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14

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, ...


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

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 ...


6

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 ...


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

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.


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 ...


4

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 ...


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

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 ...


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 ...


3

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 ...


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

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 ...


3

Because cigarette smoke contains many carcinogens. Carcinogens can cause cancer by directly affecting the genome. Wikipedia has a list of those present in cigarette smoke, which includes classics such as lead, benzene, and formaldehyde, not to mention radioactive polonium.


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

You seem to be assuming that mutation rates are somehow constant over evolutionary time. They are not. Mutation rates will change according to the stresses a species is subjected to. If you take a bacterial population and place it in a stressful environment (high/low temperatures, oxidative stress, lack of nourishment or whatever) you are likely to see an ...


3

The anthropologist Svante Pääbo is more recently famous for trying to track down the 'language gene'. There isn't a lot of reference to Chomsky in his work as I've noticed, but it is to me the same intriguing idea. That being that the chimpanzee and the bonobo have 99+% identical to human genome sequences and we also have data from human variations as ...


3

First of all I find quorum sensing to be generally facinating, so I'm happy to see the topic brought up here. Dr. Bassler has many papers on the subject, but I think one of the most relevant ones to this question is here. Regarding your question, you have the right idea, but you're missing the point of her comment. The Western shows a more dramatic ...


3

I don't believe you can produce a general function for this. It will depend on the exact gene and organism you are considering. From a molecular point of view, the vast majority of recessive mutations result from a change producing either a non-functional protein product or a truncated product that is cleaned up by the cell. We can reasonably assume that ...


3

To a good first approximation $\overline{\Delta f} = 0$. Where $\overline{\Delta f}$ is the mean change in fitness down to any point or indel mutation. The reasons for this are as follows: In the genome of higher organisms, most of the genome is non-functional ("junk") so most mutations will not have any effect regardless of the change made. A substantial ...


2

From my reading on M. tuberculosis, I know that this organism has a pretty high mutation rate Huh, that's news to me. In fact, Mtb has a rather low mutation rate and rather low genetic variance. See the paper by Sherman & Gagneux in Nature genetics. The paper does state that mutation rate in latent infection is higher than expected or previously ...


2

No. Surprisingly, there is an adaptive immune system in prokaryotes. This is still widely unknown. The newest review is S. Al-Attar, E. R. Westra et al: Clustered regularly interspaced short palindromic repeats (CRISPRs): the hallmark of an ingenious antiviral defense mechanism in prokaryotes. In: Biological chemistry. 392, 4, April 2011, 277–289. ...


2

Have you read the DNA repair article on Wikipedia? The DNA damage and mutation section answers exactly what you're asking: DNA damages and mutation are fundamentally different. Damages are physical abnormalities in the DNA... [and] can be recognized by enzymes, and, thus, they can be correctly repaired if redundant information, such as the undamaged ...


2

Recently, samples from different parts of cottonwood trees have been sequenced (Nature News). The conclusion: “The variation within a tree is as great as the variation across unrelated trees,” says Ken Paige, an evolutionary biologist at the University of Illinois at Urbana-Champaign, who led the team that made the discovery. This doesn't say anything ...


2

Really interesting question. I am not sure, if the mutation rate is something "actively done" by the virus. I think its more a byproduct of vast replication after taking over the host cell. Mutations with a negative effect are deleted, those with neutral effects will be there, and those with positive mutations will be selected for. This paper looks ...


2

For the lac operon there are two possibilities for constitutive expression mutations: The operator is never closed. Reason: Mutation of the repressor, so its not present, doesn't bind or binds only with very low affinity for the operon. The repressor can not bind. Reason: The binding site for the repressor is mutated. See this Website or this ...


2

This question is very broad. And because of its broadness, I am afraid you won't find a database that will give you what you're looking for. Are you interested in some specific phenotypic traits? Or in some specific genes? What time scale are you interested in? Do you want to know about the time that a given allele needed to reach fixation? Do you want to ...


2

Nature isn't intelligent, genes aren't intelligent, and evolution doesn't have a purpose or a goal. Mutations are random, and roughly 97% of them are deleterious while roughly 0.03% are advantageous for the species. This is the first prerequisite of evolution. The second one is differential survival. An organism with a better chance to survive or reproduce ...



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