Genetics

{{Sources needed}}{{expand}}{{evolution}}{{hatnote|Not to be confused with [[genetic fallacy]].}}
'''Genetics''' refers to the study of heredity, [[gene]]s and genetic material.<ref>[https://www.britannica.com/science/genetics], Encyclopedia Britannica. (2024, December 3). Genetics. https://www.britannica.com/science/genetics</ref> Modern genetics examines how individual genes function and are expressed within the broader context of genomics, which focuses on analyzing the entirety of an organism's genetic material, and how these genetic elements interact with environmental factors to influence traits and disease.<ref>[https://www.nature.com/articles/s41576-020-0272-6], McGuire, A. L., et al. "The road ahead in genetics and genomics." Nature Reviews Genetics 21.10 (2020): 581-596.</ref>

==Mendel and his peas==

[[Gregor Mendel|Mendel]]'s famous experiments with peas pointed the way to the information that results in visible traits being binary in nature. It has since been established that the [[DNA]] [[molecule]]s in the nucleus of [[cell]]s carry this information, on pairs of [[chromosome]]s. Of these pairs of chromosomes, in each living creature, one originates from each parent (in the case of [[sex]]ually reproducing [[species]]). This results in a continual mixing of traits present in a species across individuals.

==Non-sexual gene transmission==

Non-sexually reproducing organisms pass on genetic information to their offspring which is identical to their own, whether through division of single celled organisms like [[bacteria]], or various forms of [[cloning]] used by many [[plant]]s (budding, spreading via root systems, or layering of above-ground stalks that grow new roots and become independent). Many organisms, especially plants, are capable of sexual and asexual reproduction, with some alternating between the two from generation to generation.

==Modern fields of study==

Genetics has moved far beyond the simple tracking of traits from parent to child, however, from the identification of the [[DNA]] [[molecule]] by Watson, [[Francis Crick|Crick]], and Russell, through the modern sequencing of the [[human]] [[genome]] and the addition or subtraction of traits from existing species by [[Genetic modification|genetic engineering]].

===Sequencing===
Sequencing is the identification of the exact genetic code in the genome, in order to identify variant alleles, deletions, and insertions.

''Next-Generation'' 'high-throughput' sequencing machines can process large amounts of material, and are used for ''Whole Gnome Sequencing'' (WGS), whole exome sequencing (looking at the subset of the entire genome that 'codes' for genes) or other subsets of the genome that the scientists can tailor the 'kit' to match. A common approach uses 'shotgun sequencing', where the strands of DNA are broken up into chunks that are read by the machine in no particular order. Substantial computational effort is then needed to work out where each chunk belongs.

''Sanger Sequencing'' is an older method, less suited to sequencing such large regions, but is considered the 'gold standard'. It is often used where the region of interest is small, such as when validating results obtained from next-Gen sequencing.

In all traditional sequencing methods, the genetic material is a blend of that from a number of cells. Ideally, these cells will be of the same kind and thus be interchangeable. This is not always the case in practice and can play hob with the analysis. In particular, tumour cells can be very different to their neighbors, and those differences can have important consequences for treatment or diagnosis. A very recent development is that of ''single-cell sequencing'', whereby single cells are isolated and sequenced separately. When it works, it provides higher quality analysis, better characterisation of tumours and reduces the need to 'purify' a sample down to a single cell type before sequencing, in cases where multiple cell types are of interest. When it works.

===Gene expression===
Expression analysis takes a different approach, measuring the ''number'' of chunks associated with each particular gene rather than any variants within them. This measures differences in gene regulation between samples. This is generally done to test the difference in regards to two or more different environmental factors. This is your brain on drugs, indeed.
====Personality effects====
One area of study is how genes can influence people's personality, this is often a study of things like the heritability of temperament traits.<ref>[https://medlineplus.gov/genetics/understanding/traits/temperament/] Medline.</ref> This combines psychology with molecular genetics, and neuroscience, so it is a multi-disciplinary approach to understanding how much genes contribute to personality.<ref>[https://opentextbc.ca/introductiontopsychology/chapter/11-3-is-personality-more-nature-or-more-nurture-behavioral-and-molecular-genetics/ Is Personality More Nature or More Nurture? Behavioural and Molecular Genetics] Introduction to Psychology – 1st Canadian Edition.</ref> Nature or nurture is likely missing the point, which is that both nature and nurture play a role in shaping a person's personality. This is necessary because genes interact with the environment given context through a process best described by a complimentary field to genetics, which is epigenetics.

==Polymerase chain reaction (PCR)==
[[File:DNArot.gif|thumb|right|Brought to you by [[LSD]].<ref>David Nutt (February 28, 2021). [https://www.sciencefocus.com/the-human-body/how-psychedelics-lsd-work-brain/ "Your brain on LSD: a guide through the most mind-blowing psychedelics research"]. ''BBC Science Focus''. Quote: "[[Francis Crick]], who discovered the double helix structure of DNA with James Watson, and [[Kary Mullis]], who invented the polymerase chain reaction (PCR), had both taken the drug, and attributed some of their understanding and insights to it. Mullis has gone so far as to say: 'would I have invented PCR if I hadn’t taken LSD? I seriously doubt it… [having taken LSD] I could sit on a DNA molecule and watch the polymers go by. I learnt that partly on psychedelic drugs.'"</ref> Or maybe scientists just have ways to cope with their workload.]]
PCR is the straightforward process of amplifying a small amount of DNA in vitro, producing many copies. It is a simple extension of the DNA replication process. It involves a pair of primers (usually 20-30 bps in length) flanking the DNA target sequence. This allows a DNA polymerase enzyme to start the process of adding nucleotides (DNA polymerase needs a free 3' end to add nucleotides). The DNA polymerase used is usually Taq polymerase (isolated from the bacterium ''Thermus aquaticus'', found in the hot springs in [[Yellowstone]] National Park) as it is heat stable (although there are other heat stable DNA polymerase enzymes available, e.g. Pfu polymerase). The enzyme and primers are added into the reaction vessel, along with deoxynucleotide triphosphates and the template DNA (total reaction volume is usually about 50-100μL). This vessel is placed in a PCR machine, which runs for 30 cycles usually, with each cycle consisting of a denaturation at 94°C (DNA is denatured to allow primers access), annealing at 60°C (primers and free nucleotides hydrogen bond to complementary DNA) and an extension step at 72°C (DNA polymerase starts at the primer then moves along bonding free nucleotides together and forming a complimentary strand of DNA). This technique has had an immense impact on molecular biology, forensic science and the diagnosis of human genetic diseases.

==Genetics before [[science]]==

For thousands of years before the mechanisms were understood, man has been genetically engineering, by [[Artificial selection|selective breeding]], food crops and domesticated animals to improve their flavor, yield, hardiness, and behavior.

==Evolution==

The genes that underlie the passing on of traits are one of the fundamental building blocks of the process of [[evolution]].

==See also==
*[[Gene]]
*[[Evolution]]
*[[Inbreeding]]
*[[CRISPR]]

==External links==
*[http://www.genetics.org/ genetics.org]

==References==
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[[Category:Biology]]
[[Category:Genetics| ]]
[[Category:Science]]

[[ru:Генетика]]

Categories: Biology, Genetics, Science