Biological Molecules

Question 1

Define monomers and polymers.

Answer 1

Monomers are small units that serve as the building blocks of larger molecules, while polymers are large molecules made from many monomers joined together.

Question 2

Describe the process of condensation reaction.

Answer 2

A condensation reaction is a chemical process where monomers are joined together, resulting in the elimination of a water molecule.

Question 3

Explain hydrolysis in relation to polymers.

Answer 3

Hydrolysis is the opposite of a condensation reaction; it involves the addition of water to break a chemical bond between two molecules.

Question 4

What are carbohydrates composed of?

Answer 4

Carbohydrates consist only of carbon, hydrogen, and oxygen, forming long chains of sugar units called saccharides.

Question 5

Define monosaccharides and give examples.

Answer 5

Monosaccharides are single sugar units, examples include glucose, galactose, and fructose.

Question 6

How are disaccharides formed?

Answer 6

Disaccharides are formed when two monosaccharides join together through a condensation reaction, producing a molecule of water.

Question 7

What is a glycosidic bond?

Answer 7

A glycosidic bond is a type of covalent bond that joins monosaccharides together in carbohydrates, formed during a condensation reaction.

Question 8

Describe the structure of glucose.

Answer 8

Glucose is a monosaccharide with six carbon atoms in each molecule and exists in two isomeric forms: alpha and beta glucose.

Question 9

What is the general formula for common monosaccharides?

Answer 9

The general formula for common monosaccharides is (CH2O)n, where n can be any number from three to seven.

Question 10

Explain the significance of glucose in respiration.

Answer 10

Glucose is the main substrate for respiration, making it a crucial molecule for energy production in living organisms.

Question 11

How do alpha and beta glucose differ?

Answer 11

Alpha and beta glucose are isomers that differ in the arrangement of the hydroxyl group (-OH) on the first carbon atom.

Question 12

What happens during the formation of maltose?

Answer 12

Maltose is formed by the condensation reaction between two alpha glucose molecules, resulting in the creation of a 1,4 glycosidic bond and the release of a water molecule.

Question 13

Describe how maltose is formed.

Answer 13

Maltose is a disaccharide formed by the condensation of two glucose molecules.

Question 14

Define polysaccharides and give examples.

Answer 14

Polysaccharides are formed from many glucose units joined together, examples include glycogen, starch, and cellulose.

Question 15

How is glycogen structured and what is its function in animals?

Answer 15

Glycogen is formed from many alpha glucose molecules joined by 1, 4 and 1, 6 glycosidic bonds, serving as the main energy storage molecule in animals.

Question 16

Explain the significance of glycogen’s structure for energy release.

Answer 16

Glycogen has many side branches allowing simultaneous action by enzymes, enabling quick energy release.

Question 17

What are the two components of starch and their characteristics?

Answer 17

Starch consists of amylose, which is an unbranched chain of glucose, and amylopectin, which is branched and made of glucose molecules.

Question 18

How does amylose differ from amylopectin in structure?

Answer 18

Amylose is an unbranched chain of glucose joined by 1, 4 glycosidic bonds, while amylopectin is branched and includes both 1, 4 and 1, 6 glycosidic bonds.

Question 19

Describe the properties of starch that make it suitable for energy storage.

Answer 19

Starch is insoluble, compact, and when hydrolyzed, releases alpha glucose that can be easily transported.

Question 20

What role does cellulose play in plant cells?

Answer 20

Cellulose is a component of cell walls in plants, providing structural support and preventing bursting under osmotic pressure.

Question 21

How are microfibrils formed in cellulose?

Answer 21

Microfibrils are strong threads made of long cellulose chains running parallel, joined by hydrogen bonds forming strong cross linkages.

Question 22

Explain the importance of cellulose in maintaining plant cell structure.

Answer 22

Cellulose exerts inward pressure that prevents water influx, keeping cells turgid and rigid, which maximizes surface area for photosynthesis.

Question 23

What are the three types of bonding in biological molecules?

Answer 23

Covalent - atoms share a pair of electrons in their outer shell, making them more stable. [page 1]
Ionic - ions with opposite charges attract one another (electrostatic attraction), weaker than covalent. [page 1]
Hydrogen bonding - an electrostatic bond formed between a negatively charged region and a positively charged region.

Question 24

What is polymerisation?

Answer 24

Polymerisation is the process through which polymers are formed.

Question 25

What is metabolism?

Answer 25

Metabolism refers to all the chemical processes that take place in a living organism.

Question 26

What are lipids and their two main types?

Answer 26

Lipids are biological molecules made of carbon, hydrogen, and oxygen, soluble only in organic solvents like alcohols. The two main types are triglycerides and phospholipids.

Question 27

What are the structural components of triglycerides?

Answer 27

Triglycerides consist of one glycerol molecule and three fatty acids, joined by ester bonds formed in a condensation reaction.

Question 28

What is the difference between saturated and unsaturated lipids?

Answer 28

Saturated lipids do not contain any carbon-carbon double bonds, while unsaturated lipids contain carbon-carbon double bonds, allowing them to bend and remain liquid at room temperature.

Question 29

What are the properties of triglycerides?

Answer 29

- High ratio of energy-storing carbon-hydrogen bonds, making them excellent energy stores. [page 1] - Low mass-to-energy ratio, making them good storage molecules. [page 1] -Large and nonpolar, making them insoluble and not affecting the water potential of cells.

Question 30

What are the structural components of phospholipids?

Answer 30

Phospholipids consist of two fatty acids, one glycerol, and one phosphate molecule. They have hydrophilic heads and hydrophobic tails.

Question 31

What are the properties of phospholipids?

Answer 31

-Polar nature allows them to form bilayers. [page 1] -Hydrophilic heads can hold at the surface of the cell membrane. [page 1] -Their structure allows them to form glycolipids with carbohydrates, important for the cell surface membrane.

Question 32

What are the monomers of proteins and their structure?

Answer 32

Amino acids are the monomers of proteins, containing an amine group, a carboxylic group, and a variable R group.

Question 33

What are the levels of protein structure?

Answer 33

-Primary structure: sequence and number of amino acids, determining protein function. [page 1] -Secondary structure: alpha helix or beta-pleated sheets, formed by hydrogen bonds between amine and carboxyl groups. [page 1] -Tertiary structure: 3D shape formed by further twisting, with ionic bonds between carboxyl and amine groups.

Question 34

What are the two types of proteins?

Answer 34

- Globular proteins (e.g., enzymes) - compact. [page 1] - Fibrous proteins (e.g., keratin) - long and form fibers.

Question 35

How do enzymes increase the rate of reaction?

Answer 35

Enzymes increase the rate of reaction by lowering the activation energy. They bind to substrates to form an enzyme-substrate complex, distorting hydrogen bonds as the active site shape changes slightly.

Question 36

What factors affect enzyme activity?

Answer 36

Temperature. [page 2] pH. [page 2] Substrate concentration. [page 2] Enzyme concentration. [page 2] Concentration of competitive reversible inhibitors. [page 2] Concentration of non-competitive reversible inhibitors.

Question 37

What are the components of a nucleotide?

Answer 37

A nucleotide consists of a pentose (5-carbon sugar), a nitrogen-containing organic base, and a phosphate group

Question 38

What is the structure of DNA?

Answer 38

DNA consists of a deoxyribose sugar, a phosphate group, and one base. It is a double helix composed of two polynucleotides joined by hydrogen bonds, with a phosphodiester backbone protecting the reactive bases inside.

Question 39

What are the steps of semi-conservative replication?

Answer 39

-DNA helicase separates the two strands of -DNA by breaking hydrogen bonds. [page 2] One strand acts as a template, and complementary base pairing occurs. [page 2] -DNA polymerase joins them together, forming phosphodiester bonds.

Question 40

What is the structure of RNA?

Answer 40

RNA consists of a ribose sugar, a phosphate group, and a base. It is a short-chain molecule.

Question 41

What is ATP and its components?

Answer 41

ATP consists of ribose, adenine, and three phosphate groups.

Question 42

What happens when ATP is hydrolyzed?

Answer 42

When ATP is hydrolyzed (catalyzed by ATP hydrolase), energy is released, and the inorganic phosphate released can phosphorylate other compounds, making them more reactive.

Question 43

What are the properties of ATP?

Answer 43

-Immediate source of energy in manageable quantities. [page 2] - Not stored in large quantities. [page 2] Used in various processes: metabolic processes, movement, and active transport.

Question 44

What are the properties of water?

Answer 44

Metabolite in metabolic reactions like condensation and hydrolysis. [page 2] Solvent for transporting molecules. [page 2] High specific heat capacity to minimize temperature fluctuations. [page 2] Large latent heat of vaporization for cooling effects. [page 2] Strong cohesion for supporting water columns and surface tension.

Question 45

What are the roles of inorganic ions?

Answer 45

Hydrogen ions determine pH; higher hydrogen ion concentration lowers pH. [page 2] Iron ions are components of haemoglobin. [page 2] Sodium ions are involved in the co-transport of glucose and amino acids. [page 3] Phosphate ions are components of DNA and ATP.

Question 46

Where is the phosphodiester bond formed between 2 nucleotides?

Answer 46

between phosphate and deoxyribose

Question 47

What is the role of the DNA nucleotides in semi-conservative replication?

Answer 47

to form complimentary DNA chain