Macromolecules Goal

• Know the structure and function of all 4 macromolecules

Macromolecules : The Molecules of Life

• Within cells, small organic molecules called monomers are joined together to form larger molecules, known as Macromolecules.

• Each cell has thousands of different kinds of macromolecules.

• Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species.

Function: What do macromolecules do?

• Carbohydrates - short term energy storage; structure of some organisms

• Lipids - (also known as fats) - long term energy storage

• Nucleic Acids (DNA and RNA) - the instructions the cell uses to build proteins

• Proteins (Polypeptides): The highly variable macromolecules that make each organism unique

CarbohydratesSugars & Starches

Used for energy in all organisms and for structure in plants.

Sugars• Function: Monosaccharides serve as a major fuel

for cells and as raw material for building molecules • Monosaccharides have molecular formulas that

are usually multiples of CH2O – 1:2:1 ratio

• Glucose is the most common monosaccharide

• Structure: though often drawn as a linear skeleton, in aqueous solutions they form rings

LE 5-4

Linear andring forms

Abbreviated ringstructure

Monosaccharides (simple sugars)= monomer of carbohydrates

• Mono- = one

• Glucose (C6H12O6) = sugar used as an energy source in all cells.

• Other Examples: Fructose (Fruit sugar) & Galactose (Milk sugar)

Disaccharides (sugars) =2 monosaccharides linked together.

• Di- = two

• Examples: Lactose (milk

sugar) & Sucrose• (table sugar)

Storage and Structure Polysaccharides

3 or more monosaccharides linked.

• Poly- = Many • Glycogen = Used as energy

storage in animals.

• Cellulose = Used to form the cell wall of plants.

• Chitin- is found in the exoskeleton of arthropods and the cell walls of many fungi

Storage Polysaccharides• Starch, a storage polysaccharide of plants,

consists entirely of glucose monomers• Plants store surplus starch as granules within

chloroplasts and other plastids

LE 5-6a

Chloroplast Starch

1 µm

Amylose

Starch: a plant polysaccharide

Amylopectin

LE 5-8

Cellulosemolecules

Cellulose microfibrilsin a plant cell wall

Cell walls Microfibril

Plant cells

0.5 µm

b Glucosemonomer

• Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulose

• Cellulose in human food passes through the digestive tract as insoluble fiber

• Some microbes use enzymes to digest cellulose• Many herbivores, from cows to termites, have

symbiotic relationships with these microbes

Lipids (fats)

Used for long-term energy storage.

Steriods

Lipids are a diverse group of hydrophobic molecules

• Lipids are the one class of large biological molecules that do not form polymers

• The unifying feature of lipids is having little or no affinity for water

• Lipids are hydrophobic becausethey consist mostly of hydrocarbons, which form nonpolar covalent bonds

• The most biologically important lipids are fats, sterols and phospholipids.

• When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the interior

• The structure of phospholipids results in a bilayer arrangement found in cell membranes

• Phospholipids are the major component of all cell membranes

LE 5-14

WATERHydrophilichead

Hydrophobictails

WATER

Steroids

• Considered lipids because they are hydrophobic!!

• Consist of 4 fused rings• Cholesterol is a steroid

Nucleic Acids

DNA – your genetic code

RNA – used to make proteins

Nucleotide = monomer of nucleic acids.

• Nucleotide has 3 parts:

- phosphate

- 5-carbon sugar

- nitrogen base.

DNA & RNA = Polymers of nucleic acids

• DNA – di=2 (α-helix) carries the information on how to make proteins. Mostly 2 strands ( 1 found in viruses)

• RNA is directly involved in making proteins.( mostly 1 , two found in viruses )

Proteins

The major building block in living things. Muscles, enzymes, antibodies, cell structure

Proteins have many structures, resulting in a wide range of functions

• Proteins account for more than 50% of the dry mass of most cells

• Protein functions include enzymes*,structural support, storage, transport, cellular communications, movement, and defense against foreign substances

• Different functions=different shapes

Structure of Proteins• Protein = Polypeptide (polymer)

comprised of monomers (amino acids). There are 20 different amino acids.

• Amine Group (NH2)-Basic• Carboxylic Acid Group (COOH) –

Acidic• The center asymmetrical carbon is

called the alpha carbon. • The R group (think random) is variable

for each amino acid! Also called the side chain.

Four Levels of Protein StructurePrimary structure of a protein is its unique sequence of amino acids.

Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain. The sequence of amino acids converts into 1 of 2 forms

» α-helix » β-pleated sheets

1’ and 2’ Levels Protein Structure

Tertiary structure is determined by interactions among various side chains (R groups)

Quaternary structure results when a protein consists of multiple polypeptide chainsNot found in all proteinsSame bonds/interactions as tertiary level

Tertiary & Quaternary Levels

Protein Denaturation

Protein Denaturation

• Denaturation• Protein unravels and loses its native conformation

• Structure & Function• Change in the protein’s structure = loss of function

• Denaturation occurs:– Organic solvent– Any chemical that disrupts the tertiary

structure– Heat (excessive)

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Macromolecule Function Structure

Carbohydrate

Lipid

Nucleic Acids

Proteins

Macromolecules

Sample MC• Which molecule stores the largest amount of

energy?• A. Fat• B. Starch• C. Protein• D. Glycogen

Sample Question A molecule with the chemical formula C16H32O16 is probably a

A) carbohydrate.

B) lipid.

C) protein.

D) nucleic acid.

E) hydrocarbon.

Sample MC

Amino acids are the building blocks of

A. Proteins

B. Lipids

C. Carbohydrates

D. Nucleic Acids

Sample MC

Which polymer carries genetic information?

A. Protein

B. Lipid

C. Carbohydrate

D. Nucleic Acid

• Unlike carbohydrates and fats, proteins contain _____.

• A) nitrogen • B) carbon • C) hydrogen • D) oxygen

Sample MC

• . Which of these elements is NOT part of a carbohydrate molecule?

• A) hydrogen • B) oxygen • C) carbon• D) magnesium

Sample MC