Through a series of condensation reactions, many amino acid monomers can be joined together in a process called polymerisation, resulting in a polypeptide. The sequence of amino acids in a polypeptide chain forms the primary structure of any protein. This primary structure determines the ultimate shape and hence the function of the protein. The secondary structure is the shape which the polypeptide chain forms as a result of hydrogen bonding. This is most often an alfa-helix or beta-pleated sheet.
When several monosaccharides are bonded together a polysaccharide, or complex sugar, is created. Polysaccharides are the polymers of carbohydrates. Proteins are made up of monomers called amino acids. There are twenty amino acids and they can be strung together in unique combinations known as polypeptide chains, the polymer unit for proteins. A protein is only complete and functional when the polypeptide chain is folded into a unique 3-D shape, a concept discussed in your textbook.
In organic chemistry, the carbon directly attached to a carboxyl group is the alpha (α) position, so the amino acids in proteins are all alpha-amino acids. The side chains that distinguish one amino acid from another are attached to the alpha carbon, so the structures are often written as shown in Figure 1 , where R stands for one of the 20 side chains The side chains of amino acids give them their different chemical properties and allow proteins to have so many different structures. Each α-amino acid consists of a backbone part that is present in all the amino acid types, and a side chain that is unique to each type of residue. An exception from this rule is proline. Because the carbon atom is bound to four different groups it is chiral, however only one of the isomers occurs in biological proteins.
Ribosomes Ribosomes are small spherical organelles, composed of two subunits, which can be found on the Rough Endoplasmic Reticulum (and also in the cytoplasm and in mitochondria, and other places). Attached to a network of membranes. Where protein synthesis takes place. Ribosomes translate genetic information in the form of mRNA into proteins. Rough ER (Endoplasmic Recticulum) The Endoplasmic Reticulum (ER) is found near the Nucleas and is made up of a number of flattened sacs called Cisternae, which are continuous with the Nuclear Envelope.
This consists of 66 exons spread over 235 kb of genomic DNA. The spliced mRNA is 9749 nt long. When ribosomes start translating the mRNA the first 27 amino acids produced (the signal peptide) bind to the endoplasmic reticulum. The 2781 amino acid polypeptide is then injected into the lumen of the endoplasmic reticulum as it is synthesized. Here the signal peptide is cleaved off, the chain folds into more than 50 structural domains, each held together by multiple S–S bridges between cysteine residues and sugars are attached to 14 asparagine residues.
The primary structure of a protein consists of amino acids joined together by peptide bonds in a specific sequence, which differs for each type of protein. This primary structure can then fold into one of two main types of structure, β-sheets or α-helix, creating the secondary structure of the protein, which is held in place by hydrogen bonds. The β-sheets and α-helixes are folded into a compact globular structure called the tertiary structure, which is held together by bonds formed between the R- groups of amino acids. There are many types of bonds that occur in the tertiary structure such as disulphide bonds, hydrogen bonds and ionic bonds. If a protein is made up of several polypeptide chains, the way they are arranged is called the quaternary structure.
These proteins consist of macromolecules which are polymers consisting of one or more chains that are un-branched from monomers that are called amino acids. This molecule consists of both an amino and a carboxyl group. Proteins can contain from as few as three to fifty-thousand amino acid units and range from shape and form, to being completely soluble or insoluble to water solutions. When a protein is formed it is linked together by a peptide bond using covalent bonds to form between an amino group of one amino acid and a carboxyl group. Similarly dipeptides are formed when the peptide bond joins the two amino acids.
This energy is then in turn used by the cell to carry out various functions. Nucleus- The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle. Nucleolus- This takes up around 25% of the volume of the nucleus. This structure is made up of proteins and ribonucleic acids (RNA). Its main function is to rewrite ribosomal RNA (rRNA) and combine it with proteins.
The nucleic acid, DNA has an individual structure that act as an information storage molecule that provides instuction for assembling proteins. DNA’s primary structure involves nucleotide sequences that are monomer repeats which form polynucleotide chains. The Primary structure of DNA begins with one of the two different 5 -carbon sugar components either known as 2-deoxyribose. The particular sugar can then either be linked to a hetrocyclic base by an N – Glycosidic bond. The hetrocyclic bases are derived from two different structures which inculde Purine and Pyrimidine.
Macromolecule: Nucleic Acid Examples: DNA- Its sugar is deoxyribose; its nitrogenous bases are Adenine, Guanine, Cytosine & Thymine; the number of nucleotides in a molecule is more than 45 million; its shape resembles paired strands coiled in a double helix; and its function is to store genetic information that controls protein synthesis. RNA- Its sugar is ribose; its nitrogenous bases are Adenine, Guanine, Uracil & Cytosine; the number of nucleotides in a molecule is between 100 to 50 thousand; its shape varies with hydrogen binding along the length of the strand with three types: mRNA, tRNA & rRNA; and its function is to perform protein synthesis as directed by DNA. Structure: Nucleic acids contain carbon, oxygen, hydrogen, nitrogen and phosphorus with one or two long chains of nucleotides formed by dehydration synthesis. Each nucleotide has three components covalently bound together: a pentose (a five carbon sugar) attached to both ribose (RNA) and deoxyribose (DNA); a phosphate group; and a nitrogenous base (adenine, guanine, thymine, cytosine & uracil-which replaces thymine in RNA). All nucleic acids have two distinctive ends: the 5’ (5-prime) and 3’ (3-prime) ends, which refers to the carbons on the sugar.