Lipids serve several important functions in living organisms. They are used for long-term energy storage, provide insulation and buoyancy, and form protective membranes around cells. The main types of lipids are triglycerides, phospholipids, and steroids like cholesterol. Lipids and carbohydrates both serve as energy stores, with lipids containing more energy per gram but carbohydrates being more easily accessible. Proteins are made of amino acid subunits and form complex 3D structures essential for their diverse functions like catalysis. Nucleic acids like DNA and RNA contain nucleotide subunits and provide genetic instructions through their base-pairing structures.

1. Lipids
1

2. Functions of Lipids
• Energy storage
– In the form of fat in humans
and oil in plants
• Heat insulation
– A layer of fat under the skin
reduces heat loss
• Buoyancy
– Lipids are less dense than
water to help animals to
float
• To provide a layer of
protection
– Fat on your body
– Membranes in cells 2

3. Triglycerides (FAT)
3

4. Examples of saturated and unsaturated fats
and fatty acids
4

5. The structure of a phospholipid
5

6. Two structures formed by self-assembly of
phospholipids in aqueous environments
6

7. Cholesterol, a steroid
7

8. Steroids include cholesterol and
certain hormones
• Steroids are lipids with a carbon
skeleton consisting of four fused
carbon rings.
– Different steroids are created by varying
functional groups attached to the rings
• Cholesterol, an important steroid, is a
component in animal cell membranes.
• Cholesterol is also the precursor from
which all other steroids are
synthesized.
www.pearsonsuccessnet.com activity 5.3 page 3 8

9. Using Carbohydrates and Lipids
in Energy Storage
• Both lipids and Advantages of Advantages of
carbs can be
used for energy Lipids Carbs
storage in living Lipids contain more Carbohydrates are
organisms. energy per gram than more easily digested
Both types of carbs so stores of than lipids so the
storage lipids are lighter than energy stored by them
compound have stores of carbs that can be released more
advantages. contain the same rapidly
Carbohydrates amount of energy 4 kcal/g
are usually for 9 kcal/g
energy storage Lipids are insoluble in Carbohydrates are
over short water, so they do not soluble in water so are
periods and cause problems with easier to transport to
lipids for long- osmosis in cells and from the storage
term storage area 9

10. Proteins
10

11. basic structure of
an amino acid
R-group changes depending
upon the amino acid
R O
H
N C C
H OH
H
amine functional carboxylic acid
group functional group
11

12. • The R-group (outlined in white) changes the
properties of each amino acid
• ex: nonpolar groups are hydrophobic 12

13. • polar R-groups are hydrophilic
• electrically charged R-group will interact with
molecules of opposite charge 13

14. peptide bond formation
amino acid chain =
polypeptide chain
14

15. The primary
structure of a
protein: CHAIN
• primary protein
structure:
– polypeptide chain
• The folding of a
protein from a chain
of amino acids
occurs
spontaneously
• The precise primary
structure of a
protein is
determined by
inherited genetic
15
information.

16. • The secondary
Secondary Structure: structure of a
α Helix and β Pleated Sheets protein results
from hydrogen
bonds at
regular
intervals along
the
polypeptide
backbone.
• Typical shapes
that develop
from
secondary
structure are
coils (an alpha
helix) or folds
(beta pleated
sheets).
16

17. Tertiary Structure: Twists in on itself
• Tertiary
structure is
determined
by a variety
of
interactions
among R
groups and
between R
groups and
the
polypeptide
backbone.
17

18. The quaternary structure of proteins:
multiple chains together
18

19. Spider silk: a structural protein
• The structural properties of silk are due to beta
pleated sheets.
– The presence of so many hydrogen bonds makes each
silk fiber stronger than steel.
19
http://www.sciencedaily.com/releases/2008/02/080214114448.htm

20. A protein’s function depends on its specific
conformation
• A functional proteins consists of one or more
polypeptides that have been precisely twisted,
folded, and coiled into a unique shape.
• It is the order of amino acids that determines
what the three-dimensional conformation will
be.
20

21. At present, scientists use X-ray crystallography to
determine protein conformation.
21

22. Denaturation and renaturation of
a protein
22

23. An Overview of Protein Functions
23

24. 24

25. 25

26. 26

27. 27

28. 28

29. 29

30. enzymes: specialized proteins
ribonuclease
30

31. 31

32. Nucleic Acids
32

33. The Nucleotide Subunits of DNA
• Although DNA is the genetic
material of living organisms and
is therefore of immense
importance, it is made of
relatively simple subunits
• These are called nucleotides
P
• Each nucleotide consists of
three parts: B
S
– A sugar, deoxyribose
– A phosphate group
– And a nitrogen base
• DNA nucleotides do not all have
the same base
• Four different bases are found
33
– Adenine, guanine, cytosine, thymine

34. nucleotide
monomer
phosphate group
PO4 nitrogen base
CH2
5’
4’ 1’
3’ 2’
OH
deoxyribose sugar
Numbering the carbons on
deoxyribose:
1’ = nitrogen base
3’ = hydroxyl group 34
5’ = phosphate group

35. 35

36. Building DNA Molecules
• Two DNA nucleotides can be
linked together by a covalent
bond between the sugar of one
nucleotide and the phosphate
group of the other
• More nucleotides can be added
in a similar way to form a
strand of nucleotides
• DNA molecules consist of two
strands of nucleotides wound
together into a double helix
• Hydrogen bonds link the two
strands together
• These form between the bases
of the two strands
• However, adenine only forms
hydrogen bonds with thymine
and cytosine only forms
hydrogen bonds with guanine
• This is called complementary
base pairing
36

37. •The bonds between
5’ the phosphate group
and the deoxyribose
sugar on an
individual nucleotide
is a covalent bond –
phosphodiester
bond.
•Phosphodiester
bonds are arranged
 phosphate –
oxygen – carbon.
•Bonding nucleotides
together:
occurs between 3’
OH group on one
nucleotide and 5’
phosphate group on
the other through a •Strands run antiparallel to each
condensation other = one strand has the 5’ C on
reaction (release of the top, 3’ C on the bottom, and
water) the other is reversed
3’ •There will always be
a free 5’ end 3’ on
37
each strand of DNA

38. NUCLEOSOME STRUCTURE:
- 8 histones, (+) charged, (protein) in the core
- 2 molecules of 4 different histones
- DNA, (-) charged, wraps around the core 2x
- 1 histone holds the 2 ends of the DNA, histone H1
- with 2 ends of linker DNA
- nucleosomes help to supercoil chromosomes and help to
38
regulate transcription

39. In nuclear DNA there are three types:
1. Unique/Single-copy genes:
- genes with coding functions
- essential to producing proteins
- Human Genome Project: to sequence all the coding genes, less than 2% of
chromosomes are coding genes
- Coding parts of DNA are not strung together neatly; there are noncoding
regions interspersed within between coding regions
- coding parts = EXONS; noncoding parts = INTRONS
- EXONS are allowed to EXIT the nucleus to be translated into a protein
- INTRONS must stay IN the nucleus because they don’t code for a protein
2. Highly repetitive sequences:
- found in eukaryotes
- from 5%-45% of the total genome
- 5-300 base pairs per sequence
- Clustered together? = satellite DNA
- usually dispersed throughout the
genome = transposable
- Barbara McClintock; 1950
39

40. RNA
• Usually single
strands
• Unlike DNA,
contains the
pyrimidine
base uracil in
place of
thymine
• Contains
ribose sugar
rather than
deoxyribose
sugar
• Three types
are key players
in protein 40
synthesis