Chapter 2: The Chemistry of Life

What are Chemical elements?

Make up living and nonliving matter

Elements are in their simplest form and cannot be broken down

98.5% of your body’s mass is made up of?

Oxygen, Hydrogen, Carbon, Nitrogen, Calcium and Phosphorus

Which are called “major elements”

What are atoms?

Make up each element and are the smallest units of matter

Atoms consist of what?

Subatomic particles

Protons?

Found in the nucleus and have a positive charge (+)

Neutrons?

Found in the nucleus and have a neutral charge

Electrons?

Orbit around the nucleus, have a negative charge (-)

How many electrons move around the nucleus in the first shell?

Max of 2 electrons

Each shell fills to its max before another is added

How many electrons move around the nucleus in the second shell?

Max of 8 electrons

Each shell fills to its max before another is added

What are Isotopes?

Are atoms of the same element that differ in the number of neutrons

Which carbon isotopes are stable?

Carbon-12 and Carbon-13 are stable and do not decay overtime

Which carbon isotopes are unstable?

Carbon-14 is radioisotope; unstable, causing its nucleus to decay over time and release ionizing radiation then transforms to Nitrogen-14

What is an important tool in the medical field?

Iodine - 131

Has a biological half-life of 8 days

Used to detect thyroid cancer and treat hyperthyroidism

What are Ions?

Atoms with a positive or negative charge

These charges are created by atoms giving up or gaining electrons

Causes an unequal number of protons and electrons called ionization

What are anions?

Negatively charged ion; gains electron(s)

What is a cation?

Positively charged ion; loses electron(s)

What are electrolytes?

Minerals in your body that carry an electric charge when dissolved in water

What are molecules?

Formed by the combination of two or more atoms

What are Compounds?

Formed by the combination of two or more different atoms

The number of electrons that an element has can affect what?

Affect how it interacts with other elements

The goal is for the element to become stable

Either by the loss, gain or the sharing of electrons

What are Chemical bonds?

The forces that hold atoms together to form molecules or compounds

The formation of these bonds depends on an atoms valence shell - outermost shell

An atom is most stable and unlikely to do what?

Form bonds with another atom of it has 8 electrons in its valence shell

The elements that are most important for life do not what?

Do not have full valence shells

They form chemical bonds with other elements to fill their valence

shells with 8 electrons called the octet rule

What are Ionic bonds?

Formed by the attraction between positively and negatively charged ions

Sodium atom has how many electrons in its outer valence shell?

1 electron

Easier to give up one electron

This leaves 8 electrons in its second shell(outermost shell)

Forms a cation - positively charged ion

Chlorine atom has how many electrons in its valence shell?

7 electrons

Easier to accept one electron

This gives 8 electrons in its outermost shell

Forms an anion - negatively charged ion

Sodium and chloride become what?

Ionized(charged) by electron donation and are attracted to one another to form an ionic bond

Becomes → NaCl

Most ionic compounds are?

Solids and dissolve easily in water and form electrolytes

What are Covalent bonds?

Are formed by the sharing of electrons between two or more atoms

What are Non-polar covalent bonds?

Occur when electrons are shared equally between atoms

What are Polar covalent bonds?

Occur when electrons are shared unequally between atoms

What is electronegativity?

The power of an atom to attract electrons

How is water an example of a polar covalent bond?

Oxygen atom is more electronegative than hydrogen

Oxygen = partially negative

Hydrogen = partially positive

What are Hydrogen bonds?

A type of polar covalent bond between hydrogen atoms and another atom

Forms when a partially positive hydrogen attracts a partially negative atom nearby

Very weak atoms

What are Inorganic compounds?

Most lack carbon and are simple in structure water, salts, acids, and bases

Either ionic or covalent bonding

Explain water?

Most abundant inorganic compound in all living systems

Water is polar having partial negative oxygen and partial positive hydrogens

What is Solvent?

Dissolves another substance (solute)

Water dissolves ionized and polar substances

What is Hydrophilic?

(water loving) easily dissolve in water

Solutes with a charge (ions) or with polar covalent bonds

Ex. Suger and Salt

What is hydrophobic?

(water fearing) not soluble in water

Solutes with non-polar covalent bonds or uncharged

Ex. Fats and Oils

Water can do what?

Can absorb and release large amounts of heat with only slight changes in its own temperature

Has a high heat capacity due to hydrogen bonds

When water absorbs heat, it breaks hydrogen bonds and helps maintain body temperature

Water also has a high heat of what?

Vaporization

There is a high-energy requirement to change water from what?

Liquid to gas

What are Acids?

Substances that dissolve into hydrogen ions and anions in water

What are Bases?

Substances that dissolve into hydroxide ions and cations in water

What are Salts?

Substances that dissolve into cations and anions

Act as electrolytes by carrying electrical currents

Important in nerve and muscle tissue

What is an important balance in the body?

Acid-base balance

The more H+ increases solution acidity

The more OH- increases solution alkalinity

What is pH scale?

Used to express the acidity or alkalinity of a solution

Ranges from → 0 to 14

Based on the concentration of → H+

A pH of 7 is defined as being?

Neutral

Equal number of H+ and OH-

Acidic solution - pH?

Below 7

Solution with more → H+ than OH-

Basic solution - pH?

Above 7

Solution with more → OH- than H+

Blood pH must be maintained between?

7.35 and 7.45(slightly basic)

If pH gets above 7.45 what occurs?

Alkalosis occurs

If pH gets below 7.35 what occurs?

Acidosis occurs

What is Buffer?

Function to change strong acids and bases into weak acids an bases

Strong acids can damage many of our body’s systems

Buffers remove and add hydrogen ions(H+)

What are Chemical reactions?

Occur to either breakdown or form bonds between atoms

Reactants does what?

Starts substances

Products do what?

End substances

What are Synthesis reactions?

Occur when two or more atoms, ion, or molecules combine to form a new larger molecule

Referred to as anabolism

What are Decomposition reactions?

Occur when large molecules split into smaller atoms, ions, or molecules

Referred to as catabolism

What happens to energy when chemical reactions occur?

Absorbed or released

What is Catabolism?

Energy releasing decomposition reactions

Exergonic reactions?

Energy is released

What is Anabolism?

Energy storing synthesis reactions

Endergonic reactions?

Energy is absorbed

What are Organic compounds?

Contain carbon, most have hydrogen, and always contain covalent bonds

Large molecules with long carbon chains

What are Macromolecules?

Are made by a combination of small organic molecules (monomers) into large organic molecules (polymers)

Monomers bond together through dehydration synthesis

What is Dehydration synthesis?

Smaller molecules are joined to form larger molecules due to removal of water

Water molecule is formed as?

A product

What is Hydrolysis reaction?

Occurs when large molecules are broken down into smaller molecules due to the addition of water

Where are Carbon, Hydrogen and Oxygen found?

Found in a 1:2:1 ratio in all carbohydrates

Monosaccharides?

Carbohydrate → monomers

What are Disaccharides?

Molecules made up of two monosaccharides by dehydration synthesis

What are Polysaccharides?

Molecule contains tens or hundreds of monosaccharides by dehydration synthesis

Not soluble in water

Describe Carbohydrates?

Sugars; main/quick energy source; examples: glucose and glycogen

Describe Lipids?

Fats; energy storage and important in cell membranes; examples: triglycerides and phospholipids

Describe Proteins?

Made of amino acids; have structural/functional roles; enzymes and proteins

Describe Nucleic acids?

DNA and RNA; store/use genetic information

Describe Lipids?

Contain carbon, hydrogen, and oxygen but are insoluble in water and other polar solutes

Hydrophobic

Describe Fatty Acids?

Small monomer of large lipid molecules broken down to create energy

Contain a carboxyl group and a hydrocarbon

Describe Saturated fatty acids?

Hydrocarbon skeleton with only single covalent bonds

Describe Unsaturated fatty acids?

Hydrocarbon chain contains one or more double covalent bonds

Describe Triglycerides?

Made up of a glycerol molecules and three fatty acids that combine through dehydration synthesis

Triglycerides exists in two states which are?

Solid or Liquid, depending on types of fatty acids

Saturated Fats?

Solid at room temperature(fats)

Unsaturated fats?

Liquid at room temperature(oils)

Lipids are our body’s what?

Long-term storage of energy in the form of adipose tissue(fat tissue)

Describe Phospholipids?

Similar to neutral fats except one fatty acid is replaced by a phosphate group

Structural foundation of the cell membrane

Fatty acid “tails” are?

Hydrophobic

Phosphate “head” is?

Hydrophilic

Describe Steroids?

Made up of a four-ring structure of carbon atoms

Called → sterols

Ex. cholesterol, estrogen, and testosterone

Describe Proteins?

Essential for body structure and function

Contain carbon, hydrogen, oxygen, and nitrogen

Describe Amino acids?

Monomer of proteins

Contain unique side chain that gives the amino acid a chemical identity

Proteins are made amino acids being covalently bonded to each other through a peptide bond

Describe Primary structure?

Linear sequence of amino acids linked by peptide bonds

Form a Polypeptide chain

Describe Secondary structure?

Neighboring amino acids twist and fold

Form alpha helix and beta pleated sheets

Describe Tertiary structure?

The final 3D shape of a protein and functional

Describe Quaternary structure?

Proteins with more than one polypeptide chain

Describe Denaturation?

Occurs in proteins that are exposed to too high of temperatures

Causes loss of function

Describe Catalysts(enzymes)?

A chemical compound that speeds up chemical reactions

Decreases the amount of energy needed to start the reaction

Our body’s most important catalysts are?

Enzymes

They allow atoms to collide and interact with one another

They do not breakdown or change during chemical reactions and can be reused

Describe Nucleic acids?

Contain carbon, hydrogen, oxygen, nitrogen, and phosphorous