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Prophets or
Evolution - An LDS Perspective Chapter 22 Protein
Synthesis Introduction In the next
chapter we will begin our detailed discussion of how DNA fits into the issue of
evolution. But first, it is necessary
for the reader to understand what a "protein" really is and how
proteins are made in the body. Think, for
a minute, about a wooden rocking chair.
If you look at the individual parts which make up the chair you will see
the 4 legs, the seat, the structure the person leans back against, the wooden rods
to strengthen the back of the chair, the curved wood which allows the chair to
rock, and so on. If you took
the rocking chair apart, piece by piece, you would see several different kinds
of wooden patterns which are put together to make the chair. There are
hundreds of different kinds of cells in the human body. Each type of cell in the human body has many structures in them which can
be compared to a rocking chair. Each of
these cell structures are made up of smaller structures, much like a wooden rocking
chair is made up of smaller wooden rods and other pieces. In a cell,
the individual parts of the chair can be compared to proteins. The entire structure of the chair might be
called a "protein structure."
The pattern to make the different designed parts of the chair (i.e.
protein structure) come from sections of DNA called "genes." For
example, let us consider the "ports" in the cell membrane through
which food and other things pass into the inside of the cell. Essentially a "port" is a hole in
the side of the cell membrane. However,
it is a "hole" which is made of proteins which are bound together to
form a structure. The
"port" is a protein structure which is made up of proteins with
different shapes. The DNA includes the
templates which are used as patterns for making the different shaped proteins
used in each port. Just like a
person would look at a blueprint before starting to build the individual pieces
which make up a wooden rocking chair, the body turns to the DNA to find the
blueprint (i.e. template, pattern or cookie-cutter) to make the pieces (i.e.
proteins) which make up the structures inside of cells (or on the surface of
the cell or outside the cell). Protein
synthesis, or protein biosynthesis, is the process by which the genetic
information in DNA (deoxyribonucleic acid) is converted into proteins. All of this occurs inside the cells. The term "proteins" in this context
includes proteins, enzymes and some other complex molecules which are made from
polypeptides, which will be discussed below. A gene is a
pattern, or cookie-cutter, or blueprint, which is used by the cell, during
protein synthesis, to make the individual proteins needed by the cell. The DNA is the starting point for making
proteins. DNA is like
the blueprint of a building, however, DNA also includes the blueprint for the
construction of the building, including the supervisors (supervisor proteins),
the laborers (laborer proteins), the messengers (messenger proteins), etc., all
of which are functions accomplished by proteins inside the cell. The DNA
does not become the proteins, rather it is used like a "copy
machine," it simply allows other molecules to "copy" its
patterns over and over again. Bacterial Flagellum As one
example, in certain kinds of bacteria there is a protein structure called a
flagellum. The flagellum is like a long
tail which sticks outside of the bacteria cell, by which certain bacteria swim
around. It is a large protein structure. The "motor" which turns the tail is
inside the cell. Both the motor and the
tail are made of proteins. However,
this large protein structure is made up of smaller protein structures. Taken together, this large structure has been
compared to an outboard motor engine for a speedboat. Here are
some of the smaller protein structures which make up the flagellum, which is itself
a large protein structure: Hook
(similar to universal joint) Filament
(similar to propeller), meaning the long tail Rod
(similar to drive shaft) S ring and
M ring (similar to rotor) Bushing, L
ring and P ring Stator,
studs and C ring Inner
(plasma) membrane Outer
membrane Peptidoglycan layer Periplasmic
space and so
on. (see: The point
is that each of these smaller protein structures are
made up of individual proteins, which came from patterns on the DNA. Building
this large protein flagellum requires supervisors; just like building a
skyscraper would require supervisors.
The supervisors who oversee the construction of the flagellum are proteins. The workers
which actually put the proteins in place, as they are built, are also proteins. The accountants who tell the DNA which
proteins to make next are also proteins.
The messengers who provide information to the DNA for repairing damages
to the structure are also proteins. The entire
process by which the flagellum is made is done by proteins, even the
communication processes are accomplished by proteins. The process
by which these patterns on DNA are used to form proteins is the subject of this
chapter on protein synthesis. The terms
used in this chapter will be used freely in subsequent chapters, so it is
important to understand the process of protein synthesis, especially the last
step. While the
process of protein synthesis may seem complicated, in reality this chapter is a
highly simplified overview. An entire
book could be written on all the complexities and exceptions which occur in
different organisms with regards to protein synthesis. This chapter
will describe what goes on in a eukaryotic cell and especially in bacteria. Step One - Phase One of Transcription Transcription
is the actual act of using the DNA as a template to create a new protein. DNA resides
in the nucleus of the cell. DNA consists
of about 3 billion "nucleotides," or to be more accurate: 3 billion pairs of nucleotides. Step one is
to convert a section of DNA into RNA, which is a molecule similar to DNA. RNA itself will later be used in the process
as a template in the process of choosing the sequence of specific amino acids
which will actually make up the protein.
It is the amino acids which become part of the protein, not the original
DNA or even the RNA copy of the original DNA. Thus,
transcription takes a stationary
blueprint (the DNA) and copies it onto a traveling
blueprint (the RNA) which will travel to a different part of the cell (outside
of the nucleus) where the protein is actually built. In other
words, the DNA will stay in the nucleus, so it can be used over and over again,
but the copy of DNA, the RNA, will travel outside of the nucleus and will
become the actual pattern which will be used to make the protein. Transcription,
the conversion of DNA into messenger RNA, or mRNA, is actually in two phases. In phase
one of transcription, a molecular machine (called: RNA polymerase) unzips a
section of DNA. However it should be
noted that RNA polymerase does not act alone.
Each type of cell provides different "helper proteins" to help
the RNA polymerase do its job for that type of cell. Starting at
one end of a gene, called the "promoter sequence" or "promoter
region," and continuing until it reaches the "terminator"
sequence, it starts building a type of RNA called "pre-mRNA" (i.e.
pre-messenger RNA) or "Nuclear RNA" because it is inside the nucleus
of the cell. In other
words, the RNA polymerase "unzips" a section of DNA so that the
double helix is now two single-sided helix strands (it unzips only a single section
of DNA). The unzipped section is not the
entire DNA, only the section of DNA needed for this particular job. This
process picks one of the two sides (a specific side) of the DNA and uses it as
a template to make complementary single-sided RNA, namely pre-mRNA. On a DNA
strand, an "A" always has a "T" next to it on the DNA
(unless there has been a mutation).
However, when converting a side of DNA into pre-mRNA, an "A"
is actually paired with a "U" (uracil), as
the following chart shows: An
"A" on the DNA becomes a "U" on the pre-mRNA (uracil). A
"T" on the DNA becomes an "A" on the pre-mRNA. A
"C" on the DNA becomes a "G" on the pre-mRNA. A
"G" on the DNA becomes a "C" on the pre-mRNA. These
combinations are called "complimentary" because if you know one of
the nucleotides, you automatically know its "complement" (i.e. what
is on the other strand). Thus, DNA
has nucleotides: A, C, G, T and RNA has nucleotides: A, C, G, U. RNA
polymerase has been described as a "battery-powered spider" as it
crawls along the DNA unzipping a section of the DNA. The gene
portion of DNA, which is what is unzipped, contains alternating sequences of
exons and introns. Exons and introns are
segments of nucleotides, but like all segments of nucleotides, they have names
to identify their functions. Exons are
the section of the gene which will actually "code" for proteins,
meaning the exons actually become the finished blueprint for making the protein. Introns do
not code for proteins, thus they do not become part of the proteins, but are
thought to be instructions to determine which exons are needed for the specific
protein being requested. For
example, the average gene in human DNA can be used to create 10 different
proteins. Some genes can create 50
different proteins. It is thought that
introns contain the instructions on how to put together these different
proteins from the same gene. In any
case, in this step of transcription; both the introns and exons are kept and
are put on the pre-mRNA. The pre-mRNA is
an exact copy (actually it is a complement) of one side of a section of DNA, except
that a U replaces a T. More will be said
about exons and introns in the next step. Step Two - The Second
Phase of Transcription In the
second phase of transcription (also called "RNA splicing"), the
pre-mRNA is itself copied, and its copy is called mRNA. mRNA is the actual
blueprint to make the protein. In copying
pre-mRNA into mRNA the introns are left out of the copying, meaning they are
"spliced" out of the RNA and are not part of the mRNA. Thus,
pre-mRNA contains both exons and introns, but mRNA only contains exons. However, it
is also in this phase that "RNA splicing" removes some of the exons.
In Step One all of the exons are copied to the pre-mRNA. However, in this phase, not only are all of the
introns spliced out, but also some of the exons are intentionally spliced out. Why are
some of the exons left out? The reason
is that the DNA is being used to create one protein at a time, even though it
is capable of creating ten different proteins (in this example). In other words, there are enough exons to
create ten unique and different proteins, but it only creates one protein at a
time, thus not all of the exons are used in the creation of a single protein
(the protein at this point is still an mRNA). That is
why, in the process of creating a single protein, many of the exons are left
out during the second phase of transcription. It is in
this RNA splicing that different
patterns of exons are combined together to ultimately be the pattern to
create the exact protein which was requested!! If you
think this is simple, consider that some human genes can create 50 different
proteins. The exons on the DNA must stay
in the same sequence (i.e. order) on the mRNA, but different exons are left out
for each type of protein. Try to figure
out how to do that in your spare time!! The intron,
as it is spliced out, no doubt provides the intelligence to determine if the exon, which is next to it, is also spliced out or if it
stays to become part of the mRNA. This
is called "alternative splicing" because different sets of exons lead
to different proteins. Thus,
pre-mRNA and mRNA not only differ in the fact that there are no introns on
mRNA, but they also differ in that there is only a subset of exons on the mRNA,
so that a specific protein can be manufactured later in the process. Step Three - Moving the
mRNA out of the Nucleus In eukaryotic
cells (OK, in most eukaryotic cells) the DNA is protected inside of a membrane
called the "nuclear envelope."
The nuclear envelope has two layers.
The envelope has many ports which are called "nuclear pores." mRNA is
made inside of the nuclear envelope, but processing of the mRNA occurs outside
of the nuclear envelope. Thus, the mRNA
must travel through one of the nuclear pores.
Each nuclear pore is itself built of many proteins. Ribosomes
(to be discussed next), which are also proteins, are also created inside the
nuclear envelope in a subnuclear body called the
nucleolus. Ribosomes also must pass
through a nuclear pore. So how does
a large molecule pass through a nuclear pore?
The answer is a "carrier protein." The carrier protein must be able to latch
onto the mRNA and guide it through the nuclear pore. This is how one website describes the carrier
protein: "Each carrier protein is
designed to recognize only one substance or one group of very similar
substances. The molecule or ion to be transported (the substrate) must first
bind at a binding site at the carrier molecule, with a certain binding
affinity. Following binding, and while the binding site is facing, say,
outwards, the carrier will capture or occlude (take in and retain) the
substrate within its molecular structure and cause an internal translocation,
so that it now faces the other side of the membrane. The substrate is finally
released at that site, according to its binding affinity there. All steps are
reversible." Wikipedia - Carrier Protein Actually,
various molecules are constantly passing through the nuclear envelope in both
directions. Step Four - Translation Once the
mRNA is outside of the nucleus it then heads for a section of the cell which
includes the ribosome. The ribosome area
of a cell is one of the most fascinating areas of a cell. It is also one of the most complex areas of
the cell. The
ribosome looks like a large ball of yard.
In other words, it looks like a sphere that is made of yarn. This is how one website describes the
ribosome.
Ribosomes are among the biggest and most intricate structures in the
cell. The ribosomes of bacteria contain not only huge amounts of RNA, but also
more than 50 different proteins. Human ribosomes have even more RNA and
between 70 and 80 different proteins! . . .
For many years, researchers believed that even though RNAs formed a part
of the ribosome, the protein portion of the ribosome did all of the work.
Noller thought, instead, that maybe RNA, not proteins, performed the ribosome's
job. His idea was not popular at first, because at that time it was thought
that RNA could not perform such complex functions.
Some time later, however, the consensus changed. Sidney Altman of Yale
University in New Haven, Connecticut, and Thomas Cech, who was then at the
University of Colorado in Boulder, each discovered that RNA can perform work as
complex as that done by protein enzymes. Their "RNA-as-an-enzyme"
discovery turned the research world on its head and earned Cech and Altman the
1989 Nobel Prize in chemistry. The New Genetics, Chapter One It should
be noted that the discovery of Cech and Altman also helped the evolutionist
cause by helping evolutionists explain that complex enzymes did not need to
exist to perform some of the tasks needed for the "first living
cell." It you want to win a Nobel
Prize, discover something which helps the evolutionists. Rachel
Green, however, later discovered that the RNA nucleotides were not needed for
assembling a protein. Instead, she
found, the RNA helps the growing protein slip off the ribosome once it's
finished. By the way,
ribosomal RNA is called rRNA. There are many different kinds (i.e.
functions) of RNA. Well, now
that the history lesson is complete, let us look at what really happens in the
ribosome area. First, the
mRNA, which came through the nuclear port, and at this point is as straight as
an arrow, is attached to the ribosome.
Once attached, the ribosome can do its work. There are
four terms which need to be understood at this point: First, the
mRNA (which contains instructions/patterns taken from the DNA) Second,
amino acids (proteins start as a string of amino acids) Third, polypeptides
(polypeptides are the resulting string of amino acids) Fourth,
proteins (proteins are polypeptides which have been folded into the shape of
the protein). Study that
list for a few moments. Ribosome
looks at mRNA three consecutive nucleotides at a time. How many different ways can three consecutive
nucleotides be ordered? The answer is 43 or 64. The '4' is the number of different
nucleotides and the '3' is the number of nucleotides which are looked at at the same time by ribosome. Three
consecutive nucleotides are called a "codon"
or triplets or tri-nucleotide sequences. Now we have
a problem. There are only 20 different
kinds of amino acids. We have 64
different codons, but only 20 amino acids. Try to figure out how 64 codons
can make 20 different amino acids. Not to
worry, the ribosome can make the conversion.
The "dictionary" which controls which codon
is matched with which amino acid is called the "genetic code" (though
the genetic code is not universal between species). However,
three of the 64 codons do not translate into an amino
acid. The codons:
UAA, UGA, and UAG serve as "stop-translation" signals, which
terminate the making of the polypeptide.
AUG can be a start codon or can be made into
the amino acid methionine. Within the
cell are free-floating amino acids. A
type of RNA called transfer RNA (i.e. tRNA) captures
these amino acids and takes them to the ribosome. Actually there is a different type of tRNA for each type of amino acid and each tRNA can correspond to one or more codons. The
ribosome analyzes each codon and then selects the
correct tRNA, meaning the correct amino acid is
chosen to add to the growing polypeptide.
It does this until it reaches a "stop-translation" codon, which tells the ribosome to "stop" the
building of the polypeptide and release it. The rRNA then helps the polypeptide be removed from the
ribosome and you then have a free polypeptide. All of this
happens amazingly fast!! This step
of protein synthesis is far more complex than anyone truly understands. But given enough time, scientists will figure
it out in even more detail. Much is
already known about tRNA, but I will not discuss the
details here. Step Five - The Folding
of the Polypeptide OK, at this
point we have a polypeptide which has been removed from the ribosome. We can think of it as being "straight as
an arrow" at this point, just like the mRNA was. But
proteins are not straight; they have a very specific shape. Actually, it is the shape of the protein
which determines its ability to be integrated into a protein structure. Actually, it is more complicated than that. Not only is
the folding of the amino acids (i.e. polypeptide) important for the protein
structure, but also at certain locations on the shape certain amino acids must
be located so the different proteins will bind together or repel each other,
etc. In other
words, in order for a protein structure to be strong, it must not only have
proteins which have the right shape; so they can fit together like a puzzle;
but the proteins (i.e. the amino acids) must "stick together" or
repel each other, at just the right points.
This is accomplished because some amino acids (remember a protein is
nothing but a chain of amino acids) bind to other amino acids. Also, some
amino acids repel each other, which is also important in some cases. Some amino acids repel water and other amino
acids are attracted to water. And so
on. The point is that it is not only the
shape of the protein which is important, but also the order and types of the amino
acids on the protein which is important. So how do
polypeptides get folded into the proper shape of a protein? Polypeptides
are folded, and in many cases chemically altered, in order to become
proteins. A full discussion of this
topic is far beyond the scope of this book.
Instead a couple of key paragraphs from a book will have to suffice:
The explanation for the cell's remarkable efficiency in promoting
protein folding probably lies in chaperones, a family of proteins found
in all organisms from bacteria to humans. Chaperones are located in every
cellular compartment, bind a wide range of proteins, and may be part of a
general protein-folding mechanism. There are two general families of
chaperones: molecular chaperones, which bind and stabilize unfolded or
partially folded proteins, thereby preventing these proteins from being
degraded; and chaperonins, which directly facilitate their folding. Chaperones
have ATPase activity, and their ability to bind and
stabilize their target proteins is specific and dependent on ATP hydrolysis.
Binding of chaperones to partially folded proteins suggests that the folding
process could be regulated at intermediate steps. Molecular Cell Biology, by Lodish,
Berk, et. al. Here is a
section of another paragraph: Proper
folding of a small proportion of proteins (e.g., the cytoskeletal
proteins actin and tubulin)
requires additional assistance, which is provided by chaperonins. Eukaryotic
chaperonins, called TCiP, are large, barrel-shaped,
multimeric complexes composed of eight Hsp60 units. Molecular Cell Biology, by Lodish,
Berk, et. al. Suffice it
to say: polypeptides are folded, and in some cases chemically altered, as they
are converted into proteins. Note the
vast number of critical chemicals that are in your body, such as the amino
acids. These come from foods. Now you know why your mother told you to eat
healthy foods. Step Six - Placing the
Protein In the Cell At this
point we have the protein (so in a sense "protein synthesis" is
complete), but the protein is not in its proper place in the cell yet. A protein
can basically be placed into one of three places: 1) Inside
the cell, such as part of a protein structure, 2) Built
into the cell membrane, such as a "port," where each port is composed
of many proteins, and is itself a protein structure, 3) Placed
outside the cell membrane, such as to "bind" to something or as part
of a protein structure which extrudes outside the cell (such as the flagellum). At this
point the new protein has to be placed into the proper place. In many cases the new protein needs to be
integrated into a complex biological structure, such as a flagellum, which is
in the process of being built or
repaired. Guess
what? More proteins come into play at
this point to guide the new protein into the proper place. However, at
this point we need to pause and reflect. In Step One
above, the RNA polymerase was activated to start the process of converting a
gene into a protein. What initiated or
ordered the RNA polymerase to create a protein?
The RNA polymerase is a puppet, doing only what it is told; so what is
the puppeteer which is telling the RNA polymerase what gene to use? For
example, suppose a bacteria cell has just divided and it needs to create a
flagellum so it can glide through fluids.
Which proteins in the flagellum would logically be created first; the
proteins in the base of the flagellum or the proteins in the tip of the tail of
the flagellum? Obviously,
the proteins in the base of the flagellum would be created first. We can
compare this to the construction of a tall, one-hundred story building. What if the purchasing agent/accountant for
the construction company ordered 20,000 desks to be delivered to the
construction site before the foundation for the building was even dug? Would the construction workers be happy about
having to navigate through 20,000 desks sitting on the ground as they went to
and from the building site? Probably not. First, you
build the foundation, then you build the steel frame, then you pour the
concrete for the floors, etc. etc. Likewise,
when a new cell (created by cell division) needs to start construction on a
flagellum, it needs the proteins for the base before it needs the proteins for
the tail. The point
is that the order of the creation of the proteins is very important. Something has to control which genes the RNA
polymerase uses first, to create the proteins. In the
book: The Edge of Evolution, also by Dr. Michael Behe, he describes the
creation of the celium and flagellum in certain kinds
of bacteria. He describes the various
kinds of "control elements," "checkpoint proteins,"
"boss proteins," "subboss
proteins," "helper proteins," the proteins which actually become
part of the structure, the switching on of genes, etc. etc. All of these functions are done by different
proteins. It is
actually this phase of protein synthesis which controls the first phase of
protein synthesis, meaning the order in which the proteins are requested to be
manufactured. It is
impossible for this book to duplicate what Dr. Behe has done in explaining the
complex processes involved in building protein structures in a cell. The reader is strongly advised to obtain a
copy of Dr. Behe's "Edge" book and study
chapter 5 in detail. This chapter in
this book is only an introduction to the process. Perhaps in
20 or 30 years a complete, detailed schematic of what happens when the cell has
to create a complex protein structure, such as a flagellum, will be written. But for now, scientists are just beginning to
see the light at the end of the tunnel. Comments Do you see
a pattern here? Proteins are everywhere
in the cell, doing all of the vast number of different complex jobs in the
cell. Not only that, it is proteins
which become part of the protein structures. The DNA
must contain all of the patterns for all of the proteins in the cell, which
include the many different functions and structures which are needed by the
cell. An "irreducibly
complex" system is a "complex" system which cannot function until
all of its parts are completely in place.
Dr. Michael Behe coined the phrase and wrote the book: Darwin's Black
Box, which was written about this subject. Evolutionists
do not like Dr. Behe's books because they do not like
the concept of "irreducibly complex" systems because these systems
imply a "design," which implies a "designer," which is what
they really don't like. But the
fact is that protein synthesis (and I have just scratched the surface and given
a broad overview) is an irreducibly complex system. For
example, without RNA polymerase there would be no protein synthesis and no
proteins. Without ribosome proteins and rRNA there would be no protein synthesis and no proteins. Without a folding mechanism there would be no
complex life on earth. And so on. Science,
which fanatically tries to segregate the theory of evolution from a
"designer," would say that the protein synthesis of the "first
living cell" was simple and that as animals got more and more complex the
protein synthesis mechanisms slowly got more and more complex. What
evidence is there for this theory? None. It is pure pie
in the sky. There is no
"simple" cell on the planet earth.
All of these imaginary "simple cells" only exist in the minds
of evolutionists. Likewise, a "simple"
protein synthesis is also pie in the sky. Shall we
talk about other things that go on inside the cell, such as the mitochondria, ATP
molecules, glucose, pyruvate, the Citric Acid cycle, the Electron Transport
Chain (ETC), and so on? All of these things
are necessary to provide energy in the cell and involve the mitochondria,
which, by the way, have their own DNA (though it is very small DNA). Science has
not even proven that a "first living cell" could have formed. Nor has science explained what imaginary protein
synthesis existed in the imaginary "first living cell." The same protein synthesis which
exists in human beings also exists in single-celled bacteria.
There is no "increasingly
complex" protein synthesis in any living thing on the planet earth!! All of it is incredibly complex. The concept of an "increasingly complex
protein synthesis" is a pure scientific fairy tale. While it is
true that protein synthesis in prokaryotic cells is a little less complex than
in eukaryotic cells; even the protein synthesis in prokaryotic cells is far too
complex to have happened by accident. It
too, is highly, highly irreducibly complex. It seems
that all of the "evolution" of protein synthesis occurred in a long,
long sequence of species which are all
now extinct. How
convenient. The "evidence" is dead
and gone. Actually,
the evidence is not gone. The evidence
never existed. Is the
theory of evolution a "proven" fact of science? Considering that there is no "simple
cell" on the planet earth, and even evolutionists admit that random events
could not create a prokaryotic cell in a prebiotic pool, it would be safe to
say that the theory of evolution has no factual basis. It is a "theory," and a very unscientific
theory at that. |