mgkrebbs

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	880 reputation	bio	website		visits	member for	1 year, 5 months
17 badges		location	United States		seen	yesterday

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Aug 12	awarded	Citizen Patrol
Jun 24	comment	Which species of animals have females as dominant (alpha) The "alpha" designation in dominance is generally applied separately to each sex, as each sex has a clear dominance hierarchy among individuals of the sex, while the relations between the sexes play out by different rules. Both hyenas and wolves have an alpha male an an alpha female in a pack; what's different is that in hyenas females are dominant over the males while in wolves the reverse is true.
Jun 15	awarded	Nice Answer
May 22	revised	Is the eukaryotic nucleus composed of a single or double membrane? minor syntax, prose fixes
May 22	answered	Is the eukaryotic nucleus composed of a single or double membrane?
May 22	comment	Do somatic cells alter their own nucleotide sequence? Cells have many tandem repeats of the rDNA genes (in part to produce many transcripts simultaneously), but I believe the number of copies is generally set by inheritance, although because they are tandem repeats they are subject to copy number variation that occasionally occurs in such an arrangement.
May 22	revised	How do susceptible organisms prevent parasites from overcoming resistance? clarify title ('resistance' had 2 referents); also capitalization
May 22	suggested	suggested edit on How do susceptible organisms prevent parasites from overcoming resistance?
May 21	answered	Do somatic cells alter their own nucleotide sequence?
Apr 22	answered	Can someone identify this bird?
Apr 1	comment	How do we know the brain flips images projected on the retina back around? @nico: Of course the neurons maintain precise connection relationships with neurons carrying signals from spatially adjacent areas of the retina. Nevertheless, there is nothing about the arrangement that makes it "upside down" and thus requires further processing to "flip" it.
Mar 31	comment	How do we know the brain flips images projected on the retina back around? The question assumes there is something like a little projection screen inside the brain -- something that has an "up" and a "down". It's not like that; there are just an array of retinal cells transmitting pulses to a set of neurons. Retinal cell A talks to neuron 1, cell B to neuron 2, etc. neurons 1 and 2 are not physically arranged in space in a way that matters to image perception. There is no little man in there watching a little screen. See the CogSci question that jonsca linked to.
Mar 20	comment	What do we know about LUCA? Wikipedia's article does a pretty fair job of summarizing the likely nature of the LUCA.
Mar 12	awarded	Critic
Mar 2	answered	Why dont “growing degree days” have units of degrees Celsius (or do they)?
Feb 27	answered	What is the closest species to humans in animal kingdom?
Feb 15	awarded	Commentator
Feb 11	answered	Are human chromosomes connected or separate molecules?
Jan 25	comment	Do mitochondria simply automatically convert glucose to ATP? Mitochondria have very few genes left, many fewer than a free living organism would need. Almost all the originally present genes have been lost as unneeded, replaced by functional equivalents from the nucleus, or have effectively migrated from the mitochondrion to the nucleus. The genes left in the mitochondria are mostly the electron transport chain proteins and the ribosome and tRNA genes needed to build those proteins.
Jan 24	comment	Do mitochondria simply automatically convert glucose to ATP? @Vass - The current arrangement is not necessarily the perfect arrangement, it's just the best that has been achieved so far in the accidental history of evolution. It's quite likely that it would be better if all mitochondrial genes resided in the nucleus since the sexual recombination of genes the nuclear mechanism provides allows better maintenance and improvement of genes (unlike the purely asexual DNA reproduction in the mitochondria). This is why many genes have migrated from the mitochondrial genome to the nuclear genome, and why 99% of mitochondrial protein genes are nuclear.