6th lecture: 26/9/14

Topic: External Structure of Prokaryote (part 1)

Notes:
1) Prokaryote are organisms which lack of cell nucleus or any membrane-bound organelles.
2) Diplococci shape - round shape in pair ; Diplobacilli shape - rod shape in pair
3) Staphlyococci - grape-like clusters
4) Streptococci - round shape in chain ; Streptobacilli: rod shape in chain
5) Spiral shape that is rigid is called spirillum. Spiral shape that is flexible is called spirochete.
6) The bacteria which have smaller size are able to move easily, easier to get protection from predator and nutrients upake for them are lesser.
7) There are 4 main external structure of the cell wall: Glycocalyx, Flagella, Axial filament, Fimbriae and pili.
8) Glycocalyx is made up of extracellular polysaccharide. It is made inside the cells and excreted to the cell surface.
9) The functions of glycocalyx are to get protection from phygocytosis, attach to different surfaces and protect cell against dehydration.
10) Capsules are formed if glycocalyx is organised and slime layers are formed if glycocalyx is loosely attached.
11) Flagella made up of flagellin and consists of basal body. Basal body has a hook, rod and ring.
12) Monotrichous - one flagellum;  Lophotrichous - cluster of flagella at each end of cell; amphitrichous- one flagellum at each end of cell; peritrichous- spread over entire surface of cell.
13) Types of mortality: Tumbles and Swam
14) Spirochetes group of bacteria move by axial filament because they have no flagellum.
15) Fimbriae and pili consist of pilin and used for attachment rather than movement.
16) Fimbriae distributed entire of the cell while pili only one or two found per cell.
17) Cell wall of prokaryote is not selectively permeable.
18) Cell wall composed of peptidoglycan and peptidoglycan consists of disaccharide. The disaccharide is made up of NAG and NAM. NAG and NAM are linked by glycosidic bonds (beta 1-4).
19) There are 2 major types of cell wall : Gram-positive and Gram-negative
20) Gram-positive cell wall consists of many layers of peptidoglycan while Gram-negative cell wall consists of few layers of cell wall.

Activities: Draw Mind Map for external and internal structure of prokaryote

My own explorace:
1) Size of E.coli - 0.5um in width and 2um in length; Size of Thiomargarita -750um.
2) Myxobacteria live in soil, feed on organic substance and move by gliding.
3) Mycoplasma unaffected by antibiotics because they have no cell wall.
4) Corynebacteria is the pathogen causes diphtheria.
5) The formation of biofilem on the surface indicates that there are no pollutants in that area.
6) Virulence factors: The ability to cause disease.

Reflection on this topic:
I have learnt the structure of prokaryote before but not that specific. I will try my best to memorise all these structures. ^^