthesized in the bod

Trans Fatty Acid

orientation of the double bonds affects the chemical properties of the fat.s a type of unsaturated fat that occurs in foods. Trace concentrations of trans fats occur naturally, but large amounts are found in some processed food

Protein

a biological macromolecule composed of one or more chains of amino acids

Amino Acid

a monomer of a protein

Polypetide

a long chain of amino acids linked by peptide bonds

deoxyribonucleic acid (DNA)

a double-stranded polymer of nucleotides that carries the hereditary information of the cell

ribonucleic acid(RNA)

a single-stranded polymer of nucleotides that is involved in protein synthesis

Nucleotide

a monomer of nucleic acids; contains a pentose sugar, a phosphate group, and a nitrogenous base

Radioactive Isotope

an isotope that spontaneously emits particles or energy to form a more stable element.Used in

* Carbon dating