21

Could we use viruses that only affect bacteria to act as antibiotics? Yes. The specific class you're referring to is called a "bacteriophage". There's quite a bit of research going on surrounding phage therapy as a stand-in or replacement for traditional antibiotics. Here's a Nature Biotechnology article from 2004 that discusses your very topic. It is ...


17

Strictly speaking, all nucleated (eukaryotic) cells contain linear DNA. In addition to the nucleus, the mitochondria (which break down food molecules and create chemical energy) and chloroplasts (which facilitate photosynthesis) also have small stores of their own DNA and this DNA is circular. This adds weight to the hypothesis that these organelles were ...


14

Yes you could. It used to be a big deal before antibiotics were discovered, and continued for a bit in the Soviet Union. However, due to the success of antibiotics, it fell out of grace. Due to the lower level of applied research in the Soviet Union (not research itself, although equipment might have been often outdated a bit and the Soviets did isolate ...


14

This is one of the most intriguing questions of eukaryotic evolution. As far as I know and have read, the autogenous theory is not accepted. There are quite some reviews on this topic. Also there is a wonderful book by Nick Lane on mitochondria called Power Sex and Suicide. You would be interested to read it. There are no sufficient evidences for the ...


13

Yes there are prokaryotes with linear chromosomes (especially archaea). Eukayotic chromosomes are almost always linear but this, study reports that yeasts with a loss of function mutation in the ATM homolog genes TEL1 and rad3, form circular chromosomes as a consequence of lack of telomeres. Upon prolonged culture these yeasts were found to undergo mitosis ...


8

My attempt to find an answer has suggested that no-one knows how the DNA gets into the nucleus. This fairly recent paper reports attempts to track the pathway of DNA entry and transfer to the nucleus. Le Bihan et al. (2010) Probing the in vitro mechanism of action of cationic lipid/DNA lipoplexes at a nanometric scale. Nucl. Acids Res. 39:1595-1609 The ...


7

I would say it has to do with the amount of mitochondrial or sequence that has been transferred to the host genome. As a consequence of all this information stored in the host genome, mitochondria cannot reproduce without the host. In this way, they are not their own organisms, but rather organelles. Over evolutionary time, the line between organelle and ...


7

Update: There are plenty of eukaryotes that occur in haploid stage as the dominant life cycle stage. See metagenesis in cnidarian animals and "alternation of generation" in algae, protists and fungi. ...... I am not referring to such transient stages.- I mean extended diploid stages so I am counting as a 'haploid' organism one that only ever has two sets ...


7

I think the question is based on a false premise: Poster: Now, mitochondria are said to have been archaea, right? Me: Wrong, I’m afraid. The closest bacterial relation of mitochondria is Rickettsia, an alpha-Proteobacterium (see Lang et al. for a review). Rickettsia is a eubacterium, not an archaebacterium. The confusion is probably due to ...


6

This question has been asked before: Is there an advantage to linear chromosomes? Firstly, I should state that the generalisation that ALL prokaryotes have circular genomes is incorrect. A growing number of prokaryotes have been discovered which have linear chromosomes, such as Borrelia burgdorferi ,which causes Lyme disease, members of the Streptomyces ...


5

I think HELA cells are edible, although from moral point of view this would be cannibalism. Despite they are cancer cells, they are safe for foreign organism, because any ate matter is destroyed. Even if these cells were implanted into another being by surgery, they will be safe since immunity will recognize them as foreign and kill. They are much less ...


5

This is the figure the question is about. On the right is the control experiment with GTP-γS, on the left without it: The bands that are visible in both experiments are unspecific binding. If GTP-γS doesn't affect their presence, the mechanism by which they bind to the column can't be specific to the GTPase functionality. The proteins the authors were ...


5

Without answering the problem for you, because you have not shown work yet to try to figure out which is which, let me tell you that you have three options. Skeletal Muscle- striated, peripherally located nuclei, same thickness along length, non-branching Cardiac Muscle- striated, few centrally located nuclei, branches and anastamosis Smooth Muscle- non-...


4

You asked about eukaryotes. The genome of the yeast Saccharomyces cerevisiae is 12.2 Mb. The genome of the smallest free-living eukaryote, Ostreococcus tauri (a unicellular green alga) is 12.6 Mb There are smaller eukaryotic genomes, but these are not free-living organisms they are intracellular parasites.


4

I'm wondering if it is safe to assume that the approximate number of cells per unit mass in a mammal will remain fairly constant throughout its lifespan. Not exactly. When a tissue is put under stress, it can respond in four main ways: Hypertrophy - individual cells get larger. E.g. stressed muscle cells get bigger. Atrophy - invidivual cells get smaller....


4

My foray into the literature suggests that mature adipocytes do not divide. See, for example: Lefterova, MI et al. (2009) New developments in adipogenesis. Trends in Endocrinology and Metabolism 20:107-114 In the context of looking at the possibility of stimulating the conversion of white adipose tissue to brown adipose tissue, the authors outline the ...


4

Some apicomplexans such as Plasmodium spp. are haploid during their asexual stages. The organism spends more time (at least in the human host) in the asexual stage than sexual. source Plasmodium spp. are haploid in both human and mosquito hosts except for a brief stage in the mosquito midgut where two haploid malaria gametes present in the mosquito's ...


3

Zabner et al (J. Biol. Chem., 1995, 270, 18997-19007) monitored the lipid-DNA complex formation and uptake which was found to be predominantly by endocytosis. Dot blot experiment shows that cells (50% population) took up 60% of the DNA. The DNA-protein complex was observed to be deposited in the perinuclear cytoplasm and formed a series of regularly packed ...


3

I'll have to disagree with Alan. If the plasmid is integrated into a chromosome it doesn't lose its episomal status. Actually the integration of the plasmid is a characteristic of an episome. This is a quote from this article: http://www.qub.ac.uk/mlpage/courses/level3/plasmidhistoryreview.pdf "... For a decade or more it was confused with ‘‘episome,’’ ...


3

(Reposting my comment as an answer since it seems to be what was required.) A DNA molecule that replicates independently of chromosomal DNA is an episome. By this definition a plasmid is (usually) an episome. If a plasmid integrates into a chromosome by some mechanism (as for example in Hfr strains of E. coli where the F plasmid is integrated) the plasmid ...


3

This is not my field so I am sure there are other examples, but certain neurons will definitely be larger in adulthood than in infancy. There are motor neurons that connect the spine to, for example, the toes. These will grow in length as an animal grows. So, in a human infant they will be a few centimeters long and can reach lengths of over a meter in an ...


3

Answer to the question How much DNA is there in our cell nuclei? In humans, there are about 6 billion base pairs in the nucleus of each cell. Why 6 billions and not 3? There are 3 billions base pairs per haploid genome (see ploidy) and therefore 6 billions base pairs for the whole genome. This number may actually further double during specific phases of the ...


2

Although I have not yet done, in general, cells are happier in a conditioning medium. Grow the original cells in 10cm dishes and save the medium and use it to grow single colonies. You might want to mix used and fresh medium (1:1 ratio). Growth factors are another option. Insulin is sometimes used, but it also depends on cells. Coating the surface of well ...


2

This should be relatively straight forward. Sort the cells into single wells so all descendants are clones of the sorted cell and let them grow until they are dense enough to be transferred into a bigger plate (probably 48 or 24 well). Continue this process until you can go into big cell culture flasks or plates and make sure that you freeze away a number of ...


2

Short answer: No. Eukaryotes have more ways of maintaining telomere length than via telomerase alone and all organisms with circular genomes do not need to worry about telomere length anyway. Long answer: Firstly, the telomerase system is not the only observed mechanism in Eukaryotes that elongates telomeres. Other mechanisms such as the transposition of ...


2

Here is a study of planarian worms, which are immortal in asexual reproduction and mortal in sexual reproduction. Hydras also become mortal after they reproduce sexually. Relevant to your question: Cells within planarian worm differ in expression of telomerase active subunit depending on body part. Immortal (asexual) worms have more expression in the area ...


2

Except in the case of X inactivation in females, and genes on the Y chromosome in males, generally speaking both alleles are expressed in cells. A good example is the ABO blood type marker system. If the mother is type AA, she will pass on an A allele, which codes for the A antigen. If the father is type BB, he will pass on a B allele, coding for the B ...


2

There are two ways of classification of Prokaryotes(on the basis of mode of nutrition) that you will generally come across: Way 1 Way 2 The First classification is very much based on a complete segregation between respiration and photosynthesis. In the first classification, anything that needs another animal to get food is a 'Heterotroph'. (Here, ...


2

We need to make a distinction between the genetic map of a chromosome, which is usually built up from meiotic recombination frequencies between linked genetic markers, the physical map of a chromosome, which used to be made up of clones and contigs, but is now usually derived from the reference genome sequence, and the cytological map of a chromosome, which ...


2

Animal cells Generally all (animal) cells have different shapes because they do different things. Each cell type has a specific role which it has to play in order to assist the body in working efficiently and functionally. Thus their shape supports them to carry out these roles effectively. Look at (animal cells): Neurones Photoreceptors Immune Cells ...


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