Flashcards in Chemistry of Life Deck (54):
pH of life
7.2 - 7.4
blood has to be slightly basic to accomodate for carbonic acid
What elements is life mostly composed of?
Carbon, oxygen, hydrogen, and nitrogen
4 macromolecules and function
Lipids: membranes, hormones, communication
Nucleic acids: store genetic information (can act as catalysts)
Proteins: structure, function, catalyst
Carbohydrates: store energy, indentification
Outermost shell of electrons
What is the bonding point?
Unpaired valence electrons
4 main types of bonds
2. Polar covalent
A single covalent bond has...
Nonpolar covalent bonds
electrons are shared equally
electrons are halfway between the two atoms
atoms have no charge
Polar covalent bonds
Electrons are not shared equally due to electronegatively
Why is water a polar molecule?
Oxygen has high electronegativity that attracts electrons. This gives it a partial negative charge and hydrogen gets a partial positive charge
What is CH4?
What is NH3?
chemical property that describes the tendency of an atom to attract electrons
What factors affect electronegativity?
Atomic number (# of protons)
Greater positive charge will attract more electrons
Label the 3 atoms of life in terms of increasing electronegativity
H, C, O
Strength of bonds
Nonpolar covalent are hardest to break (methane, hydrogen)
Polar covalent (water, ammonia)
Ionic bonds (NaCl) are easiest to break
have full charge
-OH functional group
hydroxyl, probably some type of alcohol
What does a functional group with oxygen probably indicate?
The molecule is probably polar
This means that it is hydrophilic
can interact with water through their charges
if it has a partial or full charge
cannot interact with water through these partial charges
Ex: hydrocarbons have no charge
What drives protein folding?
Interactions between hydrophilic and hydrophobic molecules
Where are there hydrogen bonds in the hydrogen atom?
Between two different water molecules
(polar covalent is actually in the molecule)
an attractive interaction between polar molecules
Hydrogen bonds to atoms with a high electronegativity
What does hydrogen bonding lead to?
High specific heat
water can stick to itself
Why is water's high specific heat important?
It makes a good buffer in temperature which is important for life
water can stick to other things
Why does water expand when it freezes?
the orientation of hydrogen bonds
water molecules are spaced further apart in ice lattice structure (less dense)
Why is water a great solvent?
The partial negative and partial positive charges can break apart substances
Na is attracted to negative oxygen
Cl is attracted to positive hydrogen
How does water act as a pH buffer?
It can dissociate itself into H+ and OH-
What is the basis of the pH scale?
Proton (hydrogen ion) concentration
more hydrogen ions = lower pH
molecules that donate H+
makes sense that more hydrogen ions = lower pH, because acids are the ones that donate H+
molecules that remove H+
Is water an acid or a base?
It can act as both because it can pick up and remove hydrogen ions
carry oxygen depleted blood to the heart
carry oxygen rich blood away from the heart
Where is CO2 high in the body?
Veins and tissues
This reduces the affinity of hemoglobin for oxygen. Hemoglobin will release more oxygen to tissues
How is CO2 transported in the body?
Dissolved in blood as carbonic acid that water has to buffer
What happens when affinity of hemoglobin is lowered?
Hemoglobin is more likely to release oxygen, since it cannot carry as much
Where is CO2 low in the body?
Arteries and lungs
Hemoglobin has a high affinity for oxygen. It does not need to release oxygen in these places. It needs to carry it.
What happens when CO2 levels in the blood increase?
more H+ is produced from forming carbonic acid
hemoglobin has a lower affinity for oxygen when pH lowers because it indicates high CO2
When does hemoglobin's affinity for oxygen increase?
When pH is high
This indicates less H+ ions and correspondingly less CO2
an unstable intermediate molecule that will quickly dissociate into HCO-3 and H+
If an atom has 4 electrons in its valence shell what kinds of covalent bonds can it form?
single, double, or triple
When atoms in a covalent bond have the same electronegativity what type of bond form?
Molecule is not charged
How many other water molecules is one water molecule bonded to?
a water molecule with an extra H+
forms from water gaining a H+ from another water molecule
has a +1 charge
Why do all living things need pH buffers?
Amino acid side chains have many carboxyl and amino acid groups
A solution with a pH 5 has how many more hydrogen ions in it than a solution with pH 7?