Molecules of Life

1. PRESENTATION BY TINYIKO
SALMON SUMBANE
STUDENT NO: 201202198
CELL: 0769069736

2. THE MOLECULES OF
LIFE
This Presentation is a “Mash up” of Five
Presentations From Different Aouthers

4. The Simplest Hydrocarbon
• Methane = Carbon + Hydrogen

5. Organic Molecules
• A cell is mostly water but the rest consists mainly of
carbon based molecules
• Compounds that contain carbon are called organic
compounds
• Carbon has the ability to form the large, complex diverse,
molecules necessary for life functions
• Why are carbon atoms so versatile as molecular
ingredients?

6. Carbon Chemistry
• Carbon a versatile atom has 4 electrons in an outer shell
that holds 8
- carbon can share its electrons with other atoms to form up to 4
covalent bonds
• Carbon can use its bonds to attach to other carbons
to form an endless diversity of carbon skeletons
- each carbon in an organic molecule can branch off in up to 4
directions
• Carbon atoms of organic molecules can also bond with
other elements (hydrogen, oxygen, nitrogen)
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

7. Variations in Carbon Skeletons
• Simplest organic compounds are hydrocarbons
• Hydrocarbons consist of carbon and hydrogen
• Each C atom forms 4 bonds; each H atom forms 1 bond
Fig 3.2

8. Larger Hydrocarbons
• Main molecules in the gasoline we burn in our cars
• Hydrocarbons of fat molecules provide energy for our
bodies
Fig 3.4

9. Functional Groups
• Each type of organic molecule has a unique 3-dimensional
shape that defines its function in an organism
- the molecules of your body recognize one another based on their shapes
• The unique properties of an organic compound depend not
only on its carbon skeleton but also on the atoms attached to
the skeleton
- these atoms are called functional groups
• Functional groups behave consistently from one organic
molecule to another

10. 4 Important Functional Groups
• Many biological molecules have 2 or more functional groups
• How do cells make large molecules out of smaller organic molecules

11. Size of Molecules
• Monomers
– Molecules used as subunits to
build larger molecules (polymers)
• Polymers
– Larger molecules that are chains of monomers
– May be split and used for energy

12. Building Blocks
• On a molecular scale, many of life’s molecules are
gigantic
- biologists call them macromolecules (macro = ‘big’) such as
DNA, carbohydrates, proteins
• Most macromolecules are polymers
- polymers are made by stringing together many smaller molecules
called monomers
- cells link monomers together through a dehydration reaction
(removes a molecule of water)
• Organisms break down macromolecules (digestion)
- cells do this by a process called hydrolysis (hydro = ‘water’ lyse =
‘break’; to break with water)

13. Dehydration Reaction
Synthesis – a polymer grows in length when an incoming monomer
and the monomer at the end of the existing chain contribute to
the formation of a water molecule, the monomers then replace
their lost covalent bonds with a bond to each other

14. Hydrolysis
Breaking a polymer chain – hydrolysis reverses the process by
breaking down the polymer with the addition of water molecules, which
break the bonds between monomers

15. INPORTANT INORGANIC COMPOUNDS
• Water
• and minerals

16. Water
• Most important biochemical:
• A major component of cells (70-95% of cell mass)
• Provides environment for those organisms that live in water (3/4 of
the world)
• Interesting features:
• Exist in liquid form at normal Earth temperatures
• Provides a medium for molecules and ions to mix in and hence a
medium in which life could evolve
• Hydrogen bonds
• More energy needed to break bonds and convert water from liquid
to a gas
ALBIO9700/2006JK

17. Water as a solvent
• Excellent solvent for ions and polar molecules
because water molecules are attracted to them,
collect around and separate them (dissolve)
• Non-polar molecules are pushed together
ALBIO9700/2006JK

18. Water as a transport medium
• Blood
• Lymphatic system
• Excretory system
• Digestive system
• Vascular tissues of plants
ALBIO9700/2006JK

19. Thermal properties
• Hydrogen bonding restricts movement of water
molecules – large amount of energy needed to raise
temperature of water
 Oceans and lakes are more stable habitats
 Minimise internal (body) changes in temperature
 Evaporation transfers a large amount of energy (cooling)
 Water will not freeze easily
ALBIO9700/2006JK

20. Density and freezing properties
• Ice is less dense than liquid form
• Acts as insulates
• Changes in density of water with temperature
cause currents which help to maintain the
circulation of nutrients in the oceans
ALBIO9700/2006JK

21. High surface tension and
cohesion
• Water molecules tend to stick to each other
• Water movement through the vascular tissue in plants
• Important property in cells
• High surface tension (pond skater)
ALBIO9700/2006JK

22. ALBIO9700/2006JK

23. 2. MINERALS
a. elements extracted from the soil; consumed in our diet
b. main minerals are calcium, phosphorus, potassium, sodium,
chloride, magnesium, zinc, copper
c. are crucial for synthesis and maintenance of:
Bones
Calcium, phosphorus
Muscles
Calcium, sodium, phosphorus
Neurons
Calcium, sodium, potassium,
phosphorus

24. Text Reading: Chapter 2 (p35-40),
Chapter 3 (p53-62, 70-75)
You are What You Eat:
Macromolecules of Life & Their Relationship to Diet and Nutrition
Learning Objectives
• Name the four major classes of biological
macromolecules. Describe the composition and function
of each. Provide examples of each.
• Distinguish between steroids and anabolic steroids,
and explain how the use of anabolic steroids can be
dangerous to a person’s health.
• Apply this information to interpreting a food label and
categorize the food as either healthful or junk food.

25. Biological Macromolecules
• There are four categories of macromolecules in cells:
•
•
•
•
Carbohydrates
Lipids
Proteins
Nucleic acids

26. Carbohydrates
• Major source of energy
for cells
• Carbohydrates include
• Simple sugar molecules (fructose,
glucose, sucrose) – enter system
quickly
• Complex carbohydrates contain
branched chains of simple sugars
(starch, glycogen) – digested slowly

27. Carbohydrates (cont’d)
• 3 classes of carbohydrates:
• Monosaccharides
• Disaccharides
• Polysaccharides
Figure 2.12

28. Monosaccharides
• Monosaccharides are simple sugars.
• Examples: glucose, fructose
• Glucose found in sports drinks
• Fructose found in fruit, corn syrup
• Honey contains both glucose and fructose
• Monosaccharides are the main fuel
that cells use for cellular work.

29. Disaccharides
• A disaccharide is a double sugar.
• Constructed from two monosaccharides.
– Examples: maltose, lactose,
sucrose
• Maltose is used to make
beer, malted milk shakes,
& malted milk ball
candies.

30. Disaccharides (cont’d)
• Lactose is another type of disaccharide.
• Found in milk products.
• lactose intolerance: inability to digest lactose
• These people don’t make enough lactase, the enzyme
the breaks down lactose.

31. Disaccharides (cont’d)
• Most common disaccharide is sucrose (table sugar)
• Consists of a glucose linked to a fructose.
• Extracted from sugar cane and roots of sugar beets.
– USA is one of the world’s leading markets for
sweeteners.
• Average American consumes ~64 kg
(>140 lbs!!!) of sugar/year

32. Polysaccharides
• Complex carbohydrates are called polysaccharides.
• Long chains of sugar units.
• Polymers of monosaccharides.
– Examples: starch, glycogen, cellulose
– Fiber is an indigestible complex carbohydrate

34. Proteins
• Proteins perform most of the tasks the body needs to function.
Structure
Storage
Contractile Proteins
Signaling Proteins
Hormones
Enzymes
Defense (Antibodies)
Transport

35. The Monomers: Amino Acids
• Proteins are polymers of amino acids.
• All proteins are constructed from a common set of 20 kinds of amino acids.
– Each amino acid consists of
• A central carbon atom bonded to four
covalent partners.
• Side group is variable among all 20.
• The side group gives each amino acid
its properties.

36. Proteins as Polymers
• Cells link amino acids together to form proteins.
• The resulting bond between them is called a peptide bond.
• String of amino acids sometimes called polypeptide.
Figure 2.13

37. Protein Diversity
– Your body has tens of thousands of different kinds of
proteins.
– Different combinations of amino acids give proteins
different properties.
– Most proteins are at least 100 amino acids in length.
– Many different sequences possible with 20 amino acids.
– Analogy: 26 letters can make many different words

38. Protein Structure
• Primary structure
• Sequence of amino acids in a protein
– A slight change in the primary structure of a
protein affects its ability to function.
• The substitution of one amino acid in
hemoglobin causes sickle-cell disease.

39. Protein Shape
• Proteins have four levels of structure.
Sequence of amino acids
Local folding patterns
Examples: alpha helix, beta pleated
sheet
Overall three-dimensional shape
Overall shape when two or more
polypeptides bind each other

40. What Determines Protein Structure?
• A protein’s amino acid sequence dictates its structure.
• A protein’s shape is also sensitive to the surrounding environment.
• Unfavorable temperature and pH changes can
cause a protein to unravel and lose its shape.
• This is called denaturation.

41. Proteins as Nutrients
• Our bodies can make several amino acids.
• Essential amino acids: amino acids our bodies cannot make, must
obtain from food.
• Complete proteins: contain all essential amino acids.
• Animal proteins (meat) more likely to be complete than plant proteins.
Plant proteins can be combined to make complete.
(a) Lentils are high in lysine and low in valine.
(b) Rice is low in lysine and high in valine.
The side groups of
lysine and valine
are different.
Lysine
Valine
Lysine
Valine
Figure 3.2

47. Lipids
• Lipids are hydrophobic (water-fearing).
• They do not mix with water.
• Oil and vinegar salad dressing separates into layers.
– Examples:
fats, oils,
steroids, wax,
cholesterol,
phospholipids
Figure 2.14

48. Fats
• Dietary fat consists largely of the molecule triglyceride.
• Triglyceride is a combination of glycerol and three fatty acids.

49. Fats (cont’d)
• Fats perform essential functions in the human body:
• Energy storage
• Cushioning
• Insulation

50. Saturated vs Unsaturated Fats
Saturated fat
Unsaturated fat
• Unsaturated fatty acids
• Have less than the maximum number of hydrogens bonded to the carbons (ie
they have double bonds). Greatest called polyunsaturated.
• Saturated fatty acids
• Have the maximum number of hydrogens bonded to the carbons.
• If all three fatty acids in a fat are saturated, it is a saturated fat.
If any are unsaturated, it is an unsaturated fat.
Figure 3.4

51. Saturated vs Unsaturated Fats (cont’d)
• Most animal fats have a high proportion of saturated fatty acids, which can
be unhealthy.
• Examples: butter, lard
• Usually solid at room temperature
• Contribute to atherosclerosis and cardiovascular disease
• Most plant and fish oils tend to be low in saturated fatty acids.
• Example: corn oil, canola oil, cod liver oil
• Usually liquid at room temperature

52. Hydrogenation and Trans Fats
• Hydrogenation: Conversion
of unsaturated fats to
saturated fats by adding
hydrogen.
• Production of margarine and
peanut butter
•
Fats created by hydrogenation are unhealthy because trans fats are produced.
– Trans fats: type of unsaturated fat (shortening, margarine)
– Found in many fast food products, although now banned
– No nutritional value
– Increase risk of cardiovascular disease
– Even more unhealthy than saturated fats.

53. Steroids
• Another type of lipid.
• Different from fats in structure and function.
• Carbon skeleton is bent to form four fused rings.
• Cholesterol is the “base steroid”
from which your body produces
other steroids.
• Example: sex hormones
(testosterone, estrogen)

54. Anabolic Steroids
• Synthetic anabolic steroids are controversial.
• They are variants of testosterone.
– Some athletes use anabolic steroids to build up their muscles quickly.
• However, these substances can pose serious health risks.
• Mood swings
• Depression
• Liver damage
• High cholesterol
• Shrunken testicles, reduced sex drive, infertility

58. LIST OF REFERENCES
Slides copied from the following
sources on SlideShare:
• 2- Chemistry of Life I by tchubb on Sep 08, 2011.
http://www.slideshare.net/tchubb/2-chemistry-of-life-i?qid=c2b52b41-6c5144db-b24f-fb37d97e2acf&v=default&b=&from_search=4. Accessed:
08/03/2014. Slide no:18
• Molecules of life introby eruder on Sep 25, 2011. http
://www.slideshare.net/eruder/molecules-of-life-intro?qid=77969b92-9647492c-95e1-b85acafadc30&v=default&b=&from_search=1. Accessed:
08/03/2014. Slide no: 1-13
• 1 molecules of life by Justina, H on Sep 10, 2011.
http://www.slideshare.net/JustinaH/1-molecules-of-life?qid=77969b92-9647492c-95e1-b85acafadc30&v=default&b=&from_search=2. Accessed:
08/03/2014. Slide: 9, 10, and 22-29.

59. REFERENCE CONTINUE:
• Lecture 4 molecules of life by holmeskm on May 27, 2011.
http://www.slideshare.net/holmeskm/lecture-4-molecules-of-life?
qid=77969b92-9647-492c-95e1-b85acafadc30&v=default&b=&from_search=4.
Accessed: 08/03/2014. Slide no: 1, and 9-32
• Water by Jaya Kumar, Lecturer at KDU College Sdn Bhd on Mar 08, 2012.
http://www.slideshare.net/jayak1/water-11916115?qid=77969b92-9647-492c95e1-b85acafadc30&v=default&b=&from_search=8. Accessed: 08/03/2014