Macromolecules Flashcards
What is a biological macromolecule?
Large molecule necessary for life. Made from smaller organic molecules - monomers. They are a major component of cells.
The four main classes of macromolecules?
Carbohydrates, proteins, lipids, and nucleic acid.
Main functions of macromolecules?
Provide structure, store energy, form genetic information (DNA, RNA), and speed up biochemical reactions.
Fundamental component of macromolecules?
Carbon - versatile element, it can form covalent bonds with up to 4 different atoms. The ‘backbone’ of macromolecules. When bonded with Hydrogen, Oxygen, and Nitrogen - it forms macromolecules, essential for cellular function of living organisms.
What is a carbohydrate?
Type of macromolecule, (CH2O)n - 1 carbon, 2 hydrogen, 1 oxygen 1:2:1. Provides energy to body. The three subtypes of carbohydrates: monosaccharides, disaccharides, and polysaccharides (based on number of monomers in the molecule).
Monosaccharide
Single sugar molecule. The most basic unit of a carbohydrate. Building blocks of complex carbohydrates (disaccharides and polysaccharides). Made up of carbon, hydrogen, and oxygen atoms - CH2On. Most monosaccharides have suffix ‘-ose’. Chemical formula for three main subtypes (C6 H12 O6).
Structure of a monosaccharide?
Usually colourless, crystalline, and water-soluble organic solids. Have a backbone of 3-6 carbon atoms, and more than one hydroxyl group.
Hydroxyl group?
One hydrogen atom and one oxygen atom covalently bonded together. -OH or HO-
Structure of monosaccharides
Linear chains, or one or more ring-shaped molecule. Ring forms are more common in aqueous solutions (water-based).
Most common monosaccharide
Glucose (C6 H12 O6)
Importance of glucose
The body’s primary source of energy. Main fuel for cells (brain uses 50% body’s energy from glucose). Excess glucose stored as glycogen - energy storage for if the body isn’t getting enough glucose from food.
Three most common monosaccharides
Glucose, fructose, and galactose
What is fructose?
A naturally occurring fruit sugar - monosaccharide found in many plants and fruit
What is galactose?
Monosaccharide most commonly found in dairy products (lactose).
Disaccharides
Formed when two monosaccharides undergo a condensation/dehydration reaction (loses H2O).
Glycosidic bond
A covalent chemical bond that links a carbohydrate molecule to another group (can be a carbohydrate or other). Bonds are formed through a condensation reaction, and broken down in a hydrolysis reaction.
Three types of disaccharides
Sucrose, lactose, and maltose
What is sucrose?
(Table sugar), the most common disaccharide. Made up of the monomers glucose & fructose.
What is lactose?
Disaccharide made up of monomers glucose & galactose (naturally occurs in milk).
What is maltose?
(Malt sugar), disaccharide formed through condensation reaction of two glucose molecules (glucose & glucose).
Structure of disaccharides
Long chains of monosaccharides, linked by covalent bonds. Branched or unbranched, may contain different types of monosaccharides.
Starch
The stored form of sugars in plants. Starch consumed by humans is broken down into smaller molecules (glucose), the cells can then absorb this.
Glycogen
The animal/human equivalent of starch, usually stored in the liver and muscle cells. When glucose levels decrease, glycogen is broken down to release glucose for energy.
Lipids
Hydrophobic (water-fearing) - insoluble in water, non-polar molecules. Cells store energy for long-term use in lipids. Provide insulation, and are the building blocks of many hormones and a key constituent of the plasma membrane. Fats, oils, waxes, phospholipids, and steroids are all lipids.
What do lipids consist of?
Glycerol and fatty acids. Glycerol (3 carbon, 5 hydrogen, 3 hydroxyl groups). Fatty acids have a long chain of hydrocarbons.
Saturated fatty acids
If there are single bonds between each carbon atom in the hydrocarbon chain = the fatty acid is saturated. The number of hydrogen atoms attached to the carbon skeleton is maximised (saturated). Solid at room temperature.
Unsaturated fatty acids
Hydrogen chain containing a double bond = unsaturated fat. Most unsaturated fats are liquid at room temperature and are oils.
Benefits of unsaturated fats over saturated
Unsaturated fats (oil) usually originates from plants. Their double bond causes a ‘kink’ preventing fatty acids from packing tightly, keeping them liquid at room temperature. Olive oil, corn oil, canola oil, and cod liver oil are all unsaturated fats. They help improve blood cholesterol levels, whereas saturated fats contribute to plaque formation in arteries - increases risk of heart attack.
Phospholipids
Major constituent of the plasma membrane. Composed of fatty acid chains attached to glycerol (or similar backbone). They have two fatty acids and the third carbon atom from glycerol is bound to a phosphate group. The phosphate group is modified by the addition of a hydroxyl group.
Phospholipids structure/form
They have hydrophobic and hydrophilic regions. The fatty acid chains are hydrophobic and avoid water, whereas the phosphate is hydrophilic and interacts with water. Cells are surrounded by a membrane, which has a bilayer of phospholipids. Fatty acids in phospholipids face inside (away from water), the phosphate group can face the outside environment or the inside of the cell - as both are aqueous (water-based).
Proteins
The most abundant organic molecule in living systems, and have the most diverse range of functions of all macromolecules. Can be structured, regulatory, contractile, or protective. Serve in transport, storage, or membranes; or can be toxins or enzymes.
Protein structures
Their structures vary, but they are all polymers of amino acids arranged in a linear sequence.
Protein functions
Very diverse, as there are 20 different chemically distinct amino acids that form long chains. The amino acids can be in any order - e.g. proteins can function as enzymes or hormones.
Amino acids
They are monomers that make up proteins. They all have the same fundamental structure - a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), and a hydrogen atom. Every amino acid has another variable atom/group of atoms bonded to the central carbon atom, known as the R group. This is the only structural difference between the 20 amino acids - they are otherwise identical.
Chains of amino acids
The sequence and number of amino acids determines a proteins shape, size, and function. Each amino acid is attached to another amino acid by a peptide bond. The products formed are called polypeptides. A protein is a group of polypeptides that have combined together, and each have a unique shape and a unique function.
Proteins are unique
Each protein has a unique sequence & shape held together by chemical interactions. If the protein is subject to changes in temperature, PH, or chemical exposure - the protein structure may change (denaturation).
Denaturation
Often reversible because the primary structure is preserved if the denaturing agent is removed - allowing the protein to resume its original function. Can be irreversible, leading to a loss of function. An example of protein denaturation is an egg being cooked (once exposed to high enough heat it changes its form, becomes solid and changes colour, and cannot return to its original structure).
