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Flashcards in Chapter 2 Deck (44):
1

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

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4 Most Common Elements Found in Organisms

- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)

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Atoms

The basic units of all matter; composed of three subatomic particles:
- Neutrons
- Protons
- Electrons

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Neutrons

Uncharged particles found in the nucleus of an atom

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Protons

Positively charged particles found in the nucleus of an atom

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Electrons

Negatively charged particles that form a "cloud" around the nucleus of an atom

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Atomic Number

The number of protons in the nucleus of an atom (same number of electrons)

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Atomic Weight

The sum of the number of protons and neutrons in an atom

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Isotope

Forms of the same chemical element that differ in their number of neutrons; useful tools in biological research

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Molecule

Two or more atoms held together by chemical bonds

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Compound

A molecule consisting of more than one element

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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

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Ionic Bonds

Form between cations and anions because of strong attractions between positive and negative charges

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Cation

Negatively charged ion; gains electrons

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Anion

Positively charged ion; losses electrons

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Ion

An atom that is no longer neutral due to the loss or gain of an electron

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Covalent Bond

Strong chemical bond formed by the sharing of electrons between atoms (pairs of valence electrons)

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Valence Electrons

Found in an atom's outer shell

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Non-Polar Covalent Bond

The electrons are shared equally

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Polar Covalent Bond

The electrons are shared unequally

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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

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pH

A measure of acidity of aqueous solutions:
- 0-6: acidic
- 7: neutral
- 8-14: basic (alkaline)

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Buffer

A compound that stabilizes the pH of a solution; prevents a dramatic rise or fall in pH

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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

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4 Types of Macromolecules

- Carbohydrates
- Lipids
- Proteins
- Nucleic Acids

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Carbohydrates

Include sugars, starch, glycogen, chitin, cellulose, peptidoglycan; most are composed of ringed molecules (one up to thousands)

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Monosaccharides

Simple sugars; primary choice to make cellular energy (ATP)

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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)

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Triglycerides

Fat molecules (lipids) that cells construct to store energy:
- Saturated fat: Solid at room temperature
- Unsaturated fat: Liquid at room temperature

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Phospholipids

Fat molecules (lipids) that cells construct as building blocks for cell membranes and other membrane-bound organelles

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Steroids

Fat molecules (lipids) that have four carbon rings connected to each other (cholesterol and some hormones)

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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

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Nucleic Acids

Made up of nucleotides (1000s - 1000000s); DNA, RNA, ATP

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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

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Catalyst

A substance that speeds up the rate of a chemical reaction without being altered or depleted in the process

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Active Site

Small crevices on enzymes that allow a substrate to precisely bond to it

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Enzyme-Substrate Complex

The temporary binding of an enzyme and a substrate which lowers the activation energy for a reaction

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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

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Coenzymes

Organic substances (vitamins) that attach to enzymes and complete the active site; without them, enzymes cannot function correctly and metabolism is impaired

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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

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Allosteric Regulation

The temporary binding of regulatory molecules to the allosteric site of an enzyme

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Feedback Inhibition

The end product of a chemical reaction serves as an allosteric inhibitor

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Competitive Inhibition

An inhibitor molecule binds to the active site of an enzyme and prevents the true substrate from binding

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Non-Competitive Inhibition

An inhibitor molecule binds to the allosteric site of an enzyme and permanently changes the shape of the enzyme