Archive for the 'Word of the Week' category

Word of the week: transcription

Feb 18 2012 Published by under Uncategorized, Word of the Week

Today's word of the week is transcription, in the biological sense. Not the process of converting speech into a written document (though I know a lot of science writers who spend a lot of time doing that, so I suppose it could count as part of the biological definition), but the part of the central dogma that is incredibly important to molecular biology. The process of information flow is this:

DNA -> RNA -> protein

This represents the flow of information in a cell at its most basic level. DNA is transcribed to RNA, RNA is translated to protein. We used to think that this flow only went in one direction. We now know (thanks to retroviruses like HIV) that RNA can transcribe back to DNA. We also know that proteins can influence DNA transcription, though whether proteins can translate back to RNA is not known (it seems like a big leap to me, but a lot of this stuff seemed like big leaps to a lot of people, only a few years ago).

And in all this, there is transcription.

Transcription describes the process of DNA -> RNA, the process performed by RNA polymerase and other enzymes, which break up the bonds between two DNA strands, make a new RNA pair to one of them (RNA nucleotides are just like DNA nucleotides, with the exception of Uracil for Thymine and ribose for deoxyribose), and allow the DNA to be attached to its original pair strand, ready to be transcribed again or put away for another time. Transcription is the first step of what will become gene expression, and things that affect it affect what proteins are made, and in the end, the function of the cell as a whole.

4 responses so far

Word of the Week: Bromide

Feb 12 2012 Published by under Word of the Week

This word of the week has meanings both in science and in normal, every day language.

Bromide: An anion of the element bromine, element 35.
Bromide: A word used to indicate a platitude, especially one used WAY too often, and which has no real use or meaning, except that meant to make you feel better, like "take things a day at a time", or "go with the flow". Do you feel better yet?

I now wonder how many chemists have made bromide jokes in their dissertations.

5 responses so far

Word of the Week: CREB

Feb 05 2012 Published by under Word of the Week

Today's word of the week is actually an acronym: CREB, the c-AMP response element binding protein. CREB is a very popular protein in studies of things like addiction and mood disorders, and particularly interesting to people to study memory. It binds to specific bits of DNA (called, easily enough c-AMP response elements), and by binding to the site, can cause the genes downstream from that area to either increase or decrease in transcription. It controls the transcription of many other important proteins, including things like somatostatin, brain-derived neurotrophic factor (BDNF), and corticotropin releasing hormone. Though CREB causes changes in these proteins and others, many scientists study CREB itself, looking for changes there first, and then looking at what genes are affected.

2 responses so far

Word of the Week: Presynaptic

Jan 29 2012 Published by under Word of the Week

The word of the week this week is one that many scientists often assume that you already know: presynaptic. But do you? Pre- means before, and it's before the synapse, but what does that mean?

Presynaptic: This is an adjective really, but when I use it, I use it to talk about the neuron that releases the neurotransmitters into a synapse. A synapse (by which I usually mean the synaptic cleft technically) is a space between two neurons, through which chemicals pass to transmit a signal from one neuron to another. The neuron SENDING the signal is considered to be "presynaptic", while the one receiving the signal is "postsynaptic".

This word is very dependent on context. Neurons receive and send information, often in the same area, so whether you are looking at a presynaptic neuron depends on what neurotransmitter or modulator you are looking at, where the signal is coming from, and where it is going. Often a neuron is presynaptic in many places while being postsynaptic in many others, or even within the same signal, as it sends signals back.

3 responses so far

Word of the Week: Neurotransmitter

Jan 22 2012 Published by under Word of the Week

Last week's word of the week was not a sciencey word, but a fun word, because why not? But this word of the week is one I use ALL the time, and one that I always worry people don't know about. And your brain is full of them, so it seems relatively important to know what they are.

Neurotransmitter
: These are chemicals that are present in your brain, and serve a chemical messengers between neurons. Neurons do not actually touch each other, instead there is a little gap between one neuron and the next (called a synapse), and neurotransmitters are released from one neuron to the next, to keep a signal going.

An important note: neurotransmitters are released from inside the first neuron (from little bubbles called vesicles which bleb on to the outer membrane of the neuron and release their chemicals out into the space), but they do NOT go into the next neuron. Instead they hit the next neuron and bind to receptors on the cell surface, which change the inside of the target neuron to pass the message on.

Neurotransmitters can cause the next neuron to have an action potential and an excitatory effect, or they can cause that neuron to shut down temporarily, acting in an inhibitory manner. It all depends both on the type of neurotransmitter, and particularly on the RECEPTOR the neurotransmitter binds to. Examples of neurotransmitters include things like acetylcholine, GABA, glutamate, dopamine, serotonin, and norepinephrine (among others). But the chemical itself is merely one molecule, which is released from one neuron and binds to receptors on another. It is then taken up by transporters or degraded by enzymes.

EDIT: I would like to include a note by Dr. Zen (included in a comment below) about the difference between a neurotransmitter and a neuromodulator, which is a very fine one and worth thinking about.

A chemical that has fast, short-lived effect on a neuron is acting as a neurotransmitter. Neurotransmitters bind to receptors that are doorways in the neuron to let electrical current flow.

A chemical that has a slow, long-lasting effect on a neuron is acting as a neuromodulator. Neuromodulators bind to receptors that trigger events inside the cell, but those receptors don’t act as doorways for currents themselves.

The same chemical can be a neurotransmitter in one location and a neuromodulator in another. The same chemical can be acting as both a neurotransmitter AND a neuromodulator on the same neuron, if that neuron has two different kinds of receptors for that chemical on it.

27 responses so far

Word of the Week: Briffit

Jan 15 2012 Published by under Word of the Week

I would like to start something new on the blog, the Word of the Week! Even though I try very hard to keep my blog posts readable for people without much science background, it's really hard to not use big words. Or acronyms. Or a bunch of other things. Usually I explain them or link to Wikipedia or something else with a credible definition, but I think I'd like to make my own. Some will be serious, and some will be silly, some will be sciencey and some will not, but they will all be there for you to see, and will also be useful for linking to when I want to mean what I MEAN, in the context that I mean it, as opposed to the context in which Wikipedia may mean it. This sounds kind of odd, but when you're talking about some of the words used in neuroscience ("reward", "reinforcement", "bias", "opiate"), you need to talk about the specific neuroscientific context, without any of the possible others.

And then of course, some words are just FUN.

So we begin with today's word, which is...Briffit.

A briffit is the cloud of dust which hangs in the air behind a swiftly departing object or person.

Eat my briffits. :)

2 responses so far