Cell Forms Comparison – Launching Pad for Cell Biology

00:00 Before we move into the course, it's really important for us to establish what life is.

00:06 Some might debate that viruses and prions are non living. But certainly, cells are living.

00:13 So we're going to explore some brief comparisons between eukaryotic and bacterial or prokaryotic cells.

00:20 Yes, there's another division, another type of cells called archaeas. But they're not really components of human body.

00:26 We're going to be dealing primarily with bacterial cells and eukaryotic cells and on occasion throughout this course, we'll be exploring some mechanism of viruses.

00:39 So comparing prokaryotic and eukaryotic cells, they both have ribosomes, they both have DNA.

00:46 They both have cell membranes. Bacterial cells have cell walls whereas eukaryotic cells generally do not have cell walls.

00:57 Plant cells have cell walls. And fungal cells have cell walls.

01:02 However, animal cells lack a cell wall at all. Both cell membranes are composed of phospholipid bilayers.

01:10 Both have ribosomes although prokaryotic and eukaryotic ribosomes are slightly different.

01:18 We'll explore those in further lectures.

01:22 And then in general, a eukaryotic cell is about ten times larger than a prokaryotic cell.

01:29 And as I mentioned, in addition we'll be visiting viruses and prions briefly.

01:34 Viruses, technically they are non living. They're composed of a protein capsid, so a protein outer coat with a nucleic acid or DNA core. Sometimes an RNA core in the case of retroviruses.

01:49 In addition, some virus like the AIDS virus also have a viral envelope which has enveloped protein studded over the surface for recognition purposes.

02:02 And finally, prions. Prions have given us some questions to think about because they contain no DNA. However, they're contacting other proteins, can cause them to fold in a different way.

02:15 And they seem to have some sorts of genetic capacities, yet zero DNA.