Chapter 2 Flashcards
Element
A substance that is composed of a single type of atom and cannot be separated into simpler parts by chemical methods; 92 are naturally occurring
4 Most Common Elements Found in Organisms
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)
Atoms
The basic units of all matter; composed of three subatomic particles:
- Neutrons
- Protons
- Electrons
Neutrons
Uncharged particles found in the nucleus of an atom
Protons
Positively charged particles found in the nucleus of an atom
Electrons
Negatively charged particles that form a “cloud” around the nucleus of an atom
Atomic Number
The number of protons in the nucleus of an atom (same number of electrons)
Atomic Weight
The sum of the number of protons and neutrons in an atom
Isotope
Forms of the same chemical element that differ in their number of neutrons; useful tools in biological research
Molecule
Two or more atoms held together by chemical bonds
Compound
A molecule consisting of more than one element
Chemical Bond
Form between the outer (valence) shell of atoms when electrons are lost, gained or shared in order to achieve their most stable state
Ionic Bonds
Form between cations and anions because of strong attractions between positive and negative charges
Cation
Negatively charged ion; gains electrons
Anion
Positively charged ion; losses electrons
Ion
An atom that is no longer neutral due to the loss or gain of an electron
Covalent Bond
Strong chemical bond formed by the sharing of electrons between atoms (pairs of valence electrons)
Valence Electrons
Found in an atom’s outer shell
Non-Polar Covalent Bond
The electrons are shared equally
Polar Covalent Bond
The electrons are shared unequally
Hydrogen Bond
Weak bond formed when a hydrogen atom in a polar molecule is attracted to an electronegative atom in the same or another polar molecule
pH
A measure of acidity of aqueous solutions:
- 0-6: acidic
- 7: neutral
- 8-14: basic (alkaline)
Buffer
A compound that stabilizes the pH of a solution; prevents a dramatic rise or fall in pH
Macromolecules
Large molecules that contain 10S of atoms to billions of atoms; complex enough that life is usually necessary to make them
- organic: contain at least carbon and hydrogen
4 Types of Macromolecules
- Carbohydrates
- Lipids
- Proteins
- Nucleic Acids
Carbohydrates
Include sugars, starch, glycogen, chitin, cellulose, peptidoglycan; most are composed of ringed molecules (one up to thousands)
Monosaccharides
Simple sugars; primary choice to make cellular energy (ATP)
Polysaccharides
Carbohydrates that cells make to store energy in the form of a carbohydrate ( glycogen in animals, starch in plants); Complex carbohydrate molecules that cells use as building blocks of cell walls (chitin in fungi, cellulose in plants, peptidoglycan in bacteria)
Triglycerides
Fat molecules (lipids) that cells construct to store energy:
- Saturated fat: Solid at room temperature
- Unsaturated fat: Liquid at room temperature
Phospholipids
Fat molecules (lipids) that cells construct as building blocks for cell membranes and other membrane-bound organelles
Steroids
Fat molecules (lipids) that have four carbon rings connected to each other (cholesterol and some hormones)
Protein
Molecule made up of amino acids (20 different types); conduct most of the cellular work; used for building blocks for cell walls, cell membranes, flagella, cilia, and organelles; used as enzymes that allow cells to create chemical reactions
Nucleic Acids
Made up of nucleotides (1000s - 1000000s); DNA, RNA, ATP
Enzymes
Proteins that function as biological catalysts, facilitating the conversion of a substrate into a product; specific to one type of substrate; end in -ase
Catalyst
A substance that speeds up the rate of a chemical reaction without being altered or depleted in the process
Active Site
Small crevices on enzymes that allow a substrate to precisely bond to it
Enzyme-Substrate Complex
The temporary binding of an enzyme and a substrate which lowers the activation energy for a reaction
Cofactors
An inorganic substance (minerals) that loosely attach to enzymes and complete the active site; without them, enzymes cannot function correctly and normal metabolism is impaired
Coenzymes
Organic substances (vitamins) that attach to enzymes and complete the active site; without them, enzymes cannot function correctly and metabolism is impaired
Environmental Factors That Can Disrupt the Normal Shape and Function of Enzymes
- Temperature: speeds up or slows down the rate of reactions; too high temperatures denature enzymes
- Salt concentration: most operate best at low concentrations
- pH: best at values slightly above 7
Allosteric Regulation
The temporary binding of regulatory molecules to the allosteric site of an enzyme
Feedback Inhibition
The end product of a chemical reaction serves as an allosteric inhibitor
Competitive Inhibition
An inhibitor molecule binds to the active site of an enzyme and prevents the true substrate from binding
Non-Competitive Inhibition
An inhibitor molecule binds to the allosteric site of an enzyme and permanently changes the shape of the enzyme
