Cell Biology 1 – Prokaryotes & Viruses
* Eukaryotes have a membrane whereas a prokaryote has no nuclear membranes. Both have a double stranded DNA. * The two main types of prokaryotes are bacteria and Archaea and eukarya are types of eukaryotes. * Archaea are more closely related to eukaryotes.
* Prokaryotes have a membrane and nucleoid and most have a cell wall. * There are 3 main types of shapes of prokaryotes:
* Bacillus – rod shapes
* Spirilum – spiral shaped
* Coccus – spherical
* If they cells are a similar shape, that means they are adapted to live in a similar environment, and not necessarily closely related. * P are smaller and do not have any other membrane organelles such as mitochondria. * E is bigger and more structured than prokaryotes (bacteria) as they have more processes and transportation to do. * Smaller cells (prokaryotes) have a higher SA:VR therefore they grow faster than large cells as they have a higher metabolic rate. * Cells may exist singly or associate into clusters with a characteristic shape. * Prokaryotes have DNA, a cell wall, which determines the: * Cell shape
* It also protects from osmotic swelling and environment. * Cell wall is found outside the plasma membrane and is made of peptidoglycan
* Peptidoglycan is an alternating copolymer of N-acetyl glucosamine and N-acetylmuramic acid * It has cross-links with peptide chains.
* This gives it a 3D shape and strength.
* Prokaryotes also have a cytoplasmic cell membrane that controls what enters and leaves the cell because is has a lipid bilayer which has a hydrophobic and hydrophilic which means it only lets certain substances through. * There are also protein molecules that are responsible for transport of ions, nutrients and waste. * The Gram stain is used to determine the different structures of cell walls. * Gram +ve bacteria –...
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