Macromolecules

Question 1

What is a biological macromolecule?

Answer 1

Large molecule necessary for life. Made from smaller organic molecules - monomers. They are a major component of cells.

Question 2

The four main classes of macromolecules?

Answer 2

Carbohydrates, proteins, lipids, and nucleic acid.

Question 3

Main functions of macromolecules?

Answer 3

Provide structure, store energy, form genetic information (DNA, RNA), and speed up biochemical reactions.

Question 4

Fundamental component of macromolecules?

Answer 4

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.

Question 5

What is a carbohydrate?

Answer 5

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).

Question 6

Monosaccharide

Answer 6

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).

Question 7

Structure of a monosaccharide?

Answer 7

Usually colourless, crystalline, and water-soluble organic solids. Have a backbone of 3-6 carbon atoms, and more than one hydroxyl group.

Question 8

Hydroxyl group?

Answer 8

One hydrogen atom and one oxygen atom covalently bonded together. -OH or HO-

Question 9

Structure of monosaccharides

Answer 9

Linear chains, or one or more ring-shaped molecule. Ring forms are more common in aqueous solutions (water-based).

Question 10

Most common monosaccharide

Answer 10

Glucose (C6 H12 O6)

Question 11

Importance of glucose

Answer 11

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.

Question 12

Three most common monosaccharides

Answer 12

Glucose, fructose, and galactose

Question 13

What is fructose?

Answer 13

A naturally occurring fruit sugar - monosaccharide found in many plants and fruit

Question 14

What is galactose?

Answer 14

Monosaccharide most commonly found in dairy products (lactose).

Question 15

Disaccharides

Answer 15

Formed when two monosaccharides undergo a condensation/dehydration reaction (loses H2O).

Question 16

Glycosidic bond

Answer 16

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.

Question 17

Three types of disaccharides

Answer 17

Sucrose, lactose, and maltose

Question 18

What is sucrose?

Answer 18

(Table sugar), the most common disaccharide. Made up of the monomers glucose & fructose.

Question 19

What is lactose?

Answer 19

Disaccharide made up of monomers glucose & galactose (naturally occurs in milk).

Question 20

What is maltose?

Answer 20

(Malt sugar), disaccharide formed through condensation reaction of two glucose molecules (glucose & glucose).

Question 21

Structure of disaccharides

Answer 21

Long chains of monosaccharides, linked by covalent bonds. Branched or unbranched, may contain different types of monosaccharides.

Question 22

Starch

Answer 22

The stored form of sugars in plants. Starch consumed by humans is broken down into smaller molecules (glucose), the cells can then absorb this.

Question 23

Glycogen

Answer 23

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.

Question 24

Lipids

Answer 24

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.

Question 25

What do lipids consist of?

Answer 25

Glycerol and fatty acids. Glycerol (3 carbon, 5 hydrogen, 3 hydroxyl groups). Fatty acids have a long chain of hydrocarbons.

Question 26

Saturated fatty acids

Answer 26

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.

Question 27

Unsaturated fatty acids

Answer 27

Hydrogen chain containing a double bond = unsaturated fat. Most unsaturated fats are liquid at room temperature and are oils.

Question 28

Benefits of unsaturated fats over saturated

Answer 28

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.

Question 29

Phospholipids

Answer 29

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.

Question 30

Phospholipids structure/form

Answer 30

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).

Question 31

Proteins

Answer 31

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.

Question 32

Protein structures

Answer 32

Their structures vary, but they are all polymers of amino acids arranged in a linear sequence.

Question 33

Protein functions

Answer 33

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.

Question 34

Amino acids

Answer 34

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.

Question 35

Chains of amino acids

Answer 35

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.

Question 36

Proteins are unique

Answer 36

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).

Question 37

Denaturation

Answer 37

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).