Biochemistry Flashcards
Essential elements
Carbon (c), Hydrogen (h), Oxygen (o), Nitrogen (n) –> 96% of all living matter
Phosphorus (p), Sulfur (s) –> other 4% (CHONPS)
Molecules
Compounds compromised of ONLY nonmetals helf together by COVALENT bonds
Covalent bonds
bond of life (strongest bond), intramolecular force (atoms within molecules)
Polar Covalent Bonds
cheat : any bond between H & N, O, and F, electrons are shared unequally between two nonmetals, LARGE difference in electronegative
Nonpolar Covalent Bonds
electrons shared equally, similar ectronegativity
Electronegativity
Tendency of an atom to attract electrons to itself when it’s bonded to another atom
Weak Bonds
intermolecular force, attractions between different molecules, short term attachment (most important = Hydrogen bonds)
Hydrogen Bonds
formed between polar molecules, H atom and the O, F, or N of a second polar molecule, strongest of the weak bonds
Molecules of Life
water, carbohydrates, proteins, lipids, nucleic acids (not only organic but are POLYMERS)
Organic Molecules must have…
At least one C-C bond
Water Structure
polar covalent molecule, high electronegativity (h+, o-)
Water’s H-bonding
H-bonds form between pos H atoms of one polar molecule and the neg O atoms of neighboring H20 molecules (extensive h-bonding gives water its unique structure & properties that are needed for life on earth)
Unique Water Properties (4)
- cohesion and adhesion
- Medium of life (facilitates the chemical processes of cells)
- Moderates Temperature (result of its specific heat of vaporization)
- Surface Tension (facilitates the processes (chemical reactions) of cells)
Cohesion
When two of the SAME polar molecules form H-bonds with each other
Adhesion
when two DIFFERENT polar molecules form H-bonds with each other
Because of cohesion water…
H20 molecules H-bond to each other and resist being pulled apart
Because of adhesion water…
H20 molecules H-bond to other polar molecules or charged particles and resist being pulled apart
Capillary Action
COHESION & ADHESION create a continuous water column from the roots to the leaves, responsible for the movement of H20 against gravity from soil to the leaves of the plant for photosynthesis, water enters through microscopic veins in roots and then travels up to the leaves as H20 molecules are being evaporated off the surface of a leaf
Medium of Life
H20 is the solvent of life - most of the important molecules are polar and therefore soluble, H2O facilitates the movement of materials across cell membranes (allows for diffusion and osmosis), buffers chemical reactions of cells (allows cells to resist changes in pH)
Water Moderates Temperature
H2O can resist changes in temperature as a result of its high specific heat and heat of vaporization
Cohesion between water molecules = ___ specific heat
HIGH
can absorb a great deal of E without a significant increase in temperature as most of the absorbed used to disrupt H-bonds between the H2O molecules
Cohesion between water molecules = high heat of _____
VAPORIZATION
H2O molecules have to absorb a high amount of heat E in order to change from liquid phase to a gaseous state as most of the E absorbed must first be used to break the H-bonds between the H2O molecules
How does water help regulate Earth’s temperatures?
most of the solar E absorbed is utilized to heat large bodies of water (high specific heat, high heat of vaporization)
Evaporative Cooling
Organisms are composed mainly of H2O therefore they can moderate (resist sudden changes) their temperatures (evaporation of water to cool organisms)
exs. sweating in humans, urohydrosis in birds, licking in Kangaroos
Ice is ____ dense than H2O
LESS
frozen water molecules spread apart into a lattice –> creates air spaces in the solid ice
h2o expands as it solidifies (ICE FLOATS)
Surface Tension
the surface of liquid water exposed to the air is difficult to puncture –> cohesion between water molecules slows evaporation of water from a large body of water –> allows for the continued presence of large bodies of water on Earth (also allows water to bead up on waxy surfaces ex. leaves)
Importance of Carbon
only true nonmetal that has 4 valance electrons
can have a maximum of 4 covalent bonds around it
Organic Molecules
Molecules that contain at least one C-C bond (carbons covalently bonded to each other)
Diversity of Carbon Molecules
carbon tends to bond to itself in long chains that form the skeletons of organic molecules
- carbon chains may very in length
- can very in shape - either straight, branched or arranged in rings
- can have multiple bonds (double & triple) that very in number and location
Carbon Skeleton Attachments
distinctive properties of an organic molecule depend not only on the arrangement of the carbon skeleton but also on the attachments to that skeleton
attachments are required to complete the octet for each carbon atom most common attachment is Hydrogen
Functional Groups
Specific groups of atoms that attach to the carbon-hydrogen core of organic molecules and help to give the molecules particular function
- most of the cell’s molecules have 2 or more different functional groups
Hydroxyl group
(-OH) - functional group
can be found at a terminal carbon or within the chain
Carbonyl Group
(-CO) - functional group
can be found at a terminal carbon or within the chain
Amino Group
(-NH2) - functional group
Carboxyl Group
(-COOH) - functional group
O = C - OH
ONE carbon simultaneously DOUBLE BONDED to oxygen and bonded to a hydroxyl group
can ONLY be found at a terminal carbon
Sulfhydryl group
(-SH) - functional group
can be found at a terminal carbon or within the chain
form DISULFIDE BONDS
- special covalent bonds that are found ONLY in proteins
Phosphate Group
(-PO42-)
NEGATIVELY charges
can be found at a terminal carbon or within the chain
Importance of functional groups
help to give each type of molecule its distinctive properties
allow molecules to form WEAK BONDS with other molecules
most functional groups are POLAR (hydrophilic) –> makes the molecules with these attachments POLAR
POLAR molecules can H-bond to other POLAR molecules which allows POLAR molecules to attach temporarily
Molecular Shape
all molecules have SPECIFICITY (characteristic 3D shape)
result of carbon skeleton and functional groups
Isomers
molecules that have the SAME chemical formulas but DIFFERENT arrangements of atoms (structure) and therefore different properties
a.k.a same chemical formula + different arrangements = different properties
Structure defines function
structure = function
shape of a molecule DETERMINES its function
If the shape of a molecule changes then the function…
changes
The molecular shape is crucial to …
molecule recognition
if different molecules are complementary in shape they…
interact
ex. receptors and hormones