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BIOL 213 Chapter 2
Chemical Components of Cells
34
Biology
Undergraduate 2
12/06/2012

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Term
Why is biological chemistry important?
Definition
Understanding the structure and properties of major classes of biological molecules is essential to understanding cellular function at any level.
Term
What are the four classes of biological molecules?
Definition
Carbohydrates, lipids, proteins, and nucleic acids
Term
What does an atom consists of?
Definition
A positively charged nucleus and a negatively charged electron cloud
Term
Atom
Definition
the smallest particle of an element that still retains its distinctive chemical properties
Term
Electron cloud
Definition
held in orbit by electrostatic attraction to the nucleus
Term
The number of protons in an atom determines ____.
Definition
its atomic number and its number of electrons
Term
Atomic weight
Definition
Number of protons plus number of neutrons
Term
What charge does a neutron have?
Definition
Does not have a charge; neutral
Term
Element
Definition
substance that cannot be broken down or converted into other substances by chemical means
Term
Molecules
Definition
atoms linked together to form groups; held together by covalent bonds
Term
Isotypes
Definition
element that exist in several physically distinguishable but chemically identical form with each having a different number of neutrons but the same number of protons
Term
Dalton
Definition
an atomic mass unit approximately equal to the mass of a hydrogen atom
Term
avogabro's number
Definition
6*10^23; key scale factor describing the relationship between everyday quantities and numbers of individual atoms or molecules
Term
mole
Definition
number of molecules that are available to participate in chemical reactions
Term
Which chemical bonds are strong?
Definition
Covalent and ionic
Term
Which chemical bonds are weak?
Definition
Hydrogen, hydrophobic interactions, and Van der Waals attractions
Term
Covalent bond
Definition
2 atoms share a pair of electrons
Term
Ionic bond
Definition
electron donated by one atom to another
Term
Polar covalent bond
Definition
pair of electrons shared unequally with one atom attracting the shared electron more than the other
Term
electrostatic attraction
Definition
attractive force that occurs between oppositely charged atoms
Term
bond strength
Definition
measured by the amount of energy that must be applied to break a bond, usually expressed in units of either kilocalories per mole or kilojoules per mole
Term
enzymes
Definition
highly specific catalysts
Term
single bonds
Definition
covalent bonds involved in sharing 2 electrons, one donated by each participating atom
Term
double bond
Definition
Four electrons shared, 2 coming from each participating atom
Term
polar
Definition
positive charge is concentrated at one end of the molecule (pole) and the negative charge is concentrated at the other
Term
What kind of bonds does water have?
Definition
Polar covalent bonds
Term
What kind of bonds does oxygen have?
Definition
Nonpolar covalent bonds
Term
What can partially shield charges between ionds?
Definition
The electrical charge effects of water
Term
Why do ionic substances such as sodium chloride dissolve in water?
Definition
Water molecules are attracted to the positive or negative charge of each ion
Term
The cohesive nature of water is responsible for many of its unusual properties, such as ___.
Definition
high surface tension, specific heat, and heat of vaporization
Term
hydrogen bond
Definition
electrostatic interaction between a hydrogen held in a polar covalent bind and another atom (usually oxygen or nitrogen) also held in polar covalent bond
Term
Due to the heat energy of the molecules, hydrogen bonds ___.
Definition
are easily broken by the random thermal motions
Term
In hydrogen bonds, the positively charged region of one water molecule comes close to a ___.
Definition
negatively charged region of a second water molecule
Term
hydrophilic
Definition
molecules that are water loving, i.e. sugars, DNA, RNA, and the majority of proteins
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