IB Biology SL - Carbon, Macromolecules, Functional groups

Carbon-based molecules make up:

all living things = organic chemistry

Which carbon molecules do not make up life?

carbon dioxides: CO, CO₂

carbonates: CO₃^2-

hydrocarbonate: HCO₃^-

methane: CH₄

How many bonds does carbon make?

4 covalent bonds.

tetravalent

making 4 covalent bonds (e.g Carbon)

Carbon skeletons

chains of C. (can occur straight, branched, ringed, attached to other things.)

Hydrocarbons

Carbon skeleton with just hydrogens attached

• non-polar → hydrophobic

• hydrocarbons are seen in phospholipid layers for this reason.

Isomers

Molecules with the same molecular formula, but different forms.

e.g. butane is C₄H₁₀ → isobutane has a different structure.

Geometric isomers

What is a functional group?

Things attached to C skeleton that are involved in chemical reactions.

A certain group of atoms or bonds within a molecule that determines its properties.

Cis isomer

• note Cl is a placeholder for X

formula is C₂H₂X₂

Trans isomer

• note Cl is a placeholder for X

formula is C₂H₂X₂

Enantiomers

Mirror image isomers → left / right hand

What are macromolecules?

Large molecule made of repeating identical / similar subunits (monomers).

What are polymers, what do they make up?

Large molecules made up of small repeating monomers. They make up macromolecules.

How is a polymer made?

dehydration synthesis reactions (aka condensation).

• when 2 monomers are covalently bonded together through the removal of a water molecule.

anabolic reaction

costs E (ATP) + usually require enzymes

How are polymers broken apart?

hydrolysis reactions

• when a covalent bond between monomers is broken by the addition of water.

catabolic reaction

Release E (e.g. digestion)

Hydroxyl

- OH → R-OH

• an O bonded to C skeleton and a H.

• makes up alcohols ex: ethanol, isopropyl alcohol

• polar molecule + will dissolve in water

Carbonyl

CO

• C double bonded to an O and single bonded to C skeleton.

• ex: formaldehyde, acetone.

• where the double bond occurs determines properties.

Carboxyl

-COOH

• C with a double bonded O₂, Sb-OH, and bonded to C skeleton.

• carboxylic acids

• e.g. acetic acids (vinegar)

• donate H⁺: -COOH → COO^- + H⁺

Amino

-NH₂

• N bonded to C skeleton and 2 Hs

• monomers of proteins

• accept H⁺ (base)

• NH₂ + H⁺ → NH₃⁺

• They are buffers!

• NH₂ and COOH

Sulfhydryl

-SH
- S bonded to C-skel and H

• make up thiols

• Stabilize the structure of large molecules, like proteins.

Phosphate

-PO₄^-

• ion bonded to C skeleton

• e.g. ATP and DNA

• create energy transfers