Biol 1070 Chapter 2

Biochemistry

Properties of water (that are essential to life)

• polar (forms hydrogen bonds)

• cohesion (molecules stick together)

• adhesion (sticks to surfaces)

• solvent (dissolves chemicals)

• ice floats in liquid water

• high specific heat and heat of vaporization (takes a lot of heat to change temperature)

Why is it important that water is polar?

allows water to stay liquid at room temperature, allows for acids and bases to dissolve in water, causes the high specific heat and heat of vaporization of water, and enables water to hold cell membranes in place around cells

Carbohydrates

molecules composed of C, H, and O, typically with 2x as many H atoms as O atoms

Monosaccharides

fructose, glucose, galactose

isomers with the same chemical formula but different shape

used for energy

monomers of carbohydrates

Disaccharides

sucrose (fructose+glucose), lactose (galactose+glucose), maltose (glucose+glucose)

made of two monosaccharides joined by dehydration synthesis

Polysaccharides

starch (amylose), cellulose, glycogen, chitin

made of many monosaccharides joined by dehydration synthesis

Dehydration synthesis

The opposite of hydrolysis: during a reaction joining two monomers, an enzyme removes the components of water (OHH) and creates a bond between the two monomers, and the OHH rearrange into a stable water molecule

Hydrolysis

The opposite of dehydration synthesis: when a polymer is broken down into monomers, an enzyme takes a water molecule, and separates it, breaking the bond between the monomers and instead bonding them to the OHH.

Starch (amylose)

function: plant food storage

monomers: glucose

Cellulose

function: plant cell walls

monomers: glucose

Glycogen

function: animal food storage

monomers: glucose

Chitin

function: fungi cell walls, insect external skeletons

monomers: amino sugars

Lipids

contain many more H atoms than C atoms and do not dissolve in water to any great extent

triglycerides, phospholipids, and steroids

Triglycerides

fats and oils, containing a “backbone” of glycerol and three fatty acids

Saturated triglycerides

triglycerides that are “saturated” with H atoms, three straight fatty acids

typically come from animals and are solid at room temperature

can cause heightened cholesterol

Unsaturated triglycerides

triglycerides with a double carbon bond, causing a “kink” in the fatty acid chain

typically come from plants and are liquid at room temperature

Phospholipids

contain a glycerol, a phosphate, and two fatty acids

hydrophilic head and hydrophobic tail, form a double-layered cell membrane held together by the force of water

Steroids

estrogen, progesterone, testosterone, and cholesterol

Amino acids

2nd most common compound in humans (after H2O), the monomers of proteins.

Contain an amino group, a carboxyl group, and an R group

20 different amino acids, all differ only in the composition of the R group

Proteins

polymers made of chains of amino acids joined by peptide bonds through dehydration synthesis

Major functions of proteins

• structure

• transport

• hormones

• contractility (e.g. muscles)

• antibodies

• enzymes

• cell identification

• receptors

• membrane pumps

Enzymes

facilitate chemical reactions that would otherwise take too long in the body

two substrates bond to the active site in the enzyme, the enzyme holds them together until they form a product, which then detaches and allows another reaction to take place

Nucleic acids

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), monomers are the nucleotides: adenine, thymine, cytosine, guanine, and uracil. Thymine is replaced by uracil in RNA

DNA

deoxyribonucleic acid; functions as a code book, two stranded nucleic acid, contains the program for every protein, but will only be opened to make certain proteins

functions are: DNA replication and transcription to mRNA (messenger RNA)

RNA

ribonucleic acid; single-stranded nucleic acid, functions as DNA’s messenger in creating proteins

ATP

adenosine triphosphate, functions as the main energy source for life processes, releases a phosphate along with energy and becomes ADP (adenosine diphosphate)

Sucrose

contains one glucose and one fructose

Lactose

contains one glucose and one galactose

Maltose

contains two glucoses