Chapter 3: molecules of life

Organic Molecules

Make up the bodies of living organisms.
• Have a carbon-based core.
• The core has attached groups of atoms called functional groups.

macromolecules

The building materials of the body

4 types of macromolecules

Proteins.
2. Nucleic acids.
3. Carbohydrates.
4. Lipids

Macromolecules are assembled from

monomers

polymer

The assembled chain of monomers

All macromolecules are assembled the same way

A covalent bond is formed between two subunits by
removing a hydroxyl group (OH) from one subunit and a hydrogen (H) from another subunit.

dehydration synthesis.

removal of a molecule of water

hydrolysis

The process of disassembling polymers into component monomers is essentially the reverse of dehydration synthesis.
• A molecule of water is added to break the covalent bond between the monomers

proteins

complex macromolecules that are polymers
of many subunits called amino acids

amino acids

small molecules with a simple basic
structure, a carbon atom to which three groups are added.
• An amino group2(-NH ).
• A carboxyl group (-C O O H).
• A functional group (R)

what gives amino acids their chemical
identity

the functional group

how many different types of amino acids are there

20

why are 9 amino acids are considered essential?

they cannot be synthesized by the body

peptide bond

The covalent bond linking two amino acids together

polypeptide

The assembled polymer

The order of the what that form the polypeptide affects how the protein folds together?

amino acids

4 general levels of protein structure

1Primary structure.
2. Secondary structure.
3. Tertiary structure.
4. Quaternary structure.

primary structure

the sequence of amino acids in the
polypeptide chain.
• This determines all other levels of protein structure

secondary structure

the initial folding of the amino acid chains.
• Occurs because regions of the polypeptide that are nonpolar are forced together.
• The folded structure may resemble coils, helices, or sheets

tertiary structure

the final 3-D shape of the protein.
• The twists and folds that lead to the final shape of the protein are the result of polarity differences in regions of the polypeptide.

quaternary structure

the spatial arrangement of component polypeptides in proteins comprised of more than one polypeptide chain

denaturing of protein

Changes to the environment of the protein may cause protein to lose its characteristic structure
• Increased temperature or lower pH affects hydrogen bonding, which is involved in the folding process.
• A denatured protein is inactive

proteins that are long and cable like

serve architectural and structural roles

Proteins that act as enzymes are globular

having a special 3-D shape that fits precisely with another chemical.
• They cause the chemical that they fit with to undergo a reaction

Nucleic Acids

are very long polymers that store hereditary
information.
• Comprised of monomers called nucleotides.

Each Nucleotide has 3 parts

A 5-carbon sugar.
2. A phosphate group.
3. An organic nitrogen-containing base.

how many different types of nucleotides are there

5

how is information encoded in the nucleic acid

by different sequences of these nucleotides

2 types of nucleic acids

Deoxyribonucleic acid (DNA).
• Ribonucleic acid (RNA)

RNA is similar to DNA except that

• It uses uracil instead of thymine.
• It is comprised of just one strand.
• It has a ribose sugar

The structure of DNA is

a double helix because:
• There are only two base pairs
possible.
• Adenine (A) pairs with thymine (T).
• Cytosine (C) pairs with Guanine (G)

what bonds hold together a base pair in DNA helix

hydrogen bonds

what is the backbone of the DNA helix

A sugar-phosphate backbone comprised of phosphodiester bonds gives support.

how does the structure of DNA help it to function?

The hydrogen bonds of the base pairs can be broken to unzip the DNA so that information can be copied.
• Each strand of DNA is a mirror image so the DNA contains two copies of the information.
• Having two copies means that the information can be accurately copied and passed to the next generation.

Carbohydrates

used for energy or sometimes as structural molecules.
• A carbohydrate is any molecule that contains the elements C, H, and O in a 1:2:1 ratio

The size of carbohydrates may vary

simple carbohydrates—made up of one or two monomers.
• complex carbohydrates—long polymers.

Types of simple carbs

monosaccarides and disaccarides

monosaccarides

consist of only one monomer subunit.
• An example is the sugar glucose6 12 6(C H O )

disaccarides

consist of two monosaccharides.
• An example is the sugar sucrose, which is formed by joining together two monosaccharides, glucose and fructose

If glucose and fructose are both monosaccharides,
why does fructose get a bad rap?

unlike glucose, fructose is primarily metabolized by the liver, which can lead to issues like fat accumulation when consumed in large quantities, particularly from processed foods like high fructose corn syrup, whereas glucose is readily used by muscles for energy throughout the body

Complex carbohydrates

long polymer chains.
• Because they contain many C-H bonds, these
carbohydrates are good for storing energy.
• These bond types are the ones most often broken by organisms to obtain energy.
• The long chains are called polysaccharides.

Plants and animals store energy in polysaccharide chains formed from

glucose, plants form starch, animals form glycogen.

Some polysaccharides serve structural functions and are resistant to digestion by enzymes

Cellulose is found in the cell walls of plants.
• Chitin is found in the exoskeletons of many invertebrates and in the cell walls of fungi.

Lipids

fats and other molecules that are not soluble in
water.
- nonpolar molecules.
- include fats, phospholipids, and many other
molecules

what are fats used for

longterm energy storage

what are the 2 subunits of fats

1 Fatty acids.
2. Glycerol

Fatty acids have different chemical properties depending on

the number of hydrogens attached to the chain of carbons

If the maximum number of hydrogens are attached, then the fat is called

saturated

if there are fewer than the maximum attached, then the fat is called

unsaturated