MacromoleculesLarge molecules made up of

smaller building blocks or subunits

Chapter 2.8 – 2.21

Types of macromolecules

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Carbohydrates• Primary fuel source for cellular work• Mostly made up of C, H, & O atoms

– same # of C atoms as H2O units• glucose is C6H12O6 (6 carbons & 6 H2O units)

– the C-H bonds store a great deal of energy & are easily broken by organisms

• Two kinds; based on size– monosaccharides– polysaccharides

Monosaccharides• Monosaccharides = simple sugars• 3 – 7 carbon atoms

– ex. glucose; in sap & fruit of many plants & fructose; primary sugar of fruits, veggies & honey

• When broken down, products are not sugars• Glucose is the most important sugar

– in humans, most forms of carbohydrates converted to glucose in digestive tract then circulates in our blood; called “blood sugar”

Fate of glucose (blood sugar)• Energy for cellular activity

– energy is released when bonds b/w atoms of glucose molecule are broken

• Short term storage– stored in muscle & liver tissue

as glycogen (a polysaccharide made up of lots of glucose molecules bound together)

– when energy needed, glycogen easily broken down into glucose molecules again

• Long term storage– converted to fat

Polysaccharides• Polysaccharides = complex carbohydrates• Contain more than one sugar unit

– can be as many as 10,000 sugar molecules linked together

• Two functions– storage

• glycogen in animals• starch in plants

– structural support• cellulose in plants• chitin in insects, crustaceans, & fungi

Polysaccharides

In our diet. . . • Simple sugars (like in fruit or candy) provide

quick & short energy bursts• Complex carbs (like in oatmeal or pasta)

provide slow & steady energy release

Not all carbs are digestible• Structural polysaccharides cannot be digested

– chitin– cellulose

• in huge variety of plant structures• single most prevalent molecule on earth!• passes through our digestive tract as “fiber”• termites have microorganisms in their gut that break

down the cellulose & extract useable energy from it

Types of macromolecules

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Lipids• Diverse group of compounds with one

common trait: they are all hydrophobic• Many more C-H bonds than carbs &

contain significantly more stored energy• Types of lipids

– fat (triglycerides)– sterols– phospholipids– waxes

Fats (triglycerides)

• The fat in most foods we eat– solid at room temp = “fat”– liquid at room temp = “oil”

• 3 fatty acid chains linked to a glycerol molecule

• Main function: energy storage– also protection & insulation

• Two kinds of fat– saturated– unsaturated– (in reality, there is a range)

• Saturated fats– fat molecule with the

maximum # of H atoms– most animal fats– not essential to health

• Unsaturated fats– “missing” H atoms;

results in double bond between C atoms

– causes kinks in the fatty acid chain

• mono-unsaturated has 1 C=C bond

• polyunsaturated has > 1 C=C bond

– most plant fats

Partially hydrogenated vegetable oil• Vegetable oil with

artificially added H atoms to saturate the C atoms

• Why do it?– food has better texture

& longer shelf life• BUT is more likely to

accumulate in our bodies

• Creates trans-fats– difficult for body to

break down & accumulate in blood vessels

Sterols• Lipids made of 4 fused

carbon rings• Function is not energy

storage, but to help regulate growth & development– cholesterol

• essential component in most cell membranes

– steroid hormones• estrogen & testosterone• regulate sexual development,

maturation, & sperm & egg production

Steroids can increase muscularity, but with serious health consequences; extreme aggression, high cholesterol, cancer

Phospholipids• 1 glycerol, 2 fatty

acids, and a phosphate group

• Hydrophilic end and hydrophobic end on same molecule

• Major component of cell membranes; controls the flow of chemicals into & out of cell

Waxes

• Resemble fats but only one fatty acid chain

• natural coating on surface of many plants & many insects to prevent water loss

• on many birds’ feathers to prevent becoming water-logged when wet

Types of macromolecules

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Proteins• Chief building blocks of all life• 1000s of different proteins

– enzymes (speed up chemical reactions)– structural (connective tissue, hair, feathers, webs)– contractile (muscle)– defensive (antibodies)– signal (hormones)– receptor (in cell membrane)– transport (delivers O2 to muscles)– storage (ovalbumin (egg white))

• Can be used to fuel living processes• All proteins are made of amino acids

Amino acids• The building blocks of

proteins• Unique combinations

of amino acids result in proteins with unique structure & function

• Made of a central C atom with a carboxyl group, amino group & a side chain– the side chain

determines the characteristics of each amino acid

= side chain

Expanded amino acid structures

Making proteins

• Proteins formed by linking individual amino acids together with a peptide bond– amino group of one amino acid binds to the

carboxyl group of another– 2 linked amino acids = dipeptide– Several linked together = polypeptide chain

Protein structure and function

• Most enzymes and other proteins are globular in shape (like popcorn)

• Structural proteins typically are fibrous (like string)

• Shape is very specific to job• If proteins lose their shape they cannot

function properly, called denaturation– caused by changes in pH or excessive heat– ex. cooking eggs; heat breaks H-bonds, proteins

unfold & lose shape

Four levels of protein structure

• Primary– the unique sequence of

amino acids

• Secondary– the twists & folds

formed by H-bonding between carboxyl and amine groups the peptide chain

Four levels of protein structure

• Tertiary– the complex folding in the

polypeptide chain resulting from interactions between side chains

• Quaternary– formed when 2 or more

polypeptide chains bind together

Enzymes• Proteins that initiate & speed

up chemical reactions in living organisms

• Can be used over & over – do not get consumed by reaction

• Shape is critical, just like all other proteins– substrate-specific– even slightly altered enzymes

can become non-functioning• non-functioning enzymes are

responsible for a large # of diseases & physiological problems

How enzymes work

• The making of a product

• Enzymes can be used for building orbreaking molecules

Regulation of enzymatic activity

• Competitive inhibitors

• Non-competitive inhibitors

• Feedback inhibition

• Feedback inhibition

Types of macromolecules

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Nucleic acids• Macromolecules that store information• Two types

– DNA & RNA– both play central roles the production of

proteins & determining the inherited traits of individuals

• Made up of nucleotides– a sugar – a phosphate group – a nitrogenous base

Nucleic acids continued• Both DNA & RNA have a

sugar-phosphate backbone– attached to each sugar is

the nitrogenous base• cytosine• guanine• adenine• thymine (DNA only)• uracil (RNA only)

– different sequences of bases makes different proteins

DNA = Deoxyribonucleic acid• Holds genetic information to

build a whole organism (!!!)• 2 strands, each wrapping

around each other, forming a double helix– sugar-phosphate backbone on

the outsides and nitrogenous bases facing inward

• base bind together with hydrogen bonding

– bases pair up with each other in 2 combinations

• A with T • C with G

RNA = ribonucleic acid• The universal translator• Directs protein

production• Differs from DNA

– sugar of backbone has an extra O atom

– single stranded; bases don’t bind with anything else

– uracil instead of thymine (U instead of T)

Macromolecules summary• Carbohydrates: energy & structure

– monosaccharides– polysaccharides

• Lipids: hydrophobic– triglycerides– sterols– phospholipids– waxes

• Proteins: building blocks of life– structure & function intimately related

• Nucleic acids: store information– DNA– RNA