microbio ch. 2

What is chemistry?

The study of interactions between atoms and molecules.

What is an atom?

The smallest unit of matter that cannot be subdivided into smaller substances.

What are the three subatomic particles?

Protons, neutrons, and electrons.

What charge does a proton have?

Positive (+).

What charge does a neutron have?

No charge (neutral).

What charge does an electron have?

Negative (−).

Where are protons and neutrons located?

In the nucleus.

Where are electrons located?

Moving around the nucleus.

What defines a chemical element?

Atoms with the same number of protons.

What is atomic number?

The number of protons in the nucleus.

What is atomic weight?

The total number of protons and neutrons.

What are isotopes?

Atoms of the same element with different numbers of neutrons.

How are electrons arranged in atoms?

In electron shells at different energy levels.

What is valence?

The number of missing or extra electrons in the outermost shell.

What is a molecule?

Two or more atoms bonded together.

What is a compound?

A molecule made of two or more different kinds of atoms.

What is an ion?

A charged atom that has gained or lost electrons.

What is a cation?

A positively charged ion that has lost electrons.

What is an anion?

A negatively charged ion that has gained electrons.

What is an ionic bond?

An attraction between ions of opposite charge.

What happens in an ionic bond?

One atom loses electrons and another gains electrons.

What is a covalent bond?

A bond formed when atoms share electrons.

Why are covalent bonds important in organisms?

They are strong and common in biological molecules.

What is a hydrogen bond?

Attraction between a hydrogen bonded to O or N and another O or N atom.

What is molecular weight?

The sum of atomic weights in a molecule.

What is a mole?

The molecular weight of a substance in grams.

What happens during a chemical reaction?

Bonds are made or broken and energy changes.

What is an endergonic reaction?

A reaction that absorbs energy.

What is an exergonic reaction?

A reaction that releases energy.

What is a synthesis reaction?

Small molecules combine to form larger molecules.

What is anabolism?

Synthesis reactions in a cell.

What is a decomposition reaction?

A molecule breaks into smaller parts.

What is catabolism?

Decomposition reactions in a cell.

What is an exchange reaction?

A reaction that is part synthesis and part decomposition.

Why is water a polar molecule?

It has an unequal distribution of charges.

Why is water a good solvent?

It dissolves polar substances.

How do hydrogen bonds help living systems?

They absorb heat and stabilize temperature.

What is an acid?

A substance that releases H⁺ ions.

What is a base?

A substance that releases OH⁻ ions.

What is a salt?

A substance that dissociates into ions other than H⁺ or OH⁻.

What does pH measure?

The concentration of hydrogen ions.

What pH range supports most life?

pH 6.5 to 8.5.

What defines an organic compound?

It contains carbon and hydrogen.

What is a carbon skeleton?

The chain of carbon atoms in an organic molecule.

What is a functional group?

A group that determines chemical properties of a molecule.

What are macromolecules?

Large polymers made of repeating monomers.

How are monomers joined?

By dehydration synthesis.

What are carbohydrates used for?

Energy and structural support.

What is a monosaccharide?

A simple sugar with 3–7 carbons.

Give an example of a monosaccharide.

Glucose.

What is a disaccharide?

Two monosaccharides joined together.

What is a polysaccharide?

Many monosaccharides bonded together.

What are lipids?

Nonpolar molecules insoluble in water.

What are simple lipids?

Fats (triglycerides) made of glycerol and fatty acids.

What is a saturated fat?

A fat with no double bonds.

What is an unsaturated fat?

A fat with one or more double bonds.

What are phospholipids?

Lipids with polar heads and nonpolar tails in membranes.

What are steroids?

Lipids with four carbon rings that maintain membrane fluidity.

What are proteins made of?

Amino acids.

What functional groups do all amino acids have?

Amino group and carboxyl group.

How are amino acids linked?

By peptide bonds.

What is primary protein structure?

The amino acid sequence.

What is secondary protein structure?

Folding into helices or sheets.

What is tertiary protein structure?

Irregular folding into a 3D shape.

What is quaternary protein structure?

Two or more polypeptide chains combined.

What is denaturation?

Loss of protein shape and function.

What are nucleic acids made of?

Nucleotides.

What are the components of a nucleotide?

Sugar, phosphate, and nitrogenous base.

How does DNA differ from RNA?

DNA is double-stranded with thymine; RNA is single-stranded with uracil.

What is ATP?

A molecule that stores and releases energy for the cell.

Why does ATP provide more energy than ADP?

ATP has an extra phosphate group.