The School of Biomedical Sciences Wiki - User contributions [en]

RFLP

2018-12-08T23:25:59Z

180390191: Added links

Restriction fragment length [[Polymorphism|polymorphisms]] are a type of genetic identifiers used in the study of traits and comparison of [[Allelic restriction sites|allelic restriction sites]]. RFLPs develop due to the [[Mutation|mutations]] that occur in the sequences that code [[Restriction site|restriction sites]]; thus the mutations either result in the destruction or creation of [[Restriction site|restriction sites]]. The consequence of such mutations is that when a [[Restriction enzyme|restriction enzyme]] is used to cut the [[DNA|DNA]] sequence, where there has been destructive mutation the DNA sequence is not ligated and where there has been creation of restriction sites the DNA is [[Ligation|ligated]]. This all leads to varying lengths of DNA fragments which separate on [[Gel electrophoresis|gel electrophoresis]]. RFLPs are used for the analysis of traits and allelic mutations <ref>Lodish.H.,2007. Molecular Cell Biology. 7th ed. Basingstoke</ref>.

RFLP is a common method for determining the paternity of a child.

Another reason this test is useful is because it has a high power of exclusion (around 99%). This means that when a test is run to determine the paternity, around 99% of the population can be discounted to be the childs father. This makes the results very asccurate. Although, it is a very useful technique, it is not as commonly used as [[PCR|PCR]]. This is because it takes a long time to run the test and it requires large samples for testing <ref>RFLP is a common method for determining the paternity of a child. Another reason this test is useful is because it has a high power of exclusion (around 99%). This means that when a test is run to determine the paternity, around 99% of the population can be discounted to be the childs father. This makes the results very asccurate. Although, it is a very useful technique, it is not as commonly used as PCR. This is because it takes a long time to run the test and it requires large samples for testing.</ref><ref>http://www.dnajunction.com/technology/rflp.php</ref>.

=== References ===

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Recombinant frequency

2018-12-08T17:23:40Z

180390191: Created page with " Recombinant frequency is the distance between genes and is given by the formula: ((number of recombinants)/(total progeny))x100%."

 Recombinant frequency is the distance between genes and is given by the formula: ((number of recombinants)/(total progeny))x100%.

Centimorgan

2018-12-08T17:03:56Z

180390191: Added text

The unit of distance in a [[Genetic map|genetic map]] is called a map unit and 1 map unit is equivalent to one centimorgan (cM) named after T.H.Morgan<ref>Daniel L. Hartl, Maryellen Ruvolo,(2012) Genetic: analysis of genes and genomes, 8th edition, Burlington, Massachusetts: Jones &amp; Bartlett Learning, pg 161</ref>. In humans, a centimorgan translates to ~106 DNA base pairs<ref>https://www.genome.gov/glossary/index.cfm?id=28&textonly=true</ref>.

=== References ===

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Cilia

2018-12-08T16:59:25Z

180390191: Added links

There are two types of cilia; motile and primary, and they tend to be around 10um in length and around 0.2 µm in diameter<ref>The Histology Guide - The University of Leeds. Epithelia: Specialisations; Available from: http://www.histology.leeds.ac.uk/tissue_types/epithelia/epi_specialisations.php</ref>. Motile cilia grow in clusters e.g. the cells in the bronchial epithelium, primary cilia grow as a single cilium e.g. those on the embryonic node. Motile cilia are found on a limited range of different cell types whereas primary cilia are found on nearly every cell in the human body. Primary cilia's function is to receive signals from other cells or fluids.

=== Motile Cilia ===

[[Image:Axoneme.png|right|Figure 1 - taken from reference 4]] Cilia (singular: Cilium) are cylindrical [[Organelles|organelles]]<ref>5) “Fundamental role of microvilli in the main functions of differentiated cells: Outline of an universal regulating and signalling system at the cell periphery” K. Lange, J Cell Physiol. 2011, 226, 896-927 Abstract. https://www.ncbi.nlm.nih.gov/pubmed/20607764</ref><ref>Lynn H. (2008) The Ciliated Protozoa Characterization, Classification, and Guide to the Literature, New York: Springer</ref>, built from [[Microtubules|microtubules]], in a [[9+2_arrangement|“9 + 2” arrangement]]<ref>Lynn H. (2008) The Ciliated Protozoa Characterization, Classification, and Guide to the Literature, New York: Springer</ref>, with 9 doublet [[Microtubules|microtubules]] surrounding the circumference and a central pair in the middle. The microtubules are regularly cross-linked with accessory proteins to make up the axoneme, a central core that provides stability. Certain accessory proteins such as [[Dynein|dynein]] (see Figure 1) play a key role in the organelles movement. The 9 doublet microtubules around the circumference consist of one complete and one incomplete tubule, which are shared by common tubule wall. The organelle is also anchored to the cell membrane by the basal body, which is composed of triplet microtubules that transition into the doublet ones seen in the axoneme<ref>Jeff Hardin, Gregory Bertoni, Lewis J. Kliensmith, Becker's World of the Cell, Page 453, Eighth Edition, Benjamin Cummings and Pearson, San Francisco, 2010</ref>. The majority of cilia in different [[Eukaryotes|eukaryotes]] have this characteristic arrangement<ref>Alberts B, Johnson A, Lewis J, Morgan D, Raff M, Roberts K, Walter P. Molecular Biology of the Cell. 6th Ed, New York; Garland Science. 2015 (page 941-942)</ref>. They are [[Motile|motile]] structures whereby the rhythmic beating of cilia creates movement. Cilia are involved in [[Mucociliary clearance|mucociliary clearance]] in which [[Bacteria|bacteria]], [[Mucus|mucus]] and dust are swept up the [[Respiratory tract|respiratory tract]] into the [[Mouth|mouth]] and eliminated by swallowing. Moreover, ciliated cells move [[Oocytes|oocytes]] along the fallopian tubes, and [[Sperm|sperm]] from testes into the male reproductive tract<ref>Martini FH, Nath JL, Bartholomew EF. Fundamentals of Anatomy and Physiology. 9th Ed, San Francisco; Pearson Education Inc: 2012 (page 70-71)</ref>. Furthermore, by the beating of cilia, single cells are able to propel through fluid<ref>Alberts, Bruce et al. (2008). Molecular Biology of the Cell, 5th edition, New York: Garland Science. (Page 1031)</ref>. The movement of cilia is caused by axoneme, which can reach a length of 10-200 micrometres<ref>Alberts B, Johnson A, Lewis J, Morgan D, Raff M, Roberts K, Walter P. Molecular Biology of the Cell. 6th Ed, New York; Garland Science 2015 (page 941-942)</ref>. Dynein is a cytoskeleton motor protein within cilia which enables them to have movement. This occurs by the conversion of chemical energy in [[ATP|ATP]] to mechanical energy<ref>https://www.ncbi.nlm.nih.gov/pubmed/20607764</ref>.

=== Primary Cilia ===

Cilia can also be immotile (primary cilia) and have a “9+0” arrangement where they have 9 peripheral doublets [[Microtubules|microtubules]] and 0 single microtubules in the centre<ref>Satir P, Pedersen LB, Christensen ST. The primary cilium at a glance. Journal of Cell Science 2010; 123(499-503): 1. http://jcs.biologists.org/content/123/4/499 (accessed 14 November 2016).</ref><ref>5) “Fundamental role of microvilli in the main functions of differentiated cells: Outline of an universal regulating and signalling system at the cell periphery” K. Lange, J Cell Physiol. 2011, 226, 896-927 Abstract. https://www.ncbi.nlm.nih.gov/pubmed/20607764</ref>. One of the roles of primary cilia is to act as a sensory antennae on receptor cells, they extend out from the apical surface of the cell into the surrounding medium and are able to detect the presence of ligands better than receptors on the cell surface due to the fluid further away from the cell membrane being more mobile<ref>Marshall WF, Nonaka S. Cilia: Tuning in to the Cell’s Antenna. Current Biology, Volume 16, Issue 15, p604-614. 2006</ref>.

'''Example describing how the aberrant structure of cilia can lead to human disease'''

Primary Ciliary Dyskinesia (PCD) is a genetic disorder caused by abnormal cilia and [[Flagella|flagella]], which can lead to respiratory tract infections. Some of the symptoms of this disorder include a chronic cough, nasal congestion and chronic chest infections. In people with PCD, the cilia found in the respiratory tract are immobile and stiff due to defects in the axonemal dynein. This means they cannot move the mucus away, so the bacteria remain in the respiratory tract and cause infection. Although there is no cure, PCD can be treated with antibiotics, anti-inflammatory drugs or a bronchodilator and more importantly regular exercise is required to help clear the airway<ref>13. primary ciliary dyskinesia [Internet]. Genetics Home Reference. 2017 [cited 02 December 2017]. Available from: https://ghr.nlm.nih.gov/condition/primary-ciliary-dyskinesia#diagnosis</ref><ref>14. Daniels M, Ghosh S, Noone P. Primary ciliary dyskinesia. Current Pulmonology Reports. 2016;5(4):191-198.</ref>.

=== References ===

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Axoneme

2018-12-08T16:55:16Z

180390191: Added text

An axoneme is part of the internal structure of [[Cilia]] and [[Flagella]]. It functions as the [[Cytoskeleton]] by providing semi-rigid support, allowing the [[Organelle|organelle]] to maintain its general shape while being able to move. It is made of [[Microtubule|microtubules]] in a [[9+2_arrangement|9+2 structure]].

Axoneme

2018-12-08T16:42:28Z

180390191:

Axoneme

2018-12-08T16:41:30Z

180390191: Corrected typos

An axoneme is part of the internal structure of [[Cilia]] and [[Flagella]]. It functions as the [[Cytoskeleton]] by providing semi-rigid support, allowing organelle to maintain its general shape while being able to move.