Friday, September 16, 2011

Chapter 3: The Chemical Basis of Life II

I. Summary:
In this blog post I will only be discussing proteins and nucleic acids. But don't fret! I will explain the structure of protein, nucleotides, and the difference between DNA and RNA.

First off....what is a protein? Well proteins are polymers that are found in ALL cells and play crucial roles in most processes of life. Proteins have various functions throughout the body. However, the function of a certain protein is determined by its structure. Some of these proteins include (not all are listed below):
  • Antibodies: involved in defending the body from antigens (foreign invaders); destroy antigens by immobilizing them so that they can be destroyed by white blood cells
  • Enzymes: speed up biochemical reactions (often referred to as catalysts)
  • Structural: fibrous, stringy proteins that provide support
  • Hormones: messenger proteins which help to coordinate certain bodily activities by sending signals between cells
  • Storage: store amino acids
The structure of proteins is viewed through four levels: primary, secondary, tertiary, quaternary. These levels basically break down the folding of a protein into a 3-Dimensional structure. The protein structures are very important because they DETERMINE the FUNCTION of the protein!
  • Primary Structure is referred to as the sequence of amino acids. Proteins are large polypeptides of defined amino acid sequence. The sequence of amino acids in each protein is determined by the gene that encodes it. The gene is transcribed into a messenger RNA (mRNA) and the mRNA is translated into a protein by the ribosome.
  • Secondary Structure is a local regularly occuring structure that is mainly formed through hydrogen bonds between backbone atoms. There are two types of basic secondary structures: alpha helix and beta-pleated sheets. Alpha helix and beta-pleated sheets determine the protein's characteristics and are preferably located at the core of the protein.
  • Tertiary Structure is the 3-D shape of a single polypeptide. It includes all secondary structures and any interactions involving amino acid side chains. For single polypeptide chains, this is the final level of structure.
  • Quaternary Structure involves the association of two or more polypeptide chains into a multi-subunit structure. These types of proteins are called multimeric proteins, while individual polypeptides are called protein subunits.
Nucleic acids are biological molecules essential for life because they are responsible for the storage, expression, and transmission of genetic information. Nucleic acids are broken down into two classes: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA molecules store genetic information coded in the sequence of their monomer building blocks. Molecules of RNA are involved in decoding the info from DNA. They decode this information into instructions for linking together a specific sequence of amino acids to form a polypeptide chain.

Both DNA and RNA are polymers that consist of linear sequences of repeating monomers. A single monomer is a nucleotide, and is made up of a phosphate group, five-carbon sugar (ribose or deoxyribose), and a single/double ring of carbon and nitrogen atoms (known as a base).

DNA forms a double helix, consisting of two strands of nucleotides coiled around each other. The nucleotides in DNA have deoxyribose and are presented in four different ways. It is composed of the purine bases, adenine (A) and guanine (G), and the pyrimidine bases, cytosine (C) and thymine (T). The purine bases have double rings of carbon and nitrogen, while the pyridine bases have a single ring.

RNA differs slightly from DNA because it has a single strand of nucleotide rather than a double. Unlike DNA the sugar in RNA has ribose and the pyrimidine base of thymine is replaced. In RNA this base is the pyrimidine base of uracil (U); the other bases remain the same in both nucleic acids. There are different forms of RNA, including messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). But these types of RNA shall be discussed in a later chapter (so you will just have to wait and see what they really are)!

II. Useful Materials:
This video is a song about functional groups. It differentiates between the different types of functional groups. I think the song is super catchy and fun, meaning you should listen too it! Trust me, you will not regret it!

In my previous blog post, I posted a video from this guy, who explained the chemical basis of life. Well now I found another video from the same person. In this video he is basically giving a brief overview of chapter three. He talks about isomers, functional groups, proteins, and a lot more! I enjoy watching his videos because they are very useful and also helps me study as well.

This article from Pubmed talks about how to treat dyskinesias, which is caused from levodopa. Levodopa (L-Dopa) is an amino acid that is the metabolic precursor of dopamine, and is converted in the brain to dopamine to treat Parkinson's disease. A side effect of L-Dopa is dyskinesia (the inability to control muscles). Dyskinesia can occur in several forms; most often uncontrolled flailing of the arms and legs or chorea, rapid motions that can affect the limbs, face, tongue, mouth, and neck. Anyways, this article basically explains the common surgical targets used to treat LID and the appropriate selection of patients with LID for surgery.

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