Carbohydrates and Lipids

Carbohydrates

• Vital organic molecules are constructed from monosaccharides as building blocks
• Carbohydrates are larger molecules formed from smaller monomer units
• Cn H2n On is the basic formula, where 'n' represents the number of carbon atoms in the molecule
• Not all monosaccharides are the same so are not always monomers
• Disaccharides form when two monosaccharides combine
• Polysaccharides form when many monosaccharides combine

Lipids

• Lipids that are oils exist as liquids at warmer temperatures
• Lipids that are fats exist as solids at cooler temperatures
• The temperature at which lipids change phase (from solid to liquid or vice versa) varies depending on the specific lipid
• Triglyceride lipids have fatty acids and glycerol as building blocks
• A lipid's function relies on its fatty acid structure
• Lipids and carbohydrates both store energy, however lipids store twice as much chemical energy per gram compared to carbohydrates.

Understanding basic terms

• "Mono" means "one"
• "Saccharide" means "sugar"
• "Monosaccharide" therefore means one ring of sugar

Many monosaccharides

• Polysaccharides are complex carbohydrates
• Complex carbohydrates include chitin, it is part of the exoskeleton of arthropod insects
• Cellulose is another complex carbohydrate, forming the cell wall of plant cells
• Starches found in foods like chapati are complex carbohydrates
• Starches are broken down into monosaccharides during digestion
• Starches are easier for intestinal cells to absorb

Carbon Compounds

• Living organisms have molecules in four main groups: carbohydrates, lipids, proteins, and nucleic acids
• These molecules help cells perform metabolic activities and all contain carbon
• Carbon readily makes covalent bonds with hydrogen and the basic structure is Cn H2n On

Carbon Bonds and Ring

• Atoms cannot be too far apart or too close to each other because of single covalent bonds
• Covalent bonds formed by carbon have a tetrahedral shape, so are never in a straight line but are a zigzag
• Carbon atoms can form rings, these could be single rings like thymine, or double rings like in adenine
• Cholesterol molecules are made of four rings

Functional Groups and Examples

• Carbohydrates are categorised into:
• Monosaccharides include glucose, galactose, fructose, and ribose
• Disaccharides include maltose, lactose, and sucrose
• Polysaccharides include starch, glycogen, cellulose, and chitin
• Lipids:
• Triglycerides are fats stored in adipose cells
• Phospholipids form the bilayer in cell membranes
• Steroids include some hormones
• Proteins consist of enzymes, peptide hormones, and antibodies
• Nucleic acids consist of deoxyribonucleic Acid (DNA), Ribonucleic Acid (RNA) and Adenosine Triphosphate (ATP)

Glucose and Glycosidic Bonds

• Disaccharides glycogen, polysaccharide starch, and cellulose are made out of the monosaccharide glucose
• Glycosidic bonds link glucose molecules together
• Unbranched chains are formed when C1 is linked to C4
• Branches form when C1 is linked to C6, this creates a side branch allowing more molecules to be connected with 1→4 bonds

Macromolecule Production

• Monomers link through condensation reactions to form a polymer
• Smaller molecules are released when two molecules join together
• Polysaccharides, polypeptides, and nucleic acids all form in this way
• The smaller molecule released is always water
• Hydroxyl groups and hydrogen atoms are linked together and form a bond between two molecules to do this

Condensation and Hydrolysis

• Macromolecules are made of monomers
• Hydrolysis occurs when macromolecules are broken down into monomers in a chemical reaction
• The monomers are a result of broken covalent bonds

Molecules and Monomers

• Carbohydrates consist of monosaccharides
• Lipids consist of glycerol, fatty acids, and phosphate groups
• Proteins consist of amino acids
• Nucleic acids consist of nucleotides

Condensation

• Condensation is a chemical process joins a monomer to the polymer chain
• Monomers must be a suitable size to enter the bloodstream where they are circulated to cells of the body

Condensation Reactions

• Covalent bonds form during the body's condensation reactions
• Monomers are built up to macromolecules again
• Condensation reactions are the reverse of hydrolysis

Reversing Reactions

• Condensation reactions produce water as part of the reaction
• Adding water to split larger molecules to form two smaller molecules is hydrolysis
• Both reactions require specific enzymes

Condensation Examples

• Monomers form polymers
• Glucose + galactose forms the disaccharide lactose + water
• Glucose (many) forms the polysaccharide starch + water
• Amino acids (many) forms the polypeptide proteins + water
• Phosphate group + nitrogenous base + pentose sugar forms nucleotide + 2 water

Linking Polymers

• At the location where H and OH become H2O, there are still electrons left so a covalent bond called a peptide bond
• The process occurs between amino acids and is catalysed by an enzyme

Digesting

• Foods are chemically broken down in the alimentary canal.
• Hydrolyzing enzymes do this and require water to add and split two molecules apart
• Lactose reacting with water will form glucose and galactose

Hydrolysis Reactions

• In polysaccharide to monosaccharide reactions, starch plus water gives glucose
• In polypeptide to amino acid reactions, proteins plus water gives amino acids

Monosaccharides

• Monosaccharides consist of between 3 and 7 carbon atoms
• Ribose is a pentose monosaccharide that has 5 carbon atoms
• Glucose is a hexose monosaccharide that has 6 carbon atoms
• Knowing the name allows you to tell the entire formula of the molecule because it tells you the number of carbons
• Glucose is only applicable for monosaccharides, but that is not the case for disaccharides, polysaccharides, or modified monosaccharides like deoxyribose

Glucose

• Glucose can be used for energy storage
• Glucose can be used for structural purposes via cellulose
• Glucose is produced from photosynthesis
• Glucose is used during respiration
• A hydroxyl group (alcohol) is found five times in the molecule
• A polar-charged water molecule is formed with a covalent bond between oxygen and hydrogen

Glucose Properties

• Strong covalent bonds in the glucose molecule make it stable
• It's high solubility means that it can easily dissolve in polar solvent water
• It is easily transportable because it is transported to cells via blood and fluids
• It yields a great deal of chemical energy via an oxidation reaction when bonds are broken and is a good energy store

Polysaccharides

• Glucose can be stored as a polymer
• Plants store it in photosynthesis in the form of starch
• Starch as polysaccharide and glycogen as disaccharide
• Both are composed of large numbers of alpha glucose molecules and are a substrate in aerobic and anaerobic respiration

Starch

• To make starch as compact as possible, alpha 1-4 linkage, and alpha 1-6 linkage are both used
• Amylose is a type of starch with carbon #1 bonded to carbon #4 of adjoining glucose, is unbranched, and many result in its helix linear-shaped molecule
• Amylopectin is a type of scratch with carbon 1 to carbon 6 making it branched, it results in many branched connections

Starch Breakdown

• Because starch is very large the plant will add to it via amylose or amylopectin through condensation when compact
• When the plant uses starch, it is broken down with hydrolysis reactions and the 1→4 Glycosidic bond is broken
• Amylopectin is easier to break down because glucose is more readily able to be withdrawn through hydrolysis, amylopectin is more branched with 1→ 6 branched structure structure
• Glycogen has a 1→ 6 bond for every 10 molecules
• Amylopectin has a 1→6 bond for every 20 molecules
• Glycogen molecules are more branched

Glycogen

• Glycogen is a polysaccharide made of many glucoses, and it is similar to amylopectin in a 1-6 linkage
• Animals and humans store glycogen in muslces and the liver for energy
• Glycogen keeps an osmotic balance which glucose alone cannot do because it is not easily solute in cytoplasm and fluids

Structural Polysaccharide

• Starch and glycogen alpha-glucose
• Cellulose uses beta-glucose

Beta Glucose

• Amylose and amylopectin are two types of starch which form Beta-glucose
• Cellulose is an important component of plant cell walls, beta-glucose is thought to be the most abundant of organic molecules on Earth
• There is a 1-4 linkage in cellulose between beta-glucose molecules
• There is a 1-4 linkage in amylose 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
• The hydroxyl group of carbon #1 orients with the hydroxyl group of carbon #4
• The resulting 1-4 linkage forms a linear polymer with no branches

Long Fibres

• Long fibres run in parallel
• They form a multitude of hydrogen bonds with adjoining figures, a cross-linking attraction of hydrogen bonds
• The structure results in bundles of fibres that are held together, creating a very stable molecule of cellulose

Cellulose Function

• Cellulose is a structural molecule in nature
• It is strong and not soluble in water but allows water to pass in and out
• It is not used to store energy
• Organisms that eat plants produce cellulase, which is the enzyme needed to digest cellulose

Carbon Molecules

• Scientists often study carbohydrates, lipids, proteins, and nucleic acids separately, but they sometimes bond together for specific functions
• When lipids bond with protein, this creates lipoprotein
• When carbohydrates and lipids bond, this creates glycolipid
• When carbohydrates and proteins bond, this creates glycoprotein

Glycoproteins

• Glycoproteins offer cell recognition and a function of membrane proteins
• Function include the ability to:
• Recognise body cells versus non-body cells for immune system function
• Control molecules entering and exiting a membrane
• Initiate cell-cell chemical communication
• Catalyze a reaction from enzyme
• Cell to cell adhesion

Blood Type

• Glycoprotein on the surface of blood cells can determine a person's blood type
• Red blood cells have 2 kinds of glycoprotein called A and B (antigens) on cell plasma membranes
• If one of the glycoproteins is not present then it is detected, triggering an immune response, but the absence of each when both are present there will be no triggered response
• White blood cells help determine self cells from non self cells
• People with type O blood trigger an immune response when the proteins A or B are present, they are universal donors
• Blood Type AB are universal Recipients

Lipid Solubility

• Lipids dissolve in non-polar solvents like fats, oils, waxes, and steroids
• Lipids areas which contain hydrogen and carbon
• Hydrogen and carbon create a nonpolar covalent bond
• As a result hydrophobic they don't dissolve in water, they are attracted to non-polar substances
• Over time organisms evolved to take advantage of lipid insolubility, they came up with solutions to lipid solubility such as conjugating lipids with another molecule, glycolipids and lipoproteins

Triglycerides and Phospholipids

• Triglycerides consist of 1 glycerol + 3 fatty acids that combines to form 1 triglyceride + 3 water
• Phospholipids consist of 1 glycerol + 2 fatty acids + 1 inorganic phosphate, that combines to form 1 phospholipid + 3 water
• Glycerol is a three carbon molecule that begins with each carbon bonded to one hydroxyl group initially

Fatty Acids

• Fatty acids each have a number of carbons and a number of double bonds
• Each fatty acid has a terminal carboxyl group in the condensation reaction

Phospholipid and Triglyceride Formation

• The OH group of the glycerol molecule lines up with the OH group of a general fatty acid carboxyl group
• A condensation reaction is triggered and one molecule of water is released
• The fatty acids form a covalent bond with the glycerol
• Then a phosphate group lines up with the OH group of the glycerol molecule
• This triggers a condensation reaction to release a water molecule and a final covalent bond forms
• The product is a phospholipid of one glycerol molecule, two fatty acids, and one phosphate

Saturated Fatty Acids

• Features single bonds between carbons
• All carbons bonded to hydrogen except the carboxyl group
• Have a high melting point and are solid at room temperature
• Triglycerides made only saturated fatty acids are called fats
• Used by animals for energy storage

Unsaturated Fatty Acids

• Monounsaturated fatty acids are single double bond of the hydrocarbon chain with a variable location
• They have a lower melting point than saturated fatty acids are liquid at room temperature
• Used by animals and plants to store energy
• Polyunsaturated fatty acids have one or more double bonds in hydrocarbon chain of molecule. Number of double bonds and location can vary
• They also have a relatively low melting point and are liquid at room temperature so many plants store energy in this form
• Cis - H is on the same side
• Trans - H is on opposite sides

Adipose Tissues

• Adipose tissues store fats in the form of triglycerides formed by condensation reactions
• The reactions often happen when the organism has taken in more foods than they are using
• Hydrolysis with products -- glycogen and fatty acids -- makes triglycerides available to the organism for energy and respiration
• Quantity is dependent of if it is more organism calorie intake being more than organism calorie expenditure
• Useful for long term storage- insoluble when in fluid two adipose storage sites where energy is supplied in metabolic processes
• They provide twice as much energy as compared to carbohydrates

Blubber

• Some animals like those in colder regions have adapted a thick layer of adipose tissue in form of blubber
• Birds and mammals are endotherms, they have a steady internal environment
• Located between the animals skin and muscle, blubber maintains heat from metabolic activities.
• Animals like sea lions have issues when breeding because the air is warmer than the water so the thick layer of blubber causes overheating

Phospholipids

• Phosphate groups affect the polarity of the molecule
• Water and glucose consist of smaller polar molecules
• Phospholipids are large has a polar end (phosphate group) and non-polar end (two hydrocarbon tails)
• It is both since it contains both polar and nonpolar ends means it is amphipathic

Bilayer

• Phospholipids solve the problem of tails which are hydrophobic by forming a bilayer
• The tails extend inward to avoid contact with aqueous solution that are inside and cell
• The phosphate groups attract to aqueous solution of the cell by arranging themselves on outside the bilayer

Steroid Hormones

• Hormones are chemical messenger molecules that all the body tissues releases
• Target tissue is a tissue in respond only with one hormone made of lipid cholesterol like steroids
• Hydrocarbon molecules that are fundamental of its structure easy to identify
• Those from gonadal tissue are Oestradiol and testosterone
• Those from primary and secondary sex characteristics during puberty are:
• Lipid based molecules but hydrophobic
• Soluble in lipid-based bilayer of cells
• Enter plasma membrane and nuclear membrane of their target tissue cell
• Enter nucleus and hormones direct process of transcription in nucleus
• mRNA molecules produced