[_ Old Earth _] Lysosomes

[brother Paul]

On a question and answer forum called Biology Online one poster said

"Lysosome contain enzymes that are used to break down material and get it ready for disposal. All of these enzymes work best at a low pH, reducing the risk that these enzymes will digest the very cell they are contained in should they somehow escape from the lysosome. Keep in mind that the pH of water, from which all life spring from (according to evolution) has a pH of 7. The cell could not house these enzymes without the membrane. The conundrum of getting the enzymes inside of the membrane, or the membrane around the enzymes, or the membrane evolving, then the enzyme getting on the inside, or the enzyme evolving, then the membrane around it, is a very far stretched possibility. This is so far stretched, that it is impossible.

If the enzymes develop before the membrane, the membrane would be broken down by enzymes from the outside. If the membrane evolves before the enzymes, either the membrane is already closed and is consumed by the enzyme or the enzyme develops inside the membrane, at which point would contain water instead of cell fluid. The membrane, at that point, would be consumed from the inside out because of pH."

What do some of you think?

 

[Eugene]

If the enzymes develop before the membrane, the membrane would be broken down by enzymes from the outside. If the membrane evolves before the enzymes, either the membrane is already closed and is consumed by the enzyme or the enzyme develops inside the membrane, at which point would contain water instead of cell fluid. The membrane, at that point, would be consumed from the inside out because of pH."
What do some of you think?

Hi brother Paul, methinks much like Festus said to the Apostle Paul in Act 26:24, And as he thus spake for himself, Festus said with a loud voice, Paul, thou art beside thyself; much learning doth make thee mad.
All this science, and science has yet to know how many raindrops will fall where.

 

[Corn Pop]

Barbarian observes....?

 

[brother Paul]

Hi brother Paul, methinks much like Festus said to the Apostle Paul in Act 26:24, And as he thus spake for himself, Festus said with a loud voice, Paul, thou art beside thyself; much learning doth make thee mad.
All this science, and science has yet to know how many raindrops will fall where.

So very true....I posted this here because the logic of this Biologist is peculiar among many in this field. He/she has stumbled once again on one of those dilemmas that demonstrates the inefficiency of the notion of gradual evolution! In other words he/she realizes one did not precede the other in development but both must have become simultaneously (just like functional DNA and the Cell). the enzymes and the membrane in a gradual model negate one another's possibility. And yes science can make one mad as a March Hare....but the Lord gives us a spirit of sound mind (Hallelujah! Praise His mighty name).

Since the logic is impeccable and the fact undeniable the only position I anticipate will be an attack (somehow) on the poster (either their character or doubt of their credentials which are not discussed). In other words since denial or defeat are not optional they must default to dismissal (the typical approach of most EBs)....admission and realization are not acceptable or else they face ridicule or rejection among their peer group and will be red flagged against publishing

 

[Barbarian]

Acid hydrolases are found in bacteria, and they function quite well, in the absence of lysosomes. In fact, I don't believe that anyone has found membrane-bound organelles of any kind in bacteria. So the membrane is not essential to these chemicals. In eukaryotes, the enzymes are formed at the endoplasmic reticulum, from which vesicles pinch off and join with others to form mature lysozomes. This happens with many other substances produced by the cell, and they are moved as with other substances, in membrane packets by motor molecules along microtubules.

So nothing special. Like other irreducibly complex structures, it's clear that they can evolve by modification of existing structures in prokaryotes.

They do not have to be segregated from the rest of the cell by a mature lysosome. Indeed, they aren't so segregated in prokaryotes. Another beautiful hypothesis, done in by an ugly little fact.

I probably wouldn't have realized this, had it not been for my degree in bacteriology. So let's not pile on the biologist mentioned above.

 

[brother Paul]

Yes they do function, but in these (prokaryotes), even after over 100 years of study, we see no Endoplasmic Reticulum, nor even something close to being capable of forming Lysosome membranes....Now the poster did not say "the membrane is essential to these chemicals" (careful for the twist), he/she said that one cannot form in their presence alone because these chemicals are hostile to the evolving formation OF the membrane (if anything the prokaryotes are showing this to be the probable truth), Finally, the actual data does not suggest that they can evolve by modification of existing structures in prokaryotes (that's an assumption based conclusion in order to interpret according to the theory). What structures would you suggest may do this? The ribosomes?

Again...the poster DID NOT SAY these acids could not exist or function without a membrane,,,

 

[Barbarian]

Yes they do function, but in these (prokaryotes), even after over 100 years of study, we see no Endoplasmic Reticulum, nor even something close to being capable of forming Lysosome membranes....Now the poster did not say "the membrane is essential to these chemicals" (careful for the twist), he/she said that one cannot form in their presence alone because these chemicals are hostile to the evolving formation OF the membrane (if anything the prokaryotes are showing this to be the probable truth),

No, that fails, too. Prokaryotes have a cell membrane, but they also have those chemicals not in bound membranes. So membranes clearly do form in the presence of those chemicals. Hint: pH is a matter of concentration.

Finally, the actual data does not suggest that they can evolve by modification of existing structures in prokaryotes (that's an assumption based conclusion in order to interpret according to the theory).
What structures would you suggest may do this? The ribosomes?

Your biologist has been misled. Not all eukaryotes have lysosomes. Some simple ones lack them. And they form from structures already present in all eukaryotes. The enzymes for them are produced, like many other substances, in the Golgi apparatus, and then pinch off to form a vesicle. They join with a phagosome (formed by phagocytosis), to form a mature lysosome. So an easy evolutionary path from eukaryotes with these enzymes not contained in a lysosome, to one with them.

Again...the poster DID NOT SAY these acids could not exist or function without a membrane,,,

I was assuming you knew. The critical step between eukaryotes without lysosomes, and those with, is the formation of the lysosome. As you see, it's a rather straightforward modification of existing organelles and processes in the cell. But the real key is the formation of a membrane that encloses them. And that is the step we see in fusion of a portion of the Golgi apparatus and a phagosome.

 

[brother Paul]

no, that fails, too. Prokaryotes have a cell membrane, but they also have those chemicals not in bound membranes. So membranes clearly do form in the presence of those chemicals.

So you are proposing the prokaryote’s cell membrane formed in a medium of these enzymes? Or is that more attempts at twisting what has been said? Where on earth did you get that from? I said the poster said they would be hostile to a semi-evolved LYSOSOME membrane…that we assume would form WITHIN a cell…why do you keep trying to turn the point around and around saying it says something It does not?

Your biologist has been misled. Not all eukaryotes have lysosomes.

I’m sorry they did not say that? Are you trying to mislead?

I was assuming you knew.

Again, the poster DID NOT SAY these acids could not exist or function without a membrane

 

[Blake]

I'm humbled because it seems to me that I've just read some sort of foreign language.

 

[brother Paul]

Usually (which we have observed) is that vesicles of membrane lipids and proteins bud off from the trans-Golgi, and are then directed to their instruction determined destination which are the lysosomes, storage vesicles, or the plasma membrane. Is this not correct? The Lysosome itself is not formed by the Golgi Apparatus. If so has this actually been observed happening? Can you direct me to a source where this is actually observed?

 

[brother Paul]

I'm humbled because it seems to me that I've just read some sort of foreign language.

This is Christianity and Science is it not? Barbarian does have a degree in bacteriology. I'm more of a generalist...he is without doubt my superior in this field but that does not mean I so not or cannot propose reasonable questions

 

[Blake]

Is it? It is! I stumbled here from the "recent posts" widget. And now I'm stumbling back out. :P

 

[Barbarian]

Barbarian observes:
no, that fails, too. Prokaryotes have a cell membrane, but they also have those chemicals not in bound membranes. So membranes clearly do form in the presence of those chemicals.

So you are proposing the prokaryote’s cell membrane formed in a medium of these enzymes?

More precisely those enzymes exist in the cytoplasm of prokaryotes, and they do not at all interfere with the formation of cell membranes in those organisms.

Or is that more attempts at twisting what has been said? Where on earth did you get that from? I said the poster said they would be hostile to a semi-evolved LYSOSOME membrane…

There is no special lysosome membrane:
The lysosomal membrane, which has a typical single phospholipid bilayer, controls the passage of material into and out of lysosomes, by its permeability and ability to fuse with digestive vacuoles or engulf cytosolic material.
Lysosomal membrane proteins.
http://www.ncbi.nlm.nih.gov/pubmed/11588980

Remember, lysosomes form when vesicles from the Golgi apparatus (which is composed of the same phospholipid bilayer that the cell membrane is made of) pinch off and unite with phagosomes, which are composed of cell membrane which has engulfed materal from outside the cell, (phagocytosis).

So it's not a mystery how this evolved. It's composed of things already present in the cell. Nor is it a surprise that there are cells that lack lysosomes and still have the enzymes that are normally within lysosomes.

It's just not a problem for biology. No one with any understanding of cell biology thinks so.

that we assume would form WITHIN a cell…why do you keep trying to turn the point around and around saying it says something It does not?

I don't think you see the implications of your guy's claim. And I may be assuming knowledge you don't have in this regard. Or perhaps I'm misunderstanding his claim. The point is, there's no mystery about how lysosomes form, nor is there any barrier at all to the evolution of such things. Indeed, we can still observe the formation of them in the eukaryotes that have them.

Edit: here's a diagram that nicely outlines what goes on in most eukaryotes. Somewhat simplified: (phagosomes are labeled as "endosomes")

 

[Barbarian]

From your OP:
The cell could not house these enzymes without the membrane. The conundrum of getting the enzymes inside of the membrane, or the membrane around the enzymes, or the membrane evolving, then the enzyme getting on the inside, or the enzyme evolving, then the membrane around it, is a very far stretched possibility. This is so far stretched, that it is impossible.

As you now see, it's not only not impossible, it's directly observed. Prokaryotes have no such lysozomes, but they have the enzymes.

Reality tops anyone's reasoning.

 

[Barbarian]

Figure 2: Membrane transport into and out of the cell
Transport of molecules within a cell and out of the cell requires a complex endomembrane system. Endocytosis occurs when the cell membrane engulfs particles (dark blue) outside the cell, draws the contents in, and forms an intracellular vesicle called an endosome. This vesicle travels through the cell, and its contents are digested as it merges with vesicles containing enzymes from the Golgi. The vesicle is then known as a lysosome when its contents have been digested by the cell. Exocystosis is the process of membrane transport that releases cellular contents outside of the cell. Here, a transport vesicle from the Golgi or elsewhere in the cell merges its membrane with the plasma membrane and releases its contents. In this way, membranes are continually recycled and reused for different purposes throughout the cell. Membrane transport also occurs between the endoplasmic reticulum and the Golgi.
http://www.nature.com/scitable/topi...iculum-golgi-apparatus-and-lysosomes-14053361

 

[brother Paul]

Reality tops anyone's reasoning.

It really does...I can see your's now....

I stand corrected, the point you made makes perfect sense.and the poster was incorrect on this point

Thanks

Paul

 

[brother Paul]

Ahh! Hold on...still reading...so far all I see is the Lysosomes already existing in already formed membranes and these emzymes already existing in already formed membranes (even in the case of prokaryotes the "cell membrane" is already formed and in place....even when they divide the membrane is there)...so let me get back to you...in neither case can we see semi evolved examples of either

 

[brother Paul]

Be patient with me here as I am trying to understand more fully….

So let me see…first you say “There is no special lysosome membrane”

But then your source reference says “The lysosomal membrane, which has a typical single phospholipid bilayer, controls the passage of material into and out of lysosomes (which are already extant), by its permeability and ability to fuse with digestive vacuoles or engulf cytosolic material.” And the article you wanted me to read is titled “Lysosomal membrane proteins.”

Perhaps it is a matter of scientific semantics but the article disagrees with what you stated…there is in fact a lysosome membrane.

Then you say, “Remember, lysosomes form when vesicles from the Golgi apparatus (which is composed of the same phospholipid bilayer that the cell membrane is made of) pinch off and unite with phagosomes, which are composed of cell membrane which has engulfed material from outside the cell, (phagocytosis).”

Where I was taught in Cell Biology that endosomes (already encased materials) carry the materials from the plasma membrane TO THE Lysosomes….on the way they merge…I get this….but then it is engulfed by the Lysosome…how does that indicate the formation of Lysosomes (which must already exist)?

Also the other article you mentioned, and the Wiki on endosomes, agree that “Molecules are also transported to endosomes from the trans-golgi network, and either continue to lysosomes or recycle back to the Golgi” Hence again the Lysosomes are already extant….

The next example you give says “Endocytosis occurs when the cell membrane engulfs particles outside the cell, draws the contents in (so these are already encased at this stage by the cell membrane), and forms an intracellular vesicle called an endosome (which is itself an encasement). This vesicle travels through the cell, and its contents are digested as it merges with vesicles containing enzymes from the Golgi (which are also encased)… The vesicle (the newly merged encasement) is then known as a lysosome when its contents have been digested by the cell.”

If this is the case then why do we not see an ever changing number of Lysosomes in a cell? When we look under the microscope we see Lysosomes…so when they have served their function why do they not disappear as new ones are forming? Why are we being taught that this transports materials TO THE LYSOSOMES and then here told this forms and becomes a Lysosome?

Can you see how the examples from the scientific papers contradict the artistically diagrammed textbook example and explanation? The former describing transport to the Lysosomes (indicating they are already there) the second indicating they are only there upon the merging…if this is the case then extant Lysosomes no longer serve any purpose yet continue to exist while new ones are ever forming

Now let’s assume both are true and there are some there and others ever newly forming for this purpose each time (which would actually be happening continually)…over time we should witness a buildup of the number of Lysosomes present in the same cell….but we do not as far as anything I have seen.

Finally there is nothing here that shows the formation of these membranes in the presence of these acids but rather membranes being formed (vesicles) that house them for transport from the golgi to the endosomes (which are housed)

 

[Barbarian]

Be patient with me here as I am trying to understand more fully….

So let me see…first you say “There is no special lysosome membrane”

Yep. Notice that the lysosomal membrane comes from the Golgi apparatus and from the cell membrane itself. The phospholipid monomers are recycled for all those purposes. Since they spontaneously assemble into a bilayer, it's a rather efficient process.

[qoute]But then your source reference says “The lysosomal membrane, which has a typical single phospholipid bilayer, controls the passage of material into and out of lysosomes (which are already extant), by its permeability and ability to fuse with digestive vacuoles or engulf cytosolic material.” And the article you wanted me to read is titled “Lysosomal membrane proteins.”[/quote]

Yep. Same stuff as the other membranes in cells:

Each round ball with two "tails" represents one phopholipid monomer. Since one end is hydrophilic and one is hydrophobic, they assemble spontaneously into a bilayer. It's significant that the one essential structure for a cell is one of the simplest structures. These layers are generally penetrated by specific kinds of proteins to do various functions:

Remember, the bilayer is held together by hydrogen bonds and Van der Walls forces, so it's not very tightly bound, and the proteins stick into the layers by having hydrophobic regions in the center, and hydrophilic regions were the protein sticks out of the membrane.

Perhaps it is a matter of scientific semantics but the article disagrees with what you stated…there is in fact a lysosome membrane.

As I said, there's no special lysosomal membrane. It's a phospholipid bilayer, like the rest.

Where I was taught in Cell Biology that endosomes (already encased materials) carry the materials from the plasma membrane TO THE Lysosomes….on the way they merge…I get this….but then it is engulfed by the Lysosome…how does that indicate the formation of Lysosomes (which must already exist)?

Look at the purple cell, I showed you, above. The enzymes are produced in the Golgi apparatus, pinch off, and go into the cytoplasm. The phagosomes are produced from the cell membrane, pulling in specific materials, which then merge with the packets from the Golgi apparatus to form lysosomes.

Also the other article you mentioned, and the Wiki on endosomes, agree that “Molecules are also transported to endosomes from the trans-golgi network, and either continue to lysosomes or recycle back to the Golgi” Hence again the Lysosomes are already extant….

See above. The union of the phagosomes (endosomes) and a transport vesicle of enzymes produces a lysosome.

The next example you give says “Endocytosis occurs when the cell membrane engulfs particles outside the cell, draws the contents in (so these are already encased at this stage by the cell membrane), and forms an intracellular vesicle called an endosome (which is itself an encasement). This vesicle travels through the cell, and its contents are digested as it merges with vesicles containing enzymes from the Golgi (which are also encased)… The vesicle (the newly merged encasement) is then known as a lysosome when its contents have been digested by the cell.”

If this is the case then why do we not see an ever changing number of Lysosomes in a cell?

Because the old ones are disassembled as they complete their work and the phospholipid monomers are recycled.
http://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC2112240&blobtype=pdf

When we look under the microscope we see Lysosomes…so when they have served their function why do they not disappear as new ones are forming?

You're looking at dead cells, fixed either on slides or for electron microscopy. I don't know if anyone's done radioactive tracing on lysosomes for a video. I'll check.

Why are we being taught that this transports materials TO THE LYSOSOMES and then here told this forms and becomes a Lysosome?

Properly speaking a lysosome is a fusion of a packet of enzymes from the Golgi apparatus with an endosome.

Can you see how the examples from the scientific papers contradict the artistically diagrammed textbook example and explanation?

No, actually, I can't. I see the Wikepedia article worded it badly, but the literature clearly shows that a lysosome is formed from the union of the two.

Now let’s assume both are true and there are some there and others ever newly forming for this purpose each time (which would actually be happening continually)…over time we should witness a buildup of the number of Lysosomes present in the same cell….but we do not as far as anything I have seen.

They break down when they've digested the material in them, and the membrane monomers are recycled.

Finally there is nothing here that shows the formation of these membranes in the presence of these acids but rather membranes being formed (vesicles) that house them for transport from the golgi to the endosomes (which are housed)

They are both formed of the same bilayer. Obviously, if the monomers weren't recycled, the cell would become packed with the endosomes and vesicles.

It's an ongoing process.

 

[brother Paul]

Nice pictures but they do not mean what you concluded. You said there are no Lysosome membranes and then the site you referred me to says there is (which is what I said). So who is correct? The site you referred me to, or you? Oh I see…you added a word not used by me so you could play this game (“special”)…very tricky…I guess I have to be even more on my toes for these twists…

And because all such membranes are similarly constructed (even of the same materials) does not equal one coming from the other (though I understand the casing of the endosome vessel comes out of the plasma membrane . And I am quite familiar with the structure. So what? Yes the endosome material is encased while in the plasma membrane…then merged with already encased enzymes and other proteins…and so on...

You say the Wiki article words it badly, but your second reference says exactly the same thing. That this merged product is transported through the cytoplasm and engulfed by the Lysosome. If what you say is established as so, then this means the already present Lysosomes consume or fuse with the newly formed Lysosomes in the end.

Your Scitable article defines these as separate. It says “Today, scientists know that the endomembrane system includes the endoplasmic reticulum(ER), Golgi apparatus, AND lysosomes”…”The ER, Golgi apparatus AND lysosomes are all members of a network of membranes, but they are not continuous with one another”…

“Therefore, the membrane lipids and proteins that are synthesized in the ER must be transported through the network to their final destination in membrane-bound vesicles. Cargo-bearing vesicles pinch off of one set of membranes and travel along microtubule tracks to the next set of membranes, where they fuse with these structures. Trafficking occurs in both directions; the forward direction takes vesicles from the site of synthesis to the

a) Golgi apparatus and

b) NEXT to a cell's lysosomes or plasma membrane. Vesicles that have released their cargo return via the reverse direction.”

(Sounds like Denton and Behe's molecular trucking analogy)

Or perhaps this also is worded badly along with the first article and the Wiki which all seem to agree???? SO they all must be worded badly….hmmm?

“Any proteins that are destined for a lysosome are delivered to the lysosome interior when the vesicle that carries them (the merge of the Golgi pinch off and the endosome) fuses with the lysosomal membrane and joins its contents”… “as vesicles of membrane lipids and proteins bud off from the trans-Golgi, they are directed to their appropriate destinations — either lysosomes, storage vesicles, or the plasma membrane

No! I am afraid this time what you are telling us is not supported by the science (though it is the "theory")….Still and one final time this does not demonstrate the original point. These acids would be hostile to a “newly forming” lysosome membranes if it were a process of gradual evolution. You yourself have demonstrated they already arrive at their destination neatly packaged.

What do you suppose would happen if we submerged a phospholipid bilayer in a pool of these enzymes? Or poured these enzymes on top of a stack of phospholipid bilayer membranous materials?

Also why do you say all the cells we look at are already dead when you know I can scrape some saliva onto a slide and see living cells in motion? What you are trying to say is…well no one has actually observed this process…! Therefore IMO it is a best guess…a good one…makes sense…could be, might be…but IS???? All the artistically contrived pictures in the world do not prove this.

Who has observed it? Can we now observe it? Long process? We are talking cells here....long is a relative term.