Introduction to Microbiology and Cell Biology

Flashcards covering the history of microscopy, cell structure, organelle functions, and the differences between prokaryotic and eukaryotic cells.

Lens

A small piece of glass that is thick in the middle and thin at the edge, used to make objects look bigger.

Hans and Zacharias Janssen

Dutch spectacle makers who developed the first compound microscope around 1590.

Robert Hooke

A scientist who observed cork cells in 1665 and published his findings in a book called Micrographia.

Antonie van Leeuwenhoek

Known as the father of microbiology, he was the first person to observe living micro-organisms such as bacteria and protozoa in the 1660s.

Cell

The basic structural and functional unit of life.

Cell wall

The outermost covering of a plant cell made mainly of cellulose; it provides protection, shape, strength, and prevents the cell from bursting.

Cell membrane (Plasma membrane)

A flexible, selectively permeable layer inside the cell wall that separates the cell contents from the external environment and helps in communication.

Cytoplasm

A jelly-like fluid within the cell containing water, salts, and proteins; it holds organelles and is the site of many chemical reactions.

Nucleus

The control center of the cell, discovered by Robert Brown in 1831.

Nuclear Membrane

A double-layered membrane surrounding the nucleus containing tiny pores to allow the movement of substances in and out.

Nucleoplasm

A jelly-like fluid present inside the nucleus.

Chromatin reticulum

A thread-like network present in the nucleoplasm that condenses to form chromosomes during cell division.

Chromosomes

Structures composed of $DNA$ and proteins that store hereditary information; humans have $46$ ($23$ pairs) in each body cell.

DNA

Abbreviation for deoxyribonucleic acid, the chemical component of chromosomes.

Genes

Small units present in chromosomes that carry hereditary information.

Nucleolus

A dense spherical body inside the nucleus involved in the formation of ribosomes.

Vacuole

A sac-like structure filled with cell sap (water, sugar, salts, pigments, and waste) that maintains turgor pressure to keep plants upright.

Chloroplast

A green-coloured organelle found only in plants and algae that contains chlorophyll and serves as the site of photosynthesis.

Mitochondria

Rod-shaped organelles known as the "power house of the cell" where cellular respiration occurs to produce $ATP$.

Endoplasmic Reticulum (ER)

A network of membrane-covered tubes; Rough ER has ribosomes for protein synthesis, while Smooth ER helps make fats and detoxify substances.

Ribosomes

Tiny structures found in the cytoplasm or on Rough ER, often called "protein factories" for their role in protein synthesis.

Golgi Apparatus

A stack of flattened sacs that modifies, packages, and transports proteins, acting as the cell's packaging and distribution center.

Prokaryotic cells

Simple, small cells without a true nucleus or membrane-bound organelles, containing a single circular $DNA$ molecule (e.g., bacteria).

Eukaryotic cells

Larger, more complex cells with a true nucleus enclosed by a nuclear envelope and membrane-bound organelles (e.g., plants, animals, fungi).

Levels of Organization

The hierarchy of structure in living organisms: Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ system $\rightarrow$ Organism.