L2 - Introduction to Biological Molecules

Question 1

How many bonds does carbon form?

Answer 1

4 (tetravalent)

Question 2

What 3 forms do carbon-based molecules exist as?

Answer 2

• Simple
• Chain
• Ring

Question 3

Give an example of a simple carbon-based molecule and describe its uses.

Answer 3

• Methane: natural GHG
• Hexane: main constituent of gasoline
• Benzene: aromatic natural constituent of crude oil

Question 4

What do functional groups do when they attach to carbon-based compounds?

Answer 4

Dictate the function of compounds.

Question 5

What often occurs in cellular chemical reactions?

Answer 5

Functional group transfer (loss / gain).

Question 6

What is significant about the breakage of covalent bonds in carbon-based compounds?

Answer 6

Releases energy which can be used to sustain life.

Question 7

Name the 15 different functional groups and their prefixes / suffixes.

Answer 7

• Alkane: ‘ane’ (C-C)
• Alkene: ‘-ene’ (C=C)
• Alkyne: ‘-yne’ (C≡C)
• Alcohol: ‘-ol’ (-OH)
• Ether: ‘ether’ (-C-O-C-)
• Haloalkane: ‘halo-‘ (-C-X)
• Amine: ‘-amine’ (-C-N-)
• Aldehyde: ‘-al’ (-COH)
• Ketone: ‘-one’ (-C-CO-C-)
• Carboxylic Acid: ‘-oic acid’ (R-COOH)
• Ester: ‘-oate’ (-CO-O-C-)
• Amide: ‘-amide’ (-CO-N-)
• Amino: ‘amino-‘ (R-NH2)
• Thiol: ‘-thiol’ (R-SH)
• Phosphate: ‘phosphate’ (R-PO4)

Question 8

What is a macromolecule?

Answer 8

Large biological molecule with repeating subunits and many functional groups.

Question 9

Name the 4 groups of biologically important macromolecules.

Answer 9

• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

Question 10

How are polymers formed and what conditions are necessary?

Answer 10

• Formed by dehydration synthesis (condensation reaction)
• Water molecule removed when reactants are joined
• Requires energy in the form of ATP

Question 11

How are polymers broken down and what conditions are necessary?

Answer 11

• Broken down by hydrolysis
• Water molecule added when bonds between reactants are broken
• Energy released from bond is stored as ATP

Question 12

Why do polymers like starch need to be broken down?

Answer 12

To be easily digested and absorbed across the gut.

Question 13

What are enzymes?

Answer 13

Biological catalysts that increase the rate of chemical reactions without being used up.

Question 14

How much of the fresh mass of living organisms does water make up?

Answer 14

60-95%

Question 15

Describe and explain the 3 main roles of water in living systems.

Answer 15

• Universal solvent and transporter (all body fluids mostly water so can be used as transport medium, water aids movement of chemicals during diffusion)
• Lubricant (in joints and on tissues; moistens epithelial surfaces and acts as shock absorber)
• Regulates body temperature (water requires heat to turn to vapour = sweat absorbs heat from skin when evaporating)

Question 16

How much of body tissues are water?

Answer 16

62%

Question 17

Approximately how much water is needed a day?

Answer 17

1.5 L/day

Question 18

How is hydration status and blood flow tested? Explain the process.

Answer 18

• Capillary Refill Test

1) Pressure applied to nail bed until it turns white (blanched)
2) Pressure removed and hand is held above heart
3) Time taken for blood to return to tissue and nail to turn pink again is measured

Question 19

What conditions is dehydration associated with?

Answer 19

• Diarrhoea
• Vomiting
• Seizures
  (Can be fatal so requires rapid treatment)

Question 20

How is dehydration treated?

Answer 20

Fluid Replacement Therapy (Oral / Intravenous)

Question 21

Explain how the polarity of water comes about.

Answer 21

• Oxygen atom had 8 protons in nucleus
• Hydrogen atom has 1 proton in nucleus
• Electron pair shared in each OH covalent bond is more strongly attracted to O nucleus rather than either of the two H nuclei
• Makes water polar with slightly negative pole near O (𝛿-) and slightly positive pole near H (𝛿+)

Question 22

Describe how hydrogen bonding between water molecule occurs.

Answer 22

𝛿+ near H atoms is attracted to 𝛿- near O on nearby water molecule

Question 23

Why is water a liquid?

Answer 23

H-bonds are relatively weak and easily broken so molecules of water constantly change ‘partners’ - constant breaking and reforming of hydrogen bonds

Question 24

Explain water’s role as a powerful solvent, using NaCl as an example.

Answer 24

• Sodium chloride = lattice of sodium (Na+) ions ionically bonded to chloride (Cl-) ions
• 𝛿+ hydrogens are attracted to Cl- ions, while 𝛿- oxygens are attracted to Na+ ions
• So lattice pulls apart and salt dissolves in water

Question 25

How is water able to act as a universal solvent?

Answer 25

- All polar (charged) molecules / ions are water soluble because they can form H-bonds with water - Ions / polar molecules can move / interact freely, and take part in cellular chemical reactions

Question 26

Describe non-polar molecules.

Answer 26

- No electrical charge - Cannot form H-bonds with water - Hydrophobic (non-polar molecules repel water molecules)

Question 27

What is an amphiphilic substance?

Answer 27

Complex molecules that have both hydrophilic and hydrophobic properties.

Question 28

What is the 3D shape of many biological molecules influenced by?

Answer 28

Hydrophobic forces

Question 29

Describe the structure of the plasma membrane.

Answer 29

- Phospholipid bilayer - Hydrophilic (polar) heads point out towards extracellular fluid - Hydrophobic (non-polar) tails point in toward each other - Semipermeable membrane

Question 30

What can easily move through the plasma membrane?

Answer 30

Small molecules and larger hydrophobic molecules e.g. oxygen, carbon dioxide, water

Question 31

What is surface tension?

Answer 31

Tension of the surface film of a liquid caused by attraction of particles in the surface layer; so as to reduce surface area.

Question 32

Describe surface tension.

Answer 32

- Elastic tendency of a fluid surface - Occurs at liquid-air interfaces - Results from greater attraction of liquid molecules to each other (cohesion) than to molecules in the air

Question 33

What are surfactants?

Answer 33

Compounds that lower the surface tension between two liquids. - Between 2 liquids - Between a gas and a liquid - Between a liquid and a solid

Question 34

What may surfactants act as? (x5)

Answer 34

- Detergents - Wetting agents - Emulsifiers - Foaming agents - Dispersants

Question 35

What negative condition can surface tension cause in the body, how does the body react and what happen to babies with this condition?

Answer 35

- Tends to make lung alveoli collapse - Alveoli secrete surfactants to break down surface - Premature babies lacking surfactants experience lung collapse (atelectasis)

Question 36

How can lung alveoli collapse due to surface tension be treated?

Answer 36

Prescribed surfactant inhaler therapy