Biology - Chapter 2 Vocabulary Terms

Atom

1. the smallest fragment; smallest unit of an element

   • study of chemistry begins with this; from Greek word atomos that means “can not be cut” 

   • 3 major parts

     1. Protons (Positively Charged)

     2. Neutrons (No Charge)

     3. Electrons (Negatively Charged)

   • Have equal numbers of electrons and protons, they are electrically neutral

Nucleus

1. the center of the atom; formed by protons and neutrons; protons and neutron inside

   • Tightly packed together neutrons and protons form a ______. 

Electron

1. Electron has 1/1840 the mass of proton

   • Electron: negatively charged particle

   • In constant motion in space surrounding nucleus, Zip around in orbit of the nucleus

     • Attracted to the positively charged nucleus but remains outside because of their energy of motion

     • Travels around the nucleus at different levels (orbitals)

     • Electrons fill orbitals nearest nucleus first

       • Innermost Orbital: 2 electrons

       • Next Orbital: 8 electrons

       • Other Orbitals: story gets a little more complicated

Element

1. a pure substance that consists entirely of one type of atom

   1. On its own has a equal number of protons, neutrons, electrons

      1. If you change…

         • # of electrons: forms ions

         • # of neutrons: forms isotopes

         • # of protons: becomes a different element

      • More than 100 known elements, only about 24 found in living organisms

      • Represented by 1 or 2 letter symbols

        • C-carbon, H-hydrogen, Na-sodium, Hg-mercury

Compound

1. a substance formed by the chemical combination of two or more elements in definite proportions

   • The physical and chemical properties of a compound are usually very different from those of the elements from which it is formed

Ionic Bond

1. formed when one or more electrons are transferred from one atom to another; one atom gives an electrons or more away to another atom

   • Fills the orbital of one and empties partial orbital of the other

   • Opposite charges attract each other like a magnet

     • Ex. Sodium Chloride

Ion

1. positively and negatively charged atoms 

   • Giver: positively charged

   • Taker: negatively charged

Covalent Bond

1. formed from moving electrons that travel about the nuclei of both atoms; 2 atoms share an electron, shared electron circulates around both atoms

   • Ex. Water

   • Single Covalent: when the atoms share two (2) electrons

   • Double Covalent: when the atoms share four (4) electrons

   • Triple Covalent: when the atoms share six (6) electrons

Molecule

1. the structure that results when atoms are joined together by covalent bonds

   • It is the smallest unit of most compounds

Hydrogen Bond

1. attraction between a hydrogen atom with a partial positive charge and another atom with a partial negative charge

   • Most common is atoms involved are oxygen, nitrogen, and fluorine

   • Not as strong as covalent or ionic bonds

   • Because water is a polar molecule, it is able to form multiple hydrogen bonds, which account for many of water’s special properties

Cohesion

1.  an attraction between molecules of the same substance

   • Causes water molecules to be drawn together and produces surface tension

Adhesion

1. an attraction between molecules of different substances

   • Capillary Action: effect that causes water to rise in a narrow glass tube against the force of gravity

Mixture

1. a material composed of two or more elements or compounds that are physically mixed together but not chemically combined

   • Two types of mixtures can be made with water

Solution

1.  ions become gradually dispersed in water; all components are evenly distributed; Ex. Sugar/Salt in water

   • Ionically bonded molecules break apart and exist in the water as charged ions

Solute

the substance that is dissolved;

• Ex. sugar salt

Solvent

the substance in which something dissolves,

• Ex. Water

Suspension

nondissolved, suspended material in water; materials separate into pieces so small that they do not settle out: water and nondissolved material;

• Ex. Mud Puddle

pH

number/concentration of H+ ions in a solution, anything above a 7 is acidic, 7 is neutral, and anything below a 7 is basic/alkaline. 

Acid

1. any compound that forms H⁺ ions in a solution; contain higher concentrations of H⁺ ions than pure water

   • Ex. hydrochloric acid (HCI)

Base

1. a compound that produces hydroxide (OH^-) ions in a solutions; contain lower concentrations of H⁺ ions than pure water

   • Ex. lye (NaOH)

Buffer

1. weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH

   • Buffers dissolved in life’s fluids play an important role in maintaining homeostasis in organisms

Monomer

1. smaller units that join together; relatively small molecule that can connect to other molecules

   1. Polymerization: process in which large compounds are built by joining smaller ones together

      • Forms Macromolecules: “Giant Molecule”; made from thousands or hundreds of thousands of smaller molecules

Polymer

structure of macromolecules; result of the monomers joining together; large molecule made when many smaller molecules (monomers) chain together

Carbohydrate

1. compounds made up of Carbon, Hydrogen and Oxygen atoms; usually in ratio 1:2:1 (Carbon, Hydrogen, Oxygen), CHO 1:2:1

   • Ex. Glucose C₆H₁₂O₆

   • Living things use these as their main source of energy and also for structural purposes

Monosaccharide

1. small sugar molecules (monomer); Ex. glucose, fructose 

   • another name for single sugar molecules

   • Simple Sugars: broken down to supply immediate energy

Lipid

a large varied group of biological molecules that are usually not soluble in water; CHO less O

• A.K.A: fats, oils, waxes, steroids

• Made mostly from Carbon and Hydrogen atoms

  1. Small amount of Oxygen

• Non-polar

• Hydrophobic: repelled by water

• Used to store energy, some are important parts of biological membranes and waterproof coverings

• Steroids: lipids synthesized by the body, ex. hormones used as chemical messengers

• Formed when a glycerol molecule combines with fatty acids

  • Saturated lipid: the fatty acids contain the maximum number of hydrogen atoms, carbon-carbon single bond

  • Unsaturated lipid: at least one carbon-carbon double bond in a fatty acid

  • Polyunsaturated lipid: the fatty acids contain more that one double bond

Nucleic Acid

macromolecules containing Carbon, Hydrogen, Oxygen, Nitrogen, and Phosphorus; polymers assembled from individual monomers known as nucleotides; CHONP

• Stores and transfers genetic information

• Two types

  1. Ribonucleic Acid (RNA): single stranded

     1. Contains sugar ribose

  2. Deoxyribonucleic Acid (DNA): double stranded

     1. Contains sugar deoxyribose

Nucleotide

 individual monomers that derive from nucleic acids, has a 5-carbon sugar, a phosphate group (-PO₄), and a nitrogenous base; Ex. adenosine triphosphate (ATP)

• Individuals can be joined by covalent bonds to form a polynucleotide

Protein

macromolecules that contain Carbon, Hydrogen, Oxygen, and Nitrogen; CHON

• Large molecule

• Proteins are polymers of molecules called amino acids 

• Proteins allow chemical reactions to happen with less energy input

  • Enzyme: facilitates one very specific reaction using its shape; proteins acting to help make reactions take place

  • Some proteins control the rate of reactions and regulate cell processes. Others form important cellular structures, while still others transport substances into or out of cells or help to fight disease

Amino Acid

compounds with an amino group (-NH₂) on one end and a carboxyl group (-COOH) on the other end (subunits that make up proteins are amino acids)

• Peptide bonds: covalent bonds that link amino acids together to form one or more Polypeptide

Polar

a molecule in which the changes are unevenly distributed

• because the molecule is a bit like a magnet with two poles

• whether an atom is negatively or positively charged, or neutral, which can create attractions