AP Bio Unit 2: Chemistry of Life

Biological Macromolecules

Proteins, Carbohydrates, Lipids, & Nucleic Acids (all made up of CHONP)

Monomers

Single unit

Polymers

Many units (monomers) bound together

Dehydration Synthesis

How cells build large molecules (polymers) from smaller ones (monomers).

An enzyme removes a hydroxyl group from one molecules and a hydrogen atom from another. A covalent bond forms between the molecules, and water forms.

Hydrolysis

How cells breaks large molecules (polymers) into smaller ones (monomers).

An enzyme attaches a hydroxyl group and a hydrogen atom (both from the addition of water) at the cleavage site.

CHONP

Carbon, Hydrogen, Oxygen, Nitrogen, & Phosphorous

The building blocks of life as they make up all of the biological macromolecules.

Carbon’s Importance

Carbon is important to life because of its versatile bonding behavior. Each carbon atom can form up to four covalent bonds, can be polar or nonpolar, can form carbon rings/chains, and can be assembled and remodeled into a variety of organic compounds.

Functional Groups

Clusters of atoms on a molecule that gives the molecular polarity or acidity. They help determine how that molecule will behave.

Hydroxyl Group

Properties: Polar, forms hydrogen bonds, soluble

Found in: sugars and alcohols (ex: ethanol)

Methyl Group

Properties: Non-polar, insoluble

Found in: fatty acid chains (ex: 5-methanyl cytosine)

Carbonyl Group

Properties: Polar, can form hydrogen bonds

Found in: Carbohydrates, some amino acids, fatty acids (ex: acetone)

Carboxyl Group

Properties: Acidic, can form hydrogen bonds

Found in: Amino acids, fatty acids (ex: acetic acid)

Amino Group

Properties: basic, can form hydrogen bonds

Found in: Amino acids, proteins (ex: glycine)

Sulfhydryl Group

Properties: Can form disulfide bonds

Found in: Some amino acids (ex: cysteine)

Phosphate Group

Properties: Negatively charged, polar

Found in: Nucleic acids (ex: glycerol phosphate)

Monosaccharide

Simple ring sugars (monomers) that are mostly used as an energy source or structure. They are very soluble in water and may be in a linear or ring form

ex: glucose, fructose, galactose

Disaccharide

Two monosaccharides combined (oligosaccharides/short polymers)

ex: sucrose, lactose, maltose

Polysaccharide

Polymers of monosaccharides (complex carbs)

ex: cellulose, chitin, starch, glycogen

Carbohydrates

Consists of carbon, hydrogen, and oxygen in a 1:2:1 ratio (CHO). They can be used for energy, structure, and for storing/transporting energy.

ex: glucose, starch, etc

Lipids

Function as long term energy storage and is the structural foundation of cell membranes. They can be fatty, oily, or waxy and are insoluble in water (non-polar, hydrophobic). They are composed of CHO.

Fatty Acids

Simple organic compounds with a carboxyl group joined to a backbone of 4-36 carbon atoms. They have hydrocarbon, hydrophobic tails, and carboxyl group, hydrophilic heads.

Identifying them: they have long zig-zag chains or fused rings with few oxygens

Saturated Fatty Acids

Has single bonds within their hydrocarbon tails. They are “fully saturated” with hydrogen atoms, have flexible tails, and can “stack up” at room temperature, forming a soft solid.

ex: butter

Unsaturated Fatty Acids

They contain 1 or more double bonds in the carbon chain. This makes their hydrocarbon tail slightly bent, making them less flexible and unable to stack together (liquid at room temperature)

ex: vegetable oils

Fats

Lipids with 1-3 fatty acids bonded to glycerol (an alcohol). A fatty acid can easily bond with other molecules, like glycerol, via the carboxyl group (which loses its hydrophilic properties)

ex: triglycerides, phospholipids

Phospholipids

A part of the phospholipid bilayer and is composed of a glycerol backbone, 2 fatty acid tails, and a phosphate group. They also are amphipathic, meaning they have a hydrophilic head and hydrophobic tails.

Phospholipid Bilayer Function

Provides selective permeability (controls what enters/exits cell), fluidity (allows molecules to move within membrane), & structural integrity (maintains cell’s shape and protects it)

Wax

Complex molecules with a varied mixture of lipids with long fatty acid tails bonded to long chain alcohols or carbon rings. Wax is firm and water resistant, allowing it to serve many purpoes (ex: wax helps protect leaves, human hair, bird feathers, etc)

Steroids

Lipids with a rigid backbone of four carbon rings and no fatty acid tails

Cholesterol

The most common type of steroid in animal cells membranes (helps maintain cell structure). They don’t need a cell wall, they can change shape, and they can move freely.

Proteins

Used in all cellular processes such as structure, nutrition, enzymes, transport, communication, & cellular defense

Amino Acids

The monomer of proteins and are joined by peptide bonds. Thousands of different proteins can be made by arranging amino acids in different ways.

Polypeptide

A linear chain of amino acids

Amino Acid Structure

All amino acids have an amine group, carboxyl group, and an R-group. They are made up of CHON elements.

R-Group

a.k.a the Variable Group, and gives the amino acids its properties (hydrophobic, acidic, etc)

The 4 Protein Structures

Primary, Secondary, Tertiary, & Quaternary

Primary Protein Structure

Sequence of amino acids held by peptide bonds

Secondary Protein Structure

Local folding which forms hydrogen bonds between the amino acids, which makes two kinds of shapes → α-helix & β-sheet (hydrogen bonds)

Tertiary Protein Structure

3D shape of one chain formed, which depends on interactions between R-groups

Quaternary Protein Structure

Functional protein formed by two or more folded polypeptide chains in close association or covalently bonded together

Denature

When a protein loses its shape and no longer functions correctly

Nucleic Acids

Repeating units of nucleotides (monomers) make up DNA (polymer, nucleic acid)

Nucleotide Structure

Have three parts: negatively charged phosphate groups, 5-carbon deoxyribose sugars, and nitrogen bases (A, T, C, G).

5-carbon Deoxyribose

Deoxyribose has 5 Carbon atoms, which are numbered clockwise

DNA Directionality

DNA is antiparallel because the complementary strands run in opposite directions

(5’ → 3’ & 3’ → 5’)

Bonds in DNA

Hydrogen bonds hold bases together (pyrimidines with purines) and covalent phosphodiester bonds hold nucleotides together at the backbone.

Pyrimidines

T, C, with single rings

Remember: CUT the Py

Purines

A, G, with double rings

Remember: PUR As Gold

CHONP Elements in Carbohydrates

CHO (1:2:1)

CHONP Elements in Nucleic Acids

CHONP

CHONP Elements in Lipids

CHO

CHONP Elements in Proteins

CHON

Intramolecular Forces

Hold atoms together within a molecule

Intermolecular Forces

Forces between separate molecules