Bacteria - Concepts Flashcards
What is beneficial (for prokaryotes) about prokaryotes small size?
The small size means a faster growth rate. Allowing them to establish large populations in short time periods.
Gram-positive bacteria
Bacteria that have a thick mesh-like cell wall made of peptidoglycan. Will stain purple by crystal violet.
Gram-negative bacteria
Bacteria that have thin cell walls (thin peptidoglycan layers). Will not stain purple. Instead they are stained pink by safranin.
The two major categories of antibiotics
Beta lactam antibiotics (penicillin family) and Glycoeptide antibiotics.
How do the two main categories of antibiotics work?
They act by inhibiting peptidoglycan, making the cell more vulnerable.
What physically happens to a bacteria before it lyses?
It elongates and then the cell wall bulges.
What compound do we naturally produce that breaks down peptidoglycan?
Lysozyme
What is the difference between a prokaryote’s and a eukaryote’s cell membrane?
Prokaryotes lack steroids in their membranes.
How many layers of membrane does a prokaryote have?
2
What is the outer membrane of a prokaryote made of?
Lipopolysaccharides
LPS layer
The outer membrane of a prokaryote
Instead of internal membranes, what do prokaryotes use instead?
Infoldings of their cellular membrane. This creates more surface area.
Is prokaryote DNA double stranded or single-stranded?
Double stranded.
How many times more DNA do humans have than E. coli?
1000 times more
How many more genes do humans have than E. coli?
Seven times as many genes.
Plasmids
Small ring shaped DNA, don’t carry vital information.
Benefits conferred by plasmids…
Production of antimicrobial compounds, the facility to metabolize unusual molecules, resistance to antibiotics, pathogenicity, and the ability to transfer DNA between cells.
The three main ways that bacteria increase genetic variability.
Transformation, transduction, and conjugation.
Transformation
A way that bacteria can increase genetic variability. It occurs when a bacterium takes up free DNA from its immediate environment, and incorporates the new DNA into its genome, resulting in a change/transformation it’s typical characteristics. Not all prokaryotes can do this.
Transduction
Gene change/transfer facilitated by viral vectors.
Conjugation
Gene transfer from one bacterium to another. This is a one-way transfer. It requires the presence of conjugation plasmid.
Why is the current state of taxonomy of prokaryotes in a state of flux?
Major ongoing shifts in our understanding due to advances in molecular biology.
The four types of -trophs.
Photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs.
What is the metabolic behaviour of chemoautotrophs?
They use chemical compounds as a source of energy with which they then make organic carbon.
Who are some of the most important chemoautotrophs?
The nitrifiers.
The most common way that bacteria causes disease.
The most common mechanism is by the production of toxins.
How do exotoxins cause problems?
By interfering with normal self functioning, or by damaging the host cell, and they are usually very tissue specific.
How can someone get food poisoning without having an active bacterial infection?
Because exotoxins produce disease symptoms separately from the prokaryote that produced them.
