ch 2 chemical reactions Flashcards
chemical bonds that hold together molecules and the organic compounds created by
chemical reactions
a chemical reactions rearranges the atoms of the
reactant molecules to generate new product molecules
what are the 3 most common chemical reactions in our bodies
- synthesis
- decomposition
- exchange
synthesis
A + B –> AB
* for ex. the formation of proteins
decomposition
AB –> A + B
* for ex. nutrient digestion
exchange
AB + CD –> AC + BD
* for ex. buffers counteracting a pH change
chemical bonds
atoms tend to arrange themselves in the most stable patterns possible which means that they have a tendancy to complete or fill their
outermost electron orbits
they join with other atoms to do just that
chemical bonds
the force that holds atoms together in collections known as molcules is referred to as a
chemical bond
chemical bonds
atoms of different elements have varying affinities for electrons measured by their
electronegativity
this dictates the type of chemical bonds they will form
ionic bond
this chemical bond involves a transfer of an
electron to the atom with higher electronegativity
ionic bond
so one atom gains an electron while one atom
loses an electron
ionic bond
one of the resulting ions carries a
negatvie charge (anion) and the other ion carries a postivie charge (cation)
because opposites charges attract the atoms bond together to form a molecule
covalnet bond (non-polar)
the most common bond in
organic molcules
covalnet bond (non-polar)
this bond involves 2 atoms with similar electronegativities sharing
electrons
covalnet bond (non-polar)
in the human body this is the most
stable connection between atoms
this does not hold true outside the presence of water
polar covalent bond
polar bond
- an intermediate case between ionic and covalent bonding with one of the end of the molecule slightly negatively and the other end slightly positively charged
sometimes atoms with different electronegativity will form a covalent bond producing an unevenly distrubuted charge
polar covalent bond
these slight imbalances in charge distrubution are indicated by
lowercase delta with a charge superscript (+ or -)
although the resulting molecule is neutral at close distance the uneven charge distribution can be important
polar covalent bond
water is an ex. of a polar molcule
- the oxygen end has a slight negative charge wheras the hydrogen ends are slightly more positive
polar covalent bond
polarity explains why some substances dissolve readily in
water and others do not
hydrogen bond
because they’re polarized 2 adjacent H2O molecules (or any other polar molecules) can form a linkage known as a
hydrogen bond
where the (electropositive) hydrogen atom of one H2O molecule is electrostatically attracted to the (electronegative) oxygen atom of an adjacent water molecule
hydrogen bond
consequently molecules of water join together transiently in a
hydrgen bond lattice
hydrogen bond
hydrogen bonds have only about 1/20 the strength of a covalent bond yet even this force is sufficient to affect the
structure of water producing many of its unique properties such as:
* high surface tension
* specific heat
hydrogen bond
hydrogen bonds are important in many life processes such as
- replication
- defining the shape of DNA molecules
when different elements combine through chemical reaction they form
compounds
when compounds contain carbon they’re called
organic compounds
the 4 families of organic compounds with important biological functions are
- carbohyrdates
- lipids
- proteins
- nucleic acids
carbohydrates
these molecules consist of
- carbon
- hydrogen
- oxygen
in a ratio roughly of 1:2:1
carbohydrates
carbohydrates are formed by the chemical reaction processes of
- condensation
- dehydration synthesis
carbohydrates
carbohydrates are broken apart by
hydrolysis
* the cleavage of a compound by a reaction that adds water
carbohydrates
the subcategories of carbohydrates
- monosaccharides
- disaccharides
- oligosaccharides
- polysaccharides
carbohydrates
monosaccharides
- also known as simple sugars
- the building blocks (monomers) of larger carbohydrates molecules and are a source of stored energy
- key monomers include: glucose, fructose, galactose ; these 3 have the same numbers of carbon (6), hydrogen (12), and oxygen (6) atoms in each molecule–formally written as C6H12O6–but the bonding arrangements are different; molecules with this kind of relationship are called isomers
- two important five-carbon monosaccharides (pentose) are ribose, a component of ribonucleic acids (RNA) and deoxyribose, a component of deoxyribose nucleic acid (DNA)
carbohydrates
disaccharides
- sugars are formed by the bonding of two monosaccharides
- including sucrose (table sugar), lactose, maltose
carbohydrates
oligosaccharides
- contain 3 to 9 simple sugars that serve many functions
- found on plasma membranes of cells where they function in cell-to-cell recognition
carbohydrates
polysaccharides
- are polymers
- formed when many monomers bond into long, chainlike molecules
- glycogen is the primary polymer in the body; it breaks down into individual monomers of glucose, which cells use to generate usable energy
lipids
lipids are commonly known as
fats
lipids
these molecules consist of a
3-carbon glycerol linked to fatty acid chains
lipids
insoluble in water because they contain an abundance of
nonpolar bonds
* lipids molecules have 6 times more stored energy than carbohyrate molecules
lipids
upon hydrolysis however most fats form
glycerol and fatty acids
lipids
a fatty acid is a
long straight chain of carbon atoms with hydrogen atoms attached
lipids
if the carbon chain has its full number of hydrogen atoms the fatty acid is
saturated
* ex butter or lard
lipids
if the carbon chain has less than its full number of hydrogen atoms due to double bonds the fatty acid is
unsaturated
* ex margarine and vegetable oils
lipids
phospholipids as the name suggests
- contain phosphorus and often nitrogen in place of one fatty acid chains
- these are aligned side-by-side to form the cell membrane
lipids
other lipids include
- cholesterol
- vitamins A and D
- steroid hormones
proteins
among the largest molecules can reach molecular weights of some
40 million atomic units
proteins
proteins always contain
- hydrogen
- oxygen
- nitrogen
- carbon
- and sometimes contain phosphorus & sulfur
proteins
examples of proteins in the body include
- antibodies
- hemoglobin (the red pigment in RBCs)
- enzymes (catalysts that accelerate reactions in the body)
proteins
the human body builds protein molcules using 20 different kinds of monomers called
amino acids
proteins
an amino acid is a
carbon atom attached to a hydrogen atom, an amino group (-NH), a carboxyl group (-COOH), and a unique chain called the R group
proteins
amino acids link together by
peptide bonds to form long molecules called polypeptides, which then assemble into proteins
proteins
these bonds form when the carboxyl group of one molecule reacts with the
amino group of another molecule, releasing a molcule of water (dehyration synthesis)
proteins
a polypeptide is not a
- functioning protein
- it must then be folded, twisted, and often linked with other polypeptides to create a three-dimensional structure which allows it to carry out its function
nucleic acid
nucleic acids are long
- molecules
- found primarily in the cell’s nucleus
- act as the body’s genetic blueprint
nucleic acid
nucleic acids are comprimised of smaller building blocks called
nucleotides
nucleic acid
each nucleotide is composed of
- five-carbon sugar (deoxyribose or ribose)
- a phosphate group
- a nitrogenous base
nucleic acid
in nucleotides the sugar and phosphate groups link to form the
backbone of the molecule
nucleic acid
in nucleotides the base is attached to the
sugar and aligns with its partner on the other strand
nucleic acid
the nitrogenous bases in DNA are
- adenine
- thymine
- cytosine
- guanine
- they always pair A-T and C-G forming hydrogen bonds between the bases creating the rungs of the DNA ladder
nucleic acid
nitrogenous bases in RNA are the same except for
- thymine is replaced by uracil
- these always pair off A-U and C-G during transcription
- occur in single strand
