Prokaryotic Cells Flashcards
Types of prokaryotic organisms
Bacteria
Cyanobacteria
Archaebacteria
Examples of advantageous bacteria
Guy bacteria and in cycling of nutrients in the natural world
Features of bacteria cells that aren’t present in all bacteria
Flagellum
Plasmids
Mesosome
Capsule/slime layer
Photosynthetic membranes
How are contents around bacteria walls usually hypertonic
They are hypertonic to medium so water tends to move into cells via osmosis
Use of cell wall in bacterium cells
Prevents cell swelling and bursting
Maintains shape of bacterium
What do all cell walls consist of
A layer of peptidoglycan
What is peptidoglycan made of
Many parallel polysaccharide chains with short peptide cross linkage forming big molecule with net like structure
What do some bacteria’s have around their cells
Slime layer or capsule
What is a slime layer/ capsule formed with
Formed from starch
Gelatin
Protein or glycolipid
Function of the slime layer/ capsule
Protects the bacterium from phagocytosis by white blood cells and covers cell markers on membrane that identify cells
How does a bacterium benefit from having a capsule
Makes it more pathogenic because not so easily identified by the immune system
Examples of bacterium that are pathogenic with capsules/ slime layers
Pneumonia
Meningitis
TB
Septicaemia
How have bacteria capsules evolved
To help the bacteria survive very dry conditions
Pili/ fimbriae
Thread like protein projections on the surface on bacteriums
Examples of bacterium that have pili
ecoli
Salmonella
Function of pili/fimbriae
Used for attachment to a host cell and for sexual reproduction
How can pili make bacteria more vulnerable
As a bacteriophage can use pili as a point of entry to the cell
Flagella
Little bigger than microtubules in eukaryotic cells made of many stranded helix of the proteins flagellin
Function of flagella
Moves the bacterium by rapid rotation about 100 revolution per second
Cell surface membrane function
Bacterium have no mitochondria so cell surface membranes site of some respiration
Mesosomes
In some bacteria cell surface membranes have inner foldings called mesosomes
Function of mesosomes
Artefact of preparing cell for observation
Associated with enzyme activity during separation of dna
Inner foldings used for photosynthesis in some bacterial species
Plasmids
Some bacterial cells have one or lots of smaller circles of DNA
Function of plasmid
Codes for particular aspect of bacterial phenotype in addition to genetic information in the nucleoid
Examples of functions plasmids code for
Particular toxin
Resistance to antibiotics
How can plasmid be transferred
Transferred from one bacterium to another in a form of sexual reproduction using the pili
Nucleoid
The area in the bacterium cell where dna is coiled is called nucleoid
Where do bacterium cells carry out protein synthesis
70s ribosomes 🤠
What are 70s ribosomes made of
Two sub units
Smaller 30s
Larger 50s
what are 70s ribosomes involved in
involved in synthesis of proteins in similar way to eukaryotic ribosomes
2 main types of bacterial cell wall
gram positive and gram negative
gram staining
a method of identifying type of bacteria cell wall
who was gram staining developed by
Christian gram
why is gram staining valuable
because different types of bacteria are vulnerable to different types of antibiotics and one factor that effects the vulnerability is their cell wall
how are bacteria cell walls before staining
colourless
structure of gram positive bacteria
thick layer of peptidoglycan that have chemicals like techoic acid within net like structure
test for gram positive
crystal violet complex in gram stain trapped in thick peptidoglycan layer and resists colouring when bacteria are dehydrated using alcohol. it doesnt pick up red safranin counterstain leaving positive purple/blue colour
features of gram positive respectively
-surface proteins
-peptidoglycan
-techoic acid
-plasma membrane
-membrane proteins
features of gram negatives respectively
-lipopolysaccharides
-outer membrane proteins
-outer membrane peptidoglycan
-inner membrane
-inner membrane proteins
example of gram positive bacteria
MRSA
example of gram negative bacteria
E.coli
structure of gram negative bacteria
thin layer of peptidoglycan with no acid between layers
-outer membrane made of lipopolysaccharides
test for gram negative bacteria
after complex applied, bacteria dehydrated in ethanol. lipopolysaccharide layer dissolves in ethanol leaving thin peptidoglycan layer exposed. crystal complex washed out and peptidoglycan takes up red safarin counterstain so cell appears red
how to antibiotics work
target
-cell wall
cell membrane
genetic material
-enzymes
-ribosomes
why do doctors need to know the type of bacteria
because it will effect the type of antibiotic prescribed
