Page 1 Overview

Key Cell Structures

• Organelles: Fundamental components of cells.

  • Mitochondria: Powerhouse of the cell, generates ATP.

  • Chloroplasts: Site of photosynthesis in plant cells.

• Cell Wall:

  • Characterizes plant cells and bacteria.

  • Composition of Cell Walls:

    • Plant Cell Walls: Made of cellulose.

    • Fungi Cell Walls: Composed of chitin.

    • Bacteria: Cell wall contains cell membrane and provides shape.

• Cell Properties:

  • Contains methods for waste excretion, reproduction, and cellular differentiation.

Cellular Differentiation

• Tissues Formation:

  • Groups of similar cells form tissues, which then differentiate into organs.

Nucleic Acids

• Types: RNA and DNA, crucial for genetic function and protein synthesis.

• Importance of the Nucleus: Houses genetic material and regulates cellular processes.

Chromatin and Chromosomes

• Chromatin: Made of chromosomes, highly coiled due to space constraints.

• DNA Structure: Comprised of deoxyribose nucleic acid, and made up of nucleotides.

Page 2 Details

DNA Structure and Mutation

• Nucleotide Composition: Consists of three parts:

  1. Sugar: Deoxyribose (in DNA), ribose (in RNA).

  2. Phosphate: Forms the backbone of DNA.

  3. Nitrogenous Bases: Adenine, Guanine, Cytosine, Thymine (A-T, G-C pairing).

• Mutation: Change in the DNA sequence due to interrupted nucleotides.

Gene Function

• Genes: Segments of DNA that contain instructions for building proteins.

• Hydrogen Bonds: Hold nucleotide bases together, stabilizing DNA structure.

Pollution and Nitrogen in Organisms

• Nitrogen Cycle: Animals excrete nitrogenous waste; decomposes back into soil.

• Atmospheric Composition: 78% nitrogen, 20% oxygen, 2-3% carbon dioxide.

Malaria Study

• Cause of Malaria: Female Aedes mosquito as a vector.

• Plasmodium: Organism found in infected individuals.

• Scientific Observation: Hypothesis transitioning to theory under investigation.

Page 3 Disease Types

Infectious vs. Non-infectious Diseases

• Infectious Diseases: Caused by microorganisms.

• Vector-borne Infections: e.g., Malaria transmitted by mosquitoes.

• Cancer: Can be linked to viruses but not always transmissible.

Types of Infections

• Categories:

  • Bacterial: e.g., sore throat.

  • Protozoan: e.g., malaria.

  • Viral: e.g., coronavirus, acne.

• Brain-eating Amoeba: Example of nematode action in infections.

Evolution and DNA Structure

• Importance: DNA structure crucial for evolutionary biology.

• Electron Microscope: Helps in the study of nanoscale structures.

Theories of Galaxy Dynamics

• Types of Theories:

  • Cyclic Theory: Big Bang after billions of years.

  • Exclusion vs. Expansion Theory: Different models of cosmic expansion.

  • Steady State Theory: Replacement of old stars by new ones.

• Milky Way: Described as a spiral galaxy.

Stellar Composition

• Stars: Composed of energy and undergo fusion to emit light.

• Planetary Motion: Planets revolve around stars due to gravitational forces.

• Types of Nuclear Reactions: Fusion and fission.

Page 4 Planetary Overview

The Solar System

• Mercury: Closest and smallest planet; no moons.

• Venus: Similar to Earth; high temperatures and no moons.

• Earth: Largest terrestrial planet; known as the Blue Planet.

• Mars: Known as the Red Planet; has two moons, no water.

• Jupiter: Largest; made of hydrogen and helium, with 16 moons.

• Saturn: Second largest; known for its prominent rings and 22 moons.

• Uranus: Green planet with 15 moons.

• Neptune: Similar to Uranus with 2 moons.

• Pluto: Smallest and most distant planet.

Earth's Structure

• Layers of Earth:

  • Crust: Two types (oceanic and continental).

  • Mantle: Divided into upper (asthenosphere) and lower mantle.

  • Core: Made of iron (solid inner and liquid outer core).

• Atmospheric Composition: Nitrogen, oxygen, and carbon dioxide present; ozone layer is crucial for protection.