83 Answered Questions for the topic molecular biology
Transmembrane Protein Problem?
A transmembrane protein has 1000 aa. The 5th aa is found on the external side of the cell membrane. It interacts with the aqueous environment outside the cell. Amino acid 90 is inside the membrane... more
Photosynthesis: What Powers the Splitting of Water?
The splitting of water is an endergonic (non-spontaneous) reaction, and thus would require energy (chemical work to be done) in order to happen.In Photosystem II, an enzyme catalyzes this... more
How do centrioles auto-locate to opposite sides of cell during mitosis?
I realize that centrioles are made of 9 triplets of microtubulin wound together with a hollow core, and that they are responsible for the configuration of the spindle during mitosis. The spindle... more
What do sphingolipids do in humans?
I want to know the significance of sphingolipids in human. I have learnt that sphingomyelin is the most significant type of sphingolipid in human. Also that the sphingomyelin serves as a structural... more
What is the relationship between the light and dark reactions of photosynthesis?
My main concern is why are the dark reactions (those that produce hexose) needed? As far as I understand, the sole purpose of photosynthesis is to synthesize carbohydrates, which are only used for... more
Why are proteins always made in N to C direction??
Why are proteins always synthesized from the *N*-terminus to the *C*-terminus? Can there be any “reverse” peptide-bond formation to synthesize proteins in the *C*-terminal to the *N*-terminal... more
Role of calcium chloride during competent cell preparation?
I am aware of the fact that $CaCl_2$ settles down on the cell wall making it less negative may be by forming bond with Teichoic acid. Also due to the positive charge it attracts DNA (DNA is... more
Where do all the NAD+s come from?
In the mitochondrial respiration (of plant cells) NADH is reduced from Nad+ as part of the TCA (converting malate to oxaleoacetate). But where do the NAD+s come from? The TCA cycle is working even... more
Is tyrosine hydrophobic or hydrophilic?
I’ve seen tyrosine classified as a hydrophobic amino acid due to its aromatic ring in some textbooks and as hydrophilic due to its hydroxyl group in other textbooks. How does tyrosine actually... more
Randomness in living systems?
The point of my question is not to talk about events that are uncontrolled by living organisms. My question is about controlled randomness, or I'd like to say adaptive random process. Process that... more
Transport of newly synthesized proteins to cellular organelles?
In the nucleus the DNA is transcribed and processed to mRNA which is translated into proteins in the cytoplasm. What happens between the time a protein is made and that when it reaches the cellular... more
What came first? The DNA or the DNA polymerases?
I know this sounds a lot like chicken and egg question and while the latter has an answer, I am intrigued about the former.A modified form of the question would be, in the course of abiogenesis,... more
What is our skin made up of?
Again, it is a basic question. What is our skin made up of? is it made up of many cells arranged in a systematic way or is it just like any layer say of a book?? what is the difference? where is... more
Why is the DNA helix anti-parallel?
Why is it that DNA strands are running in anti-parallel fashion? Given the chemical base-pairing, they could have been parallel just as well.
Do non-enzyme catalysed reaction pathways exist?
Can their be a kind of chemical reaction pathway in a cell, that is catalyzed or regulated but NOT necessarily by enzymes? I could not find anything on Google.I have almost no background in... more
Non-ribosomal peptide synthesis: why Glutathione cannot be produced by the ribosome?
**Case**: I am writing a summary for a class in protein structure and function, and was asked to describe some different ways that peptides are synthesized (that does not involve the ribosome). I... more
What method would you use to genotype SNPs in low quality samples?
What method would you use to genotype SNPs in low quality samples? I ideally want to genotype hundreds of SNPs in hundreds of scat samples (very low amount of target DNA, potentially degraded and... more
Do strictly anaerobic organisms use metabolic reactions requiring oxygen?
When looking through genome annotations of strictly anaerobic organisms I see reactions featuring oxygen. I suspect these are likely an artifact of the annotation process. But I am wondering if it... more
How did genome duplication in jawed vertebrates allow gene specialization?
I am currently reading from Chapter 15 in Principles of Life, 2nd Edition:>Many gene duplications affect only one or a few genes at a time, but in some cases entire genomes may be duplicated.... more
What is the advantage of using plant-derived antibacterials rather than bacteria-derived antibacterials?
So obviously we have a big problem with antibiotic resistance. Most of our antibiotics originate from bacteria themselves (or are synthetic variations on scaffolds which originate from bacteria). I... more
Explanation of the terms "downstream signaling" and "upstream signaling"?
In molecular biology, what's the meaning of the terms "downstream signaling" and "upstream signaling"? What's the difference between them?
Molecular Biology Genetics
Why are some genes dominant over others? What is the mechanism behind it?
If I have a brown eye gene which encodes the protein that is responsible for the brown color and have a blue eye gene as well, what is the reason that my eye color is brown? How does one gene... more
What is the function of the RNA primer in DNA replication?
During DNA replication, RNA primase puts an RNA primer in the lagging strand. What is the function of this RNA primer? Why can't the enzymes put DNA fragments directly?
What makes DNA sticky-ends sticky?
When restriction enzymes jaggedly cut double stranded DNA it results in so called sticky ends. What is the substance that makes the DNA sticky?