<< Chapter < Page Chapter >> Page >

To screen a genomic library for a particular gene or sequence of interest, researchers must know something about that gene. If researchers have a portion of the sequence of DNA for the gene of interest, they can design a DNA probe , a single-stranded DNA fragment that is complementary to part of the gene of interest and different from other DNA sequences in the sample. The DNA probe may be synthesized chemically by commercial laboratories, or it may be created by cloning, isolating, and denaturing a DNA fragment from a living organism. In either case, the DNA probe must be labeled with a molecular tag or beacon, such as a radioactive phosphorus atom (as is used for autoradiography ) or a fluorescent dye (as is used in fluorescent in situ hybridization, or FISH), so that the probe and the DNA it binds to can be seen ( [link] ). The DNA sample being probed must also be denatured to make it single-stranded so that the single-stranded DNA probe can anneal to the single-stranded DNA sample at locations where their sequences are complementary. While these techniques are valuable for diagnosis, their direct use on sputum and other bodily samples may be problematic due to the complex nature of these samples. DNA often must first be isolated from bodily samples through chemical extraction methods before a DNA probe can be used to identify pathogens.

A diagram of DNA probe. First a gene of interest is identified and cloned. Then single stranded probes are labeled with a molecular beacon. Finally, the DNA probe binds to complementary sequences in a DNA sample. The complementary sequences are single stranded DNA. The probe only attaches to one of the ssDNA sequences since it has the gene of interest in it
DNA probes can be used to confirm the presence of a suspected pathogen in patient samples. This diagram illustrates how a DNA probe can be used to search for a gene of interest associated with the suspected pathogen.

Part 2

The mild, flu-like symptoms that Kayla is experiencing could be caused by any number of infectious agents. In addition, several non-infectious autoimmune conditions, such as multiple sclerosis, systemic lupus erythematosus (SLE), and amyotrophic lateral sclerosis (ALS), also have symptoms that are consistent with Kayla’s early symptoms. However, over the course of several weeks, Kayla’s symptoms worsened. She began to experience joint pain in her knees, heart palpitations, and a strange limpness in her facial muscles. In addition, she suffered from a stiff neck and painful headaches. Reluctantly, she decided it was time to seek medical attention.

  • Do Kayla’s new symptoms provide any clues as to what type of infection or other medical condition she may have?
  • What tests or tools might a health-care provider use to pinpoint the pathogen causing Kayla’s symptoms?

Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box.

Agarose gel electrophoresis

There are a number of situations in which a researcher might want to physically separate a collection of DNA fragments of different sizes. A researcher may also digest a DNA sample with a restriction enzyme to form fragments. The resulting size and fragment distribution pattern can often yield useful information about the sequence of DNA bases that can be used, much like a bar-code scan, to identify the individual or species to which the DNA belongs.

Gel electrophoresis is a technique commonly used to separate biological molecules based on size and biochemical characteristics, such as charge and polarity. Agarose gel electrophoresis is widely used to separate DNA (or RNA) of varying sizes that may be generated by restriction enzyme digestion or by other means, such as the PCR ( [link] ).

Questions & Answers

what are thermophile's bacteria
evon Reply
bacteria which can survive in high temperature.
Jayeeta
Thanks
Prudence
why do we study microbiology?
Joyce Reply
For the classification, identification of pathogenic microbes ...
Bharat
thanks
Joyce
what is pathogenicity
jesca
diseases causing activity ...
Bharat
of microbes..
Bharat
sorry ability not activity..
Bharat
I think it's the degree of a pathogen to cause infection
Foster
what is prokaryotes
PRALHAD Reply
are micro-organisms that have no nucleus e.g bacteria
Foster
and they do not possess membrane bound organelles e.g mitochondria
Bharat
yes
Foster
they are single cellular organisms,
Rajasekhar
all the organelles are embedded in cytoplasm of the cell
Rajasekhar
They don't possess true nucleus
PREMI
they're unicellular organisms
Kamaluddeen
they are classified as bacteria and. archaea. bacteria have a cell membrane conposed of peptidoglycan and archaea is composed of psuedomu
Tara
pseudomurein
Tara
organelles are non membraneous as the nucleus
Tara
What is the biosynthesis of a bacteria cell
Adesina Reply
biosynthesis is multiple step enzymes catalyze process which occur in bacterial cell
Jayeeta
biological way of manufacturing food and utilizes it for growth, multiplication and development
Kamaluddeen
prokaryot
PRALHAD
what is microbiology
Kiirya Reply
which organism can not be seen necked eyes is knowm as microbiology
meet
microorganisms
Jayeeta
micro can be define as d smallest living organisms dat can not be see wit naked eyes only with the aid of a microscope 🔬
muhammed
bio means life logy means study
muhammed
biology can b define as the systematic study of living things
muhammed
microbiology can be define as the study of tiny organisms, that's according to my understanding
muhammed
Microbiology is the study of living organisms which cannot be seen by the naked eye but only with the aid of a microscope. These microorganisms can be classified as bacteria, fungi, micro-algae, protozoa and virus.
Tatz
microbes that can't seen in naked eyes. upto 100micrometer we can see in naked eyes but 1 microns or nanometers are invisible in naked eye.
Jayeeta
what is a cell
Oteri Reply
cell can be define as smallest indivisible organism in the body
muhammed
cell is the smallest unit which makes up the whole body
Yue
cell is smallest unit and there are two types prokaryotic cell and eukaryote cell. bacteria a prokaryotic cell which works independently.
Jayeeta
nice forum
muhammed
Which parasite competes with the host for vitamin B12 to cause pernicious anaemia
Abubakar
Diphyllobothrium latum for vit B12
Jayeeta
it is also fish tapeworm
Jayeeta
Diphyllobothrium sp feed vitB 12
Jayeeta
recent trends in microbiology of biofertilizer
Ykomalipriya Reply
using nano technology
Jayeeta
what is transposors
EMMANUEL Reply
Junk DNA, jumping gene.
Pradeep
transposon elements are jumping gene as DNA sequence move from one location to anothet
Jayeeta
Yes
Pradeep
what is microbiology
Usama Reply
Microbiology is the study of organisms, most of which are too small to be seen with the naked eye, including bacteria, algae, protozoa, and fungi, as well as acellular agents, such as viruses and prions.
digvijaya
what is gram +ve and gram - ve bacteria?
Sharma
gm- contain lipid layer so it take counter stain during gram staining and pink or red in color but gm + does have thick LPS layer.
Jayeeta
what year microbiology started
Kartik
Robert Koch was the first to detect microorganisms
Jayeeta
what appears microorganisms
Kartik
clear the questions please
Jayeeta
was it robert koch or robert hooke?
digvijaya
microbiology word came from microns. study microbes that not recognize in naked eyes.
Jayeeta
what are the branch of microbiology
Oyemade Reply
We can basically classify into pure and applied microbiology
Ozzie
what is arabinose operon and it's stucture
Pooja Reply
The L-arabinose operon, also called the ara or araBAD operon, is an operon required for the breakdown of the five-carbon sugar, L-arabinose, in Escherichia coli
Tharra
kya hum operon ko divide kar skate hain
Kartik
reactions if viruses to physical and chemical agents?
VICTOR Reply
All viruses contain the following two components: 1) a nucleic acid genome and 2) a protein capsid that covers the genome. Together this is called the nucleocapsid. In addition, many animal viruses contain a 3) lipid envelope. The entire intact virus is called the virion.
Asali
assume you have performed a gram stain on a sample of pus from a patients urethra. you see red, nucleated cells and purple rods. what can you conclude
Petty Reply
bacteria
ABUBAKAR
gram negative bacteria hence gonococcal infection
Kiirya
Study of micro organisation which we cannot see with naked eye...
shyam Reply
Despite their bad reputation, microbes are mostly beneficial or have a neutral effect on our lives. Microbiology is the scientific study of these microorganisms. Microorganisms are those organisms that are too small to see with the naked eye and include things like bacteria, fungi, and viruses.
Asali
yes
Dhirender
not 'things'...'organisms' like bacterias, viruses and fungi
Sinmi
simi, it's not bacterias but bacteria which is the plural form of the word while bacterium is the singular of it
Richard
bacterium is obvio in a singular form but plural of bacterium is bacterias
Sinmi
Richard is right it's bacterium which is the singular form and plural is bacteria. *Bacterias* doesn't exist.
Aakriti
that is microbiology which is deals with microbes only their structure
Kiirya
what is microbiology?
Sandeep Reply
what is microbiology
Glory
is the study of small microorganisms that can't be viewed by our naked eyes under a microscope
Nabukwasi
it's the study of microbes their classification, diversity, their cellular structure and processes, their applications and interaction with other organisms.
Chaitanya
what is EMP pathway
rajesh

Get the best Microbiology course in your pocket!





Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Microbiology' conversation and receive update notifications?

Ask