Chapter 2 - The Chemistry of Life (Professor’s Study Guide)

CHOPKINS CaFe Mg Na Cl

What are the symbols for the 13 major elements found in the body?

CHON

What are the 4 major elements found in the body?

Elements needed in very small amounts

Ex: Iron, Iodine, Zinc

What are trace elements? What are some examples?

Protons and Neutrons

What subatomic particles are found in the nucleus of an atom?

Electrons

What subatomic particles orbit the nucleus?

Number of protons

What is the atomic number of an atom?

Number of protons + neutrons

What is the mass number of an atom?

Isotope

What does an atom become if you change the number of neutrons it has?

You change the element that it is

What happens if you change the number of protons an atom has?

It becomes a negatively charged ion, called an anion

What happens if an atom gains electrons?

It becomes a positively charged ion, called a cation

What happens if an atom loses electrons?

Up to 2

How many electrons can the first electron shell hold?

Up to 8

How many electrons can all the other electron shells hold?

1. Share electrons with another atom (Covalent Bonding)

2. Donate electrons / accept electrons from another atom (Ionic Bonding)

What 2 things can atoms do to fill their outer electron shells?

Valence shell is full of electrons, so the atom will not interact with other atoms.

What does it mean if an atom is inert?

Valence shell is not full of electrons, so the atom will interact with other atoms to try to fill the valence shell.

What does it mean if an atom is reactive?

Physically mixed together

In mixtures, are atoms chemically bonded or physically mixed together?

Mixture that contains large particles that stay suspended

What is a colloid?

Mixture where particles will fall out of the mixture; Suspensions must be shaken to resuspend particles.

What is a suspension?

Solute is dissolved in solvent

What is a solution?

Solvent dissolves the solute so that there are no particles to stay suspended.

How do a solute and solvent make a solution?

An atom that has become charged by either gaining or losing an electron

What is an ion?

Cations have lost an electron(s) and become positively charged

Anions have gained an electron(s) and become negatively charged

How are cations and anions different?

Na⁺ , K⁺ , Ca₂⁺

What is an example of a cation?

Cl^- , I^-

What is an example of an anion?

Positive charge on cation is attracted to negative charge on anion

How do ionic bonds form?

1 and 2 create cations; 7 creates anions

What columns of the periodic table contain the atoms that are most likely to participate in ionic bonds?

Salts (NaCl, Kcl, etc.)

When 2 ions interact to form an ionic bond, what do they form?

Ability of an atom’s protons to attract electrons

What is electronegativity?

Lower

Do metals have a lower or higher electronegativity?

Higher

Do non-metals have a lower or higher electronegativity?

Oxygen is more electronegative, so will have a stronger pull on shared electrons than Carbon will have

Based on electronegativity, what will happen when an Oxygen interact with a Carbon?

Electrons are shared between atoms by overlapping their valence shells

What happens to electrons in covalent bonds?

Single - one electron is shared

Double - two electrons are shared

Triple - three electrons are shared

Triple is strongest

How are single, double, and triple covalent bonds different? Which is the strongest?

Equal sharing between atoms

How are electrons shared in nonpolar covalent bonds?

Unequal sharing between atoms

How are electrons shared in polar covalent bonds?

One atom will be more electronegative and will pull more electrons to it than the less electronegative atom. The more electronegative will have a partial negative charge and the less electronegative atom will have a partial positive charge.

Explain why a dipole is formed in polar covalent bonds.

Similar electronegativities = Nonpolar covalent bond

*occurs between atoms of same element and atoms arranged so electronegativities cancel out

Different electronegativities = Polar covalent bond

*occurs because the more electronegative atom will have a stronger pull on shared electrons

How does an atom’s electronegativity determine if a polar or nonpolar covalent bond will form between two atoms?

Polar molecules have dipoles, with opposite charges. Nonpolar molecules are not charged. Dipoles allow attraction between partial charges w/ polar molecules.

Explain why polar molecules can form hydrogen bonds but nonpolar molecules cannot.

Since e^- are shared equally, there is no charge. Therefore they cannot interact with polar water molecules that have dipoles. So hydrophobic means that nonpolar molecules stay separate from water due to their lack of charge.

What does it mean that nonpolar molecules are hydrophobic?

Polar molecules are charged, so they can interact with partial charges on water molecules. Hydrophilic means attraction to water. Since polar molecules can interact with water through their charge, they are hydrophilic.

What does it mean that polar molecules are hydrophilic?

Ionic bonds are formed when one atom donates electrons to another atom.

Covalent bonds are formed when atoms share electrons by overlapping their valence shells.

How are ionic and covalent bonds different?

Polar - share electrons unequally due to different electronegativities

Nonpolar - share electrons equally due to similar electronegativities

How are polar and nonpolar bonds different?

Covalent

Which type of bond is the strongest?

Hydrogen

Which type of bond is the weakest?

Attraction of charges of nearby molecules

*There is no electron sharing/donating

*The interaction is between molecules, not atoms

What is a hydrogen bond? Why is it not a true bond?

Reactant/Substrate

In a chem rxn, what is the starting material called?

Product

In a chem rxn, what is the ending material called?

Dehydration: Water is created by removing -H & -OH from ends of monomers that are connected to form a larger product

What is a Synthesis/Dehydration reaction?

Hydrolysis: Water is broken apart to provide the -H and -OH to put on the
ends of the monomers that are broken apart

What is a Decomposition/Hydrolysis reaction?

Reaction can run forward or backwards

What is a reversible reaction?

Electron is transferred from one molecule to another

Molecule receiving the electron is reduced

Molecule donating the electron is oxidized

What happens in a RedOx/Oxidation-Reduction reaction?

Chemical: energy stored in the bonds of food

Potential: stored energy

Kinetic: energy of movement

How are kinetic, chemical, and potential energy different? Give an example of each.

Amount of energy needed to start a chemical reaction

What is activation energy?

Exergonic - produces more energy than it needs

Endergonic - needs more energy than it produces

How are exergonic and endergonic reactions different?

Lower the activation energy to jumpstart chemical reactions

How do enzymes/catalysts speed up chemical reactions?

Organic contains Carbon and contains covalent bonds

Inorganic usually lacks Carbon and are usually simpler (water, salts, acids, bases)

How are organic and inorganic compounds different?

Universal solvent, lubricant, high heat vaporization, high heat capacity, involved in many chemical reactions

Explain some of the important properties of water

Ions

What are electrolytes?

0-7-14

zero: most acidic (most H+)

seven: neutral

fourteen: most basic (most OH-)

pH scale range

Acidic! More acidic = more H+ !

Will an acidic, neutral, or basic pH have more H+?

Weak acid and weak base

What are buffers?

Prevent large changes in pH

What is the purpose of buffers?

Weak acid can donate H+ to lower pH is too basic

Weak base can bind H+ to raise pH if its too acidic

How do buffers work?

Major source of energy

Source of dietary fiber to maintain regularity of bowel movements

What are some functions of carbohydrates?

Monosaccharides: 1 sugar

Disaccharides: 2 sugars; 2 monosaccharides connected by a covalent bond

Polysaccharides: multiple sugars connected by covalent bonds

How are the following types of carbohydrates different: monosaccharides, disaccharides, and polysaccharides?

Glycogen

What carbohydrate is used for energy storage in humans?

Cellulose

What storage carbohydrate of plants cannot be digested by humans and is called fiber?

Nonpolar (think of how oil and water don’t mix!)

Are lipids (fats and oils) polar or non polar?

Hydrophobic! (think of how oil and water don’t mix!)

Are lipids (fats and oils) hydrophilic 💙💧 or hydrophobic💧❌?

Long chains of Carbons with Hydrogens attached

What is a fatty acid?

Saturated: Carbons are connected with single bonds and are completely saturated with Hydrogens

Unsaturated: At least one double bond between Carbons, so Carbons are not saturated with Hydrogens

How are saturated and unsaturated fatty acids different?

Hydrogens are on opposite side of Carbon double bond. (they would normally be on the same side)

What are trans fats and how are they different from regular unsaturated fatty acids?

Leukotrienes - cause inflammation

Prostaglandins - cause inflammation, increase pain, blood clotting, produce mucus in stomach

What are two examples of Eicosanoids?

1 Glycerol, 3 Fatty Acid Chains

Diagram of a triglyceride

Energy storage

Insulation

Protection

What are the (3) functions of triglycerides?

Polar head/Nonpolar tail

Diagram of a phospholipid

In cell membranes that surround all of our cells

Where are phospholipids found in the body?

Cholesterol

What lipid are steroids made from?

Testosterone, Estrogen, Cortisol

What are some examples of steroids?

Liver

Where are LDL and HDL made in the body?

Carries cholesterol from the liver out to the body

What is the function of LDL

Low - too much cholesterol carried in the blood vessels can increase BP, risk of heart attack and stroke

Is it better to have high or low LDL? Why?

Carries cholesterol from the body back to the liver

What is the function of HDL?

Sometimes: Support Cells

Mamaw: Movement of Muscles

Always: Amino Acids buffer pH

Tries: Transport

Eating: Enzymes that catalyze rxns

A: Antibodies

Hamburger: Hormones maintaining Homeostasis

What are some functions of proteins?

Amino Acids

What are the building blocks for proteins?

Primary = sequence of amino acids

Secondary = small areas of structure form from hydrogen bonding, such as alpha-helix & beta sheet

Tertiary = 3D structure of protein due to bonding between secondary structures

Quaternary = 2 more more tertiary structures form subunits of a large protein (Globular/Fibrous)

Describe the 4 levels of protein structure

The place where the substrate binds

What is the active site of an enzyme?

When a protein unfolds and structure is lost

What is protein denaturation?

Since structure is lost, the active site is also lost

What happens to the active site of an enzyme when a protein is denatured?

Since the active site is lost, there is no place to bind the substrate. So protein function will also be lost.

What happens to protein function when a protein is denatured?

High temp, extreme pH (too acidic /too basic)

What are some things that cause protein denaturation?

Each enzyme is specific for a particular substrate that it can bind to. In the Lock and Key model, the enzyme is the lock and the substrate is the key.

Briefly explain how the Lock and Key model describes what substrate an enzyme can bind to and work on

Nucleotides

What are the building blocks of nucleic acids?

Nitrogenous base, sugar, phosphate

What are the 3 components of a nucleotide?

In both DNA & RNA: GAC Guanine, Adenine, Cytosine

In DNA only: Thymine (T)

In RNA only: Uracil (U)

What are the 5 nitrogenous bases?

Which is found only in DNA?

Which is found only in RNA?

Adenine & Thymine or Uracil (depends on DNA/RNA)
Cytosine & Guanine

Which nucleotides base pair together?

DNA - double strand, sugar = deoxyribose, nucleotides: GACT

RNA - single strand, sugar = ribose, nucleotides: GACU

What are some differences between DNA and RNA?

Adenine, Ribose, and 3 phosphates

Major storage molecule for energy

What is ATP?

Removing the 3rd phosphate releases a large amount of energy

Sometimes the 2nd can be removed, but doesn’t release as much energy as the 3rd

How is energy released from ATP?