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15

My friend Brightblades is right in one thing. It seems your teacher was working off a caricature of what the theory of evolution actually says. First of all, you should read Sklivvz's excellent answer at this question. Now to address the elephant in the room, the accident at Chernobyl only happened in 1986. That was only 26 years ago. In that timeframe, ...


13

Change in genetic variance From what I have been taught, Natural Selection (or even Artificial Selection) is great for panning favorable genes from a species and bringing them to the fore, however, it does not introduce new genetic changes. Yes, you are pretty much right. In a given population, directional selection will ultimately reduce genetic ...


12

The answer is chance or, even better, contingency. About your calculations, it is true that the theoretical sequences are almost unlimited, but the basic scaffolds are not. Very different sequences can fold into the same basic scaffold and have a similar reactivity/function. So, even if not all the sequences have been explored on this planet, most of the ...


11

All mutagens are potential carcinogens. Unless the mutagen is highly specific to a site. HPV causes oncogenic transformation of a cell because of certain proteins that it expresses. Its mechanism is directed and specific. Most "carcinogens" are non-specific agents. However according to the definition, HPV can be called a carcinogen. Retroviruses can ...


9

A single substitution can often be silent, or at least not impact the structure and function of the resulting protein in a significant way. But what you describe is a frameshift, and that is one of the most destructive mutations. It will completely change the sequence of the protein after this mutation and disrupt the function of those parts of the protein. ...


8

I think we may be missing a piece from Darwin's original hypothesis. An outline of the first 4 chapters of Origin of Species form the kernel of the Theory of Evolution: 1: Variation under Domestication 2: Variation under Nature 3: Struggle for Existence 4: Natural Selection Really you can't reduce evolution to less than variations; competition ...


8

I don't know, whether the organism you are working with is diploid, but suspect it's an animal (or even a mammal), so the most parsimonious explanation would be that you have homozygotes and heterozygotes at this SNP-position.


7

Cancer cells and normal cells differ on the genetic basis but they share the same genetic background, so they have not different DNA in the sense of two different people. They have to be different, since cancer cells have to accumulate mutations on a number of genes to become a cancer cell, which can survive and will not directed into apoptosis. These are ...


7

That would be hard to say because really beneficial mutations become well distributed through the genome. Basically the differences between us and chimpanzees are a catalog of all the beneficial (or completely neutral) mutations since the ~4.7 M years since we diverged from each other. Separating them from changes which have no special effect would be ...


7

Pink individuals of the katydid species Amblycorypha oblongifolia are a relatively uncommon but natural phenomenon with a long history of research. It looks from popular press accounts (Science Friday, Scientific American) that the pink coloration may be caused by a dominant allele, and is only rare because of a high selection pressure against pink ...


7

It is called conditional mutation. You flox (put lox sites around) gene of interest and express Cre recombinase driven by tissue-of-interest-specific promoter. Illustration from here: Using chemically-activatable variant of Cre recombinase (cre-ER) you can create knock-out in some cells of tissue of interest, not every. Addition: a bit weird but still ...


6

Just continue scrolling down wikipedia: there are also listed two examples of beneficial mutations: the one conferring HIV resistance, and the one conferring malaria resistance. Note that 'beneficial' is relative. The mutation associated to malaria resistance is actually causing sickle cell disease.


6

Purified DNA contains negligible amounts of ethidium bromide. PCR and gel clean-up kits remove it quite well. There is, though, a risk of mutation from the fact that you're visualizing the gel in UV light with ethidium bromide. The risk of mutation from UV is minimized by exposing the gel as little as possible, and by using "preparative" transilluminators ...


6

You're right that the mutation must be in a germ cell in order to be passed on. Most errors are introduced during DNA replication (at a rate of around 10-10), which occurs a number of times between the zygote stage and mature gametes. This book estimates that there are 24 divisions between zygote and egg and 23n+34 divisions between zygote and sperm, where n ...


5

Yes, you can find mutations in the genomic DNA which affect splice acceptor sites. Wikipedia lists the following outcome: Mutation of a splice site resulting in loss of function of that site. Results in exposure of a premature stop codon, loss of an exon, or inclusion of an intron. Mutation of a splice site reducing specificity. May result in variation in ...


5

Others have posted that the term beneficial in genetics is contextual - single mutations may be harmless, unless another mutation is co-inherited; this is called epistasis (where more than a single mutation/genotype/allele is required for the phenotype). I have not studied the list comprehensively, but there is a 'catalog' of all robust genome-wide ...


5

I can't answer your third, but I can answer your first two. With one word, in fact: Bioluminescence http://brightnepenthe.blogspot.com/2010/08/palate-cleanser-90.html That's the deep ocean at night for ya. Unlike underground environments and caves, it's not pitch black pretty much anywhere in the ocean. There are things to see everywhere, and they play ...


5

Welcome to Biology.SE! Your question is very broad. Also, your post has the default of containing severals questions in it. Make sure in the future to restrict your post to only question, it will be much more likely that you receive a good answer then. I hope that I can give some indications about how to get some more knowledge in this answer. In this ...


4

Red blood cell Will probably not. You inherit blood type, but not actual erythrocytes (though the mother's erythrocytes do interact with a fetus). T cell Will probably not. However, while in the uterus and for the first few weeks outside the uterus the Mother's immune system is effectively the newborn's immune system. While the mother doesn't pass on any ...


4

There seems to be some solid evidence that transcription promotes mutation because the untranscribed strand is able to form secondary structures which expose bases to chemical mutagenesis. Here is a recent paper about transcription-associated mutagenesis: Kim H et al.(2010) Transcription-associated mutagenesis increases protein sequence diversity more ...


4

Thats basically the oldest method to induce such mutations. For this purpose either radiation (x-rays) or mutagenic chemicals (like Ethylnitrosourea) have been used for this purpose. This method is undirected, so you never know what the outcome will be untill you see the off-springs. Using this method to get specific mutations is relative difficult. Its used ...


4

Too long for a comment: Evolution and mutation has nothing to do with intelligence and is not influenced by the cells itself. It happens by chance and if the mutation turns out to be beneficial (or at least not harmful for the moment) it will be a selection advantage. Something to think about: If a mutation in an enzyme which is responsible for Glucose ...


4

There's a 2003 paper published in the Journal of Korean Medical Science describing a case of a 'homunculus' within a teratoma: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3055135/ It contained some hair, brain tissues, cranial and other bones, but no internal organs.


4

There are twenty standard amino acids, and some of them are structurally/functionally similar to each other, such as aspartate and glutamate, or asparagine and glutamine, or glycine and alanine. In general, mutations that cause these amino acid switches don't change the function of the protein, but that's just a general rule - it also depends on where these ...


4

Cancer is commonly defined as uninhibited cellular replication caused by mutations to the genome. Genes where cancer-causing mutations have been identified are known as oncogenes; the COSMIC (Catalogue Of Somatic Mutations In Cancer) database lists all of the known oncogenes (547 to date - 23rd Jan 2015 - 1% of all human genes!) [1]. The effect of a ...


4

welcome to Biology.SE! can environmental factors play a role in the amount of mutations that occur? Yes! These environmental factors that increase the mutation rate are called mutagens. You will definitely want to have a look in the wikipedia article. You may also want to read the wikipedia page on mutagenesis Some chemicals increase the mutation ...


4

Lets state what a Mutation is first. Mutation: A mutation is any change in an organism's genetic sequence which varies from that of the wild-type reference sequence (hg19/GrCH37 from 2009 or hg38/GrCH38 from 2013, which are the most current genome assembly). Single Nucleotide Polymorphisms (SNPs): These are any single nucleotide base mutations which have ...


3

While it is possible to get mutations from the ethidium bromide, this is hardly the only source of mutations in the process. Taq itself will introduce mutations fairly frequently, so sequence sensitive procedures typically use a higher accuracy (but slower and more expensive) polymerase, like Pfu. As stated before, the UV can also cause mutations. The PCR ...


3

The processes are called gene rearrangement and somatic hypermutation, and are used by maturing B-cells to generate very (very) large amounts of diversity in the antibody repertoire. If your institution has access, this great article in Annual Reviews in Immunology has all the details, or you can read about it in Janeway (slightly outdated edition). ...


3

I think you assumed that synonymous mutation means silent mutation. But this is not correct. From Wikipedia (synonymous mutation) : Synonymous substitutions and mutations affecting noncoding DNA are often considered silent mutations, however this is not always the case. Synonymous mutations can affect transcription, splicing, mRNA tranport, and ...



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