Chapter 2 Reading Guide
Overview
This reading guide is intended to be used with the Open Stax Anatomy and Physiology textbook.
Open Stax Anatomy and Physiology Chapter 2 Reading Guide
Human Anatomy and Physiology
Chapter 2: The Chemical Foundation of Life
2.1 Atoms, Isotopes, Ions, and Molecules: The Building Blocks
____________________ is any substance that occupies space and has mass.
______________ are specific types of matter with unique chemical and physical properties.
_______ naturally occurring elements with 118 recognized elements, some man made.
Four elements are common to all living organisms
_________________ (C)
_________________ (O)
_________________ (N)
_________________ (H)
The structure of the atom
___________ are the smallest part of an element that retains the properties of that element.
Atoms are made up of two regions
__________ – the center of the atom which holds the positively charged __________ and non-charged (neutral) __________. Protons and neutrons contribute to the total mass of the atom
____________________– is the outermost region where the negatively charged __________ are found, very little mass, 1/1800 of a proton.
Atomic Number and Mass
Atoms of a given element have a characteristic number of protons and electrons.
___________– the number of protons in the nucleus of an atom.
Each element has its own unique atomic number.
Each element has a variable number of neutrons which results in ___________. Atoms of the same element can vary in their number of neutrons.
______________________– the sum of the protons and neutrons in the nucleus of an atom.
______________________– the calculated mean of the mass numbers of the naturally occurring isotopes for a given element.
Isotopes
___________ are the different forms of an element that have the same number of protons but vary in the number of neutrons.
______________________ are isotopes that emit energy and particles in the process of radioactive decay to seek a more stable configuration.
The Behavior of Electrons
Atoms interact with other atoms to form ___________ by chemical bonding
In the electron cloud electrons occupy discrete areas of space called ___________.
Electrons also form discrete energy levels from the nucleus called ___________.
The shell closes to the nucleus can only hold a maximum number of___electrons
Once the first shell is full, the second shell can hold up to a maximum of_____electrons.
Once the second shell is filled the third shell will hold a maximum of 18 electrons.
______________________is the outermost shell of an atom. The number of electrons in this shell determines an atoms reactivity, the tendency by which it will form bonds with other atoms.
2.2 Chemical Bonds
A ___________ is an electrostatic attraction between atoms that holds them in the same general vicinity.
Two or more atoms with a stable chemical bond together form a ___________.
If the atoms are the same element, molecular hydrogen, or molecular oxygen, H2 or O2
If two or more atoms bonded are different elements, that is called a compound, H2O, CH4, NaCl; water, methane and table salt are compounds.
Types of Chemical Bonding
Ionic bonding
When an atom loses or gains one or more electrons it becomes an ion.
A ___________ is a positively charged ion, H+, Ca2+, or Al3+ it donates one or more electrons to another atom
An ___________ is a negatively charged ion O2-, Clꟷ, it accepts one or more electrons from an electron donor.
This results in an ionic compound held together by ionic bonding, Na+ Cl ꟷ
Covalent bonding:
Result from the sharing of one or more pairs of electrons between atoms
Sharing of electrons result in stable chemical bonds that are stronger than ionic bonds
Types of covalent bonds:
______________________– result from the equal sharing of electrons between atoms in a molecule.
E.g. H2, O2, and CO2
Polar Covalent Bonding:
Occur due to the unequal sharing of electrons in a molecule
Results in a molecule that will have regions of opposite charge
Best example is a molecule of water.
Hydrogen bonding
An interaction between a weakly positive hydrogen atom and a more electronegative atom (oxygen or nitrogen) in a different molecule.
______________________ form between water molecules (H2O) or molecules of ammonia (NH3).
Hydrogen bonds link the base pairs in a molecule of DNA.
Hydrogen bonds are responsible for secondary structure in protein molecules.
2.3 Chemical Reactions
The role of energy in chemical reactions
Energy is required for any chemical reaction to take place.
There are different types of energy.
______________________– energy available to do work, make things happen.
______________________– the energy stored in the chemical bonds of a molecule.
______________________– energy of motion, energy doing work, making things happen.
Chemical reactions that overall release energy is called ______________________
Chemical reactions that store energy in chemical bonds are called ______________________.
Types of Chemical Reactions
______________________– joins different substances together to produce a new substance. A + B →AB
______________________– breaks down a larger substance into two or more smaller substances. AB → A + B
______________________– a chemical reaction in which synthesis and decomposition occur simultaneously. AB + CD → AC + BD
Factors that influence the rate of chemical reactions
Properties of the reactants
Different elements are more reactive than others.
Atoms of the reactants have easy access to one another
Size of the reactants, smaller molecules will react faster than larger ones due to the number of chemical bonds involved.
Temperature
Temperature has a direct effect on reaction rates, the higher the temperature the faster the reaction occurs.
Concentration
The more particles in a specific area means the faster the reaction will occur.
Pressure
By decreasing the area increase the amount of force (pressure) pushing on the reactants, thus speeding up the reaction accordingly
Enzymes and other catalysts
___________– is any substance that can speed up a chemical reaction without being changed by the reaction.
___________ – biological catalysts composed of either protein or RNA molecules.
___________ – the amount of kinetic energy needed to start a chemical reaction.
Enzymes facilitate the chemical reactions of metabolism. Enzymes lower the activation energy requirement for a reaction to occur.
2.4 Inorganic Compounds Essential to Human Functioning
Inorganic vs Organic Compounds
______________________– any substance that does not contain carbon and hydrogen together.
E.g. HCl, H2O, CO2, NaCl, NaOH
______________________– any substance that contains carbon and hydrogen together and synthesized into covalent bonds.
The role of water in the functioning of the human body.
Water is essential to the functioning of the human body; it plays several important roles. Approximately, 70% of the adult human is made up of water.
Lubrication and Cooling
Heat sink – water cools the body and dissipates heat without a change in temperature.
Water is a component of liquid mixtures
All cells are kept moist by a water-based mixture called a ___________.
A solution is a mixture of___________dissolved into a ___________.
Water is the universal solvent of biological systems
The role of water in biological based chemical reactions
In biological systems water is either created or consumed by the reaction.
______________________reactions – create water by forming covalent bonds between different atoms. One reactant gives up a hydrogen atom (H) and the other a hydroxyl group (OH).
______________________– consumer water molecules by adding a hydrogen atom to one reactant and the hydroxyl group to the other reactant when breaking a covalent bond.
Salts
Salts are the products that form as a result of ionic bonding. When salts are dissolved in water, they dissociate into ions other than H+ and OHꟷ
Dissolved salts in solution are ___________, they can transmit electrical impulses
This is important for nerve cell conduction and muscle contractions.
Acids and Bases
Acids and bases dissociate into ions dissolved in solution. They are electrolytes and they change the properties of the solution they are dissolved into.
___________ – any substance that releases hydrogen ions into a solution.
A ______________________ is any acid that dissociates completely into ions in a solution.
E.g. include hydrochloric acid (HCl) and sulfuric acid (H2SO4)
A ______________________does not dissociate completely into a solution.
E.g. include acetic acid (vinegar) and citric acid.
___________ – any substance that releases hydroxide ions (OHꟷ) into solution or accepts H+ dissolved in solution.
A ______________________will dissociate completely into ions in solution
E.g. are sodium hydroxide (NaOH) or potassium hydroxide (KOH).
A ______________________does not dissociate complete into solution.
The concept of pH
The pH scale measures the relative acidity or alkalinity of a solution
pH = negative base 10 logarithm of the hydrogen ion concentration of a solution.
pH = ꟷ log10 [H+]
A solution with a pH of 4 is 10 times more acidic than a solution with a pH of 5
A solution with a pH of 10 is ten times more alkaline than a solution with a pH of 9.
Buffers
A buffer is a mixture of a weak acid and its conjugate base.
Buffers are important in living systems in minimizing pH changes by tying up any excess hydrogen or hydroxide ions in solution.
Buffers maintain acid-base balance or homeostasis.
2.5 Organic Compounds Essential to Human Functioning
The Chemistry of Carbon
Carbon atoms have a valence of four
They will share electrons with up to four different atoms forming stable covalent bonds, thus can form large structures with a carbon backbone.
Functional groups
Small grouping of atoms linked by covalent bonds, that similarly covalently bond with a carbon backbone.
Function together in chemical reactions as a single unit.
The functional groups most important to human physiology.
___________ (ꟷOH) are polar groups involved in dehydration and hydrolysis reactions
___________ (ꟷ ) components of fatty acids and amino acids
___________ (ꟷNH3) a component of amino acids
___________ (ꟷCH3) associated with fatty acids and amino acids
___________ (ꟷPO4) associated with phospholipids and nucleotides
Biological macromolecules
A structure with a carbon backbone that is made up of smaller repeating units called ___________. Biological macromolecules may also be called ___________.
Carbohydrates
A molecule with the basic chemical formula C(H2O)n which literally means watered carbon.
______________________ are the monomers of carbohydrates; they are also called simple sugars. Simple sugars are a source of energy for cells and tissues.
E.g. include glucose (C6H12O6) and fructose and galactose.
______________________ consist of two simple sugar molecules joined in a dehydration synthesis reaction.
E.g. include lactose (glucose + galactose), sucrose (fructose + glucose).
______________________ are the polymers of carbohydrates. They consist of hundreds and thousands of sugars joined. The storage form of carbohydrates and a structural component of plant cell walls.
E.g. include the starches amylose, amylopectin, glycogen, and cellulose.
Lipids
Are a source of energy for cells, they are hydrocarbon molecules with few oxygen atoms attached.
Types of Lipids
______________________ a common dietary lipid otherwise known as fat.
Formed from the synthesis of one ___________ molecule and three fatty acid molecules joined by dehydration synthesis reactions.
Fatty acids are long chains of hydrocarbons with a methyl group at one end and a carboxyl group at the opposite end
___________ Fatty acids have no carbon-carbon double bonds in the hydrocarbon tail.
___________ fatty acids will have one or more carbon-carbon double bonds in the hydrocarbon tail.
___________ – consist of a hydrophilic, phosphate head joined to two hydrophobic fatty acids. They create the phospholipid bilayer structure of all cell membranes.
___________ consist of four fused carbon rings. Cholesterol is the base steroid of animal systems, they maintain the integrity of cell membranes, provide the foundation for steroid hormones, and compose bile salts.
___________ – are derived from unsaturated fatty acids that serve as a signaling mechanism, they regulate blood pressure and inflammation and sensitivity to pain.
Proteins
Proteins make up the structure of hair, keratin of skin, collagen of bones, the meninges covering the brain and spinal cord. They also function as enzymes inside cells.
Proteins are a polymer made up of monomers called ______________________.
All amino acids have the same basic structure
An amino group attached to a central carbon atom called the alpha carbon.
A hydrogen atom attached to the alpha carbon
A carboxyl group attached to another side of the alpha carbon
An R group attached to the fourth side; the R group is unique to each amino acid. There are 20 different amino acids that make up the proteins of the human body.
Amino acids link together by peptide bonds, a covalent bond between the amino group of one amino acid and the carboxyl group of the adjacent amino acid by dehydration synthesis reactions.
The basic amino acid structure. Each amino acid has its own unique side chain or R group.
Amino acids join by covalent bonds called peptide bonds. Each peptide bond results in the formation of a water molecule
Shape of proteins
A protein’s shape is crucial to its function. If the protein does not have the correct shape it does not function.
The shape of the protein is initially determined by the sequence of amino acids in a polypeptide chain, this is called ______________________.
______________________is the polypeptide chain twisting to another shape called an ___________ helix or ______________________sheet.
The secondary structure further folds into a 3-D shape called ______________________. Disulfide bridges covalent link different cysteine residues in a single polypeptide chain. Hydrogen bonds and other interactions help maintain a proteins 3D shape.
When proteins are exposed to high heat or drastic changes in pH, they will lose their shape, which is called ______________________.
Nucleotides – are the building blocks of DNA and RNA and certain other molecules such as ATP, NADH, NADPH.
Each nucleotide is made up of three subunits
Pentose sugar
Nitrogen containing base
Phosphate group
______________________ are made up of nucleotides. The two nucleic acids DNA and RNA only differ in the type of pentose sugar associated with their nucleotides.
Nucleotides are organized into two groups
Purines (adenine and guanine)
Composed of a double ring structure with several nitrogen atoms covalently bonded together.
Pyrimidines (cytosine, thymine, and uracil)
Nitrogen containing bases with a single ring structure.
Chapter 2: The Chemical Foundation of Life