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a) Guanine has 2 carbon and nitrogen rings. If the hydrogen atoms are changed to alkyl groups, the guanine bonds to thymine. B) formeldahyde has 1 carbon, glutaraldehyde has 5 carbons, o-phthalaldehyde has a carbon ring with 2 carbons off the ring, ethylelene oxide has 2 carbons and an oxygen forming a triange. Beta-propionolactone has 3 carbons and an oxygen forming a square.
(a) Alkylating agents replace hydrogen atoms with alkyl groups. Here, guanine is alkylated, resulting in its hydrogen bonding with thymine, instead of cytosine. (b) The chemical structures of several alkylating agents.
  • What chemical reaction do alkylating agents participate in?
  • Why are alkylating agents not used as antiseptics?

Diehard prions

Prions, the acellular, misfolded proteins responsible for incurable and fatal diseases such as kuru and Creutzfeldt-Jakob disease (see Viroids, Virusoids, and Prions ), are notoriously difficult to destroy. Prions are extremely resistant to heat, chemicals, and radiation. They are also extremely infectious and deadly; thus, handling and disposing of prion-infected items requires extensive training and extreme caution.

Typical methods of disinfection can reduce but not eliminate the infectivity of prions. Autoclaving is not completely effective, nor are chemicals such as phenol, alcohols, formalin, and β-propiolactone. Even when fixed in formalin, affected brain and spinal cord tissues remain infectious.

Personnel who handle contaminated specimens or equipment or work with infected patients must wear a protective coat, face protection, and cut-resistant gloves. Any contact with skin must be immediately washed with detergent and warm water without scrubbing. The skin should then be washed with 1 N NaOH or a 1:10 dilution of bleach for 1 minute. Contaminated waste must be incinerated or autoclaved in a strong basic solution, and instruments must be cleaned and soaked in a strong basic solution.


Peroxygens are strong oxidizing agents that can be used as disinfectants or antiseptics. The most widely used peroxygen is hydrogen peroxide (H 2 O 2 ), which is often used in solution to disinfect surfaces and may also be used as a gaseous agent. Hydrogen peroxide solutions are inexpensive skin antiseptics that break down into water and oxygen gas, both of which are environmentally safe. This decomposition is accelerated in the presence of light, so hydrogen peroxide solutions typically are sold in brown or opaque bottles. One disadvantage of using hydrogen peroxide as an antiseptic is that it also causes damage to skin that may delay healing or lead to scarring. Contact lens cleaners often include hydrogen peroxide as a disinfectant.

Hydrogen peroxide works by producing free radicals that damage cellular macromolecules. Hydrogen peroxide has broad-spectrum activity, working against gram-positive and gram-negative bacteria (with slightly greater efficacy against gram-positive bacteria), fungi, viruses, and endospores. However, bacteria that produce the oxygen-detoxifying enzymes catalase or peroxidase may have inherent tolerance to low hydrogen peroxide concentrations ( [link] ). To kill endospores, the length of exposure or concentration of solutions of hydrogen peroxide must be increased. Gaseous hydrogen peroxide has greater efficacy and can be used as a sterilant for rooms or equipment.

Questions & Answers

Explain about enzyme transportation
Shahla Reply
Enzyme transportation
what is the infectious disease process
Patience Reply
what are differences between endotoxins and exotoxins
sabote Reply
endo toxins work in the nuceus. i think
tell me if im right tho
Exotoxins are toxic substances secreted by bacteria and released outside the cell. Both gram positive and gram negative bacteria can produce and secrete exotoxins. Whereas Endotoxins are bacterial toxins consisting of lipids that are located within a cell. Only lysed gram negatives.
Remebr the Lipid A portion of LPS is what's toxic.
oh yeah. thanks
Your welcome :)
How did you learn this?
For me personally the best book is 'microbiology made ridiculously simple'
I got my basics from there and slowly added information from other sources.
thats cool! yeah i like microbiology too! especially the molecular proteins theyre sooooooooooo cool!
what are the prokaryotic
Lungu Reply
prokaraytotic is a unicellular organizm that lacks membrane bound nucleus
and whats eukaryotic
eukaryotic cell are cell which contain anuclues and organells
eukaryotes are the cells that have organells which are protected by membranes
eukaryotic is are multicellular organisms which are open nucleus.
Explain on the Francisco reddi did to prove the theory of spontaneous generation
Diana Reply
what is parasite
Abdirizack Reply
parasite are organisms feeds on a host for food and survival.e.g round worm for animal, Dodder for plant parasites.
parasite are organisms that feeds on a host for food and survival.e.g round worm for animal and mistletoe for plant parasites.
parasite are organisms that feed on their host
designing of aseptic area
Aashish Reply
I don't know
what is rickettsia
what is microbiology
Is the science that works with microorganisms.
richettsa is small microorganisms that cause disease in human like typhus; they are like viruses that can grow only inside living cells, they're transmitted by mites, ticks or lices.
what is plasmid?
plasmid is extra chromosomal body present in bacteria...which have additional genetic functions example... antibiotic resistance genes....etc etc
state the theory of spontaneous generation of micro oranisms and germ theory of disease
what are the advantages of high note numerical aperture
Genius Reply
list if non flagellated pritozoa
Mepung Reply
Can someone that's understanding of the Kreb Cycle please explain & breakdown it down to me in the simplest way without giving me the dictionary version or Google version. Basically in there own words of knowledge....!
please can someone help explain positive and negative feedback in simple term
negative feedback is the arresting of reaction or reverse of the reaction according to the response and postive feed back is the direct response without reversing or arresting a reaction.
pls can someone explained Kinney stone in memorising in shot time
what tyoebif microorganism will be killed by antibiotic trwatmeant
Mary Reply
I don't really don't understand aerobic respiration anaerobic respiration and fermentation. Can someone explain & breakdown this in the simplest way please.
Anaerobic Respiration in which foodstuffs are partially oxidized, with the release of chemical energy, in a process not involving atmospheric oxygen, such as alcoholic fermentation, in which one of the end products is ethanol.
aerobic respiration A type of respiration in which foodstuffs are completely oxidized to carbon dioxide and water, with the release of chemical energy, in a process requiring atmospheric oxygen.
please can someone explain what pseudomonas species and biofilm is?
Fermentation is the growth of cells or microorganisms in bioreactors (fermenters) to synthesize special products. Fermentation in biochemistry refers to the biodegradation of carbon compounds by cells or organisms under anaerobic (lack of oxygen) conditions.
Please under which conditions does pathogens become established in the human tissues and can cause diseases
please the life cycle of plasmodium parasite
who is John Needham
Mary Reply
John Needham is one of the researcher in microbiology. He also experimented when scientists did not believe animals could arise spontaneously ,but did believe microbes could.
okay is he late
by the way what are the list of courses offered by a newly admitted student for microbiology
Needham's experiments with beef gravy and infusions of plants material reinforced this idea.
what drugs are given to a person with Otis nerve problem(ear problem)
Gum Reply
good morning to you all.
Muhammad Reply
Dr.A.K.S.P.G. college Akbarpur Ambedkar Nagar
Shailesh Vishwakarma BSc 1st year

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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