Cytology: The Study of Cells

Study Notes

Cytology and Cell Structure

Cytology is the science that studies cells, which are the units of composition and function in living organisms.
The discovery of the microscope by Anthony Levinhock enabled the observation of cells and the discovery of microorganisms like bacteria and yeast.
Cells vary in size, but are too small to be seen with the naked eye, requiring the use of a microscope to study them.

Cell Theory

The cell theory, proposed by Botanist Mathias Schleiden and Zoologist Theodor Schwann, states that:
- All living things are composed of one or more cells.
- The cell is the basic unit of life.
- New cells arise from existing cells.

Cell Structure

All cells share four common components:
- Cytoplasm: where cellular components are found.
- DNA: the genetic material of the cell.
- Plasma (cell) membrane: an outer covering that separates the cell's interior from its surroundings.
- Ribosome: responsible for protein synthesis.

Types of Cells

Prokaryotic Cells

Simple cells, found in bacteria and archaea (unicellular organisms).
Lack a nucleus and membranous organelles.
DNA is found in the central part of the cell, called the nucleoid.
Cell wall is made up of peptidoglycan and has a capsule made up of polysaccharide.
Functions of the cell wall:
- Prevents dehydration.
- Provides extra layer for protection.
- Helps maintain cell shape.
Functions of the capsule:
- Enables cell attachment to surfaces.
- Some prokaryotes have flagella for locomotion and pili for genetic material exchange during conjugation.

Eukaryotic Cells

More complex cells, found in animals, plants, fungi, and protists.
Have a true nucleus and membranous organelles like mitochondria, endoplasmic reticulum, Golgi, and chloroplasts.
Have several rod-shaped chromosomes.

Cell Components

Nucleus

Contains genetic material DNA in the form of filaments.
Usually spherical in shape, with a large size.
Surrounded by a nuclear envelope composed of two layers of membranes separated by 20-40nm.
Nuclear pores form where the two layers merge.
Functions of the nucleus:
- Contains genetic material inherited from one cell to another during division.
- Regulates cell activity.

Cytoplasm

Located between the cell membrane and the nucleus.
Composed of about 80% water, 15% proteins, and 5% fats, sugars, and mineral salts.
Cytoplasm is the medium in which chemical reactions occur.
Cytosol is the part of cytoplasm that does not contain organelles.
Functions of cytoplasm:
- Most important cell activities occur in cytoplasm.
- Gives the cell its shape and helps maintain organelle position.
- Without cytoplasm, the cell would be deflated.

Description

Explore the science of cytology, which focuses on studying the structure and function of cells. Learn about the history of cytology, including the role of the microscope in discovering the complexity of cell structure. Dive into the significance of cells as the fundamental unit of life.