Topics
Sexual Reproduction in Flowering Plants
- Flower
- Pre-fertilisation in Flowering Plant: Structures and Events
- Structure and Development of Anther
- Microsporogenesis
- Structure and Development of Male Gametophyte
- Pollen Viability and Storage
- Structure and Development of Ovule
- Megasporogenesis
- Development of Female Gametophyte or Embryo Sac
- Pollination
- Autogamy
- Geitonogamy
- Cross-pollination
- Agents of Pollination
- Anemophily
- Hydrophily
- Animal-Mediated Pollination (Zoophily)
- Outbreeding Devices
- Pollen Pistil Interaction
- Artificial Hybridization or Artificial Fertilization
- Double Fertilization and Triple Fusion
- Events in Sexual Reproduction > Post-Fertilization Structures and Events
- Endosperm
- Embryo
- The Seed
- Apomixis
- Polyembryony
Reproduction
Reproduction in Organisms
Human Reproduction
- Human Reproduction
- The Male Reproductive System
- The Female Reproductive System
- Gametogenesis
- Spermatogenesis
- Structure of Sperm
- Spermiogenesis
- Oogenesis
- Menstrual Cycle (Ovarian Cycle)
- Major Events of Menstrual Cycle
- Menstrual Hygiene
- Fertilisation in Human
- Implantation in Human
- Pregnancy and Embryonic Development
- Parturition (Birth) in Human
- Lactation in Human
Genetics and Evolution
Reproductive Health
- Concept of Reproductive Health
- Population Explosion and Control Measures
- Birth Control
- Natural Contraceptive Methods
- Artificial Contraceptive Methods
- Induced Abortion or Medical Termination of Pregnancy (MTP)
- Sexually Transmitted Diseases (STD) or Sexually Transmitted Infections (STI)
- Infertility
- Assisted Reproductive Technology (ART)
- Amniocentesis
- Genetic Counselling
Biology and Human Welfare
Principles of Inheritance and Variation
- Heredity and Variation
- Gregor Johann Mendel – Father of Genetics
- Mendel's Experiments on Inheritance
- Monohybrid Cross
- Punnett Square
- Back Cross and Test Cross
- Mendel's Laws > The Law of Dominance
- Mendel's Laws > The Law of Segregation (Law of Purity of Gametes)
- Exceptions to Mendel's Principles > Incomplete Dominance
- Exceptions to Mendel's Principles > Co-Dominance
- Dihybrid Cross
- Mendel's Laws > The Law of Independent Assortment
- Chromosomal Theory of Inheritance
- Linkage and Recombination
- Polygenic Inheritance
- Exceptions to Mendel's Principles > Pleiotropy
- Sex Determination
- Sex Determination in Humans
- Sex Determination in Honey Bees
- Mutations
- Pedigree Analysis
- Mendelian Disorders in Humans
- Chromosomal Disorders or Abnormalities
Environmental Issues
- Controlling Vehicular Air Pollution: a Case Study of Delhi
- Effects of Domestic Sewage and Industrial Effluents on Water
- Solid Wastes
- Radioactive Wastes
- Greenhouse Effect and Climate Change
- Ozone Depletion in the Stratosphere
- Degradation by Improper Resource Utilisation and Maintenance
- Radioactive Waste Management and E-waste
Biotechnology
Ecology
Molecular Basis of Inheritance
- Deoxyribonucleic Acid (DNA)
- Structure of Polynucleotide Chain
- Packaging of DNA Helix
- Search for Genetic Material
- Griffith’s Experiment
- Avery, McCarty and MacLeod’s Experiment
- The Hershey-Chase Experiment
- Properties of Genetic Material
- The RNA World
- DNA Replication
- Conservative Replication
- Dispersive Replication
- Semi-Conservative Replication
- Meselson and Stahl’s Experiment
- Enzymes used in DNA Replication
- Mechanism of DNA Replication
- Protein Synthesis
- Reverse Transcription (Teminism)
- Transcription
- Transcription Unit and the Gene
- Process of Transcription in Bacteria
- Process of Transcription in Eukaryotes
- Genetic Code
- Characteristics of the Genetic Code
- Mutations and Genetic Code
- tRNA – the Adapter Molecule
- Translation
- Regulation of Gene Expression
- The Lac Operon
- Human Genome Project
- DNA Fingerprinting
Evolution
Human Health and Diseases
- Concept and Determinants of Health
- Modes of Transmission of Diseases through Pathogens
- Diseases Caused by Bacteria > Typhoid
- Diseases Caused by Bacteria > Pneumonia
- Diseases Caused by Viruses > Common Cold
- Diseases Caused by Protozoa > Malaria
- Diseases Caused by Protozoa > Amoebiasis (Amoeboic dysentery)
- Diseases Caused by Helminths > Ascariasis
- Diseases Caused by Helminths > Filariasis (Elephantiasis)
- Diseases Caused by Fungi > Ringworm
- Prevention and Control of Infectious Diseases
- Immunity
- Types of Immunity > Innate Immunity
- Types of Immunity > Acquired Immunity
- Vaccination and Immunization
- Allergies
- Autoimmunity
- The Immune System
- Acquired Immuno Deficiency Syndrome (AIDS)
- Cancer
- Causes of Cancer
- Symptoms and Diagnosis of Cancer
- Prevention/Treatment of Cancer
- Drugs and Alcohol Abuse
- Addiction and Dependence
- Effects of Drug and Alcohol Abuse
- Prevention and Control of Drugs and Alcohol Abuse
Strategies for Enhancement in Food Production
Microbes in Human Welfare
Biotechnology - Principles and Processes
Biotechnology and Its Application
- Concept of Biotechnology
- Biotechnological Application in Agriculture
- Biotechnological Application in Medicine
- Transgenic Animals
- Bioethics
- Overview of Biotechnology and Its Application
Organisms and Populations
- Organisms and Their Environment
- Ecology
- Population Attributes
- Population Growth
- Life History Variation
- Population Interactions
- Negative Interactions > Predation
- Negative Interactions > Competition
- Negative Interactions > Parasitism
- Positive Interactions > Commensalism
- Positive Interactions > Mutualism (Symbiosis)
- Overview of Organisms and Populations
Ecosystem
Biodiversity and Its Conservation
Estimated time: 14 minutes
CBSE: Class 12
Introduction
- A vector is a DNA molecule that carries foreign DNA into a host cell.
- It helps replicate and maintain inserted DNA inside the host.
- Two main types: Plasmids and Bacteriophages.
CBSE: Class 12
Plasmids Vs Bacteriophages
| Feature | Plasmids | Bacteriophages |
|---|---|---|
| Basic nature | Circular DNA molecules in bacteria | Viruses that infect bacteria |
| Main use | Common cloning vectors in bacteria | Alternative DNA delivery system |
| Example | pBR322 | Bacteriophage-based vectors |
| Student note | Easy to remember for boards and NEET | Important as a standard vector category |
CBSE: Class 12
Essential Features
| Feature | Meaning | Function | Example |
|---|---|---|---|
| Origin of replication (ori) | A DNA sequence from where replication begins. | It allows the vector to replicate inside the host cell. | ori region in plasmid vectors |
| Selectable marker | A gene that helps identify transformants and non-transformants. | It allows selection of cells carrying the vector. | Antibiotic resistance genes, such as ampicillin resistance and tetracycline resistance |
| Cloning site | A specific recognition site for restriction enzymes. | It provides the position where foreign DNA can be inserted. | Restriction sites in pBR322 |
| Special host-transfer feature | A property that helps transfer DNA into special organisms such as plants or animals. | It allows successful gene transfer beyond bacteria. | Ti plasmid, retroviral vectors |
CBSE: Class 12
pBR322: A Standard Cloning Vector
- pBR322 is an important plasmid vector used in cloning.
- It contains an origin of replication, antibiotic resistance genes, and several restriction sites.
- Its antibiotic resistance genes make it useful in selection experiments.
CBSE: Class 12
Vectors and Recombinant Selection
Insertional Inactivation:
- Foreign DNA inserted into a marker gene → disrupts its function
- Used to identify recombinant vs non-recombinant colonies
Blue–White Selection:
- Based on the disruption of beta-galactosidase gene
- Blue colony = gene intact = non-recombinant
- White colony = gene disrupted = recombinant
Vectors for Plants & Animals:
- Plants → Ti plasmid (Agrobacterium tumefaciens)
- Animals → Retrovirus, SV40, Adenovirus, Papilloma virus
CBSE: Class 12
Key Points: Cloning Vectors
- Vectors (like plasmids and bacteriophages) are DNA molecules used to carry and replicate foreign DNA inside a host cell.
- An ideal vector must have an origin of replication (ori), selectable markers, and specific cloning sites.
- pBR322 is a widely used standard bacterial plasmid vector containing these essential features.
- Recombinant DNA is identified using insertional inactivation (e.g., in blue-white selection, recombinant colonies appear white due to a disrupted gene).
- Higher organisms require specific vectors: Ti plasmids for plants and modified retroviruses for animals.
