BIOL Chap 2

What does “structure determines function” mean in biology?

The shape/structure of something gives clues about what it does, and knowing its function can give clues about its structure.

What are the five properties of life?

Cellular organization, homeostasis, energy utilization/metabolism, heredity, and growth/development/reproduction.

What is the basic unit of life?

The cell.

What is homeostasis?

The maintenance of a stable internal environment, such as body temperature, oxygen levels, or pH.

What are the three main parts of cell theory?

Cells are the fundamental units of life; all cells come from pre-existing cells; life’s biochemical reactions occur within cells.

What are the CHNOPS elements?

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

What are the charges of protons, neutrons, and electrons?

Protons are positive, neutrons are neutral, and electrons are negative.

What identifies an element?

The number of protons, also called the atomic number.

What is atomic mass?

The number of protons plus the number of neutrons.

If carbon has atomic number 6 and 7 neutrons, what is its atomic mass?

13 amu, because 6 protons + 7 neutrons = 13.

What are isotopes?

Atoms of the same element with the same number of protons but different numbers of neutrons.

What is an ion?

An atom or molecule with an electrical charge because it gained or lost electrons.

What is a cation?

A positively charged ion formed when an atom loses electrons.

What is an anion?

A negatively charged ion formed when an atom gains electrons.

What are valence electrons?

Electrons in the outermost shell that can interact with other atoms.

What is the octet rule?

Atoms tend to interact so their outer shell has 8 electrons.

How do you decide if an atom with 9 protons is reactive or inert?

Assume it has 9 electrons, fill shells 2 then 7; the outer shell is not full, so it is reactive.

What is an ionic bond?

A bond formed when electrons are transferred between atoms, creating oppositely charged ions that attract.

What is a covalent bond?

A bond formed when atoms share electrons.

What is a nonpolar covalent bond?

A covalent bond where electrons are shared equally.

What is a polar covalent bond?

A covalent bond where electrons are shared unequally, creating partial charges.

What does electronegativity mean?

An atom’s attraction for electrons.

Why is water polar?

Oxygen pulls electrons more strongly than hydrogen, giving oxygen a partial negative charge and hydrogens partial positive charges.

What does hydrophilic mean?

Water-loving; interacts well with water.

What does hydrophobic mean?

Water-fearing; does not interact well with water.

What is a hydrogen bond?

A weak attraction between a partially positive hydrogen and a full or partial negative charge on another molecule or region.

What does it mean that water is a universal solvent?

Water dissolves many ionic compounds and polar molecules.

In salt water, what is the solute and what is the solvent?

NaCl/salt is the solute; water is the solvent.

What happens when NaCl dissolves in water?

It separates into Na+ and Cl- ions surrounded by water molecules.

What is cohesion?

Water sticking to itself.

What is adhesion?

Water sticking to other surfaces.

Why does water resist changes in temperature?

Hydrogen bonds require extra energy to break, so water heats and cools slowly.

Why does sweating cool you down?

Evaporation requires energy to break hydrogen bonds, pulling heat away from the body.

Why does ice float?

Water expands when it freezes, making solid ice less dense than liquid water.

What determines pH?

The concentration of hydrogen ions (H+).

What is the pH formula?

pH = -log[H+].

What is an acid?

A substance with pH below 7 that increases H+ concentration.

What is a base?

A substance with pH above 7 that releases OH- or combines with H+.

If [H+] = 10^-4, what is the pH?

pH 4.

If [H+] = 10^-6, is the solution acidic or basic?

Acidic, because pH = 6, which is below 7.

If [OH-] = 10^-10, what is the pH?

pH 4, because [H+] must be 10^-4 to total 10^-14.

How much stronger is pH 3 than pH 5?

100 times stronger, because each pH unit changes by a factor of 10.

Does adding NaCl to water change pH?

No. NaCl adds Na+ and Cl-, not H+ or OH-.

What is an electrolyte?

An ion in solution that allows water to conduct electricity.

What are buffers?

Compounds that resist changes in pH by absorbing excess H+ or OH-.

Why is carbon important for life?

Carbon can form up to four covalent bonds, allowing many complex organic molecules.

What makes a molecule organic?

A carbon-based backbone with at least one C-H bond.

What are the four major biological macromolecule groups?

Carbohydrates, lipids, proteins, and nucleic acids.

What is dehydration synthesis?

A reaction that joins monomers by removing water; it requires energy.

What is hydrolysis?

A reaction that breaks polymers apart by adding water.

What elements are in carbohydrates?

Carbon, hydrogen, and oxygen, usually in a 1:2:1 ratio.

How can you tell carbohydrates and lipids apart by formula?

Carbohydrates have about the same number of carbons and oxygens; lipids have many more carbons/hydrogens than oxygens.

What are the three main six-carbon monosaccharides to recognize?

Glucose, fructose, and galactose; all are C6H12O6 isomers.

What sugar is found in RNA?

Ribose.

What sugar is found in DNA?

Deoxyribose.

What monosaccharides make sucrose?

Glucose + fructose.

What monosaccharides make lactose?

Galactose + glucose.

What monosaccharides make maltose?

Glucose + glucose.

What is starch?

A glucose polymer used for energy storage in plants.

What is glycogen?

A glucose polymer used for energy storage in animals.

What is cellulose?

A glucose polymer used for structural support in plant cell walls.

What is chitin?

A structural polysaccharide in insect/crab exoskeletons and fungal cell walls.

Are lipids hydrophilic or hydrophobic?

Hydrophobic.

What are the major lipid types discussed?

Fats/oils, waxes, steroids, and phospholipids.

What is a phospholipid?

A lipid with a phosphate group; a main component of cellular membranes.

What does amphipathic mean?

Having both hydrophilic and hydrophobic parts.

What is a triglyceride made of?

One glycerol and three fatty acids.

What is a saturated fat?

A fatty acid with no carbon-carbon double bonds; usually more solid at room temperature.

What is an unsaturated fat?

A fatty acid with one or more carbon-carbon double bonds; usually more liquid at room temperature.

What are protein monomers?

Amino acids.

What are the three basic parts of an amino acid?

Amino group, carboxyl group, and R group/side chain.

What bond links amino acids together?

A peptide bond.

What is primary protein structure?

The sequence/order of amino acids in a polypeptide chain.

What is secondary protein structure?

Local folding caused by hydrogen bonding, forming alpha helices or beta pleated sheets.

What is tertiary protein structure?

The overall 3-D shape caused by R-group interactions.

What is quaternary protein structure?

Two or more polypeptide chains joining to form a functional protein.

What is denaturation?

The breakdown of a protein’s 3-D shape, causing loss of function.

What are nucleic acids made of?

Nucleotide monomers.

What are the three parts of a nucleotide?

A 5-carbon sugar, a phosphate group, and a nitrogenous base.

How do ribose and deoxyribose differ?

Deoxyribose has one fewer oxygen than ribose.

Which base is in DNA but not RNA?

Thymine.

Which base is in RNA but not DNA?

Uracil.

Which DNA/RNA bases are purines?

Adenine and guanine.

Which DNA/RNA bases are pyrimidines?

Cytosine, thymine, and uracil.

What does adenine pair with in DNA?

Thymine.

What does adenine pair with in RNA?

Uracil.

What does guanine pair with?

Cytosine.

Which base pair takes more energy to break: A-T or G-C?

G-C, because it has three hydrogen bonds instead of two.

What does antiparallel mean in DNA?

The two DNA strands run in opposite directions, with 5’ and 3’ ends opposite each other.