3.1) Prokaryotes and Eukaryotes

Anton Van Leeuwenhoek

a Dutch scientist known for his works with microscopy and considered one of the pillars of microbiology.

Robert Hooke

English scientist who first observed cells and also coined the term due to the appearance of what he saw as being those of a honeycomb shape.

Light microscope

Most common type of microscope

Cell theory

Through microscopes this concept was born. It is the idea that living organisms are composed of basic, structural units called cells.

1. All living organisms are composed of one or many cells.

2. Cells are the basic unit of structure and organization in organisms.

3. Cells must come from pre-existing cells.

Give the 3 main ideas of cell theory

1. DNA is passed between cells during cell division.

2. All cells of organisms have the same basic chemical composition.

3. Energy flow occurs within cells.

Advancements in technology also added 3 more concepts with regared to the cell theory, these are:

1. Prokaryotic

2. Eukaryotic

What are the 2 types of cell?

1. Plasma membrane

2. Cytosol

3. Chromosomes

4. Ribosome

What components do all cells share in common?

Plasma membrane

• serves as an outer covering that protects the insides of a cell from its surrounding environment.

• It is usually composed of phospholipids arranged in a bilayer;

Cytosol

fluid region in the cell where other cell components are found

Chromosomes

structures that contain genetic material in the form of DNA

Ribosomes

Particles that synthesize proteins

Cytoplasm

This refers to the inside of both cell types but in eukaryotic cells, this refers to the region between the nucleus and the plasma membrane.

Permeable

This term is used to describe a material that allows all substances (both large and small molecules) to pass through it freely.

Plasma Membrane

• A semi-permeable layer that separates the insides of a cell from the external environment

• the location of chemical exchanges for many life functions.

Cytoplasm

The fluid internal environment of the cell where all internal components of the cell (called “organelles”) are suspended.

Nucleus

Stores the genetic material of the cell.

Nucleoid

In prokaryotes, this genetic material is located in a region called the _______?

Nuclear Membrane

Encloses the nucleus and protects the genetic material.

Nucleoplasm

The environment within the nucleus.

Nucleolus

An area in the nucleoplasm where the genetic material is highly concentrated.

“Highly concentrated genetic material" means there's a lot of DNA in a specific area, often packed tightly for organization, storage, or efficiency in processes like cell division or gene expression.

Nuclear Pore

Gateway of materials into or out of the nucleus

Mitochondrion

Produces energy for the organism, having the moniker “powerhouse of the cell" due to this function.

Endoplasmic Reticulum (ER)

Sites for lipid and protein synthesis.

Rough ER

• Contains ribosomes

• site for protein synthesis

• In addition, it also functions as the cell’s membrane-making machine.

Smooth ER

Contains cell types used in metabolic processes, especially lipid synthesis, as well as storage of calcium ions.

Golgi Apparatus

Site for modifying, sorting, and storing of compounds synthesized by the ER.

Lysosome

Contains digestive enzymes that help break down food or damaged organelles.

Peroxisome

Helps break down fatty acids to be used as cellular fuel.

Ribosome

• Sites of protein synthesis.

• Can be found attached to the rough ER or free in the cytosol.

Vacuoles

Storage of food and other chemicals.

Centriole

Organelle for cell division.

Prokaryotes

refers to organisms with cells that are simple, often single (unicellular), and lack a nucleus, or any other membrane-bound organelle.

Its DNA is found in the central part of the cell: a darkened region called the nucleoid.

How different are prokaryotes and eukaryotes?

1. Bacteria

2. Archaea

What are the two distinct groups of prokaryotes?

Peptidoglycan

What do we call the cell wall of bacteria?

• it is composed of sugar and amino acids

• Have many polysaccharide capsule

• This cell wall acts as an extra layer of protection, helping maintain cell shape, and preventing dehydration

Bacteria

Identify which type of prokaryote:

✅ Description:

• Most common and widespread prokaryotes.

• Found in soil, water, air, and inside living organisms.

• Can be harmful (pathogenic) or beneficial (e.g., gut bacteria).

Bacteria

Identify which type of prokaryote:

🔧 Structure / Parts:

• Cell wall made of peptidoglycan

• Plasma membrane

• Cytoplasm with ribosomes

• Nucleoid (region containing circular DNA)

• May have:

  • Capsule (for protection, attchment to surface)

  • Flagella (for locomotion)

  • Pili (for attachment, exhange genetic material)

  • Plasmids (extra DNA)

Bacteria

Identify which type of prokaryote:

🧪 Examples:

• Escherichia coli (E. coli) – lives in human intestines

• Streptococcus pneumoniae – causes pneumonia

• Lactobacillus – used in yogurt production

Conjugation

the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. This takes place through a pilus. It is a parasexual mode of reproduction in bacteria.

Archaea

Identify which type of prokaryote:

✅ Description:

• Look similar to bacteria but are genetically and chemically different.

• Often live in extreme environments (heat, salt, acid).

• Considered ancient life forms.

🔧 Structure / Parts:

• No peptidoglycan in cell walls (unlike bacteria)

• Plasma membrane has unique lipids

• Cytoplasm, ribosomes, and nucleoid like bacteria

• May also have:

  • Flagella

  • Pili

  • Plasmids

Archaea

Identify which type of prokaryote:

🧪 Examples:

• Halobacterium – lives in salty environments

• Thermophiles – live in hot springs or hydrothermal vents

• Methanogens – produce methane gas; found in swamps or animal guts