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11

Biological examples similar to programming statements: IF : Transcriptional activator; when present a gene will be transcribed. In general there is no termination of events unless the signal is gone; the program ends only with the death of the cell. So the IF statement is always a part of a loop. WHILE : Transcriptional repressor; gene will be transcribed ...


8

The pKas of (neutral) guanine and thymine are 9-10 (ref). At high pH (>~10), those bases will be deprotonated and exist as negatively charged conjugate bases. As the deprotonated species, part of the G/C and A/T hydrogen bonding networks are eliminated. In the figure below, green dotted lines represent the hydrogen bonds that explain the observed base ...


7

Housekeeping genes aren't clustered on a single chromosome. It is perhaps not that 'housekeeping' genes - broadly expressed genes - are 'above the laws of regulation'; rather that their regulation is merely more straight-forward than that of specialised genes. I can think of 2 factors that could be relevant: Abundance of methylation sites (CpG sites) ...


6

The problem with housekeeping genes is that they are often not stable and their expression depends on the cell types as well as the conditions. They can be stable under one condition, but are not under another. So this needs to be tested every time you have to choose a housekeeping gene - always use GAPDH or beta-Actin simply doesn't work or skews the ...


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

There are multiple answers to this question depending on who you ask (meaning, what their field of expertise is). The biological dark matter from the wikipedia article in question seems to mean sequence from metagenomic samples which was not assigned to any of our commonly known domains of life. That might not necessarily mean that it does not belong to ...


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 ...


5

Retroviruses depend on being able to convert their RNA genome into a DNA copy, and have a reverse transcriptase enzyme to do that. This unique activity is not found in human cells, allowing for potential antiviral therapy if a drug can be used to inhibit the reverse transcriptase while not affecting the human enzymes. AZT is one such drug, by mimicking the ...


5

They are not chosen, they represent an even half, a complete set of chromosomes. The entirity of a cells genes (found on the chromosomes) is called a genome. Somatic cells are the cells in our bodies that exclude sperm and egg. Sperm and egg are called germline cells. The billions of somatic cells in a homo sapien have the same 46 chromosomes. 23 ( ...


5

Such genome transplantation was performed between two Mycoplasma species in Craig Venter institute Genome transplantation in bacteria: changing one species to another. They found that the donor genome completely changes the recipient cell to accept the identity of the original donor cell. Note of caution: the above experiment was conducted between two ...


4

There are certainly some comparisons that could be made between the way genes are expressed from DNA and logic functions, but they aren't great. But synthetic Biology is really a blossoming new field that is attempting to integrate logic functions into biology, see e.g. Siuti et al (2013). The above paper is a brilliant example of a group using using ...


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 ...


3

As pointed out by aandreev, the greater the size of the insert relative to the flanks lower will be the recombination rate. This is because the donor DNA essentially becomes non-homologous. See the figures below:                 Figure1: Effect of insert size on recombination ...


3

You've done a pretty decent job of answering your own question, but there are a few things that can be elaborated on. The general convention is to use the mitochondrial Cytochrome C Oxidase 1 (COI) gene for barcoding animals and chloroplast genes (rbcL, matK, and trnH-psbA) for plants. The three biggest reasons for selecting these genes are 1) their ...


2

It depends what you mean by "predict". Consider that the faces on genetically identical individuals, such as identical twins, are very similar, even in old age. If you look at the processes of development over the life of an individual as a more-or-less deterministic and predictable phenomenon, then you might argue that faces are predictable from DNA info. ...


2

This recent Cell paper mentions a ribozyme (RNA enzyme) that ligates two oligonucleotides into itself. Given a sufficient source of input oligonucleotides and the correct conditions, it can catalyse its own replication and undergo Darwinian evolution, and can be thought of as a rudimentary form of RNA-based life. The authors hypothesise that ligase-based ...


2

A heterozygous locus has two different alleles and therefore it is possible that their DNA sequence lengths are different. However, it is unlikely that they are so different so as to be clearly resolved in a gel electrophoresis. Agarose gels can at best resolve 20bp; polyacrylamide gels can resolve smaller differences but it is only done for small DNA ...


2

This question can't be answered with a simple yes/no, but I would say that the analogy of DNA being the "code" used by cells is a reasonable one, if taken with a number of other considerations. DNA function When Watson and Crick first described the structure of DNA (being a double-stranded sequence of the nucleotides Adenine, Cytosine, Guanine and ...


2

DNA Barcoding is a method or a protocol which, as you have already mentioned, uses genetic markers to identify species. The barcodes can be "scanned" using PCR. Now Real-Time PCR is just a quantitative version of PCR. You don't need that to look for qualitative aspects. However in a mixed sample you may be able to calculate percentage constitution of the ...


2

There are many different types ('scales', you might say, and mechanisms) of mutation in the genome. Maybe your question was really about base mutations, but I want to add one interesting tangential thing (which also points out the importance of clarifying the term 'mutation'): Segmental Duplications - non-random genomic mutation There are mutations that ...


2

So this question is difficult to answer because it has some errors in it, in that lifeforms being dependent on rarely used elements is a different question than lifeforms using different DNA bases, but I will answer both. So for the question about whether or not organisms could exist that use DNA bases not found in organisms on earth, the answer is ...


2

Just to add to previous answers, but transcriptional interference (see e.g. Shearwin et al., 2005) can be seen as a form of IF-statement (or WHILE) in the sense that: if(x transcribed){not y transcribed} The interference does not have to be binary though, and more common are graded responses. Transcriptional interference can also take place at the RNA ...


1

DNA is not analogous to computer code which renders your search for similar constructs in it meaningless. To give a couple of simple examples why this is: Computer code has a sequential order of execution; DNA acts in parallel and out of sequence, it is not "executed". Computer code has a strict and consistent meaning so the line if x==4 : x=7 always does ...


1

As WYSIWYG said there is no equivalent for function calls, as there will always be some interference. However one could argue that some modular pathways (eg. apoptosis signalling) can be seen as a "code block" where a certain input will (almost) certainly lead to a certain effect. The analogy with function calls is that, in describing many different ...


1

Genome editing techniques like CRISPR-Cas and TALEN use non-specific recombinases coupled to a DNA-recognizing part that can be designed to be specific for any stretch of sequence, as it is constructed out of single zinc-finger 'modules' that each specifically bind a couple of nucleotides (one nucleotide each in the case of TALEN).


1

Since these cells are there by the development of the immune system, the immune cells recognize them as self. By blood transfusion with incompatible blood type, the immune system recognizes the blood cells with different histocompatibility antigens (A,B,Rh etc...) as non-self, that's why it attacks them.


1

In my view there is direct link between probability of recombination and size of the insert. Smaller inserts with larger flanks get incorporated easier. That I understand from reviewing studies based on Cas9/CRISPRs system. Same should stand for HR-mutagenesis in yeast. So, short answer will be: shorter inserts are more efficient. However, I couldn't find ...


1

Enter it in BLASTX. This will give you any protein sequence matches as well as likely homologues given a nucleotide sequence.


1

You might want to try searching against NR/NT database using BLAST. This way you will get to know what this sequence might be similar too. The length of the sequence is too short to code for any meaningful protein.


1

Heterozygous loci have both alleles present at a given time, for example Aa (considering diploid organism), where as homozygous have only one type (AA or aa). Generally, both alleles have different sequence lengths due to deletions, insertions etc. so if any locus is homozygous, it will produce only one length but heterozygous will produce two different ...



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