Cell Biology, Genetics, and Biological Processes

Fundamentals of Cellular Biology

  • Cell: The basic unit of life.

  • Organelle: A specialised structure inside a cell with a specific function.

  • Hierarchy of Biological Organization: This order represents the increasing complexity of life:

    • Organelle→Cell→Tissue→Organ→Organ system→Organism\text{Organelle} \rightarrow \text{Cell} \rightarrow \text{Tissue} \rightarrow \text{Organ} \rightarrow \text{Organ system} \rightarrow \text{Organism}

Cellular Structures and Their Functions

  • Nucleus: This structure contains DNA and is responsible for controlling cell activities.

  • Cytoplasm: A jelly-like material which serves as the site where many chemical reactions occur.

  • Cell membrane: A structure that controls what enters and leaves the cell.

  • Cell wall: A rigid layer that supports and protects some cells.

  • Mitochondria: These are organelles where aerobic respiration releases energy.

  • Ribosome: The structure responsible for making proteins.

  • Chloroplast: The specific site of photosynthesis in plant cells.

  • Vacuole: A structure used to store substances. In plant cells, there is typically a large central vacuole.

Taxonomy and Cell Types

  • Prokaryotic: A cell without a nucleus; for example, bacteria.

  • Eukaryotic: A cell that possesses a nucleus; for example, plant or animal cells.

  • Bacteria: Defined as single-celled prokaryotic organisms.

  • Protist: Eukaryotic organisms that do not fit into the animal, plant, or fungi groups.

Principles of Genetics

  • DNA: The molecule that carries genetic information.

  • Gene: A specific section of DNA that contains information for a particular trait or protein.

  • Chromosome: A long, organised structure composed of DNA.

  • Genome: The collective sum of all the genetic material of an organism.

  • Allele: A version of a gene.

  • Mutation: A change in DNA.

  • Trait: A characteristic of an organism.

Biological Processes and Maintenance

  • Photosynthesis: The process by which plants use light energy to make glucose from CO2CO_2 and water.

  • Cellular respiration: The biological process that releases energy from glucose.

  • Diffusion: The movement of particles from an area of high concentration to an area of low concentration.

  • Osmosis: The movement of water across a selectively permeable membrane.

  • Active transport: The movement of substances against the concentration gradient, a process that requires the use of energy.

  • Homeostasis: The process of maintaining stable internal conditions.

  • Metabolism: The sum total of all the chemical reactions occurring in an organism.