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.
These charged molecules combine with oxygen and produce ATP molecules. This process is known as oxidative phosphorylation. Ribosomes: the ribosomes are the cellular component that make proteins from all amino acids. Ribosomes are made from complexes of RNAs and proteins.They assemble amino acids to form specific proteins, proteins are essential to carry out cellular activities. Rough endoplasmic reticulum: The surface of the rough endoplasmic reticulum is studded with the protein manufacturing ribosome, which gives it a rough appearance.The rough
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.
As this bonds are the ones that join the individual amino acid residues in a protein the biuret reagent can effectively confirm the presence of protein in a substance. A polypeptide is a single linear polymer chain from the condensation of amino acids.. The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids. There are seven main groups of proteins, this groups are: structural proteins, storage proteins, defensive proteins, transport proteins, signal proteins, contractile proteins, and enzymes.
The primary structure is unique to a given protein. The primary structure can fold regularly to form either an α-helix or β-pleated sheet. The secondary structure is held together by hydrogen bonds between adjacent peptide bonds. The primary structure can further fold to form an overall three dimensional shape that more specifically determines the biological functions of the individual protein. This 3D structure is held together by bonds formed between the R-groups of amino acids.
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.
A polynucleotide has a free phosphate group at one end and a free OH group at the other end. Structure of DNA: The main features of the three-dimensional structure of DNA are: • DNA is double-stranded, so there are two polynucleotide stands alongside each other. • The two strands are wound round each other to form a double helix. • The two strands are joined together by hydrogen bonds between the bases. The bases therefore form base pairs, which are like rungs of a ladder.
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.
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.