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So, a quick molecular biology lesson. Proteins are the things that make up a good percentage of our cells (which make up a good percentage of us), and are the things that do the work of the cells - many are catalysts and are known as "enzymes". Proteins are encoded by genes - while the statement that one gene codes for one protein is not quite correct (...


18

Blood is considered a type of connective tissue (sometimes). However, an organ is formed of multiple different tissues. Thus, blood is a tissue, not an organ.


17

Since it was my edit of your question that started all this, I may as well weigh in. I will give a simplified version of genes and gene transcription, there are various details that make the process much more complicated than what I will describe but they are not relevant to the basic question here. First of all, as others have mentioned, genes are specific ...


14

Official definition Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly? I don't think there is such a concept as an "official definition" of any concept in science. There are common definitions though. The definitions you cite Let's go through your three definitions ...


11

I am pretty sure you cannot jump from an oak tree to an ape with whatever common definition of species you're using. But this is some kind of practical implication of your question. The concept of species was already being used by Aristotle and was kept up to now although the grouping of living things into species might not be a clever thing to do. I don't ...


11

The whole point of Darwin's theory was that transition from one species to another is extremely slow and gradual. There are plenty of quotes in "Origin of Species" stating this, and also affirming that there is no clear boundary between species and subspecies, or "races". Quotes from Origin of Species > Variation under Nature (Chapter 2) Quote 1 ...


10

Spiders are part of a taxon called Arachnida. Arachnida also contain scorpions, Oppiliones, acari, … The science of arachnids is logically called Arachnology However, (wikipedia): Entomology (from Greek ἔντομος, entomos, "that which is cut in pieces or engraved/segmented", hence "insect"; and -λογία, -logia) is the scientific study of insects, a branch ...


9

In short, yes, the definitions are still correct: The number of copies of a plasmid in the cell is determined by the mechanism of its replication: whether it is synchronized with the replication of the bacterial chromosome or is independent of it. In the first case, the initiation of replication is performed by the same mechanisms of replication of the ...


9

Yes, selective breeding results in evolution. Definitions of evolution I don't understand why you say that for 3 of the definitions you found, selective breeding would not be considered as evolution. To me, all of these definitions match with the idea that selective breeding results in evolution. If you think otherwise, can you please explain why? There ...


8

[D]o homeothermic and poikilothermic have the same meaning as endothermic and ectothermic respectively[?] No. Once you are referring to the source of the heat, while the other time you are referring to whether the internal temperature varies through time. Source of heat endo = inside exo = outside Variance in internal temperature Poikilo = varies homeo ...


8

I've adapted your definitions to another process that I think will be less controversial to you. Eating is the intake of food by taking into the mouth, chewing, and swallowing. Eating, the process that results in digestion by taking in food and chewing and then swallowing. Eating, then, can be defined as the intake and digestion of food items, ...


7

Just to clarify definitions, your genome is made up of sequences of DNA. DNA is constructed pairs of four nucleic acids, or nucleotides (A,G,T,C). That DNA has many loci within it, each codes for a gene. Loci are given gene names such as SHH (sonic hedgehog) which is part of a discipline called gene nomenclature. Humans have two versions of each gene, one ...


7

Parts of the answer are in the text that you provide yourself. But I shall try to add where i can. What do each of these three terms [hormone, cytokine and protein hormone] mean and how are they different? Both cytokines and hormones are a class of signalling molecules that are secreted by cells. Cytokines are a group of small protein that have a ...


6

Crystallography requires the collection of many measurements (could be a few thousand to even millions depending on the size of the molecule and complexity of the crystal (technically speaking, the size of the crystal's unit cell is a major determining factor for the size of the data set). I'm not going to assume this is a small molecule crystal like a salt ...


6

It seems like your question might contain two separate and linked issues, both of which are perhaps equally confusing and equally interesting. They're both really discussion questions in a sense, but they've also both been dealt with in the literature in thoughtful ways, so here's a stab at an "answer". Issue One: how does your species concept deal with ...


6

From Illinois Wesleyan University: One way in which tardigrades have adapted to various types of environments, has been to reversibly suspend their metabolism. This state is known as cryptobiosis [ 'hidden life' (Clegg, 2001) ] and is a truly deathlike state. Metabolism lowers to 0.01% of normal or is entirely undetectable and the water content of ...


6

But in order to find shortest path, which is known well from algorithmic theory, you have to be as broad as possible. You try to explore as many vertices, as possible, which means you're creating creatures with all those properties (see #2) and measure their "goodness" with help of your metrics (see #3). The problem here is that you have to track/memorize ...


5

As can be inferred from the Shanks et al. paper linked in the question: In molecular biology, "suicide plasmid" is a term that refers to a plasmid which is replication incompetent.* Plasmids normally bear a sequence called "origin of replication" Ori which marks the plasmid for replication by the host cell. Plasmids that lack this Ori will not be replicated ...


5

While organs are generally considered to have a single, specified function (or perhaps a group of closely-related functions), blood (the fluid inside the vessels, not the vessels themselves) has many different functions: deliver $O_2$ from lungs to cells remove waste $CO_2$ from cells to lungs respond to injury by clotting carry multiple different types of ...


5

Good question! The term mutation can be used with two different meanings. Each definition can further be split into two different more detailed definitions. The reason for this slight mess is mainly historical. In short, a mutation can refer to An event narrow sense broad sense An allele definition based on ancestral/derived states definition based on ...


5

If you look at the Google ngram for the term ‘Molecular Biology’ you will see that it first appears just before 1960, and it is relevant that the Journal of Molecular Biology was founded in 1959. It is not biochemistry — indeed the name was meant to indicate its difference from biochemistry, and I heard second-hand (so I cannot vouch for its truth) that Hans ...


5

The fundamental 'problem' with acetyl-CoA is that it cannot be converted to glucose via the tricarboxylic acid (TCA) cycle: a two-carbon compound (acetyl-CoA) enters the TCA cycle, but two carbons are lost as CO$_2$ during each round of the cycle (in the two decarboxylation steps, ie in the reactions catalyzed by isocitrate dehydrogenase and by the alpha-...


4

According to my Henderson's Dictionary of Biological Terms, dry weight is The weight or mass of organic matter or soil after removal of water by heating to constant weight. So yes, your definition is correct and it is also applicable to cells. The dry weight of cells is the weight left when their water content has been removed by heating.


4

it seems to mean persistent or long-lived. Is that correct...? Yes, it's correct, but how persistent the effect is is related to the rate of dissociation or rate of turnover of the receptor. It is relative, so to speak; relative to the effect of non-irreversible receptor binding. Irreversible inhibition of, say, a cell surface receptor means that a drug (...


4

Osmosis is the diffusion of water. Pinocytosis is the endocytosis of liquid/water.


4

The answer is "yes". Evolution is defined as a change in heritable characteristics of a population over generations, and to me, there is no reason not to define domestic animals as populations. The statements you list can all be refuted: Part of the selection human-driven, part "natural". You cannot control all genes. The concept of fitness talks about ...


4

Your theory is based on many false assumptions. Evolution becomes nothing but a finding a shortest path in that unbelievably huge directed graph. What makes you think that evolution followed the shortest path? The best known way to do this is to copy information about entire process (since very beginning) to each and every Life-being you ever ...


4

F(1,22) is the result of an F-test with degrees of freedom 1 and 22, in this context most likely this is an F-test in the context of ANOVA; for the meaning of those degrees of freedom I would suggest further reading on ANOVA. Specifically, in this table it looks like we have a 2x2 ANOVA: with stimulus songs or tones and treatment E2 or none, and the ...


4

The difference is referring to the directionality of gene flow. We talk about genetic introgression when there is some gene flow from one population (say, population A) to the other (say, population B). We would say that population A introgresses into population B. If gene flow goes both ways, then the two populations A and B are admixing. From Wikipedia > ...


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