GRADE 12 BIOLOGY (SBI4U)MACROMOLECULES

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Macromolecules:What you need to know!1. Structure of the basic unit (carbohydrates, lipids,

proteins, nucleic acids)

2. How they react to form larger molecules

3. How the larger molecules are broken down into basic units

4. Functions of the molecules in living organisms

What is a …

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Polyester

Polygamy

Polygons

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Greek poly =

many, mer =

parts

Polymers

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• long molecules • have many similar or identical repeating

building blocks (structural units, monomers, small molecules)

• connected by chemical bonds (covalent bonds)

Monomers

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• The smallest repeating unit of a polymer• Can exist individually

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• Organic molecules constructed of smaller units called polymers – these polymers are subdivided into their basic units called monomers

Macromolecules

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+

+

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• a macromolecule is also called

… biological macromolecule… biomolecule… organic molecule… large carbon-carbon molecule

to name a few…

Macromolecules

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• fall into 4 major categories – can you name them?

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Macromolecules

Hint: 3 of the 4 can be found in foods!

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Macromolecules:4 major categories

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Macromolecules:Question: Which one isn’t

considered a polymer and why?

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• Start with water, add lots of small carbon-containing

molecules and …….

• Macromolecules are the molecules of life!

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Macromolecules:Why do we care?

• How do you build a cell?

use these four major classes of macromolecules

Macromolecules

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• All living things are made of cells • Cells are:

~72% H2O ~3% salts (Na, Cl, K…)~25% carbon compounds (macromolecules)

Macromolecules

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Ions, small molecules (4%)Lipids (2%)Nucleic Acids (DNAand RNA (1% + 6%)

Proteins (15%)

Carbohydrates (2%)

Making and Breaking of Polymers

MAKE BREAKor

“Condensation” or “Dehydration” Synthesis (aka polymerization)

why synthesis? – a polymer grows in length (a new bond is made)

why dehydration (or condensation) – formation of a water molecule

MAKE

“Addition” polymerization

monomer molecules added to a growing polymer chain

NO molecules are eliminated in the process

monomer is unsaturated (e.g., had a double bond)

after an addition reaction it becomes saturated

MAKECan we add a monomer to a polymerwithout losing a water molecule?

Hydrolysis (Cleavage)

hydrolysis (hydro = water, lysis = break) – reverses the process of dehydration by breaking down the polymer with the addition of water molecules

BREAK

Carbohydrates (sugar/starch)• Monosaccharide (b/w 3-7 carbon atoms)

- Contain multiple hydroxyl groups and a carbonyl group

– the simplest sugars glucose

fructose, galactose

ribose deoxyribose

- Contains C, H, O in ratio of 1:2:1

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IsomersIsomers – one of two or more molecules with the same number and type of atoms, but different structural arrangements

e.g. glucose, fructose, galactose

- Also differ in chemical and physical properties

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Carbohydrates• Disaccharides – 2 simple sugars (sucrose, lactose = glucose + galactose, maltose = glucose + glucose)- Bond linking monosaccarides together = glycosidic linkage

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Carbohydrates

• Polysaccharides (‘complex’)

– many sugars (e.g. starch, cellulose, glycogen, chitin)– energy storage– structural materials

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glycogen

cellulose

Note the linking of simple repeating units25

Carbohydrates (polysaccharides)

Carbohydrates (polysaccharides)

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Lipids• hydrocarbons• comprised of fatty acids• hydrophobic• reservoirs of energy• structural materials

– cell membrane• 4 forms of lipids

– neutral fats, phospholipids, sterols, waxes

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fatty acids

Lipids – Neutral fats• neutral fats

– three fatty acids and a glycerol– body’s most abundant lipid

• functions– energy reservoir– insulation

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Fats

glycerol + 3 fatty acid fat (triglyceride)

Ester linkage

Fats

Animal vs. Plant Fats

Animal Fats Plant Fats

- Triglycerols containing mostly saturated fatty acids

-triglycerols are unsaturated and polyunsaturated FA

- Straight hydrocarbon chains allowing for van der Waal attractions

-Hydrocarbon chains have double bonds and many kinks, ↓ van der Waal attractions

- Solid at room temperature - Liquid at room temperature

Fatty Acids

saturated fat unsaturated fattrans-unsaturated

fat

• Can be used for insulation

adipose tissue

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Lipids – Neutral fats

Lipids - Phospholipids• form double-layered cell membranes

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Phospholipids

Glycerol backbone + 2 fatty acids + phosphate phospholipid

Phospholipids

Phospholipids have:1. a hydrophobic head2. a hydrophobic tail

Due to the dual chemical nature of the molecule, it is said to be amphipathic.

Phospholipids

Phospholipids

Phospholipid Bilayer

Sterols also known as steroids

ProteinsProteins are used for:

structure metabolism (enzymes) immunological protection molecular transport

Proteins are made of subunits of amino acids.

Proteins are the most diverse class of macromolecules due to 20 available amino acids.

Amino Acids

Amino Acids in Aqueous Solutions

• Amino acids contain a basic amine group, which can act as a proton acceptor, and an acidic carboxylic acid group, which can act as a proton donor

Amino Acids

Essential vs. Non-essential Amino AcidsEssential Amino Acids: Cannot be produced by the body,

therefore must be consumed in ones diet 8 essential Amino Acids

Non-essential Amino Acids: Can be produced by the body 13 Non-essential Amino Acids

Peptides

amide bond

Protein Organization

Four layers of protein organization:1. primary (1°) structure2. secondary (2°) structure3. tertiary (3°) structure4. quaternary (4°) structure

Primary (1°) Structure sequence of amino acids polypeptide chain

Second (2°) Structure

H-bond between peptide bonds

1. a-helix

2. b-pleated sheets

not necessarily in all proteins

Second (2°) Structure

Tertiary (3°) Structure provides protein a final 3-D structure four major bond types between R groups of

amino acids

1. H-bonding2. ionic bonding3. hydrophobic interactions4. covalent bond (disulfide bridge)

Tertiary (3°) Structure

General Protein Shapes

Globular Proteins (Hemoglobin) Fibrous Proteins

(Tropomyosin & Keratin)

Quaternary (4°) Structure

fully functional protein requires all subunits present

not all proteins have quaternary structure

Protein PropertiesProteins have optimal conditions at which they

function.When exposed to extreme conditions, proteins

begin to unfold – denature.If denaturation occurs moderately over time,

returning to the original conditions may result in renaturation.

Protein Folding

Proper folding in the cell is completed by chaperonin molecules.

Utilizes ATP to help proteins fold properly.

Nucleic AcidsNucleic acids are used for:

maintaining genetic continuity delivering information for protein synthesis energy molecule (ATP – adenosine triphosphate)

Two major nucleic acid polymers:1. DNA – deoxyribonucleic acid2. RNA – ribonucleic acid

Nucleic Acids

DNA RNA

located in the nucleus

double-stranded, double helix structure

stable molecule

mainly found in cytoplasm

single-stranded structure

unstable molecule

NucleotidesThe basic subunit of nucleic acids is a

nucleotide.

Three components:1. phosphate2. pentose sugar3. nitrogenous base

Pentose Sugar

Nitrogenous Bases

purines

pyrimidines

Nucleic Acid

reaction between 1. pentose sugar OH

group of one nucleotide

2. phosphate group of another nucleotide

forms phosphodiester bond

In Conclusion

The building blocks (monomers) of macromolecules are amino acids, nucleotides, simple sugars, and fatty acids

In Conclusion

• Name the two main chemical reactions shown making and breaking organic molecules

In Conclusion

Carbohydrates are use for energy storage and as structural materials

Lipids are used as energy storage and structural components

Proteins are made of amino acids which form structures, enzymes, transport, movement, and are part of the immune system

Nucleic acids are the basis of inheritance and reproduction

In Conclusion

The versatility of carbon makes possible the great diversity of organic molecules

Variation at the molecular level lies at the foundation of all biological diversity

Macromolecule Example(s) of subunits

Main functions Examples of macromolecules

carbohydrates sugars (such as glucose) and polymers of glucose

energy storage sugars, starches, and glycogen

lipids glycerol and three fatty acids or glycerol and two fatty acids

energy storage and cell membranes

fats, oils, and phospholipids

proteins polymers of amino acids transport, blood clotting, support, immunity, catalysis, and muscle action

hemoglobin, fibrin, collagen, antibodies, enzymes, actin, and myosin

nucleic acids polymers of nucleotides transfer and expression of genetic information

DNA and RNA

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Answers to post-presentation activity #1 – the activity could be use alone as a pre-assessment (what should be known from Grade 11 SBI3U)

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Day 2

• In building large macromolecules carbon usually combines with other carbons

… AND with one or more functional groups

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Why study Functional Groups?• These are the building blocks for organic

molecules (or macromolecules – large organic molecules)

the components of organic molecules most commonly involved in chemical reactions

the number and arrangement of functional groups give each organic molecule unique properties

Why study Functional Groups?

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Types of functional groups

• 6 functional groups most important to chemistry of life:

hydroxyl amino carbonyl sulfhydryl carboxyl phosphate

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Functional groups

• they affect reactivity (e.g., hydrophilic, increase solubility in water)

Hydroxyl

organic compounds with OH = alcohols alcohols, carbohydrates, nucleic acids,

some acids, and steroids highly polar (makes molecules more soluble) e.g., ethanol

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Carbonyl if C=O at end molecule = aldelhyde if C=O in middle of molecule = ketone react with molecules (H-R2) to form H-

R2-C-OH a ketone and an aldehyde may be

structural isomers with different properties, e.g., acetone and propanal

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Carboxyl

compounds with COOH = acids fatty acids, amino acids acidic – tends to lose a proton (COO-) involved in peptide bonds e.g., acetic acid - gives vinegar its sour

taste

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Amino compounds with NH2 = amines amino acids, nucleic acids NH2 acts as base - can pick up a proton

(H+) from the surrounding solution (ionized)

glycine (has amine and carboxyl groups) – replace an H with an R group to get an amino acid

under cellular conditions

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Sulfhydryl

compounds with SH = thiols 2 sulfhydryl groups can interact to help

stabilize protein structure (S-S, disulfide bonds)

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Phosphate • compounds called organic phosphates• Acidic – up to 2 negative charges when H+

dissociates• Links nucleotides in nucleic acids• Energy-carrier group in ATP

Review

Review

Review

2003-200483

Do the functional groups make that much

difference? identical basic structure of male & female hormones

attachment of different functional groups interact with different targets in the body

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A Bit of Honey: Bee keeping was used in Crete over 4000 years ago to allow for the collection of honey, a highly prized food having great value in ancient civilizations Field bees gather the

nectar, a sweet secretion in plant blossoms that contains fructose, glucose and sucrose

Some worker bees secrete beeswax - Hexacosanoic acid, C26H52O2, and triacontanol, C30H62O