Molecules of Life

Chapter 2

Chemistry of Life•Living things are made of 5 main atoms–Carbon, Hydrogen Oxygen, Nitrogen, Phosphorus

Organic MoleculesOrganic molecules have carbon

Carbon is able to form strong covalent bonds

Inorganic moleculesInorganic molecules USUALLY do not have carbon. i.e. H2O, NaCl

Carbon dioxide (CO2) is the exception. It has carbon but is inorganic

Macromolecules•“Large” molecule•Formed by monomers (small molecules) bonding together

•Large molecule with many monomers is a polymer

There are four main macromolecules in living things

•Carbohydrates, lipids, nucleic acids, proteins

CarbohydratesSugars and starchesMade of 3 atoms: Carbon, Hydrogen and Oxygen

Most carbs. have a C1:H2:O1 ratio (1:2:1)

Carbs.Monosaccharides are the monomer.

Simple SugarsGlucose (C6H12O6)

Carbs.Monosaccharides bond together to form Polysaccharides

Carbos. have two main functions.

1. Usable (short-term) Energy storage

2. Structure and support

Cellular EnergySugars (monosaccharides) are usable energy for cells. (glucose, fructose, sucrose)

Glucose most common sugar in cells

Energy StoragePolysaccharides provide short term energy storage.

Plants use starch (in roots and stems)

Animals store glycogen in the liver.

Structural SupportPolysaccharides can also support both plants and animals.

Cellulose is in the cell wall of plant cells to make them stronger. (indigestible)

Structural SupportChitin is a polysaccharide used in the exoskeletons of insects and crabs

LIPIDS• Fats, oils, and waxes

LipidsUses:1. Long term energy

storage. Six times more energy storage than carbohydrates. (fats, oils, waxes)

LipidsUses:2. Cellular Membranes-

phospholipids3. Chemical Messengers-

steroids and cholesterol

Basic Fatty Acid Chain

C C C C HH H H H

HHHHCO

OH

Long carbon chain (16-24C)

C C C C HH H H H

HHHH

Fat Types•Fatty acids can be saturated, unsaturated, or polyunsaturated.

Saturated Fats•Saturated fats have only single bonds between the carbons on the long fatty acid chains.

Saturated Fats

C C C CH H H H

HHHHCO

OC C

H H

HHC C

H H

HH

Saturated Fats•Found in animals•Solid at room temperature

•Taste good but bad for you (heart disease)

Unsaturated Fats•Unsaturated fats have one double bond between two of the carbons on the long carbon chain of the fatty acid.

Unsaturated Fats

C C C CH H H

HHHCO

OC C

H

HHC

HH

Polyunsaturated Fats•Polyunsaturated fats have two or more double bonds between the carbons on the long carbon chain of the fatty acid.

Polyunsaturated Fats

C C C CH H H

HHHCO

OC C

H

HHC

H

Unsat. & Polyunsat Fats•Found in plants•Called oils•Liquid at room temperature

•Better for you, but don’t taste as good.

Phospholipids•Phospholipids are special lipids that make up cellular membranes.

•Phospholipids are made of two fatty acid chains attached to a phosphate group.

PhospholipidsPhosphate

Head

Fatty AcidChains

Phospholipids•Phospholipids are found in a bilayer (two layers).

•The long carbon chains face the middle and the phosphate groups face the outsides.

Phospholipids

NUCLEIC ACIDS

Nucleic Acids• Nucleic Acids have two

main functions-1. Genetic material for all

life forms (DNA, RNA)2. Energy for all life forms

(ATP)

Nucleic AcidsThe monomer for a

nucleic acid is a nucleotide.

Nucleic AcidsNucleotides made of

three parts1. phosphate group2. 5 carbon (pentose)

sugar3. Nitrogenous Base

PROTEINS

Proteins•When you look at someone, the main things you see are proteins.

•Proteins do many jobs for living things

Protein Functions•Structure- found in hair, horns and spider’s silk.

•Transport- moving materials

•Defense- antibodies•Enzymes- helping chemical reactions

Amino Acids•Proteins are made of smaller molecules called amino acids.

C CHH

H RN

O

O H

Amino Acids

C CHH

H RN

O

O HAmine Group (NH2)

Carboxyl Group (COOH)

Amino Acids•A protein is made of up to a few hundred amino acids bonded together.

•The bonds between amino acids are Peptide bonds

C CHH

H RN

O

O HC CHH

H RN

O

O H

H2O

C CHH

H RN

OC CH

H RN

O

O HPeptide Bond

Amino Acids Peptide Bond

•The long chain of amino acids are called polypeptide chains

Amino Acids•There are 20 different amino acids.

•The differences are changes in the R group on the amino acid.

ACIDS & BASES

•Acid: any solution (something mixed with water) that causes there to be a greater amount of H+ than –OH.

H+ -OH

C. Acids and Bases

–This is significant because the H+ ion is the most reactive ion known.

–H+ ions will attack the chemical bonds in many compounds

C. Acids and Bases

C. Acids and Bases (cont)• Acid Examples:

HCl H+ + Cl-

H2SO4 2H+ + (SO4)-

HCl

H+

H+

H+

H+

H+

H+

H+

H+

Cl-

Cl-

Cl-

Cl-

Cl-Cl-

Cl-

Cl-

•Some acids are formed when -OH ions are removed from the solution.

•Base: A solution when there is a greater amount of –OH than H+.

H+ < -OH

C. Acids and Bases (cont)

–This is significant because the OH - ion is also highly reactive.

C. Acids and Bases (cont)

NaOH

Na+OH-

Na+

Na+

Na+Na+

OH-

OH-OH-

OH-

OH-

Na+

Na+

• Base Examples:

NaOH Na+ + OH-

Mg(OH)2 Mg+2 + 2OH-

C. Acids and Bases (cont)

•Acids and bases are placed on a scale to show how strong they are.

•The scale is called the pH scale

C. Acids and Bases (cont)

•Acids are ranked from 0 to 6.9

•Strong acids are a 1 (Many more H+ than -OH)

•Weak acids are 6.9 (almost equal H+ to –OH)

D. pH scale

•Bases are ranked from 7.1 to 14

•Strong Bases are a 14 (Many more –OH than H+)

•Water is ranked 7 (Equal amounts of H+ to –OH)

D. pH scale

• Example:

H+ + OH- H2O

C. Acids and Bases (cont)

H+ OH-

H+

H+H+

H+

OH-

OH-

OH-

OH-

OH-

H+

H20H20 H20

H20 H20

H20

H+ OH-

Section 2.4

Enzymes•One of the most critical types of proteins are enzymes.

•Enzymes help chemical reactions happen inside the body.

Enzymes•Catalase, Lactase, Amylase, ATP Synthase are all examples of human enzymes

Enzymes•An enzyme is called a biological catalyst.

•Catalysts are chemicals that helps to lower the amount of energy needed for a chemical reaction to start.

Enzymes• If a chemical reaction is to happen, energy is required start the reaction (striking a match)

•Called Activation Energy

Activation Energy GraphActivation Energy

Energy Available

Enzymes•An enzyme or catalyst does the job of lowering the activation energy needed to start chemical reactions.

Activation Energy GraphActivation Energy with enzyme

Energy Available

Enzymes•An enzyme is not changed during the reaction. This allows the enzyme to be reused over and over.

Enzymes•Enzymes are used to break molecules apart

•Enzymes synthesize (build) new molecules from smaller pieces

Synthesis Reaction

Degradation Reaction

Enzymes•Enzymes are also specific in nature. They will only work with a single molecule or chemical. (lock and key)

Active Site•The molecule or chemical the enzyme attaches to is called the Substrate.

•The place where the substrate attaches to the enzyme is the Active Site

Enzyme Environment•Enzymes require specific environments to do their job.

Enzyme Environment• Two major factors

affect enzyme activity.1. Temperature2. pH (acidic or basic)

Enzyme Environment• The environment can

cause an enzyme to change its shape and make it ineffective

• If an enzyme has changed its shape, it has become Denatured

• If an enzyme has become denatured, it’s active site will also change and will not be able to attach to the substrate.