Chemical Components of Cells
Terms in this set (58)
What is an element?
cannot be broken down or converted into other substances by chemical means
What is an atom?
smallest particle of an element that still retains its distinctive chemical properties
What is an electron?
a negative subatomic particle held in orbit around the nucleus by electrostatic attraction
What is a proton?
a positively charged subatomic particle found in the nucleus
What is a neutron?
a neutral subatomic particle found in the nucleus. contribute to the structural stability of the nucleus. if there are too many or too few, radioactive decay may occur
What is the atomic number equivalent to?
the average number of protons that an element has. dictates the chemical behavior of the element
What is an isotope?
forms of the same element that have different numbers of neutrons
What is the atomic weight?
protons + neutrons
What is Avagadro's number?
6*10^23. number of things in a mass molecular weight of M (one molar)
What is an electron shell?
strict limit to the number of electrons an orbit can accomodate
When is an atom most stable?
when all electrons are in their most tightly bound states
What is a chemical bond?
bind items together in order to create a complete outer shell
What is an ionic bond?
formed when electrons are donated by one atom to another, creating charges that electrostaticaly attract the atoms to each other
are classified as salts
What is a covalent bond?
the sharing of electrons to create a bond. when shared unequally, the bond is said to be polar
What are the most common elements in living cells and what kind of bonds do they typically form?
C, N, O, S, and P. Generally form covalent bonds
What is an ion?
an electrically charged atom
Positive - cation
Negative - anion
What is a molecule?
a cluster of atoms held together by covalent bonds
How is bond strength measured?
by the amount of energy that must be supplied to break a bond. takes about 100 times the amount of energy when two molecules bump in to each other to break a single covalent bond
What are enzymes?
What percentage of a cell's weight can be attributed to water?
What is a hydrogen bond?
when a positively charged region (Hydrogen) in one water molecule is attracted to a negatively charged region (Oxygen) of another water molecule
particles carrying charges
uncharged and do not form hydrogen bonds with water
Define an acid.
substances that release protons when they dissolve in water, forming an hydronium ion
What is the pH scale?
the logarithmic scale used to describe the concentration of hydronium ion
>7 = basic
<7 = acid
==7 = neutral, water
What defines if an acid is strong or weak?
how easily it gives up a proton to water
Define a base.
any molecule that is capable of accepting a proton
also called alkaline
weak acids and bases that can release or take up protons near pH of 7
keeps the environment of the cell constant under a variety of conditions
What are chemical groups and provide examples.
distinct chemical and physical properties that influence the behavior of the molecule in which the group occurs
What are the four major families of small organic molecules?
also called carbohydrates
What are the two forms that sugars can take?
mirror images of each other
What is an isomer?
came chemical formula but different structures
What is an optical isomer?
mirror image pairs of the same molecule
What kind of bonds link carbohydrates?
What is a condensation reaction?
bond formed between the -OH group on one sugar and the -OH on the next
a molecule of water is expelled to form the bond
What is hydrolysis?
the breaking of a bond via the addition of water
What is a fatty acid?
two chemically distinct regions:
long hydrocarbon chain (hydrophobic and not very reactive)
carboxyl group (ionized to a carboxylic acid that is extremely hydrophilic and chemically reactive)
together it is an amphipathic molecule
When is a hydrocarbon termed saturated?
when it has no double bonds, max number of hydrogens
saturated means a hard fat
also affects fluidity
What are fatty acids most important function?
the formation of membranes
What is the construct of phospholipids?
glycerol and two fatty acids
What is the structure of an amino acid?
a carboxylic acid group and an amino group, both linked to the same carbon atom called the alpha carbon
chemical variety comes from their side chain
what is a protein?
comprised of linked amino acids that is then folded into a three-dimensional shape
what type of bond links amino acids?
what is a nucleoside?
a molecule made of nitrogen-containing ring compound linked to a 5 carbon sugar
What is the difference between a nucleoside and nucleotide?
nucleotide has one or more phosphate groups lined to the sugar
ribose - ribonucleotide
deoxyribose - deoxyribosenucleotide
what are pyrimidines?
what are the purines?
five-membered ring fused to the 6-membered ring
what is adenosine triphosphate?
transfer of energy in hundreds of cellular reactions
three phosphates are linked by two phosphoanhydride bonds
What is the fundamental role of nucleotides?
the storage and retrieval of biological information
building blocks for the nucleic acids
Bases in RNA?
A, G, C, U
Bases in DNA?
A, G, C, T
polymers constructed by covalently linking small organic molecules (monomers) into long chains (polymers)
Define sequence and its context.
the order by which subunits are connected. particularly relevant in protein structure
What is the significance of noncovalent bonds in macromolecules?
constrains the molecule because of these bonds that form between different parts of the molecule
in sufficient numbers, the polymer chain will adopt a certain conformation
determine their chemistry and activity as well as what other biological molecules they may interact with
What are Van der Waals attractions?
a for of electrical attraction caused by fluctuating electric charges that arise whenever two atoms come within a very short distance of each other
What is a hydrophobic interaction and how is it relevant in a cell?
hydrophobic groups are forced together so as to not disrupt the hydrogen bonding in water
this expulsion forces phospholipids together in a cell, forming the cell membrane