Biospace

Structure of Nucleic acids DNA and RNA form the genetic material of all living organisms. They store the information in biochemical form. What is a gene?   A gene is a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein.  The genes are expressed by two important process - Transcription of genes from DNA to RNA and then Translation of Genes into Proteins. While DNA makes multiple copies of itself by the process of DNA replication. We will discuss all of them in detail later. Structure of DNA  DNA is a double helical structure. J.D. Watson  and F.H.C. Crick proposed the three-dimensional model of physiological DNA in 1953 on the basis of X-ray diffraction studies of DNA obtained by Franklin and Wilkins. They gave the structure of B- DNA.  The important features of Watson – Crick Model or double helix model of DNA are as follows: 1. The DNA molecule consists of two polynucleotide chains or strands that spirally tw

Now we will study the Cyanobacteria.... CYANOBACTERIA These are blue-green bacterias  photosynthetic , mostly photolysis mediated oxygen evolveing prokaryotes Come among the oldest organisms Thallus ranges from unicellular , colonial to filamentous, multiseriate branched filamentous condition Their distinguishing characters are- Grow on diverse habitats for they have dual-capacity of oxygenic as well as facultatively anoxygenic photosynthesis. possess various morphologically distinctive structures like akinetes and heterocyst. cell wall is made up of peptidoglycan cyanobacterial cytoplasm is covered extensively by flattened vesicular structures called thylakoids or lamellae which are the photosynthetic sites Pigments present are-Chlorophyll-a , Beta-carotene , phycobiliproteins (which include phycocyanin , allophycocyanin , phycoerythrin and allophycocyanin B) . Some are motile and some show gliding movement when not having flagella. Ultrastructure of cyanobacte