Changes

Jump to navigation Jump to search
no edit summary
Line 41: Line 41:  
produce  endospores are Bacillus and Clostridium. Endospores have a “spore coat”  and are effectively in a dehydrated state with negligible metabolic  activity. Due to the thermostability of endospores they can only be  destroyed with certainty by moist heat at 121C for 15 mins.<br />
 
produce  endospores are Bacillus and Clostridium. Endospores have a “spore coat”  and are effectively in a dehydrated state with negligible metabolic  activity. Due to the thermostability of endospores they can only be  destroyed with certainty by moist heat at 121C for 15 mins.<br />
 
An  endospore will reactivate in response to environmental factors such as  exposure to heat, abrasion of the spore coat or environmental acidity.  Reactivation occurs in three stages; activation, initiation and  outgrowth. In the correct conditions, germination will occur in which  the spore coat is degraded and water is absorbed.<br />
 
An  endospore will reactivate in response to environmental factors such as  exposure to heat, abrasion of the spore coat or environmental acidity.  Reactivation occurs in three stages; activation, initiation and  outgrowth. In the correct conditions, germination will occur in which  the spore coat is degraded and water is absorbed.<br />
 +
 +
==To Incorporate==
 +
'''Bacterial genome''':
 +
*Contains double-stranded DNA
 +
*Prokaryotic DNA differs to eukaryotic DNA:
 +
**Few repeated sequences
 +
**Most of the DNA is transcribed
 +
**No intervening sequences within structural genes
 +
'''Cytoplasm''':
 +
*Does not contain mitochondria, lysosomes or Golgi bodies (found in eukaryotic cells)
 +
*Contains mesosomes- thought to be primitive endoplasmic reticulum
 +
'''Surface components''':[[Image:478px-Bacteria cell wall svg- franciscosp2.png|thumb|right|100px|'''Structure of cell wall''' Franciscop2 2008, WikiMedia Commons]]
 +
*Fimbriae- also known as pili, these are hair-like structures that allow bacteria to adhere to each other
 +
*F-type pili- also known as sex pili, these act as conjugation tubes during sexual reproduction
 +
*Capsules/slime- serve to adhere bacteria to cells and provide protection from phagocytosis and dehydration, e.g. hyaluronic acid
 +
*Flagella- help the bacteria move around
 +
 +
One way bacteria can be classified is by the structure of the cell wall:
 +
*'''[[:Category:Gram positive bacteria|Gram-positive bacteria]]''': cell wall consists of peptidoglycan layer, with teichoic polymers attached, e.g. ''Staphylococcus''
 +
*'''[[:Category:Gram negative bacteria|Gram-negative bacteria]]''':peptidoglycan layer is thinner, but surrounded by outer membrane of lipopolysaccharides and lipoproteins, e.g. salmonella
 +
 +
[[Image:427px-Arrangement of bacilli bacteria svg.png|thumb|right|100px|'''Arrangement of bacilli bacteria''' LadyofHats 2006, WikiMedia Commons]]
 +
[[Image:497px-Arrangement of cocci bacteria svg.png|thumb|right|100px|'''Arrangement of cocci bacteria''' LadyofHats 2006, WikiMedia Commons]]
 +
{| border="1"
 +
|+ Components of bacterial envelope
 +
! Component !! Gram positive !! Gram negative
 +
|-
 +
! Peptidoglycan
 +
| Yes || Yes
 +
|-
 +
! Teichoic acid
 +
|Yes
 +
|No
 +
|-
 +
! Lipoprotein
 +
|No
 +
|Yes
 +
|-
 +
! Lipopolysaccharide
 +
|No
 +
|Yes
 +
|-
 +
! Phospholipid
 +
|No
 +
|Yes
 +
|}
 +
 +
 +
Another method of classification is the shape and arrangement of the bacteria themselves:
 +
 +
*'''[[:Category:Cocci|Cocci]]'''- round shape, e.g. Streptococci, Staphylococci, Neisseria
 +
*'''[[:Category:Rods|Rods]]''' or '''bacilli'''- long shape, e.g. Coliforms, Bacillus, Spirochaetes
 +
    
[[Category:Bacteria - Overview|A]]
 
[[Category:Bacteria - Overview|A]]
 +
 +
[[Category:To_Do_-_Bacteria]]
Author, Donkey, Bureaucrats, Administrators
53,803

edits

Navigation menu