3
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2answers
19k views

What does 5' and 3' mean in DNA and RNA strands?

What are 5' and 3' in DNA and RNA strands? Please clarify with some images and please use simple English.
3
votes
2answers
148 views

Hardy Weinberg Equilibrium problem

In a small tribal population, the frequencies of two alleles A and a at a particular locus were 0.3 and 0.7, respectively. However, not all the individuals with genotype aa could live up to the ...
3
votes
1answer
113 views

Why insects are so small compared to mammals?

I was wondering what biological limitations make the dimension of the insects small compared to the dimension of the mammals. I know in other eras insect were bigger!
3
votes
3answers
73 views

Can genes that activate transcription factors also called be called transcription factors?

If the sole known function of a gene is to activate a transcription factor, would that gene also be considered a transcription factor, or is there a word for such genes that are further upstream on ...
3
votes
2answers
148 views

What is a bacterial biofilm?

Bacteria produce something called a biofilm. I have found a few definitions; some say it is a complex of live and dead bacteria and others say it is a layer on cell wall. What is it made of? What ...
3
votes
4answers
857 views

What evolutionary reason is there for having the urinary duct and reproductive organs so close together?

As the old joke goes, "God must have been a civil engineer. Who else would put a waste facility straight through a recreational area?" But maybe it wasn't God. Is there any evolutionary reason (or ...
3
votes
2answers
1k views

Why is Paracetamol so great?

Every time I get ill (cold, flu etc) I take a couple of these wonderful tablets for up to 4 times a day and I, eventually, get better. What exactly is paracetamol? Why is it so effective and is it ...
3
votes
2answers
725 views

Difference between mice and rats

What is the actual biological difference between mice and rats? Are they actually the same thing with two different names depending on appearance (are they all mice for instance and we call the larger ...
3
votes
3answers
385 views

Looking for Kelly Chibale's paper on Malaria cure

From National Geographic, there has been a lot of hype on Kelly Chibale's work from University of Cape Town on the aminopyridine MMV390048. Unfortunately, this was from an announcement from an ...
3
votes
2answers
149 views

Is it possible to correctly identify presence of Y chromosome with external physical test only?

I asked a question related to the third sex, and I came to know that its always possible to categorize a human to male or female with presence of Y chromosome. Now, I have another question. Is there ...
3
votes
2answers
107 views

Why do we have to exhale (or inhale) in order to speak?

Every time we speak, sing, or make any other kind of advanced noise with our throats, we exhale, or to put it that way, blow air through our throats. Why is this required? After all, speakers do not ...
3
votes
3answers
104 views

Why does a cockroach not die even after decapitation?

Why does a cockroach not die after its head is cut off?
3
votes
1answer
110 views

What kind of fly is this?

I found this dude hanging out in my sink, but he didn't fly away when I put a dish in the sink. Turned out it was dead. The front part looks exactly like a housefly. But, I've never seen the back end ...
3
votes
2answers
105 views

Name of This Black and White Dove

I spotted this dove in a park. It was foraging among Rock Doves, Seagulls, Ibises and a few others. It appears similar to Pied Rock Doves, but I am not certain if this is correct. Any idea what ...
3
votes
4answers
238 views

Is there a correlation between total neurons and intelligence?

Thanks for looking. First off, I am not a biologist, just a curious layman, so I apologize in advance if this isn't a "good" question. Please don't downvote me into oblivion. I read today that the ...
3
votes
2answers
262 views

How are two species with similar phenotypes identified as different?

How are two species with similar phenotypes identified as different? Have two different individuals that were thought to be different species ever been determined to be from the same species ( or ...
3
votes
3answers
400 views

The effect of pH on enzymes

I am currently studying biology and have a question. I know that as pH increases, enzyme activity increase until the enzyme's optimum pH is reached. However, I would like to know why as pH increases ...
3
votes
2answers
481 views

Initial population when i count backwards?

My question is dealing with how many ancestors it took to produce me: --> to produce me it took 2 people (my parents) = ($2^1$) people = 2 --> one generation further included = ($2^1 + 2^2$) people ...
3
votes
2answers
130 views

High sequence similarity but start codon isn't methionine

I have noticed in a particular genome sequence of a prokaryote that various regions in a sequence share similarity which is high(>80%) with known proteins. However, the start is not a methionine. Is ...
3
votes
2answers
514 views

Why does Glutamine have the symbol Q?

Spent a half hour googling this and the best I could find was this: Now for some rhymes: Arginine = R. R we having fun yet? Asparagine = N The kNights of Ne say "Ne". Glutamine is a cute ...
3
votes
2answers
2k views

Is there any complex organism that is both autotroph and heterotroph?

Possibility also include "adaptation mode" if such exist. I don't discern whether autotrophic/heterotrophic part play only minor role either.
3
votes
1answer
2k views

What factors are known to affect evolution?

My understanding is that the possible mechanisms of evolution are: Environmental changes Cultural/mating preferences Population Immigration Genetic Mutation Am I missing anything? I've heard that ...
3
votes
1answer
89 views

Majority of transcripts are from sense strand?

I am wondering whether majority of transcripts are transcribed from the 5'->3' strand? Because I encounter a lot of expressions like "anti-sense transcripts". Could anybody help clarify this? Thanks.
3
votes
2answers
67 views

Why does caffeine give you so much energy, while being so low on calories?

There's definitely something I'm missing here. Since calories is a unit of measurement for energy, and caffeine seemingly gives you a lot, how can the labels on caffeinated products have such a low ...
3
votes
2answers
352 views

How to calculate relatedness in haplodiploid organisms (mainly full sisters and full brothers)?

I have tried to calculate the relatedness for haplodiploid organisms, but cannot understand the calculations behind full sister and full brother. (taken from Wikipedia: haplodiploidy I have managed ...
3
votes
3answers
141 views

Why has grey hair evolved?

A vast majority of humans get at least some grey hair as they age. As far as I know this applies to both genders and all races. Presumably this means that at least some grey haired humans have ...
3
votes
3answers
123 views

More entropy: Atom or Macromolecule? [closed]

A question that appeared on my last exam was : Which of the following has greater entropy A) An atom B) A macromolecule The question doesn't specify anything else(i.e. type/size of atom or ...
3
votes
3answers
60 views

what are good sources of free-to-use images and diagrams

I am looking for good image repositories for biology teaching. Photos and textbook-like diagrams. I am interested in images that can be used commercially without payment, or, at least, that require ...
3
votes
3answers
41 views

Immune reaction to “new” protein

I read in Bruce Alberts Molecular Biology of the cell : Normal mice,for example, cannot make an immune response against one of their own protein components of the complement system called C5. ...
3
votes
1answer
383 views

Family tree for edible plants?

I am looking for a family tree for plants, particularly veg / herbs / fruit. Something similar to: If it could be slightly less technical than all the Latin ...
3
votes
3answers
315 views

Bioinformatics tool for “pairwise alignment” of complementary sequences?

I'm currently working on some ribozyme binding, and I'm looking for a tool that will essentially analyze the regions of the degree of complementarity in two sequences in order to extrapolate ...
3
votes
2answers
5k views

Why Do Healing Wounds Feel Warmer To The Touch?

I fell over on my bicycle trying to avoid running over a rattlesnake, and ended up badly skinning my knee. It immediately began to bleed, but soon clotted. It has been 2 days now and it has formed a ...
3
votes
2answers
90 views

How long can C. Tetani survive in soil?

Clostridium tetani (C. tetani) is a bacterium commonly found in soil and is excreted in the faeces of many animals (both mammals and birds) and serves, by means of the exotoxin, tetanospasmin, causes ...
3
votes
3answers
442 views

Is there variation of AT/CG ratio along species?

Chargaff's rules say that the number of Adenine of the number of Thymine in a genome are equal (nA=nT) and similarly nC=nG. This makes obvious sense knowing that C binds to G and A to T. But what ...
3
votes
1answer
330 views

What hair color will result in someone inheriting both blond and ginger genes?

Both the genes for blond hair and ginger hair are recessive, so they need both parents to give the same gene for it to take affect. What happens when a person has 1 copy of a recessive gene and ...
3
votes
3answers
3k views

Separating DNA Fragments by Gel Electrophoresis. Are all the strands for one size the same?

My apologies if my question is too basic, and please point me to a more appropriate forum. I am reading the textbook "Essential Cell Biology" by Alberts et al, and am consulting other sources as ...
3
votes
1answer
220 views

Macroevolution vs. microevolution

Where is the line usually drawn between macroevolution and microevolution? I thought that, although similar processes govern both, the line was at the species level, with macroevolution being changes ...
3
votes
2answers
74 views

Why don't we form immunity to some infections?

I read another question, and its answers, about how vaccines work, but I don't see there, and and don't understand, why some infections can, seemingly, not be immunized against at all. For example, ...
3
votes
3answers
175 views

What Defines a Food as Edible?

With many foods today containing chemicals, agents and preservatives etc... What biological criteria must a new food and its constituent components satisfy biologically, to be defined as edible? ...
3
votes
1answer
4k views

What does the term 'bioavailability' mean?

From what I've read, Bioavailability is the degree to which food nutrients are available for absorption and utilization in the body. How would you explain this with an example?
3
votes
1answer
95 views

Color of the Fur coat of Polar bears

Recently I was playing a quiz and a question was asked about the color of the fur coat of a polar bear. To my surprise the answer was black. I thought it was yellowish white or creamy. Why so ?
3
votes
2answers
114 views

What risk to DNA does long-term exposure to low-dose radiation pose?

A new study from MIT scientists suggests that long-term exposure to low-radiation poses no risk of DNA damage for mice (it is also important to note that mice are unusually susceptible to cancer). So ...
3
votes
2answers
64 views

How to inactivate trypsin permanently by boiling?

I have to perform a hydrolysis of BSA with the enzyme trypsin. As a control I want to inactivate the trypsin enzyme. Can I inactivate it permanently by boiling (100oC) for 10 minutes, or does it it ...
3
votes
1answer
84 views

Why did humans lose their fur?

The little amount of body hair humans have don't seem to be of much use for keeping warm. Our Simian cousins on the other hand sport thick furs. At which point during the species evolution and why ...
3
votes
2answers
68 views

Is there a difference between any of these terms for proteins: “crystal structure,” “NMR structure,” “solution structure,” and “complex structure”?

My homework wants me to plot all crystal structures determined per year, but when I search on PDB for all structures, many of the articles say "crystal structure," but some say "solution structure" or ...
3
votes
2answers
581 views

What happens if a person has the right side of the body totally removed (including the brain)? [closed]

I guess humans could live without just the right lobe of the liver or the right brain. Could a person without the whole right side of body survive? The left brain controls the right side of the ...
3
votes
2answers
57 views

What is an Ihh-/- mouse?

This one is too basic question: I just came across $Ihh^{-/-}\ $ mouse. Is that means this mouse devoid of that gene Ihh. What is this sign called and are there other such representations?
3
votes
2answers
81 views

positive and negative feedback

I want to know more about positive feedback in gene regulation and what the different between positive and negative feedback is and the similarity.
3
votes
2answers
104 views

Human Evolution in Modern Times

I understand that evolution occurred to form the current hominids from a common ancestor millions of years ago. As evolutionary processes take a long time, is there proof of evolution occurring with ...
3
votes
1answer
525 views

What is the name of this flower with purple leaves and orange inner part in NYC?

I've photographed this flower a few days ago in New York City: Does anybody know the name of it? (and how is the orange part called?)

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