65
edits
Changes
no edit summary
===Nuclear Material===
===Nuclear Material===
The bacterial genome is composed if a single haploid circular chromosome containing double-stranded DNA (dsDNA). Bacterial genomes
The bacterial genome is composed of a single haploid circular chromosome containing double-stranded DNA (dsDNA). Bacterial genomes
vary in size depending on species but often has a folded structure to form a dense body which is visible using a scanning electron microscope. During replication the DNA helix unwinds and both daughter cells (produced by binary fission) receive
vary in size depending on species but often has a folded structure to form a dense body which is visible using a scanning electron microscope. During replication the DNA helix unwinds and both daughter cells (produced by binary fission) receive
a copy of the original genome.<br />
a copy of the original genome.<br />
The cytoplasm also contains Plasmids. Plasmids are small circular pieces of DNA that are separate from the genome and are capable of autonomous replication. Several different plasmids can be within the cytoplasm of a single bacteria. Plasmids
The cytoplasm also contains Plasmids. Plasmids are small circular pieces of DNA that are separate from the genome and are capable of autonomous replication. Several different plasmids can be within the cytoplasm of a single bacteria. Plasmids
can be transferred between bacteria during binary fission or through a process called conjugation. Plasmid DNA codes for characteristics including antibiotic resistance and endotoxin production.<br />
can be transferred between bacteria during binary fission or through a process called conjugation. Plasmid DNA codes for characteristics including antibiotic resistance and endotoxin production.<br />
===Flagella & Pili/Fimbrae===
===Flagella & Pili/Fimbrae===
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 />
[[Category:Bacteria - Overview]]
==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
{{Learning
|Vetstream = [https://www.vetstream.com/equis/Content/Freeform/fre00370.asp Bacteriology]}}
[[Category:Bacteria|A]]
[[Category:To_Do_-_Bacteria]]