DAMAGE AND REPAIR Introduction to DNA Damage and Repair: DAMAGE Types of Damage: Damage to DNA includes any deviation from the usual double helix structure. 1. Simple Mutations: 2. Deamination: 3. Missing Bases: 4. Chemical Modification of Bases: 5. Formation of Pyrimidine Dimers (Thymine Dimers): 6. Strand Breaks: Repair Mechanisms: 1. Direct Repair: 2. Excision … Read more
REPLICATION Semi-conservative replication of Chromosomes in eukaryotes: Theoretically, there may be following three possible modes of DNA replication: Semiconservative mode is the most accepted of all. DNA Replication is Semi-Conservative: Meselson and Stahl Experiment: Fig. Semiconservative replication. STEPS OF DNA REPLICATION DNA-Replication Stages of Replication The DNA synthesis or replication can be divided into three … Read more
A, B and Z forms Right handed DNA 1. ‘A’-DNA 2. B’-DNA or Right handed DNA 3. ‘C’-DNA and ‘D’-DNA 4. ‘Z-DNA or Left handed DNA MCQs on Right-Handed and Left-Handed DNA 1. What is the length of the helix in A-DNA? a) 34 Åb) 28.15 Åc) 20.2 Åd) 31 Å 2. How many base … Read more
DNA STRUCTURE DNA STRUCTURE – Biochemical composition of DNA (1) A pentose sugar -the 5 carbon deoxyribose sugar (2) 2. Phosphoric Acid (H₃PO₄) (3) Nitrogenous base-a heterocyclic ring containing nitrogen 1. Pentose sugar molecule These are Two type – (2) 2. Phosphoric Acid (H₃PO₄) 3. Nitrogenous bases (a) Purines and (b) Pyrimidines. (a) Purines : … Read more
NUCLEOSOME ORGANIZATION Important points of this model are as follows: SOLENOID MODEL: Ubiquitination, acetylation, methylation and phosphorylation of histones in the nucleosome. 1-10: Basic Concepts of Nucleosome Organization 11-20: Solenoid Model and Higher Order Chromatin Structure 21-30: Histone Modifications in Chromatin Regulation 31-40: Chromatin Structure and Function 41-50: Chromatin Compaction and Higher-Order Organization
Nuclear Pores 1. Introduction to Nuclear Pores Nuclear pores are large protein complexes that penetrate the nuclear envelope, regulating the movement of molecules between the nucleus and cytoplasm. These pores are essential for cellular communication, gene expression, and protein synthesis. 🔹 Found in all eukaryotic cells🔹 Composed of a nuclear pore complex (NPC)🔹 Act as … Read more
NUCLEUS STRUCTURE OF NUCLEUS 1. Nuclear Membrane: 2. Nucleoplasm: Functions : 3. Chromatin Net or thread : Heterochromatin : Euchromatin : 4. Nucleolus : Ultrastructure : I. Fibrillar regions: Ii. Granular regions : Iii. Protein region: iv.Chromatin part: a) Perinucleolar Chromatin: b) Intra-nucleolar chromatin: Functions of Nucleolus Functions of Nucleus NUCLEOLUS cycle & NUCLEOLOGENESIS … Read more
Tonoplast membrane, ATPase, transporters, asstorage organelle. The tonoplast membrane, also called the vacuolar membrane, is a selectively permeable phospholipid bilayer that surrounds the vacuole in plant cells, fungi, and some protists. It acts as a gatekeeper, regulating the transport of ions, nutrients, and waste products between the cytoplasm and the vacuole. The tonoplast plays a … Read more
Vacuole Structure of Vacuoles Types of Vacuoles MCQs on Vacuoles Basic Concepts Types of Vacuoles Functions of Vacuoles Vacuoles in Different Organisms Miscellaneous
Biogenesis of Mitochondria Mitochondria are essential organelles responsible for cellular respiration and energy production. They primarily arise through the growth and division of pre-existing mitochondria or from promitochondria. Microscopic evidence strongly supports this theory. Observations under a phase-contrast microscope have revealed mitochondria in the process of dividing. Additionally, electron microscopy studies on green algae Micromonas—which … Read more
