Your answers to:

1
Your answers to

• What are two characteristic properties of
  hydrocarbons ?

Next time Quiz 3! Mainly on new material,
including todays class. Do practice questions.
Review last quiz.
2
Today
Getting energy in living systems Different
types of respirationDifferent types of
isomersCis trans isomersMolecules that can be
left-handed or right-handedSugars and sweet
nectar

• Glucose and other sugars

3
Larger molecules are broken into smaller ones
with the help of enzymes Complex multi-step
reactions!Respiration produces energy, and
high-energy compounds like ATP
Providing Energy Respiration In plants, animals,
humans
4
Aerobic Respiration respiration in the presence
of plenty of oxygen

Larger molecules, like sugars and fats, are
decomposing to form water and carbon
dioxide C6H12O6 6 O2 ? 6 CO2 6 H2O
E ATP Reverse of photosynthesis! An
oxidation reaction
5
Anaerobic respiration respiration in the
absence of air (oxygen).
Fermentation

Yeast, Water
C
H
O

ATP
CH
CH
OH
CO
2
2
Heat
6
12
6
3
2
2
several steps!
6
Anaerobic respiration respiration in the
absence of air (oxygen).
Tired muscles

OH
enzymes
C
H
O
C
H
C
C
O
2
Heat
ATP
6
12
6
3
several steps!
OH
H
Lactic acid

7
Practice

• What are the products of a complete combustion
  of hydrocarbons (any) with plenty of oxygen?
• Write the structure of two isomers with the
  molecular formula of C6H14 (can you find more
  than two?)
• Write the structure of two isomers with the
  molecular formula of C4H8 (can you find more than
  two?)

8
1) constitutional isomers e.g. isomers of C4H10
Types of isomers Same molecular formula,
different structures
2) cis-trans isomers3) Molecules that can be
left-handed or right-handed
9
cis/ trans Isomersa double bond is needed (or
a carbon cycle)
Trans fats
10
trans
?
cis
11
cis/ trans Isomers
12
constitutional isomers e.g. isomers of C4H102)
cis-trans isomers3) Molecules that can be
left-handed or right-handed DEMO.
Types of isomers Same molecular formula,
different structures
13
Molecules that can be left-handed or
right-handed
Asymmetric Molecules Chiral
MoleculesOptical Isomers

A
CH
CH
3
3
H
H
B
C
C
C
COOH
OH
OH
HOOC
D
E
a chiral molecule
Lactic acid
mirror image
Enantiomers Mirror images
14
Molecules that can be left-handed or
right-handed

A
CH
CH
3
3


H
H
B

C
C
C
COOH
OH
OH
HOOC
D
E
a chiral molecule
Lactic acid
mirror image
asymmetric carbon or center of asymmetry
15
What makes chiral molecules special ?

• They interact selectively with other chiral
  molecules (like enzymes)
• They interact differently with polarized light

16
A sweet chapterSugars and sweet nectar
17
Chiral (or asymmetric) carbons in this molecule?
18





19
Next time

• More on sweet sugars and nectar - and on
  molecules that can be left-handed or right-handed
• Your questions
• Quiz 3
• Mainly on new material, including todays class.
• Do practice questions. Review last quiz.