Submitted by spudfolio t3_ymdkuj in askscience
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spudfolio OP t1_iv3ri9c wrote
Yeah that's what I was wondering about- but what about methylation and epigenetics? That's a normal way gene expression changes.
BioTechproject t1_iv3udk0 wrote
DNA does change over your whole lifetime. A lot, actually.
That being said the question was about gene expression, not manipulation.
[deleted] t1_iv44pch wrote
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ChillaVen t1_iv48p3m wrote
Err… cancer?
Furrypocketpussy t1_iv49sjr wrote
Your DNA does not change a lot, this is wrong. While your DNA undergoes many mutations, the overall "code" remains essentially the same
solarwinggx t1_iv4h020 wrote
Most of your DNA in the body doesn't change except for B and T cells. These are the only types of cells that actively mutate their receptor genes via a protein called RAG1 and 2.
Their ability to randomly mutate and the body's ability to remove the ones that are bad are the basis for how our immune system can seemingly fight off most pathogenic diseases that infect the body.
Germ layer cells that produce sperm and egg produce cells that are genetically distinct from the hosts original (somatic) cells through recombination and cross over events during meiosis. I would consider this to be another genetically different cell type because the code has been shuffled (the linear sequence of DNA is no longer the same). Keep in mind that the large majority of the DNA is still identical to the host, it's just a few shuffled genes and alleles.
DNA repair over an organism's lifetime will result in mutations in the DNA of the damaged cell. cells that undergo mitosis frequently also mutate via mistakes made by DNA polymerase. I don't know the mutation statistic off hand but it happens. Most of the time these mutated cells will kill themselves via apoptosis or your immune system will kill the cells for you. The ones that get away with it are cancer cells that form tumors or stem cells gone rouge that form teratomas.
Virus and other genetic elements like transposons can also cause mutations when they jump around your genome.
InstanceNoodle t1_iv4l07n wrote
Growth hormone? Start a cascade effect in producing multiple different proteins. Glands produce stuffs to start production of more proteins where there are receptors for it.
If you are asking for all specific expression (gene -> protein) and how all of them create different physical changes... I would be here for the next 20 years writing 30 books on the subjects.
The_Sishen t1_iv4m03s wrote
What starts it all, how does the body suddenly kick this into motion?
[deleted] t1_iv4qogm wrote
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OzOntario t1_iv4sg6p wrote
"epigenetics" (which methylation would fall under) is a catch-all for gene regulation that isn't specifically protein caused (i.e. proteins may deposit methyl groups to cause methylation, but it isn't the protein blocking transcription).
As with any biological state, genes will be repressed or upregulated during puberty, some of it by epigenetics, some of it by other methods.
TwentyCharactersShor t1_iv4sgwd wrote
Great question, I've been asking it for years. The answer remains unknown.
PersephoneIsNotHome t1_iv51uw8 wrote
The structure of the genes changing is a mutation.
The expression of genes is very flexible and dependents on multiple regulatory elements. You think you make exactly the same amount of insulin exactly every single hour of the day from the time you are born till the time you die?
Gene expression is changed over the course of a DAY.
PersephoneIsNotHome t1_iv51yrp wrote
The normal way gene expression is regulated involves promoters and repressors and other regulatory elements including transcription factors.
SlightlyAlmighty t1_iv52msm wrote
Bit long, but I explained this to my 5yo and they got it.
I think a more appropriate word for "a lot" is "often".
DNA is mostly information about how the cells work and how stuff is made in our body (this is how we share 70% of our DNA with cucumbers and 90 something % with rats).
Only a very small percentage is related to aspect (human vs ape for example), less for geographical features (caucasian vs african for example) and even less for individual features (Bob vs Mike). Our genes suffer constant mutations over our lifetime (this is how evolution works, btw), but only a distinct few can "survive" and change something.
Think of yourself: your cells work the same way as they always did, so the big part of your DNA didn't change. You still look human with aging, albeit with minor changes in appearance (but that is due to other factors), so that part didn't really change. So while mutations occur often, they don't really change that much DNA.
Any time a mutation occurs, it alters what was already there, it doesn' create something new. A good analogy is with BMW and payable options: they are there but just need to be activated (and sometimes, when they activate, something goes wrong and your blinkers blink blue).
Between extreme causes of mutation you can find autoimmune diseases and cancer
-Metacelsus- t1_iv5426w wrote
One major change that happens during puberty is an increase in the levels of sex hormones such as estradiol and testosterone, which are produced by the gonads. These steroid hormones bind to nuclear receptors (estrogen receptor and androgen receptor). These receptors are transcription factors that regulate the expression of many genes, including ones related to secondary sex characteristics such as breast development (estrogen) and facial hair growth (androgen).
windowsfrozenshut t1_iv55hg9 wrote
So you will pass different DNA on if you conceive a child at say 20 years old vs 40 years old? If you're 40 and developed say for example diabetes and hypertension from a bad diet and no exercise and conceive a child, they will inherit that stuff even if you were healthy and fit when you were 20?
tchomptchomp t1_iv55wep wrote
There's also a shift in thyroid hormone levels with a similar result, as well as competition for binding sites with other NHRs such as RAR and RXR.
Additionally, many of these are upstream of other transcription factors either directly or via classic signaling pathways, so there's a whole range of ways in which puberty acts on gene transcription!
SlightlyAlmighty t1_iv56bug wrote
I believe you pass on some sensibility in that area, like the kids will be more prone to get the disease, not that they will actually develop it. Major influence if both parents have it, even more if their parents had it.
For example, if your grandparents had lung cancer, your parents have lung cancer, it would be wise if you didn't smoke or inhale toxic chemicals on a regular basis.
Edit for clarification: by inhaling toxic chemicals on a regular basis I mean work in places where said chemicals are present: factories, paint shops, gas stations etc
naturehattrick t1_iv5b2ep wrote
It's all kicked into motion as soon as the genetic material of the ovum and sperm come together, it's a cascade of events to develop the zygote into a fetus into a baby into a child into a mature adult to do it all over again. What kicks off any of it? Hormones and cell line development.
LFmemes t1_iv5bfq3 wrote
There is an important distinction that needs to made, which is germ line cells vs somatic cells. Germ line cells form into the gametes, which contain the DNA that gets passed on to their offspring. On the other hand, somatic cell DNA doesn't get passed on (e.g. a random lung cell is a somatic cell).
Germ line cell DNA also doesn't mutate as readily as somatic cell DNA. However, a bad diet can lead to epigenetic changes (that influences gene activity and expression without actual changes in the DNA sequence) in germ line DNA, which can affect the offspring.
Of course, it's a lot more complex than I just described.
Solutions_for_all_ya t1_iv5e576 wrote
During puberty, there is an increase in the expression of DNA that is associated with sexual maturation. This increase in expression allows for the production of hormones that are necessary for the development of secondary sex characteristics. Additionally, there is an increase in the expression of DNA that is involved in regulating metabolism and stress responses. This increase helps to prepare the body for the changes that occur during puberty.
windowsfrozenshut t1_iv5j9ha wrote
Thanks for the answer!
windowsfrozenshut t1_iv5jgp5 wrote
Thanks for the answer.
captaincumsock69 t1_iv5jvl1 wrote
Do we know what ultimately causes the gonads to release these hormones? How does this process get started about 12ish years after birth?
klartraume t1_iv5mbd4 wrote
From what I recall, it requires a certain level of body fat in women (i.e. the body wants to know it can sustain a pregnancy) and a certain level of bone density in men.
[deleted] t1_iv5of50 wrote
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TikkiTakiTomtom t1_iv5xbqb wrote
Perhaps its an accumulation of certain constitutively produced enzymes and proteins to reach threshold over time?
TikkiTakiTomtom t1_iv5xszx wrote
> some of it by epigenetics, some of it by other methods
Could you define “other” methods? I was under the impression that anything that would have an effect on gene product would fall under epigenetics.
TwentyCharactersShor t1_iv5ycwv wrote
Probably, but like many things it seems very hard to identify the actual trigger proteins / enzymes or whatever. It's fascinating to study but depressing how little we know.
Incidentally, I think the initial cell fusion that kicks off the growth process is equally interesting. We know some but not all of the protein interactions.
-Metacelsus- t1_iv633r9 wrote
It requires the hormone leptin which is produced by body fat.
Notably the average age of onset of puberty is getting younger and younger. This might have something to do with obesity.
klartraume t1_iv681or wrote
Thank you for clarifying!
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BioTechproject t1_iv84h0g wrote
Not to be the "actually"🤓 guy, buuuuut:
> I think a more appropriate word for "a lot" is "often".
I'd say "a lot" is more appropriate, as "often" seems to kind of imply that it's the same change all over your body.
> Any time a mutation occurs, it alters what was already there, it doesn' create something new.
Well.... technically it can ||a mutation like e.g. duplication can happen, where that gene can then mutate and start doing wonky stuff||
> Between extreme causes of mutation you can find autoimmune diseases and cancer
Very true, those are then the examples that are bad for the whole organism. As you already said most mutations don't really do much, and if they do usually PCD sets in or the cell simply won't function and die off that way.
BioTechproject t1_iv85339 wrote
Yes, those mutations are the change? Also the DNA becomes more and more susceptible to harmful mutations, which is a part of aging, that's why I would not necessarily call it the same.
OzOntario t1_iv98zay wrote
The most common way that people think of a gene being turned on is via transcription factors. Transcription factors are proteins that bind to specific sequences of DNA (e.g. TAATA), that are found in a "promoter region" before any specific gene. They also tend to be at the end of long and complex signalling pathways (think a circuit). Typically, this form of gene activation is considered separate to epigenetics.
Epigenetic modifications are things that allow transcription factors access to those specific promotor regions. For example, DNA methylation occurs on the promotor region, and blocks transcription factor access to the binding site, effectively silencing that gene.
Likewise, access to DNA by transcription factors is dependent on the structure of the histone. DNA wraps itself around histones like a hose around a spool. Histones can either become methylated or acetylated on specific parts that change that structure to deny/allow transcription factors access to the DNA.
This is very important in embryogenesis - once your brain cell has been programmed to be a brain cell, you don't want the heart cell DNA turning on, so certain histones are "locked" by epigenetic mechanisms.
Additionally, mutations to genes encoding the histones have found to be the cause (or one of) of multiple childhood cancers in the last decade, including most notably one of the deadliest brain cancers called Diffuse Midline Glioma. In this cancer, a histone gene is mutated such that one of the histones can't be turned off, so the cell remains in a progenitor-like cell state.
Furrypocketpussy t1_ivbi386 wrote
Those mutations are not significant in the grand scheme. While they accumulate over ones life and proteins will be changed here and there, you have 22,000 genes. We would have some crazy changes as we aged if the DNA was significantly changing
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[deleted] t1_iv3r9kz wrote
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