Overview
The lecture discussed the history of cell theory, its main postulates, and the different parts of the cell along with their functions.
History of Cell Theory
- Zacharias Jansen invented the first microscope in the 1590s.
- Robert Hooke was the first to use the term "cell" in 1665 after observing cork under the microscope.
- Anton van Leeuwenhoek saw "animalcules" in pond water in 1674, known as the father of microbiology.
- Matthias Schleiden (1838) stated that plants are made up of cells.
- Theodor Schwann (1839) stated that animals are also made up of cells.
- Rudolf Virchow (1855) stated that cells come from other existing cells through cell division.
Postulates of Cell Theory
- All living things are made up of cells.
- The cell is the basic unit of structure and function in organisms.
- Cells only come from other existing cells.
Modern Cell Theory (Additional Postulates)
- Cells contain genetic material that is passed on during cell division.
- All cells of the same species have the same structure and chemical composition.
- Energy flow and biochemical processes occur within the cell.
Parts and Organelles of the Cell
- Cell membrane – Outer part that serves as protection and controls substances entering and leaving.
- Cell wall – Found in plants; provides strength and shape to the cell.
- Nucleus – Contains DNA and controls cell activities; the "brain" of the cell.
- Nucleolus – Inside the nucleus and produces ribosomes.
- Ribosome – Site of protein synthesis.
- Mitochondria – The cell's "powerhouse"; produces ATP (energy).
- Endoplasmic reticulum (ER) – Has two types: rough (with ribosomes) and smooth (without); involved in making, modifying, and transporting proteins/lipids.
- Golgi body – Sorts, packages, and distributes proteins and lipids.
- Lysosome – Digests nutrients and damaged organelles; the "suicide bag" of animal cells.
- Chloroplast – Contains chlorophyll; site of photosynthesis in plants.
- Vacuole – Stores water and nutrients; maintains the shape of plant cells.
- Cytoskeleton – Framework that provides shape and movement to the cell.
Key Terms & Definitions
- Cell theory — The main theory about the structure of life; composed of three main postulates.
- Cell division — The process of a cell splitting to form a new cell.
- Organelle — Small "organs" of the cell with specific functions.
Action Items / Next Steps
- Create a cell model using art materials or recycled materials and send a photo to the teacher/tutor.
- Review the parts of the cell and their functions.
- Complete learning tasks or quizzes about cell theory and organelles.