Carbohydrates, Lipids and Monomers

• Organic molecules include carbohydrates and lipids.
• Monosaccharides form carbohydrates.
• Lipids exist as oils at warmer temperatures and fats at cooler temperatures.

Carbohydrates

• Vital organic molecules
• Contain the elements C, H, and O in the ratio Cn H2n On, where 'n' is the number of carbon atoms.
• Monosaccharides are the monomers or building blocks of carbohydrates.
• All monosaccharides are monomers.
• Monosaccharide + monosaccharide = Disaccharide
• Many monosaccharides = Polysaccharides

Lipids

• Lipids' phase change temperature depends on the specific lipids.
• Triglyceride lipids consist of fatty acids and glycerol monomers.
• The function of lipids varies depending on the fatty acids they contain.
• Lipids store energy efficiently.
• Lipids store twice as much chemical energy per gram compared to carbohydrates.

Understanding Carbohydrates and Lipids

• Mono means one, saccharide means sugar.
• A monosaccharide is a one-ring sugar.

Polysaccharides

• Complex carbohydrates include chitin, which forms the exoskeleton of arthropod insects.
• Cellulose forms the cell wall of plant cells.
• Starch, such as in chapati, breaks down into monosaccharides during digestion.
• Intestinal cells absorb the simpler forms of carbohydrates.
• Disaccharides can also be absorbed in the intestine.

Compounds Containing Carbon

• Living organisms' molecules consist of four groups: carbohydrates, lipids, proteins, and nucleic acids.
• Carbon forms covalent bonds with hydrogen in the form Cn H2n On.

Carbon Bonds

• Single covalent bonds do not allow atoms to be too far apart or too close together.
• Covalent bonds formed by carbon result in a tetrahedral shape that zigzag.
• Carbon atoms form rings, such as single rings like thymine or double rings like adenine.
• Cholesterol molecules have four rings.

Functional Groups

• Category Sub-category Example Molecule
• Carbohydrates Monosaccharides Glucose, galactose, fructose, ribose
• Carbohydrates Disaccharides Maltose, lactose, sucrose
• Carbohydrates Polysaccharides Starch, glycogen, cellulose, chitin
• Lipids Triglyceride Fat stored in adipose cells
• Lipids Phospholipid Lipids forming bilayer in cell membranes
• Lipids Steroids Some hormones
• Proteins Nucleotides Enzymes, peptide hormones, antibodies
• Nucleic acids Nucleotides Deoxyribonucleic Acid (DNA), Ribonucleic Acid (RNA) and Adenosine Triphosphate (ATP)
• Glucose, a monosaccharide, is used to make disaccharides, glycogen, and polysaccharides like starch and cellulose.
• Glucose molecules are linked with glycosidic bonds.
• In unbranched chains, glucose molecules are linked from C1 to C4.
• In branched chains, glucose molecules are linked from C1 to C6.
• This chain forms a side branch where more molecules can be added from C1 to C4.

Production of Macromolecules

• Macromolecules are produced by condensation reactions that link monomers to form a polymer.
• Two molecules join together to release a smaller molecule, always water.
• Polysaccharides, polypeptides, and nucleic acids are made of monomers joined together in a chain.
• Condensation reactions link a hydroxyl group from one molecule and a hydrogen from the other molecule.
• Condensation reactions bond two molecules.

Condensation and Hydrolysis

• Hydrolysis breaks down macromolecules into monomers.
• Food is in the form of macromolecules.
• Hydrolysis is a chemical reaction that breaks macromolecules down into monomers.
• It breaks the covalent bond between the monomers.

Condensation Chemical Process

• Condensation is a chemical process that links a monomer to the end of a chain of polymer.
• Monomers become a suitable size to be absorbed into the bloodstream and then circulated to body cells.
• Body cells form covalent bonds during condensation reactions.
• Monomers combine to form macromolecules again.

Reversal of Each Other

• Condensation forms water as part of the reaction.
• Hydrolysis splits water and adds it to the two new smaller molecules formed.
• Both condensation and hydrolysis require specific enzymes.

Examples of Condensation Reactions

• During the formation of disaccharides, glucose and galactose combine to form lactose and water.
• During the formation of polysaccharides, many glucose molecules combine to form starch and water.
• During the formation of polypeptides, many amino acids combine to form proteins and water.
• During the formation of RNA/DNA, a phosphate group, a nitrogenous base, and a pentose sugar combine to form a nucleotide and 2 water molecules.

Peptide Bond

• At the location where H and OH become H2O, there are still electrons left so a covalent bond called a peptide bond is formed- this happens between amino acids.
• The reaction is catalysed by an enzyme.
• Digestion breaks polymers into monomers via chemical digestion in the alimentary canal.
• Hydrolyzing enzymes, which require water, accomplish this.
• Water is split and added to the two molecules formed during digestion
• For example, disaccharides are broken down to monosaccharides: Lactose + water becomes glucose + galactose.

Hydrolysis Reactions

• Example equation: Lactose + water produces glucose + galactose.
• Starch + (many) water produces glucose (many).
• Proteins + (many) water produces amino acids (many).

Monosaccharides

• Monosaccharides have between 3 and 7 carbon atoms.
• Ribose, a pentose monosaccharide, has 5 carbons.
• Glucose, a hexose monosaccharide, has 6 carbons.
• The entire formula of a molecule can be determined based on the number of carbons it contains.
• This is applicable only for monosaccharides, not disaccharides, polysaccharides, or modified monosaccharides like deoxyribose.

Properties and Use of Glucose

• Glucose is produced during photosynthesis and is used for energy storage and structural purposes (cellulose)
• It is polar due to the covalent bond between oxygen and hydrogen atoms.
• The five hydroxyl groups in the glucose molecule make it polar
• Because of all this glucose is easily dissolved in water
• Used during respiration
• Glucose has molecular stability due to the strong covalent bonds that hold it together.
• It yields a great deal of chemical energy when its covalent bonds are broken during the oxidation reaction
• Transporters easily move around glucose

Polysaccharides and Energy Storage

• Glucose in polymer form is used for energy storage.
• Plants store glucose in the form of starch.
• Starch is a polysaccharide containing hundreds of glucose monomers.
• Starch and glycogen, polysaccharide and disaccharide are both composed of large numbers of alpha glucose molecules.
• Both are substrates in aerobic and anaerobic respiration.
• To make starch more compact, alpha 1-4 and alpha 1-6 linkages are used.
• Amylose has carbon #1 bonded to carbon #4 of an adjoining glucose, resulting in an unbranched and linear helix-shaped molecule
• Amylopectin consists of carbon 1 to carbon 6 which is branched.

Glycogen

• Glycogen is a polysaccharide made of many glucose molecules.
• It has a similar pattern of linkage as in amylopectin 1-6 linkage.
• Many animals and humans store glycogen in muscle and liver for energy.
• It keeps the osmotic balance in living tissues- which glucose alone cannot do
• Glygogen molecules are more branched
• Glycogen → 1 in 10 molecules have a 1→ 6 bond
• Amylopectin → 1 in 20 molecules have a 1→6 bond Starch Starch is a very large molecule so it cannot be easily dissolved in water Starch is compact so during photosynthesis plants can add starch to amylose or amylopectin through condensation reactions When the plant needs to use the starch, it will break it down through hydrolysis reactions 1→4 Glycosidic bond is broken Easier to break down amylopectin compared to amylose because the 1→ 6 branched structure allows more openings to the chain from which a glucose molecule can be withdrawn through hydrolysis

Cellulose

• Cellulose uses the beta version
• Cellulose is an important component of plant cell walls which is thought to be the most abundant of organic molecules on Earth
• The 1-4 linkage forms a linear polymer with no branches
• It uses beta-glucose
• Alpha and amylopectin have starch

Linking Glucose

• In cellulose linkage 1-4 is there between beta-glucose molecules
• In amylose 1-4 linkage is between alpha glucose molecules
• For condensation reaction to occur during 1-4 bond, every second beta-glucose molecule needs to be oriented upside down for the 1st carbon to be connected to the 4th carbon
• Orinets hydroxyl group of carbon #1 with the hydroxyl group of carbon #4

Cellulose

• Long fibres run parallel, forming multitude of hydrogen bonds, which cross-link, creating a very stable molecule
• Strong
• Not soluble in water
• Allows water to easily pass in and out
• It used as structural molecule in nature and not to store energy
• Few organisms produce cellulase, which is the enzyme needed to digest cellulose -plant eating organisms because the cell wall of plants have cellulose

Conjugated Carbon Molecules

• Studied carbohydrates, lipids, proteins and nucleic acids acids separately
• Sometimes they bond together to perform specific functions
• Studied carbohydrates, lipids, proteins and nucleic acids acids separately
• Lipid + protein = lipoprotein
• Carbohydrate + lipid = glycolipid
• Carbohydrate + protein = glycoprotein

Glycoproteins and Cell-Cell Recognition

• Function of membrane proteins is to recognise body cells vs non body cells for immune system function, and to control molecules going in and out of membrane

Glycoprotein and ABO Blood Type

• Glycoprotein on surface of blood cell can determine person's blood type
• Red blood cells have two types of glycoprotein - A and B (antigens) on their plasma membranes

Lipid Solubility

• Dissolve well in non-polar solvents like fats, oils, waxes, steroids
• Areas that contain hydrogen and carbon only
• So they cannot dissolve in water but can dissolve in nonpolar solvents
• Lipids contain many areas of hydrocarbons
• Organisms have evolved to take advantage of lipid insolubility They have come up with unique solutions to lipid's solubility

Triglycerides and Phospholipids

• Triglycerides consist of 1 glycerol + 3 fatty acids which forms 1 triglyceride + 3 water
• Phospholipids consist of 1 glycerol + 2 fatty acids + 1 inorganic phosphate which forms 1 phospholipid + 3 water
• Each fatty acid contains a terminal carboxyl group that is involved in the condensation reaction
• Fatty acids vary and depend on number of carbons and presence of double bonds between one or more carbons
• Glycerol is a three carbon molecule
• Each carbon bonds to one hydroxyl group initially

Saturated Fatty Acids

• Saturated fatty acids: Single bond between carbons and has high melting point
• All carbons bonded to hydrogen except carboxyl group
• Solid at room temperature
• Triglycerides with only saturated fatty acids are called fats and are used by animals to store energy

Monounsaturated

• Monounsaturated fatty acids: One double bond found between two carbons in hydrocarbon chain of molecule
• Lower melting point than saturated fatty acid & liquid at room temperature and location of double bond can vary
• Used by animals and also many plants to store energy

Polyunsaturated

• Polyunsaturated fatty acids: One or more double bonds in hydrocarbon chain of molecule and has a relatively also lower melting point
• The number of double bonds and location can vary
• Many plants store energy in this form
• Liquid at room temperature
• Cis - H on same side, Trans - H on opposite sides

Adipose Tissues

• Adipose tissues contain triglycerides that are formed by condensation reactions, used for long term storage, and provide more energy than carbohydrates

Phospholipids and Hormones

• Phospholipids have a polar and non-polar end.
• Phospholipids: molecule, has a polar end (phosphate group) and an even longer non-polar end (two hydrocarbon tails) and it solves the problem of having hydrophobic tails by forming a bilayer
• Phospholipid's Bilayer contain a phosphate groups which is attracted to the aqueous solution and so arrange themselves on the outside of the bilayer
• The tails extend towards each other to be away from the aqueous solution inside and outside the cell

Steroid Hormones

• Tissue that responds to any one hormone = target tissue of that hormone which are lipid-based molecules but are hydrophobic and soluble in lipid-based bilayer of cells
• Steroid hormones are chemical messenger molecules that are released to all body tissues
• Enter plasma membrane and nuclear membrane of their target tissue cell and retain hydrocarbon makeup
• Enter nucleus and hormones direct process of transcription in nucleus, which creates mRNA molecules

Explore the molecular composition of Carbohydrates, Lipids and Monomers. Understand carbohydrate formulas, building blocks, and condensation reactions. Learn about energy storage in lipids and the formation of bonds in polypeptides.