Chapter 2: The Chemistry of Life Flashcards
What is an element?
The simplest form of matter to have unique chemical properties. Cannot be broken down by ordinary chemical means. There are 91 naturally occuring elements (atoms are building blocks)
What are the elements that make up 98.5% of human body weight?
- Oxygen (O)
- Carbon (C)
- Hydrogen (H)
- Nitrogen (N)
- Calcium (Ca)
- Phosphorus (P)
What are the lesser and trace elements and minerals that make up the human body?
Lesser elements (.0.8%): Na, K, Cl, S, Fe
Trace Elements (less than 0.7%): required in minute amounts, found as part of enzymes (I, Fe, metals)
Minerals (about 4%): usually salts, inorganic elements extracted from soil by plants and passed to humans (Ca, P mostly, also Cl, Mg, K, Na, and S)
What determines the atomic number v. the atomic mass? What is an isotope (in relation)?
Atomic number: number of protons (Hydrogen has 1, Carbon has 6, Oxygen has 8), unique to each element
Atomic mass / weight: number of neutrons + number of protons
Isotope: element with can have atoms with a different number of neutrons (but the same number of protons)(some isotopes of Hydrogen are Hydrogen-0 neutron, Deutirium-1 neutron, and Tritium-2 neutron)
What is atomic weight?
The average of mass numbers for an element.
What is the overall structure of an atom?
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Define the following: ions, ionization
Ion: charged particle with unequal number of protons and electrons
Ionization: transfer of electrons from one atom to another
What are electrolytes and why are they important?
Electrolytes: substances that ionize in water (acids, bases, or salts) form solutions capable of coducting electric currents
They are important in chemical reactivity, osmotic effects, electrical excitability of nerve and muscle. Imbalance can lead to coma or cardiac arrest.
What are free radicals?
Short lived particles with an unusual number of electrons. Produced by metabolic reactions, radiation, and certain chemicals. Trigger reactions that destroy molecules (can cause cancer, death of heart tissue, and aging…)
Fought by antioxidants, which neutralize free radicals (some are in the body, some can be obtained through diet).
What is a molecule?
A chemical particle composed of two or more atoms united by a chemical bond.
What is a compound?
Molecule composed of two or more elements.
What is the octet rule?
Bonds are formed using electrons in the valence shell (outermost layer). Atoms interact in order to have 8 electrons in their valence shell.
Examples: Inert element won’t react (full shell). Hydrogen has 1 (will give it up), Carbon has 4 (wants 4 more), Oxygen has 6 (wants 2 more), Sodium has 1 (gets rid of it, next layer has 8)
What is distinction between intra and inter?
Intra: inside/within
Inter: between
What is a mixture and how does it apply to the human body?
Mixtures are physically blended but not chemically combinded. Body fluids are complex mixtures. The human body is 50 to 75% water (babies have more water–cartilage, men have more water, women have less-more adipose)
What are the properties of water?
- solvency (ability to dissolve other chemicals)
- cohesion (surface tension!)
- adhesion
- chemical reactivity
- thermal stability (water absorbs heat)
What does / does not dissolve in water?
Does: hydrophilic compounds, polar molecules, ionic compounds
Does not: oils, fats, waxes, lipids, nonpolar molecules, hydrophobic compounds
What are the 3 major mixtures in the body?
- Solution: solutes small and dissolved in solvent, usually clear (e.g. urine)
- Colloid: solutes larger (scatter light), but don’t settle out (e.g. milk)
- suspension: solutes large and will settle out (emulsion is a suspension of one liquid in another)
- Example: blood (solution is electrolytes, colloid is plasma proteins, suspension is red blood cells)
Define the following: acid, base, salt
Acid: A substance that dissociates in solution to produce hydrogen ions (H+). Proton donor.
Base: a substance that dissociates in a solution to yield cations and hydroxide ions (OH-).
Salt: a substance that dissociates in solution producing cations and anions, but not hydrogen or hydroxide ions.
What are the acid/base concentration numbers on the pH scale?
Acidic (more and more hydrogen): pH 0-6.99
Neutral: pH 7
Basic (less and less hydrogen, more hydroxide): pH 7.01-14
Buffers are built to prevent large changes in pH.
Define energy (and its types) and work.
Energy: capacity to do work
- potential energy: stored in an object, but not currently doing work
- chemical: in molecular/chemical bonds
- free: available in a system to do useful work
- kinetic: energy of motion, doing work
- heat: kinetic energy of motion
- electromagnetic energy: moving packets of radiation called photons
Work: to move
What are the definition and classes of chemical reactions?
Chemical reaction: a process in which a covalent or ionic bond is formed or broken. (Chemical equation symbolizes the course–reactants / arrow (enzyme?) / products)
- decomposition (large molecule breaks down into two or more smaller ones, e.g. hydrolysis)
- synthesis (two or more molecules combine, e.g. dehydration synthesis)
- exchange (two molecules exhange atoms or groups of atoms)
What are reversible reactions?
Reactions that can go either way under different circumstances. Reach equilibrium when ratio of products to reactants is stable.
What causes reaction rates to increase?
- high concentration
- temperature rises
- a catalyst (enzyme) is present
Explain metabolism and its substrates as chemical reactions
- Metabolism: all chemical reactions of the body
- Catabolism: decomposition (breaks covalent bonds)
- Anabolism: energy storing synthesis reactions (requires energy input, production of protein or fat)
- Link: anabolism is driven by energy released by catabolism
