bio: Biochemistry Study Guide

Explain how carbons electron configuration determines the kinds and number of bonds it can form.

Carbon has a valence of 4. Because of this, it can pair with up to 4 different atoms. It usually forms covalent bonds. Although carbon can bond with up to four other atoms, it sometimes instead forms double bonds.

List the four emergent properties of water

Cohesion, moderation of temperature, expansion, solvent

Define electronegativity and explain how it influences the formation of chemical bonds

Electronegativity: the attraction of a particular kind of atom for the electrons of a covalent bond. The shared electrons are pulled more toward the more electronegative element.

Define Element and compound

Element: a substance that cannot be broken down to other substances by chemical reactions Compound: a substance consisting of two or more different elements combined in a fixed ratio

Explain why water has such a high specific heat

Heat must be absorbed in order to break hydrogen bonds, and heat is released when hydrogen bonds form.

Explain the density of water and ice

Ice is less dense than water because the molecules slow down as their temperature lowers. this causes them to form stable hydrogen bonds and be more evenly spaced.

Explain how expansion upon freezing is biologically significant

If ice sank, eventually all bodies of water would freeze solid, making life impossible.

Describe the biological importance of cohisiveness and adhesiveness of water

They allow water to have a greater surface tension than most other liquids. some animals can stand, walk, or run on water without breaking the surface

Describe water's heat of vaporization

Water has a high heat of vaporization caused by hydrogen bonds. This helps moderate Earth's climate

define acid and define base

acid: a substance that increases the hydrogen ion concentration of a solution. H>OH (pH under 7) base: a substance that reduces the hydrogen ion concentration of a solution. H<OH (pH over 7)

Define and distinuish between atomic number, mass number, and valence

atomic number: the number of protons in an atom. unique to each element. mass number: the sum of protons plus neutrons in the nucleus of an atom. valence: The number of unpaired electrons in the outer shell of an atom (the atom's bonding capacity)

State the four elements essential to life that make up 96% of living matter

carbon, oxygen, hydrogen, and nitrogen

Describe how evaporative cooling is significant in animals

evaporation of sweat from human skin dissipates tbody heat and helps prevent overheating

Define hydrogen bond and explain how it differes from ionic and covalent

hydrogen bond: forms when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom. Hydrogen bonds are more of a temporary bond

Define kinetic engery and relate it to heat and temperature

kinetic energy: the energy of motion heat: measure of the TOTAL amount of kinetic energy due to molecular motion in a body of matter temperature: measure of the intensity of heat due to the AVERAGE kinetic energy of the molecules

Define hydrocarbon

made up only of hydrogen and carbons, nonpolar and not soluble in water

Know the difference between a molecular formula and a structural formula

molecular: indicates what atoms the molecule consists of structural: represents both atoms and bonding

Distinguish among nonpolar covalent, polar covalent, and ionic bonds

nonpolar covalent: the sharing of electrons between elements of the same electronegativity polar covalent: the sharing of electrons between elements of unequal electronegativity ionic: results from the attraction between oppositely charged ions

Define isotope

one of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass

Explain how water interacts with hydrophobic substances and hydrophillic substances

phobic: do not dissolve in water phillic: dissolve in water

Describe the structure of an atom

protons and neutrons in the nucleus. Electrons revolving around the nucleus

Distinguish among the three types of isomers: structural, geometric, and enantiomers.

structural: the bonds differ geometric: on the same side or opposite side of a double bonded carbon enatiomers: asymmetric carbon, mirror images

On the pH scale, each number represents an actual _______ change in pH

tenfold

Define specific heat

the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temperature by 1 degree Celcius

Explain the relationship between the polar nature of water and its ability to form hydrogen bonds

the attraction is electrical. the slightly positive hydrogen of one molecule is attracted to the slightly negative oxygen of a nearby molecule

Define hydration shell

the sphere of water molecules around each dissolved ion

Explain why radioactive isotopes can be useful to biologists

they can be used as tracers to follow atoms through metabolsim

Describe the structure of a water molecule

two hydrogen atoms joined to an oxygen atom by single covalent bonds. oxygen is more electronegative, so the shared electrons spend more time closer to the oxygen's nucleus than to the hydrogens' nucleus.

Use the bicarbonate buffering system as an example to explain how buffers work.

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Explain asymmetric carbons

A carbon bonded to 4 different atoms or groups of atoms

Describe why water is so important to life

All organisms are made up of mostly water and live in an environment dominated by water

Define isomer

Isomers are itoms with the same molecular formular, but have different structural formulas.

Explain how the polarity of the water molecule makes it a versatile solvent

It is able to dissolve ionic and polar covalent bonded solutes

Be able to determine the number of neutrons in an atom.

Mass number minus atomic number

Explain why noble gases are inactive

Noble gases are inactive because their outer shell is full of electrons and therefore cannot bond with any other elements

Explain how this characteristic is biologically important

Stabilizes ocean temperatures, therefore creating a favorable environment for marine life. Organisms are more able to resist changed in their own temperature being made primarily of water