79 Answered Questions for the topic molecular biology

Can PCR tubes be made of different materials than plastic?

Does it matter if I replace the PCR tube (usually made of plastic) with another material like aluminum, glass, or something similar?

Bacterial cell lysis - what solution to use?

I am trying to determine how quickly detergents act on bacterial cells (cell lysis). I would like to compare some detergents at difference concentrations for bacteriolytic activity. I don’t care... more

How can E. coli affect C. elegans expression?

Plasmids can be transferred to *E. coli*. These transformed *E. coli* can be fed to *C. elegans* to silence its gene expression by RNAi. How can *E.coli* release RNAi to *C. elegans*? Even if we... more

Why do neurones use chemical signalling at synaptic junctions?

When a neurone fires, it sends an electrical signal that jumps down the axon via the nodes of Ranvier very rapidly. At a synaptic junction, chemical Brownian diffusion signalling with receptor... more

Do lysosomes play any role in cell division?

My biology textbook includes a point that lysosomes stimulates cell division without further elaborating. But studying it, I felt eerie about this function of lysosome. Then, I checked on the... more

Do two compatible tRNA codons bond together?

Can two tRNA with complementary anti-codons link together? For instance UUU with AAA. If not, why not?

Do chaperone proteins misfold?

If molecular chaperone proteins assist in the folding process of other proteins and misfolded proteins, can chaperone themselves misfold since they are also proteins? What would happen if... more

Why should phospholipid non-polar tails be "protected" in the membrane bilayer?

>lipids are arranged within the membrane with polar head towards the outer side and non polar tails towards inner side, this ensures that the non polar tail is protected from aqueous... more

Is there a reliable source for storage and stability of reducing agents like DTT?

Reading the literature on DTT, one is confronted with a confusing mass of papers; some claim that a 1M solution in water is stable, other papers say it is not. I use the reaction with DTNB to show... more

What stops messenger RNA from binding to itself?

Since mRNA is single-stranded, and (mostly) floats freely within the cytosol, what stops it from folding onto itself (like DNA) and preventing transcription?

What exactly happens if during translation, an amino acid is not present?

Lets say that the cell wants to make a particular protein. Transcription of the appropriate gene is done and the mRNA is made. mRNA attaches to the ribosome and the translation is initiated in a... more

Why does high pH result in the denaturation of DNA?

In the Southern blot method, for example, a solution of NaOH is used to denature the DNA in the sample. I find this counterintuitive since I expected that $\ ext{Na}^+$ cations would neutralize... more

What are the different ways an exon gets spliced?

Exons are produced by more than one mechanism, e.g. splicing out introns after transcription, if I remember correctly. Please list all mechanisms.

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

why is AUG the initiation codon?

Is there any reason why AUG is the initiation codon ?Why is there a need for an initiation codon ? Can't translation start with different codons?

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?

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
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