Fundamentals of Microscopy Techniques and Cell Theory
History of Optical Microscopy
Key Milestones
- 1611: Johannes Kepler suggests how to construct a compound microscope.
- 1655: Robert Hooke publishes Micrographia, introducing the concept of the cell.
- In parallel, Antonie van Leeuwenhoek built more than 200 microscopes (simple magnifying glasses).
Early Optical Microscopy Pioneers
Robert Hooke (1655)
In 1655, Robert Hooke observed a piece of cork under his self-built microscope. He used the word cell to describe the small, closed compartments he noted.
Antonie
Read MoreDNA Replication and RNA Transcription in Prokaryotes and Eukaryotes
DNA Replication in Prokaryotes
In bacteria, in addition to the main DNA molecule, there are small circular DNA molecules called plasmids. These plasmids may or may not replicate simultaneously with the main chromosome using a similar mechanism. All plasmid DNA introduced into bacteria must possess a replication origin sequence to be multiplied by the replication machinery.
Eukaryotic DNA Replication Complexity
In eukaryotes, the rate of replication of nuclear DNA is more complex than in bacteria for
Read MoreComparative Anatomy: Digestion, Circulation, and Homeostasis
Primitive Digestion: Intracellular Systems
The Porifera (sponges) are primitive organisms that lack true tissues or organs. They perform the digestion of food particles in specialized cells called choanocytes. Food, carried by water, penetrates through pores. The beating of the flagellum pushes water toward the collar, and food is captured by endocytosis. The resulting vacuole fuses with digestive enzymes from lysosomes. Undigested waste is expelled by exocytosis (intracellular digestion).
The primary
Read MoreCardiovascular System Anatomy: Blood Vessels and Heart Structure
Blood Vessels: Structure and Labeling
Figure 1: Blood Vessel Anatomy
Instruction: Complete the labels of Figure 1 using the following terms: venules, capillaries, valves, arterioles, artery, vein.
Answer Key: A: Artery, B: Arterioles, C: Capillaries, D: Venules, E: Valves, F: Vein
Figure 2: Blood Vessel Cross-Section
Instruction: Complete the labels of Figure 2 using the following terms: vein, capillary, artery (you will need to use some terms more than once).
Answer Key: A: Artery, B: Vein, C: Capillary,
Read MoreFood Chains, Production Methods, and Preservation Techniques
The Food Chain Structure
The food chain describes the transfer of energy between organisms. It is typically divided into three main links:
First Link: Producing Organisms (Autotrophs)
These organisms, primarily vegetables, are autotrophs, meaning they produce their own food.
Second Link: Consumer Organisms (Heterotrophs)
These are heterotrophic beings that consume other organisms. They are categorized by their diet:
- Primary Consumers: Herbivores.
- Secondary Consumers: Such as reptiles or fish, which consume
Human Reproduction: Anatomy, Life Stages, and Sexual Health
1. Reproduction and Sexuality Fundamentals
Reproduction is a key function: the birth of new individuals. Sexual reproduction is characterized by two main features:
- The new individual is formed from a single cell, called a zygote.
- A zygote originates from the union (fertilization) of two gametes (sex cells).
While male and female reproductive systems are different, they both have gonads. Humans have two kinds of gametes: sperm and ova.
Key characteristics of human sexual reproduction:
- Maturation into an