Mini-lesson on prokaryotic and eukaryotic cells

What the words mean Prokaryotes Pro = before Karyose = kernel, which represents the nucleus So prokaryotes occurred before cells with a nucleus Eukaryotes Eu = true Karyose = kernel, the nucleus So eukaryotes are the cells with a true nucleus

A prokaryotic cell

Eukaryotic cell

Similarities and Differences Prokaryotic cell DNA- circular, has no ends Bacteria Nucleoid – not a real structure, just a word to describe the inside of the cell where the nuclear material sits Tiny cells- tough to see on 400x Eukaryotic cell DNA- linear, has ends Found in animals, plants, and fungi (yeast) True membrane bound nucleus surrounding chromosomes Larger cells- could be seen on 400x

More similarities and differences Prokaryotes Ribosomes are simple No membrane bound organelles Believed to be what led to chloroplasts and mitochondria (see next slide) Eukaryotes Ribosomes are complex Membrane bound organelles

Chloroplasts and mitochondria Evidence suggests that chloroplasts and mitochondria were once bacteria that developed a symbiotic relationship with cells that have a nucleus Chloroplasts and mitochondria have their own circular DNA that is not a part of the host’s genome. Yes plants have both chloroplasts and mitochondria.

What happened with the gram staining? Gram stains work because of their membrane structure Methylene blue works, but the buttermilk was too messy to really be able to see all of the teeny tiny dots (sorry) Gram stains work because of their membrane structure Methylene blue works, but the buttermilk was too messy to really be able to see all of the teeny tiny dots (sorry) Staining Bacteria

Staining Yeast Gram stains won’t work because of their membrane structure Ethanol shrunk the cells in the gram stain so the cells looked like tiny dots, if you could find them Methylene blue works great All of your yeast should have been killed from the heat and therefore were blue Gram stains won’t work because of their membrane structure Ethanol shrunk the cells in the gram stain so the cells looked like tiny dots, if you could find them Methylene blue works great All of your yeast should have been killed from the heat and therefore were blue

If the world was perfect… (which it is not, by the way) The bacteria would have come out gram positive because they were Streptococcus You would have been able to see teeny tiny little balls on the slide You did NOTHING WRONG. The destaining step needs to be explained better in the protocol. Next year we’ll try culturing the cells before making slides of them. Sorry for the frustration. (But this is how science is sometimes…)