LMG_BIO

In the nineteenth century, there were several theories that attempted to explain the heredity of characteristics. Lamark proposed the inheritance of acquired characteristics , where traits are modified by use or disuse during individual’s lifetime and inherited by offspring. On the other hand, Darwin theorized the blending inheritance , where hereditary material of parents “mixes” in offspring, giving intermediate phenotypes and predicting erosion of variation over generations. Mendel proposed that traits are determined by discrete hereditary factors (that we now call alleles), transmitted intact across generations (particulate inheritance). This explains two observations: - Why recessive phenotypes can disappear in one generation and reappear in later ones (alleles persist in heterozygotes); - Why offspring phenotypes can be either identical or different from parents. Neither inheritance of acquired characteristics nor blending inheritance explain these observations. Nowada...

Death is a non-experience. There is fear of the unknown – but the unknown presupposes habitation. From an absolute standpoint, free of mysticism or religiosity, if there is no consciousness to inhabit death, then there is no unknown to be inhabited. Thus, the fear of death as fear of the unknown becomes unsustainable. What truly persists is the implicit belief in permanence – and the fear that such permanence may not hold. We do not fear death as absence, but the collapse of the fiction of continuity that sustains the self.

Think about this in the first person: I only know one thing with absolute certainty: I am conscious. This subjective core of experience, in which I feel myself here, now, in this moment reading this sentence - this  qualia  - is something undeniably mine. My entire reality begins from this point. I only assume, as a social and empathetic human being, that other people (and maybe other living beings?) are also conscious. Without entering metaphysics or religiosity, consciousness requires a support. For now, we only know the biological - the brain - as capable of supporting consciousness. We don’t know about the future. But let’s consider the following hypothesis: Consciousness (as experiential qualia ) never dies in its own world, because it only persists where there is a world it can experience. When the world ceases, there is no experiential void - there is simply the end of the field in which experience could happen. We cannot experience non-happening, nor register the cessa...

    Supposing space and time to be infinite and cyclic, as theorized by Linde and Penrose, the probability that the same molecular arrangement as the one existing right now will reoccur becomes certain. The probability that “you” will read this very line again becomes certain as well.      But the real question is this:      Is that truly you?      Is it the same  qualia ?      The answer, like many others in philosophy is simple - I don’t know. And maybe that’s the only true answer this side of experience.      I only know consciousness exists because I experience it. I can’t prove anyone else has it - I can only infer.       Qualia  isn’t just hard to define; it’s untranslatable into mechanical or functional terms.      Maybe it’s a fundamental property of the universe, like space or time.      Maybe it only emerges when complexity crosses a ...

FST (fixation index) measures how much of the total genetic variation is due to differences between populations. It is a measure of genetic differentiation between populations. Its mathematical value varies between 0 (genetically identical populations)  and 1 (totally genetically differentiated populations). The classic formula to define FST is: where: H T is the expected heterozygosity (if all populations were one) H S is the mean heterozygosity within populations Relation with migration: In simple model in equilibrium between migration and drift, FST has the following value: where N m is the number of migrants per generation . So, if the number of migrants is high (high gene flow), FST tends to zero. The opposite occurs for isolation. Relation with genetic variance: A third way of defining FST is the most straightforward, using Wright's formula (as we'll see next): where: Var( p ) is the  variance of allele frequencies among populations p is the  mean allele fre...

Nucleotide diversity (π) measures the mean nucleotide differences per site between two randomly chosen sequences from a population. In simpler terms, it is the probability of two alleles being different at a given nucleotide. The formula that represents π is the following: where: n is the number of sequences or individuals in the population, d ij is the number of nucleotide differences between sequences i and j , L is the alignment length, ( n 2) is the number of possible pairs of sequences. Nucleotide diversity values of 0.01-0.05 are considered high (found in Drosophila , for example), while 0.001 is considered low (found in humans). Relationship between π and natural selection: 1. Neutral regions: π remains at its baseline level , determined mainly by the mutation rate (μ) and effective population size (Ne): In the absence of selection, π reflects only the balance between mutation introducing variation and drift removing it. Different neutral loci in the genome should show s...

  For every publication where Next-generation-sequencing data was obtained, that data was uploaded to NCBI‘s Short Read Archive (SRA). This share opened the possibility for other scientists to test the data, learn with that data, or use it in their own studies to search for other conclusions. One can obtain all SRA available on  https://www.ncbi.nlm.nih.gov/sra . Here, you can search for a specific SRA, or a species’ whole genomic sequencing data or even RNA-seq data. After you choose the SRA, you need to obtain the access ID (SRR), which is easily found in the SRA page you selected. NCBI offered a command-line toolkit that allowed users to interact with the database and each SRA itself – the SRA Toolkit. It can be installed by running the following commands: $ sudo apt update $ sudo apt install sra-toolkit The two most used sra-toolkit commands are  prefetch  and  fastq-dump . The  prefetch  command is used to download the compressed archives from SRA...