L.2 The Chemistry of Life

Question 1

L.O.

Answer 1

• Appreciate the common origins and makeup of the molecules of life.
• Explore the properties of living organisms.
• Appreciate that life is made up of a small number of elements of which carbon is particularly important
• Define the terms polar/hydrophilic and non-polar/hydrophobic
• Describe the building blocks of life: water, carbohydrates (sugars), lipids, amino acids and nucleic acids.
• Describe some chemical properties of amino acids (solubility hydrophobic/hydrophilic, polarity, charge), given their chemical structures.

Question 2

Properties of life

Answer 2

• Order
  From cellular to organ to performing a task
• Energy processing
  Capture energy from sun & convert
• Sensitivity or response to stimuli
  How & to what extent organism reacts
• Reproduction
  Moving info in DNA, parent cell into daughter cells
• Growth and development
  Cellular mitosis
• Regulation/homeostasis
  Maintaining internal conditions, despite env. changes
• Adaptation
  Physical, behavioral, physiological
• Evolution
  Adapting to env.

Question 3

Essential elements of life

Answer 3

Carbon:
- Bonds with self & other elements
- Strong but breakable covalent bonds
- Neutral charge
- nonpolar
- Hydrophobic

Question 4

Hydrophobicity and polarity

Answer 4

Carbon:
- Neutral charge, nonpolar, hydrophobic

O, N, P, S:
- Polar, hydrophilic

Hydrogen:
- Depends what element it is bonded with

Question 5

Main molecules in biology

Answer 5

• Water
• carbohydrates / sugars / saccharides
• Lipids
• amino acids
• Nucleotides

Question 6

Water

Answer 6

• Polar compound
• Strong H bonds
• Good solvent of polar molecules
• Poor solvent of hydrophobic molecules
• Stabilizes temp.
• Water tension / capilary action

Question 7

Carbohydrates / sugars / saccharides

Answer 7

• Monosaccharides (base)
• Composed of C,H,O
• Very polar to many O’s
• Monosaccharides usually form rings
• Disaccharides = 2 monosaccharides
• Polymer/ polysaccharides = long chain on mono.

Question 8

Lipids

Answer 8

• Diverse set of molecules, fat, oil, wax, steroids
• Poorly soluble in water
• Soluble in organic (hydrophobic) solvents
• High proportions of C and H
• Saturated = bad
• Unsaturated = good (double bond)

Question 9

Functions of lipids

Answer 9

• Energy store (triglycerides)
• Signalling molecules (steroids)
• Protection & waterproofing (wax)
• Structure / barriers (wax / phospholipids)

Question 10

Phospholipids

Answer 10

• Hydrophobic tail
• Hydrophilic head
• Polar heads interact with aqueous env. and seperate it from the tail by clustering togetehr.
• Created compartmentalization

Question 11

Amino acids

Answer 11

• Building block of proteins
• 20 common amino acids all have the same basic alpha structure
• Amino group + carbolylic group (NH2 + COOH)
• In aqueous solution the (-NH3+) & (COOH-) groups are charged.

Question 12

Nucleotides

Answer 12

• Nucleic acid building blocks
• Phosphate group (+ve charge)
• A sugar (Ribose/ deoxyribose)
• A Nucleobase ( A, G, C, T, ‘U’)

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