Download Assignment No: One (1) Student details: Chebo

INFORMATION AND COMMUNICATIONS UNIVERSITY
SCHOOL OF ENGINEERING
BIOLOGICAL CHEMISTRY
An assignment submitted in partial fulfillment of the requirements for
the BA Degree in AGRICULTURAL SCIENCES
Assignment No:
One (1)
Student details:
Chebo Mukandawire
Student Identity No:
1608119912
Lecturer’s Name:
Mr. Muvwanga Maxon
Year:
1st
1. What are saturated and unsaturated fatty acids?
Saturated fatty acids are fats that contain no double bonds between the carbon atoms, so it is
saturated with hydrogen. This is the technical terminology. The important thing to remember is
that saturated fatty acids are fats that cannot break down in the body and therefore, collect in
places in the body and get stored. As saturated fatty acid collects within the body, it wreaks
havoc and causes detrimental health issues.
Some examples of saturated fatty acids are: lauric, myristic, palmitic and stearic acids. These
saturated fatty acids can be found in certain food choices that should be limited or avoided
altogether.
A fat is made of two kinds of smaller molecules: monoglyceride and fatty acids. Fats are made of
long chains of carbon (C) atoms. Some carbon atoms are linked by single bonds (-C-C-) and
others are linked by double bonds (-C=C-).Double bonds can react with hydrogen to form single
bonds. They are called saturated, because the second bond is broken up and each half of the bond
is attached to (saturated with) a hydrogen atom. Most animal fats are saturated. The fats of plants
and fish are generally unsaturated. Saturated fats tend to have higher melting points than their
corresponding unsaturated fats, leading to the popular understanding that saturated fats tend to be
solids at body temperatures, while unsaturated fats tend to be liquid oils.
Various fats contain different proportions of saturated and unsaturated fat. Examples of foods
containing a high proportion of saturated fat include animal fat products such as cream, cheese,
butter, other whole milk dairy products and fatty meats which also contain dietary cholesterol.
Certain vegetable products have high saturated fat content, such as coconut oil and palm kernel
oil. Many prepared foods are high in saturated fat content, such as pizza, dairy desserts, and
sausage.
The effect of saturated fat on risk of disease is controversial. Many reviews recommend a diet
low in saturated fat and argue it will lower risks of cardiovascular diseases, diabetes, or death.[5]
However, other reviews have rejected those arguments or advocated for examining the
proportion of saturated to unsaturated fat in the diet.
Some common examples of fatty acids and chemical structures:
Propionic acid Propanoic acid CH3CH2COOH
Butyric acid
Butanoic acid CH3(CH2)2COOH
Valeric acid
Pentanoic acid CH3(CH2)3COOH
Caproic acid Hexanoic acid CH3(CH2)4COOH
Unsaturated fat
An unsaturated fat is a fat or fatty acid in which there is one or more double bond in the fatty
acid chain.
A fat molecule is monounsaturated if it contains one double bond and polyunsaturated if it
contains more than one double bond.
Where double bonds are formed, hydrogen atoms are eliminated.
Thus, a saturated fat is "saturated" with hydrogen atoms.
The greater the degree of unsaturation in a fatty acid (i.e., the more double bonds in the fatty
acid), the more vulnerable it is to lipid peroxidation (rancidity).
Antioxidants can protect unsaturated fat from lipid peroxidation.
Foods containing unsaturated fats include avocado, nuts, and soybean, canola, and olive oils.
Meat products contain both saturated and unsaturated fats.
Unsaturated fats are liquid at room temperature.
The following are examples of unsaturated there chemical structures:
I.
Myristoleic acid
CH3(CH2)3CH=CH(CH2)7COOH
II.
Palmitoleic acid
CH3(CH2)5CH=CH(CH2)7COOH
III.
Sapienic acid CH3(CH2)8CH=CH(CH2)4COOH
2. Based on the hydrolysis products of proteins, describe the three major classes of
proteins.
Proteins are naturally occurring polypeptides. They:





contribute to the mechanical structure of animals, including humans, e.g. keratin in hair
and fingernails, and fibrous proteins such as collagen in tendons
enable animals to move, e.g. myosin in muscle
facilitate transport of smaller molecules around animals' bodies, e.g. hemoglobin
control the types and rates of chemical reactions in living things; then they are
called enzymes, e.g. amylase
are important components of the human immune system, e.g. immunoglobins
Protein structures
The sequence of amino acids in a protein is called its primary structure. Within a chain the
atoms are held together by covalent bonds. Each protein has its own characteristic sequence of
amino acids.
Three types of bonding can happen within a protein molecule (intermolecular bonding) and
between protein molecules (intermolecular bonding):

Hydrogen bonds

Covalent bonds

Ionic bonds
Protein chains arrange themselves to maximize the intra- and intermolecular bonding. The
structure when protein chains are held in place is called the secondary structure. This may be:

helical, e.g. keratin (the protein found in hair), or

pleated sheet, e.g. fibroin (the protein found in silk)
These structures are held in place by hydrogen bonds.
Protein chains may fold into a globular shape. This is the tertiary structure of a protein. These
globular proteins include enzymes and immunoglobins. The structures are held in place by
hydrogen bonds, disulfide bridges and ionic bonds.
The precise structure of a globular protein is the key to specificity of enzymes. Similarly proteins
that act as receptor sites on the cell surface can recognize specific molecules because of their
shapes.
Finally some proteins have a quaternary structure. These contain more than one protein chain.
Examples are insulin and hemoglobin.
Try these websites for a good description of formation of peptides and their primary, secondary,
tertiary and quaternary structures.
Bibliography
1. Nelson DL, Cox MM (2005). Lehninger's Principles of Biochemistry (4th ed.).
New York, New York: W. H. Freeman and Company
2. Gutteridge A, Thornton JM (2005). "Understanding nature's catalytic toolkit".
Trends in Biochemical Sciences.
3. Dobson CM (2000). "The nature and significance of protein folding". In Pain RH.
Mechanisms of Protein Folding. Oxford, Oxfordshire: Oxford University Press.
pp. 1–28.
4.
Fulton A, Isaacs W (1991). "Titin, a huge, elastic sarcomeric protein with a
probable role in morphogenesis". BioEssays.
5.
Bruckdorfer T, Marder O, Albericio F (2004). "From production of peptides in
milligram amounts for research to multi-tons quantities for drugs of the future".
Current Pharmaceutical Biotechnology.
6.
Schwarzer D, Cole P (2005). "Protein semisynthesis and expressed protein
ligation: chasing a protein's tail". Current Opinion in Chemical Biology.
7.
Kent SB (2009). "Total chemical synthesis of proteins". Chemical Society
Reviews.
8. Fernández A, Scott R (2003). "Dehydron: a structurally encoded signal for protein
interaction". Biophysical Journal.