Prokaryotes and Eukaryotes

Prokaryotes – What are they? Cells (usually single-celled) with no nucleus Have no specialized organelles Usually have: cell wall, cell membrane, ribosomes, genetic material, cytoplasm, and flagella or cilia Examples: bacteria and archae Reproduce through binary fission Get energy through photosynthesis, chemosynthesis, (inorganic chemicals) or digesting other organisms Begin by asking students to share what they learned during their research, then reinforce by showing them the bullets on this slide. Take time to briefly explain the cell structures (cell wall, etc.), but do not go too in-depth right now, as students will be researching these structures in a subsequent activity.

Eukaryotes – What are they? Cells with a nucleus and other membrane-bound organelles that perform special functions Always have a nucleus May also have: chloroplasts, Golgi apparatus, lysosomes, mitochondrion, plastids, rough endoplasmic reticulum, smooth endoplasmic reticulum, vacuoles, and vesicles Examples: fungi, protists, plant and animal cells Reproduce by mitosis or meiosis Get energy through photosynthesis or by digesting other organisms. Begin by asking students to share what they learned during their research, then reinforce by showing them the bullets on this slide. Take time to briefly explain the cell structures (nucleus, etc.), but do not go too in-depth right now, as again, students will be researching these structures in a subsequent activity.

Prokaryote or Eukaryote? Ask students to identify the cell as prokaryote or eukaryote. Consider giving each student two different colored sticky-notes or note cards and, have them raise a specific color for each cell (or have them raise their right hand for prokaryote/left hand for eukaryote), this will allow you to assess if students can identify the cell type. Ask for volunteers to explain why they answered what they answered. Graphic: http://commons.wikimedia.org/wiki/File:Prokaryote_cell_diagram_international.svg By Mariana Ruiz (internationalized by Vjncenzo) (Image:Prokaryote cell diagram.svg) [Public domain], via Wikimedia Commons

What is the Endosymbiotic Theory? The endosymbiotic theory proposes that eukaryotic cells formed from symbiotic relationships among prokaryotes. The theory proposes that mitochondria evolved from free- living aerobic bacteria that began to live inside anaerobic prokaryotes. Chloroplasts evolved from free-living photosynthetic bacteria paired with the earliest eukaryotes.

What is the Endosymbiotic Theory?

What evidence supports the Endosymbiotic Theory? Mitochondria and chloroplasts are similar in size to bacteria, have their own genomes, contain ribosomes similar to those of prokaryotes, and are formed by division of preexisting mitochondria and chloroplasts. The membrane systems of chloroplasts resemble those of photosynthetic prokaryotes. Some cells today contain endosymbiotic bacteria and algae.

What is the Cell Theory? All living things are made of cells Cells are the basic unit of structure and function in an organism (basic unit of life) Cells come from the reproduction of existing cells (cell division)