Are The Four Macromolecules Do You Believe To Be The Most Important For Life

PROTEINS AND NUCLEIC ACIDS
28/11/13
Qn. Which two of the four macromolecules do you believe to be the most important for life? Give evidence to support your suggestion (include a full description of the macromolecules you describe both in terms of structure and function)
Introduction
All the four macromolecules=lipids, proteins, carbohydrates and nucleic acids= are essential for the functioning of an organism 's body (Campbell, biology). They work hand in hand to help us survive. For example, Lipids are an immediate energy source. ATP, for example, is used by the body when in energy deficit. Proteins are needed to form muscles and bones. Carbohydrates are the main energy source for the body. Without this energy, we would not be able to
function. And finally, Nucleic Acids contain the DNA required to make us who we are. Without DNA, we would not be alive.
It is obvious that without these four macromolecules we would not exist. However from the four of them, I believe proteins and nucleic acids to be the most important as they both carry out major functions in our bodies.
PROTEIN
Structure of proteins
Proteins are polymers composed of 20 amino acids which are joined together by a peptide bond which forms a polypeptide chain.
A polypeptide coiled into a specific 3-dimensional shape makes a protein. (Campbell, biology, pp78)
Proteins are divided into two classes: fibrous and globular proteins. Globular proteins are compact, soluble, and spherical in shape, while Fibrous proteins are elongated and insoluble. Globular and fibrous proteins may sometimes display different types of protein structure. These structure types are; primary, secondary and tertiary structure (Campbell biology, pp82-83)
1. Primary structure
Primary structure refers to the unique order of amino acids to form a protein.Protein is constructed from 20 amino acids. All amino acids have a hydrogen atom (H), carboxyl group (-COOH), and an amino R group. The R group is the one that determines the difference between proteins because it varies for every protein
structure.
2.
Secondary structure
The structure involves the folding and coiling of the polypeptide chain to give protein its 3-dimensional shape. Protein has two types of secondary structure; the alpha (α) helix and the beta (β) pleated sheet, refer to figure 3. The α helix is coiled and held together by a hydrogen bond in the polypeptide chain, whereas the beta sheet has pleated sheets of the "polypeptide chain lying side by side and connected by hydrogen bonds"(Campell,Biology,pp82 )
3. Tertiary structure
Tertiary structure focuses on the polypeptide and the interaction between the R groups of the various amino acids. There are many interactions but I am going to discuss only two. The first interaction is called Hydrophobic-Hydrophobic interaction. In this interaction, the R groups of the protein are either hydrophobic or hydrophilic. The Hydrophilic R groups want a water environment while hydrophobic R groups repel water environments. Hydrogen bonding is the second interaction. This exists between polypeptides and R groups to help the protein stick together, thus to maintain its shape and stability.

Importance of
proteins
Proteins are essential for all cell functions. Proteins have a specific role in the body which is vital for our survival. In fact, except for water, protein is the most abundant substance in the body (Janice R. Hermann, Protein and the body).The three main functions of proteins that I believe to be important are: protection against disease, provision of structural support and transportation of substances.
1. Protect against disease
Proteins produce antibodies that help to fight infections and disease. They work in connection with the immune system by recognising antigens and binding to them until they are destroyed by white blood cells. Antibodies are produced by B lymphocytes which develop in the bone marrow.
2. Structural support
Fibrous proteins provide mechanical support to the cell. For example keratin, a protein for the hair provides a protective covering for the hair. "Collagen and elastin provide a fibrous framework in animal connective tissues"(Campbell biology, pp78).In eukaryotic cells, that are bigger, mechanical support is mostly required. Microtubules, Micro filaments and intermediate filaments are responsible for providing a cytoskeleton for the cell. Microtubules maintain the cell’s shape by forming "compression-resisting girders’’ (Campbell, Biology). Microfilaments allow cell locomotion for the cell. And finally intermediate filaments are strong fibres that provide support inside the cell.
3. Transport substances
Proteins move molecules from one part of the body to another part where they are effective. For example haemoglobin transports oxygen from the lungs to other parts of the body through the blood.
NUCLEIC ACIDS
Structure of Nucleic Acids
Nucleic acids are important molecules as they carry the information for living organisms. They consist of nucleotides; thymine (T), Adenine (A), cytosine(C), Guanine (G) and Uracil (U). They also consist of a carbon sugar (ribose) and a phosphate group.
Nucleic Acids are divided in to DNA (deoxyribonucleic) and RNA (ribonucleic acid).
1. DNA: Is composed of two complimentary polynucleotide strands coiled together to form a double helix. The strands have anti-parallel paired nitrogenous bases, namely Adenine, Cytosine, Thymine and Guanine, which are held together by hydrogen bonding.
a. Importance of DNA
Every cell in an organism’s body contains DNA and this enables the growth and repair of body cells.
DNA is biologically vital for life because it stores information (genes) which define our identity, nature, behaviour and individuality.
The majority of police and investigation agencies depend upon DNA tests when solving crime.
2. RNA: Is a single stranded polynucleotide. It is almost similar to DNA but instead of having thymine, it has Uracil, as well as a ribose sugar instead of 2-deoxyribose.There are 3 there subtypes of RNA, they include: mRNA, tRNA and rRNA mRNA: Is a molecule that is responsible for carrying instructions (about what protein to make) from the nucleus to the cytoplasm. tRNA: Transfers amino acids to the ribosome which code for the production of proteins. rRna: Combines with ribosome to make protein by translating the coded amino acids sequences.
b. Importance of RNA
RNA is involved in the production (synthesis) of protein. Protein is needed for the growth and repair of the body.RNA also acts as an enzyme (called ribozyme) to speed up chemical reactions in the body.
Conclusion
In conclusion, Proteins and Nucleic acids in my opinion are the most important macromolecules amongst all the four macro molecules. Proteins build our muscles and are vital for bone growth. On the other hand Nucleic acids contain DNA that defines our individuality and uniqueness.

Bibliography
Campbell Reece, Biology, Eighth edition, Benjamin Cummings, 2008.
Janice R. Herman. Protein and the body. Oklahoma Cooperative Extension Service.