1. Lipids Lipids are hydrophobic molecules Mostly C-H (non-polar)
are the one class of large biological molecules that do not consist of polymers
Uses: structure of cell membranes, energy source

2. Lipids
Fats
Phospholipids
Steroids

3. Fats Are constructed from two types of smaller molecules:
single glycerol and
three fatty acids
Fatty Acid

4. Glycerol
Glycerol is a 3 carbon alcohol

5. ESTER LINKAGE
Ester linkage – formed by the dehydration (condensation) of a carboxyl group from the fatty acid to the hydroxyl group of glycerol

6. (a) Saturated fat and fatty acid
Saturated fatty acids
Have the maximum number of hydrogen atoms possible
Have no double bonds
Are solid at room temperature (e.g. animal fats)
(a) Saturated fat and fatty acid
Stearic acid
Figure 5.12

7. (b) Unsaturated fat and fatty acid
Unsaturated fatty acids
Have one or more double bonds, causing a bend in its structure
Are liquids at room temperature (e.g. vegetable fats)
(b) Unsaturated fat and fatty acid
cis double bond
causes bending
Oleic acid
Figure 5.12

8. Unsaturated Fats Monounsaturated fats (MUFA)
Have one double bond in their fatty acids
Polyunsaturated fats (PUFA)
Have more than one double bond in their fatty acid chains

10. Saturated fats – solid at room temperature, unsaturated – liquid at room temperature

11. Phospholipids Have only two fatty acids
Have a phosphate group instead of a third fatty acid

12. (a) Structural formula (b) Space-filling model
Phospholipid structure
Consists of a hydrophilic “head” and hydrophobic “tails”
CH2 O P CH C
Phosphate
Glycerol
(a) Structural formula
(b) Space-filling model
Fatty acids
(c) Phospholipid
symbol
Hydrophobic tails
Hydrophilic
head
Hydrophobic
tails –
Hydrophilic head
Choline +
Figure 5.13
N(CH3)3

13. Micelles
When phospholipids are added to water, they form micelles

14. Results in a phospholipid bilayer arrangement found in cell membranes
Hydrophilic
head
WATER
Hydrophobic
tail
Figure 5.14
Water and other polar and ionic materials cannot pass through the membrane except by the help of proteins in the membrane

15. Steroids
Steroids
Are lipids that have a carbon skeleton consisting of four fused rings
Contain many different functional groups

16. One steroid, cholesterol
Is found in cell membranes
Is a precursor for some hormones HO
CH3
H3C
Figure 5.15

17. Nucleic Acids Nucleic acids store and transmit hereditary information
There are two types of nucleic acids
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)

18. Function of DNA and RNA DNA RNA
Stores information for the synthesis of specific proteins
Found in the nucleus of cells
RNA
Reads information in DNA
Transports information to protein building structures within cell

19. The Structure of Nucleic Acids
5’ end
5’C
3’ end OH
Figure 5.26 O
Nucleic acids (also called Polynucleotides)
Are polymers made up of individual nucleotide monomers
(a) Polynucleotide,
or nucleic acid

20. Each Nucleotide contains
Sugar + phosphate + nitrogen base
Nitrogenous
base
Nucleoside O O O P
CH2
5’C
3’C
Phosphate
group
Pentose
sugar
(b) Nucleotide
Figure 5.26

21. (c) Nucleoside components
Nucleotide Monomers CH
Uracil (in RNA) U
Ribose (in RNA)
Nitrogenous bases Pyrimidines C N O H
NH2 HN
CH3
Cytosine
Thymine (in DNA) T HC NH
Adenine A
Guanine G
HOCH2 OH
Pentose sugars
Deoxyribose (in DNA) 4’ 5” 3’ 2’ 1’
(c) Nucleoside components
Pyrimidines
(single ring)
Purines
(double ring)
Deoxyribose (carbon 2  no oxygen), Ribose (carbon 2 has an oxygen – hydroxyl group)
Figure 5.26

22. Nucleotide Polymers
3’C
5’ end
5’C
3’ end OH
Figure 5.26 O
nucleotides linked by the–OH group on the 3´ carbon of one nucleotide and the phosphate on the 5´ carbon on the next
Phosphodiester bond

23. Gene The sequence of bases along a nucleotide polymer
Is unique for each gene

24. The DNA Double Helix
Have two polynucleotides that spiral around each other
held together by hydrogen bonds between nitrogenous bases
A (adenine) will always bond with T (thymine – DNA only), or U (uracil – RNA only)  2 hydrogen bonds
C (cytosine) will always bond with G (guanine)  3 hydrogen bonds

25. The DNA double helix Consists of two antiparallel nucleotide strands
3’ end
Sugar-phosphate backbone
Base pair (joined by hydrogen bonding)
Old strands
Nucleotide about to be added to a new strand A
5’ end
New strands
Figure 5.27