Please enable JavaScript.

Coggle requires JavaScript to display documents.

Chapter 3: Nutrients/Biomolecules - Coggle Diagram

- - - - Monosaccharides
        
        Single sugars (mono = 1)
        
        Glucose
        
        Fructose
        
        Galactose
        
        C6H12O6
        
        Deoxyribose
        
        Ribose
      - Disaccharides
        
        Double sugars (di = 2)
        
        C12H22O11
        
        Maltose
        
        (reducing sugar) Maltose --> (maltase) glucose + glucose
        
        Lactose
        
        (reducing sugar) Lactose --> (lactase) glucose + galactose
        
        Sucrose
        
        (non-reducing sugar) Sucrose --> (sucrase) glucose + fructose
        
        Formed when a dehydration reaction joins 2 monosaccharides, with glycosidic bonds
      - Polysaccharides
        
        Poly = many
        
        Polymers of sugars with storage and structural roles, linked by glycosidic bonds
        
        Types
        
        Starch
        
        Long straight chains of glucose molecules
        
        Few side branches
        
        Energy storage for plant cells
        
        Enzyme hydrolysis
        
        Starch firstly broken down by amylase
        
        Amylase enzymes break down the bonds, releasing maltose
        
        Maltose molecules cannot be broken down by amylase
        
        Maltose molecules are broken down by maltase
        
        Further bond-breaking by maltase releases glucose
        
        Glycogen
        
        Highly branched polymer of glucose molecules
        
        Storage carbohydrate of animals
        
        In liver and muscles
        
        Cellulose
        
        Straight chain of glucose molecules
        
        Structural carbohydrate in plant cell walls
        
        Chitin
        
        Polymer of glucose with amino acids attached to it
        
        Primary constituent of exoskeleton
      - Functions
        
        Energy
        
        Cellulose cell walls in plant cells
        
        Converted to amino acids and fats/lipids
        
        Nucleic acid (DNA, RNA)
        
        Lubricants like mucus
        
        Nectar in flowers
    - - Consists of 1 glycerol and 3 fatty acids
        
        Glycerol is a 3-carbon alcohol with a hydroxyl group (OH) attached to each carbon
        
        Fatty acid consists of a carboxyl group (COOH) attached to a long carbon skeleton
        
        Products of fat hydrolysis with a lipase enzyme/catalyst
      - Diverse of hydrophobic molecules
      - Consists of hydrocarbons, forming non-polar covalent bonds
      - Do not form polymers
      - Phospholipids, steroids
      - Saturated VS Unsaturated
        
        Saturated
        
        Fatty acid chains are straight
        
        Most are solid at room temperature (butter)
        
        Each carbon atom is maximumly bonded to the hydrogen atoms
        
        Unsaturated fats
        
        Fatty acid chains have kinks
        
        Liquids at room temperature (olive oil)
        
        Each carbon atom is not maximumly bonded to the hydrogen atoms
      - Cis VS Trans
        
        Cis fats
        
        Mostly bends towards one side
        
        Trans fats
        
        Bends towards many sides
      - Functions
        
        Source/stored form of energy
        
        Insulation, to prevent heat loss (whales)
        
        Absorption and transport, like fat-soluble vitamins
        
        Part of all cell membranes
        
        Reduces water loss from skin surfaces (oils from glands in skin)
        
        Cushions and protects organs
        
        Forms hormones
        
        Satiety/fullness, flavour to foods
        
        Most suitable for long-term energy storage in humans
    - - Amino acids
        
        20 different types
        
        Building blocks for protein molecules in polypeptides synthesized on ribosomes
        
        Each amino acid contains an amine group (H2N), a carboxyl group (COOH) and a functional, variable R group of hydrogen and oxygen
        
        Differences in the R group make each amino acid chemically unique
        
        Proteins are polymers (polypeptides) of amino acids held together by peptide bonds, with the amine end (H2N) of 1 amino acid linked to the carboxyl (COOH) end of the other
        
        The order of the sequence of the amino acids determine the function of the protein
        
        DNA (sequence) --> mRNA --> polypeptides (ribosomes) --> proteins --> physical traits
      - Formation
        
        Amino acids are the building blocks of proteins
        
        The amino acids can be linked together in any sequence, resulting in a huge range of possible polypeptides
        
        A protein may contain of a single polypeptide or more than 1 polypeptide linked together like hemoglobin
        
        Amino acids link up to form polypeptides or peptones
        
        The bond formed between 2 amino acids is strong and is a peptide bond, formed in a condensation reaction
        
        Polypeptides in turn may be linked up to form an even longer chain of amino acids
        
        Coils are held together in place by weak bonds
        
        A protein molecule is made up of 1 or more long chains of amino acids folded together, which are coiled or folded together to give the protein a three-dimensional shape (3D)
      - Structural Levels of Proteins
        
        Primary
        
        Linear sequence of amino acids composing the polypeptide chain, a strand of amino acid "beads"
        
        Secondary
        
        Alpha-helix or beta-pleated sheets
        
        Stabilised by hydrogen bonds
        
        Weak hydrogen bonds easily disrupted by heat and pH changes (acids, alkali or presence of H/OH ions)
        
        Tertiary
        
        Superimposed folding of secondary structures producing a ball-like or globular structure
        
        Quarternary
        
        Polypeptide chains linked together in a specific manner (hemoglobin molecules with heme groups in them)
      - Denaturation
        
        Weak hydrogen bonds easily broken down by heat and chemicals like acids and alkalis
        
        When these bonds are broken, the protein loses its three-dimensional shape
        
        Denatured proteins involves a loss of function of the protein
        
        A protein is denatured when it unfolds and loses its three-dimensional shape (conformation)
        
        Depending on the severity of the change, the denaturation may be irreversible (when the change in shape affects the active site)
      - Functions
        
        Synthesis of new protoplasm (living parts of the cell), for growth and repair of worn-out body cells), building blocks of muscle, skin, bones, cartilage
        
        Form enzymes
        
        Form some hormones
        
        Form antibodies
        
        Fluid balance (osmotic pressure)
        
        pH balance
        
        Should not be used for energy (calories)
        
        Protein deficiency disease in childen called Kwashiorkor, causing swollen stomachs, cracked and scaly skin
      - Why must proteins be broken down in the Body?
        
        Animals cannot directly absorb the proteins taken in as protein molecules are too large to pass through living cell surface plasma membranes
        
        Protein molecules must be broken down by enzymes during digestion
        
        Digestion is a series of hydrolyic reactions
        
        Proteins are first hydrolysed by enzymatic proteases into short polypeptides/peptones
        
        Polypeptides are in turn hydrolysed by enzymatic peptidases into amino acids
        
        Amino acids are much simpler and smaller molecules than proteins
        
        Amino acids are soluble in water and dmall enough to diffuse through living membranes via carrier proteins (facilitated diffusion) / active transport, thus they can be easily absorbed into an animal's body
        
        When amino acids enter the body cells, they are linked up again to form the protein needed by the animal
    - - Macromolecules are polymers, built from monomers
      - Long molecules consisting of many similar/identical building blocks (monomers) linked together by covalent bonds
      - Synthesis
        
        2 monomers bind together through the loss of a water molecule, forming large molecules
        
        Condensation reaction
        
        Chemical reaction where 2 simple molecules are joined together to form a larger molecule with the removal of 1 water molecule
        
        H and OH molecules detach from both the monomer/polymer and bind together, producing a water molecule
        
        Enzymes are involved
      - Breakdown
        
        Polymers are disassembled to monomers, a reverse of a dehydration reaction, breaking down large molecules
        
        Hydrolysis reaction
        
        Hydrolytic chemical reaction where a water molecule is needed to break up a complex molecule into smaller molecules
        
        A water molecule breaks up into H and OH, and each molecule attaches to respective polymer/monomer
- - - - Medium where chemical reactions occur
      - Transport
        
        Digested products (glucose, amino acids) in the ileum (small intestines) to other parts of the body
        
        Excretory/waste products like urea from cells to kidneys
        
        Hormones like insulin from glands to body
      - Key component of protoplasm, lubricants in joints, digestive juices, blood, tissue fluid
      - Animals
        
        Digestion hydrolysis (using water to break down substances)
        
        Regulates body temperature (cooling through sweating)
        
        Respiration
        
        Water has a high heat of vaporisation (high specific heat)
      - Plants
        
        Photosynthesis (water and carbon dioxide forms glucose and oxygen)
        
        Turgidity of plant cells (plant keeps upright)
        
        Transport of mineral salts from roots to leaves through the xylem
        
        Transport of food from photosynthesis from leaves to whole plant through phloem
        
        Cohesive and adhesive properties of water causes transpiration pull
    - - Water is lost from the body when we breathe, sweat or urinate, which needs to be replaced.
      - Amount of water needed depends on
        
        How active the person is
        
        How healthy the person is
        
        Environmental conditions
- - - - Carrying out the Benedict's test
      - Add equal volumes (2cm3) of food sample and Benedict's solution into a test tube
      - Shake the mixture, with a light blue solution observed in the test tube
      - Place the test tube containing the mixture into a boiling water bath for 2-3 minutes
      - Colour changes to green, then yellow/orange before a red-brick precipitate (solids in liquid) is observed
      - Copper (II) oxide forms
        
        Cu2+ ion (blue) --> (reduced) Cu+ ion (red)
      - Green/yellow/brick-red precipitate is formed if reducing sugar is present in trace, moderate, or large amounts (respectively stated)
      - More on Reducing Sugars
        
        Any sugar that is capable of acting as a reducing agent as it has a free aldehyde group or a free ketone group
        
        All monosaccharides are reducing sugars, including, glucose, fructose, galactose, ribose and deoxyribose
        
        Some disaccharides like lactose and maltose have a reducing form, except for sucrose
        
        Sucrose, a non-reducing disaccharide, must be hydrolysed (boiled with acid, neutralised with alkaline, to form glucose and fructose to have a positive Benedict's test
    - - Add 2cm3 of food sample into a test tube, recording the initial colour
      - Add 2-3 drops of iodine solution
      - Blue-black colouration observed whenn yellow-brown iodine solution mixes with starch