Biochemistry (midterm)

Six most common elements in living organisms

C, H, N, O, P, S

Three trace elements in living organisms

Fe, Zn, Mg

Polar covalent bonds

Unequal sharing of electrons, have partial charges

Nonpolar covalent bonds

Equal sharing of electrons, no partial charges

Water (P or NP?)

Polar covalent because of the difference in electronegativity between oxygen and hydrogen

Electronegativity

The ability of atoms to “attract” others

Electronegativity trend

Increases up and right on the periodic table

Hydrogen bonds

When hydrogen bonds to N, O, or F

Intramolecular forces

Forces within a molecule, such as ion-ion

Intermolecular forces

Forces between molecules, such as H-bonds or LDFs

Emergent properties

New characteristics that arise from the arrangement and interaction of parts within a system—whole is better than parts

Emergent properties in water

Cohesion, adhesion, and surface tension all arise from the H-bonding in water

Cohesion

Water molecules sticking to each other—hydrogen bonding

Adhesion

Water molecules sticking to other surfaces—hydrogen bonding

High specific heat of water

Water takes lots of NRG to heat up—hydrogen bonds require lots of NRG to break

Ice density

Water molecules form a lattice when frozen—hydrogen bonding

Capillary action

The ability of water to flow through narrow spaces—a combination of cohesion and adhesion

Water (polarity?)

Polar

How does life depend on cohesion?

It helps water flow against gravity in plants (trees)

How does life depend on the high specific heat of water?

It stabilizes oceanic temperatures, allowing life to form underwater

How many valence electrons does Carbon have?

Four

Three reasons Carbon’s four valence electrons make it suitable for life

Complex structures, very abundant, and very stable

Organic molecules contain what?

C-H bonds

Inorganic molecules do not contain what?

C-H bonds

Isomers

Compounds with same molecular formulas but differing structures

Structure determines ________

function

Functional group

They change the chemical and physical makeup of a hydrocarbon

Elements in carbohydrates

C, H₂, O

Carbohydrate monomer

Monosaccharides

Carbohydrate functions

Energy storage, structural support

Elements in lipids

C, H, O

Lipid monomers

None specific, but triglyceride, steroids, and cholesterol are examples

Lipid functions

Long term energy storage, insulation

Elements in nucleic acids

C, H, O, N, P

Nucleic acid monomers

Nucleotides (DNA, RNA)

Nucleic acid functions

Store genetic information

Elements in proteins

C, H, O, N, S

Protein monomer

Amino acid (20 per human protein)

Protein function

Enzymes, the workers

Carbohydrate chemical test

Benedicts (simple sugars) or Iodine (complex sugars)

Lipid chemical test

Sudan III

Protein chemical test

Biuret