Chapter 9 Molecular structure of DNA and RNA
9.1
The four criteria of genetic material:
Information: the genetic material has information for the build of an entire organism. So the
genetic material must contain the blueprint for the traits of the organism.
Transmission: During reproduction, the genetic material must be passed from parent to
offspring.
Replication: it must be copied, in order to be passed from parent to offspring.
Variation: evolution/adaptation, variation between phenotypic (fenotype) in species
Griffith experiment:
Why did the mouse in part d die? → Something from the dead type S bacteria was
transforming the type R bacteria. This process is called transformation.
So this ‘thing’ transported information from the type S bacteria to make a capsule in the type
R bacteria, what let the mouse die. So Griffith’s experiments showed that some genetic
material from the dead bacteria (type S) had been transferred to the living bacteria (type R)
and provided them with a new trait. But Griffith didn’t know what the transforming substance
was.
MacLeod and McCarty:
These two geneticists asked themselves the question: What substance is being transferred
from the dead type S bacteria to the live type R? At the time of the experiment it was already
known that DNA, RNA, proteins and carbohydrates are major constituents of living cells.
What they didn’t know is which of the above was the genetic material. So the geneticists
made extracts off every known major constituent of cells and added the extract from type S
bacterial. After many repeated attempts with different types of extracts, they discovered that
only one of the extracts, the one that contained purified DNA from type S bacteria, was able
to convert type R bacteria into type S. There is a point of discussion because you can argue
that the DNA extract may not be 100% pure. This means that the contaminating material in
the DNA extract might actually be the genetic material. The most likely contaminating
substances in this case would be RNA or protein. To verify if the DNA extract was 100%
pure the geneticists conducted an experiment: They treated samples of DNA extract with
enzymes that digest DNA (DNase), RNA (RNase) or protein (protease). This led to the
conclusion that RNA or protein was not the genetic material. Because when DNA extracts
were treated with RNase or protease they still converted type R bacteria into type S.
Whereas when the extract was treated with DNase, it lost its ability to convert type R into
type S bacteria.
So the DNA is the transforming principle.
Hershey and Chase:
These two geneticists have conducted an experiment about the T2 Phage. The T2 Phage is
a virus that infects E. coli bacterial cells. The goal of this experiment was to prove that DNA
is the genetic material of the T2 Phage. The external Phage consists of a so-called phage
coat and this contains a head, sheath (soort stengel), tail fibers and base plate. The internal
of the phage only consists of DNA that is based in the head of the phage. Biochemically the
phage coat is composed entirely of proteins. In the Phage’s head there is DNA. So from a
molecular point of view the Phage only has two types of macromolecules: proteins and DNA.
The Phage contains the blueprint to make new viruses (the DNA), but it can not synthesize
new viruses itself. Instead a T2 Phage must introduce its genetic material into the cytoplasm
of a living cell. When this happens the Phage will grab a living cell with his tail fibers and will
then inject the genetic material. To prove that DNA is indeed the genetic material of the T2
Phage the geneticists conducted another experiment. When the phage was bound to the
bacterial cell (the host cell) the phage injected its genetic material into the bacterial. After
,this they used a blender treatment that caused the separation between the phage and the
bacterial cell. To determine what the genetic material was they used radioisotopes, to
distinguish proteins from DNA. So for example Sulfur atoms are found in proteins but not in
DNA, whereas phosphorus atoms are found in DNA but not in phage proteins. Then they
grew E. coli in media that contained Sulfur or Phosphorus and then infected these E. coli
cells with T2 phages. In this way the newly made phages were radiolabeled with Sulfur or
Phosphors. The geneticists put the S-labeled phage and the P-labeled phage in separate
flasks and added to both E. coli cells. Then the phages injected their genetic material (this
time radiolabeled) into the E. coli cells. Then they used a blender to remove the phage coat
from the bacterial cell. Then both flasks were centrifuged so that the heavier bacterial cells
would form a pellet at the bottom, whereas the lighter phage coats remained in the
supernatant, the liquid above the pellet. Only the genetic material of the phage is injected
into the bacterium. Isotope labeling will reveal if it is DNA or protein. The radioactivity was
determined with a Geiger counter. The results showed that the amount of isotope in the
supernatant for S-labeled phage was 80% and for P-labeled phage this was 35%. So there
was more S-labeled phage in the supernatant compared to the supernatant of the P-labeled
phage. Which means that in the pellet there was a 20% S-labeled phage compared to a 65%
P-labeled phage in the other flask. The pellet contained the heavier ‘infected’ E. coli cells,
which were the radioactive particles.
9.2
DNA and its molecular cousin, RNA are known as nucleic acids. As the structures of DNA
and RNA became better understood, it was determined that they are acidic (zuur) molecules,
which means they release hydrogen ions (H+) in solution and have a net negative charge at
neutral pH (in een pH neutrale oplossing staat een zuur zijn H+ af waardoor het negatief
geladen wordt). Because of these findings DNA and RNA were now called nucleic acids. To
further understand DNA and RNA it is important to consider 4 levels of complexity:
1. Nucleotides (base + deoxyribose/ribose + fosfaat) form a repeating structural unit.
2. Nucleotides are linked together in a linear manner to form a strand (of DNA or RNA).
3. Two strands of DNA (sometimes RNA) interact with each other to form a double
helix.
4. The final three-dimensional structure results from the folding and bending of a double
helix.
9.3
The nucleotide is the repeating structural unit of DNA and RNA it consists of a phosphate, a
pentose (5 C’s) sugar (deoxyribose/ribose) and a base. Deoxyribose is the sugar for the
DNA and ribose is the sugar for RNA. The bases are divided in two groups:
the purines: Adenine and Guanine contain a double ring structure.
the pyrimidine: Thymine, Cytosine and Uracil contain a single ring structure.
DNA contains the bases Adenine, Guanine, Cytosine and Thymine, whereas RNA contains
Adenine, Guanine, Cytosine and Uracil.
The Nitrogen and Carbon atoms are numbered 1-9 in Purines and 1-6 in Pyrimidines (so
normal numbers are used for the numbering of the bases). The 5 Carbon atoms in the
sugars are numbered 1’ - 5’ to avoid mistakes. The base is always connected with the 1’
carbon of the sugar. The phosphate(s) are always connected with the 5’ carbon of the sugar,
which is the only carbon outside the ring structure.
The difference between Deoxyribose and Ribose is that on the 2’ carbon there is on
deoxyribose only a hydrogen atom (H) and on the ribose there is a hydrogen and an oxygen
,atom (OH). The 3’ carbon is important because this is the carbon who has a connection with
the next phosphate of a different nucleotide. So the 3’ is the connection between
nucleotides.
When a sugar is attached to only a base, this pair is called a nucleoside.
Nucleosides made of deoxyribose and A, G, C and T are called deoxyA, deoxyG, etc.
Nucleosides made of ribose and A, G, C and U are called Adenosine, Guanosine, cytidine
and uridine. To the sugar there could be 1, 2 or 3 phosphates attached. These phosphates
are connected with ester bindings with each other.
A nucleotide composed of ribose, adenine and three phosphates is called ATP.
A nucleotide composed of deoxyribose, adenine and three phosphates is called dATP.
9.4
DNA and RNA strands have 2 structural features. The first one is:
The phosphate from a nucleotide is connected with the 3’ carbon of the other nucleotide.
This connection is an ester bond. For this reason the linkage between nucleotides is called
Phosphodiester linkage. The Phosphates and sugars form the backbone of the DNA or
RNA strand. The backbone is negatively charged because the phosphate is negative.
The second one is:
The orientation of nucleotides is special because the 5’ carbons in every sugar molecule are
above the 3’ carbons. Because of this the strand has a directionality and because all sugar
molecules have the same orientation this directionality keeps going throughout the whole
strand.
Because the bases are so dependent on each other to keep the strand connected, the base
sequence will never change. The only possible way is when a mutation occurs.
9.5
In 1953 there was a major discovery in molecular genetics. It was known that DNA consisted
of nucleotides. However it was not known how these nucleotides are bonded together to
form a DNA strand. A method that was important for the discovery of the double helix was
model building. A Second important method was X-ray diffraction data. This method uses
wet DNA fibers that are beamed by X-ray. This will give a pattern that will give an indication
of the structural features of DNA.
Erwin Chargaff:
At the time of Chargaff’s research it was already known that nucleotides consisted partially
of bases, like Thymine and Cytosine. Chargaff was interested about the composition of the
bases in DNA. Chargaff was able to remove the chromosomes from the cells and treated
them with Protease, to separate the DNA from chromosomal proteins. Then he treated the
DNA with acid to cleave the sugar from the base. This caused the single bases to be
released from the DNA strand. The base mixture was then subjected to paper
chromatography to divide the four different bases. In this way there were hundreds of these
experiments by Chargaff. After all these experiments he concluded that the amount of
Adenine was always as high as Thymine. And the amount of Cytosine was as high as
Guanine. This is now known as Chargaff’s rule. In the beginning the models that were
made with the model building had the backbones of both DNA strands on the inside and the
bases on the outside. But Watson and Crick realised that the bases could not fit together this
way. So from then on the model is that the bases are on the inside and the backbone (Sugar
+ Phosphorus group(s)) are on the outside of the double helix.
9.6
In a DNA double helix, two DNA strands are twisted together around a common axis. This
double stranded structure is stabilized by base pairs from opposite strands base pairs (bp)
that are connected with a hydrogen bond (waterstofbrug). The Chargaff rule explained
, earlier indicates that purines (A and G) always bond with pyrimidines (T and C). There are
three hydrogen bonds between G and C and two between A and T. For this reason a DNA
sequence with a high quantity of G and C bases will make a stronger double helix structure.
The Chargaff rule implies that if we know one of the strands we know the other too. The two
DNA strands are antiparallel. This is because one strand is going 5’ to 3’ and the other 3’ to
5’. A right-handed helix will spiral clockwise when you will lay it down. A left-handed helix will
spiral counterclockwise when laid down.
The double helix knows 2 so called grooves: a minor groove has less space and therefore
a worse ‘entrance’ to the bases. Minor grooves have therefore more connections with
proteins. The other groove is the major groove with a bigger opening and therefore a better
‘entrance’ to the bases for connection with some proteins.
The DNA helix can form different types of structures: B DNA and Z DNA. B DNA is the most
common form. B DNA is a right-handed helix with grooves. On the other hand Z DNA is left-
handed helix without grooves. Another difference between the two is that B is 10 BP (base
pairs) per 360°, while Z has 12 BP per 360°.
In 1957 there was a surprising discovery made. It was found that DNA can form a triple helical
structure, called triplex DNA. This triplex DNA can be made by adding a single strand synthetic
DNA to a double helix in vitro. The synthetic strand will bind into the major groove. When the
strand binds to a gene, it inhibits transcription. The synthetic DNA can contain reactive groups
that cause mutations in a gene, thereby inactivating it. This could silence the expression of
particular genes. Like genes that become overactive in cancer cells.
9.7
RNA strands are usually a few hundred to several thousand nucleotides in length. Much shorter
than DNA strands. When RNA is made during transcription, the DNA is used as a template to
make a copy of single-stranded RNA. In most cases, only one of the two DNA strands is used as
a template for RNA synthesis. Therefore, only one complementary strand of RNA is usually
made. It may occur that A&U and G&C will form bonds during transcription. When this happens a
short segment of the RNA will be double-stranded, like DNA. This can have multiple forms: Bulge
loop, internal loop, multibranched junction and stem-loop (hair pin).
RNA double helices are antiparallel, right-handed and with 11-12 BP (base pairs) per 360° turn.
If there are multiple double stranded sections in the RNA strand it will give a three-dimensional
structure. When this happens the important parts of the strand like the so called 3’ acceptor and
the anticodon will be free, so they can still interact with proteins and other molecules.
Chapter 12 Gene transcription and RNA modification
The primary function of DNA is to store information necessary to create a living organism.
The information is contained within so called genes. A gene is a segment of DNA that is
used to pass on information to the offspring. This information is used to make a functional
product. Genes are a part of chromosomes and are made of DNA. How is this information
accessed and used? The first step is transcription. Transcription is the process of making a
copy. In genetics this is referred to synthesizing of RNA form a DNA template. After this
process the DNA is still intact and can still be used to store information.
Proteins encoding genes carry the information for the amino acid of a polypeptide. When a
protein encoding gene is transcribed, the first product is an RNA molecule known as mRNA.
mRNA is a temporary copy of a gene that contains information to make a polypeptide. When
the mRNA is formed a process called translation takes place. Translation means the
production of a polypeptide using the information in mRNA. One or more polypeptides then
assemble into a functional protein.
The cohesion of the process from a gene to a functional protein is called the central dogma
of genetics.
9.1
The four criteria of genetic material:
Information: the genetic material has information for the build of an entire organism. So the
genetic material must contain the blueprint for the traits of the organism.
Transmission: During reproduction, the genetic material must be passed from parent to
offspring.
Replication: it must be copied, in order to be passed from parent to offspring.
Variation: evolution/adaptation, variation between phenotypic (fenotype) in species
Griffith experiment:
Why did the mouse in part d die? → Something from the dead type S bacteria was
transforming the type R bacteria. This process is called transformation.
So this ‘thing’ transported information from the type S bacteria to make a capsule in the type
R bacteria, what let the mouse die. So Griffith’s experiments showed that some genetic
material from the dead bacteria (type S) had been transferred to the living bacteria (type R)
and provided them with a new trait. But Griffith didn’t know what the transforming substance
was.
MacLeod and McCarty:
These two geneticists asked themselves the question: What substance is being transferred
from the dead type S bacteria to the live type R? At the time of the experiment it was already
known that DNA, RNA, proteins and carbohydrates are major constituents of living cells.
What they didn’t know is which of the above was the genetic material. So the geneticists
made extracts off every known major constituent of cells and added the extract from type S
bacterial. After many repeated attempts with different types of extracts, they discovered that
only one of the extracts, the one that contained purified DNA from type S bacteria, was able
to convert type R bacteria into type S. There is a point of discussion because you can argue
that the DNA extract may not be 100% pure. This means that the contaminating material in
the DNA extract might actually be the genetic material. The most likely contaminating
substances in this case would be RNA or protein. To verify if the DNA extract was 100%
pure the geneticists conducted an experiment: They treated samples of DNA extract with
enzymes that digest DNA (DNase), RNA (RNase) or protein (protease). This led to the
conclusion that RNA or protein was not the genetic material. Because when DNA extracts
were treated with RNase or protease they still converted type R bacteria into type S.
Whereas when the extract was treated with DNase, it lost its ability to convert type R into
type S bacteria.
So the DNA is the transforming principle.
Hershey and Chase:
These two geneticists have conducted an experiment about the T2 Phage. The T2 Phage is
a virus that infects E. coli bacterial cells. The goal of this experiment was to prove that DNA
is the genetic material of the T2 Phage. The external Phage consists of a so-called phage
coat and this contains a head, sheath (soort stengel), tail fibers and base plate. The internal
of the phage only consists of DNA that is based in the head of the phage. Biochemically the
phage coat is composed entirely of proteins. In the Phage’s head there is DNA. So from a
molecular point of view the Phage only has two types of macromolecules: proteins and DNA.
The Phage contains the blueprint to make new viruses (the DNA), but it can not synthesize
new viruses itself. Instead a T2 Phage must introduce its genetic material into the cytoplasm
of a living cell. When this happens the Phage will grab a living cell with his tail fibers and will
then inject the genetic material. To prove that DNA is indeed the genetic material of the T2
Phage the geneticists conducted another experiment. When the phage was bound to the
bacterial cell (the host cell) the phage injected its genetic material into the bacterial. After
,this they used a blender treatment that caused the separation between the phage and the
bacterial cell. To determine what the genetic material was they used radioisotopes, to
distinguish proteins from DNA. So for example Sulfur atoms are found in proteins but not in
DNA, whereas phosphorus atoms are found in DNA but not in phage proteins. Then they
grew E. coli in media that contained Sulfur or Phosphorus and then infected these E. coli
cells with T2 phages. In this way the newly made phages were radiolabeled with Sulfur or
Phosphors. The geneticists put the S-labeled phage and the P-labeled phage in separate
flasks and added to both E. coli cells. Then the phages injected their genetic material (this
time radiolabeled) into the E. coli cells. Then they used a blender to remove the phage coat
from the bacterial cell. Then both flasks were centrifuged so that the heavier bacterial cells
would form a pellet at the bottom, whereas the lighter phage coats remained in the
supernatant, the liquid above the pellet. Only the genetic material of the phage is injected
into the bacterium. Isotope labeling will reveal if it is DNA or protein. The radioactivity was
determined with a Geiger counter. The results showed that the amount of isotope in the
supernatant for S-labeled phage was 80% and for P-labeled phage this was 35%. So there
was more S-labeled phage in the supernatant compared to the supernatant of the P-labeled
phage. Which means that in the pellet there was a 20% S-labeled phage compared to a 65%
P-labeled phage in the other flask. The pellet contained the heavier ‘infected’ E. coli cells,
which were the radioactive particles.
9.2
DNA and its molecular cousin, RNA are known as nucleic acids. As the structures of DNA
and RNA became better understood, it was determined that they are acidic (zuur) molecules,
which means they release hydrogen ions (H+) in solution and have a net negative charge at
neutral pH (in een pH neutrale oplossing staat een zuur zijn H+ af waardoor het negatief
geladen wordt). Because of these findings DNA and RNA were now called nucleic acids. To
further understand DNA and RNA it is important to consider 4 levels of complexity:
1. Nucleotides (base + deoxyribose/ribose + fosfaat) form a repeating structural unit.
2. Nucleotides are linked together in a linear manner to form a strand (of DNA or RNA).
3. Two strands of DNA (sometimes RNA) interact with each other to form a double
helix.
4. The final three-dimensional structure results from the folding and bending of a double
helix.
9.3
The nucleotide is the repeating structural unit of DNA and RNA it consists of a phosphate, a
pentose (5 C’s) sugar (deoxyribose/ribose) and a base. Deoxyribose is the sugar for the
DNA and ribose is the sugar for RNA. The bases are divided in two groups:
the purines: Adenine and Guanine contain a double ring structure.
the pyrimidine: Thymine, Cytosine and Uracil contain a single ring structure.
DNA contains the bases Adenine, Guanine, Cytosine and Thymine, whereas RNA contains
Adenine, Guanine, Cytosine and Uracil.
The Nitrogen and Carbon atoms are numbered 1-9 in Purines and 1-6 in Pyrimidines (so
normal numbers are used for the numbering of the bases). The 5 Carbon atoms in the
sugars are numbered 1’ - 5’ to avoid mistakes. The base is always connected with the 1’
carbon of the sugar. The phosphate(s) are always connected with the 5’ carbon of the sugar,
which is the only carbon outside the ring structure.
The difference between Deoxyribose and Ribose is that on the 2’ carbon there is on
deoxyribose only a hydrogen atom (H) and on the ribose there is a hydrogen and an oxygen
,atom (OH). The 3’ carbon is important because this is the carbon who has a connection with
the next phosphate of a different nucleotide. So the 3’ is the connection between
nucleotides.
When a sugar is attached to only a base, this pair is called a nucleoside.
Nucleosides made of deoxyribose and A, G, C and T are called deoxyA, deoxyG, etc.
Nucleosides made of ribose and A, G, C and U are called Adenosine, Guanosine, cytidine
and uridine. To the sugar there could be 1, 2 or 3 phosphates attached. These phosphates
are connected with ester bindings with each other.
A nucleotide composed of ribose, adenine and three phosphates is called ATP.
A nucleotide composed of deoxyribose, adenine and three phosphates is called dATP.
9.4
DNA and RNA strands have 2 structural features. The first one is:
The phosphate from a nucleotide is connected with the 3’ carbon of the other nucleotide.
This connection is an ester bond. For this reason the linkage between nucleotides is called
Phosphodiester linkage. The Phosphates and sugars form the backbone of the DNA or
RNA strand. The backbone is negatively charged because the phosphate is negative.
The second one is:
The orientation of nucleotides is special because the 5’ carbons in every sugar molecule are
above the 3’ carbons. Because of this the strand has a directionality and because all sugar
molecules have the same orientation this directionality keeps going throughout the whole
strand.
Because the bases are so dependent on each other to keep the strand connected, the base
sequence will never change. The only possible way is when a mutation occurs.
9.5
In 1953 there was a major discovery in molecular genetics. It was known that DNA consisted
of nucleotides. However it was not known how these nucleotides are bonded together to
form a DNA strand. A method that was important for the discovery of the double helix was
model building. A Second important method was X-ray diffraction data. This method uses
wet DNA fibers that are beamed by X-ray. This will give a pattern that will give an indication
of the structural features of DNA.
Erwin Chargaff:
At the time of Chargaff’s research it was already known that nucleotides consisted partially
of bases, like Thymine and Cytosine. Chargaff was interested about the composition of the
bases in DNA. Chargaff was able to remove the chromosomes from the cells and treated
them with Protease, to separate the DNA from chromosomal proteins. Then he treated the
DNA with acid to cleave the sugar from the base. This caused the single bases to be
released from the DNA strand. The base mixture was then subjected to paper
chromatography to divide the four different bases. In this way there were hundreds of these
experiments by Chargaff. After all these experiments he concluded that the amount of
Adenine was always as high as Thymine. And the amount of Cytosine was as high as
Guanine. This is now known as Chargaff’s rule. In the beginning the models that were
made with the model building had the backbones of both DNA strands on the inside and the
bases on the outside. But Watson and Crick realised that the bases could not fit together this
way. So from then on the model is that the bases are on the inside and the backbone (Sugar
+ Phosphorus group(s)) are on the outside of the double helix.
9.6
In a DNA double helix, two DNA strands are twisted together around a common axis. This
double stranded structure is stabilized by base pairs from opposite strands base pairs (bp)
that are connected with a hydrogen bond (waterstofbrug). The Chargaff rule explained
, earlier indicates that purines (A and G) always bond with pyrimidines (T and C). There are
three hydrogen bonds between G and C and two between A and T. For this reason a DNA
sequence with a high quantity of G and C bases will make a stronger double helix structure.
The Chargaff rule implies that if we know one of the strands we know the other too. The two
DNA strands are antiparallel. This is because one strand is going 5’ to 3’ and the other 3’ to
5’. A right-handed helix will spiral clockwise when you will lay it down. A left-handed helix will
spiral counterclockwise when laid down.
The double helix knows 2 so called grooves: a minor groove has less space and therefore
a worse ‘entrance’ to the bases. Minor grooves have therefore more connections with
proteins. The other groove is the major groove with a bigger opening and therefore a better
‘entrance’ to the bases for connection with some proteins.
The DNA helix can form different types of structures: B DNA and Z DNA. B DNA is the most
common form. B DNA is a right-handed helix with grooves. On the other hand Z DNA is left-
handed helix without grooves. Another difference between the two is that B is 10 BP (base
pairs) per 360°, while Z has 12 BP per 360°.
In 1957 there was a surprising discovery made. It was found that DNA can form a triple helical
structure, called triplex DNA. This triplex DNA can be made by adding a single strand synthetic
DNA to a double helix in vitro. The synthetic strand will bind into the major groove. When the
strand binds to a gene, it inhibits transcription. The synthetic DNA can contain reactive groups
that cause mutations in a gene, thereby inactivating it. This could silence the expression of
particular genes. Like genes that become overactive in cancer cells.
9.7
RNA strands are usually a few hundred to several thousand nucleotides in length. Much shorter
than DNA strands. When RNA is made during transcription, the DNA is used as a template to
make a copy of single-stranded RNA. In most cases, only one of the two DNA strands is used as
a template for RNA synthesis. Therefore, only one complementary strand of RNA is usually
made. It may occur that A&U and G&C will form bonds during transcription. When this happens a
short segment of the RNA will be double-stranded, like DNA. This can have multiple forms: Bulge
loop, internal loop, multibranched junction and stem-loop (hair pin).
RNA double helices are antiparallel, right-handed and with 11-12 BP (base pairs) per 360° turn.
If there are multiple double stranded sections in the RNA strand it will give a three-dimensional
structure. When this happens the important parts of the strand like the so called 3’ acceptor and
the anticodon will be free, so they can still interact with proteins and other molecules.
Chapter 12 Gene transcription and RNA modification
The primary function of DNA is to store information necessary to create a living organism.
The information is contained within so called genes. A gene is a segment of DNA that is
used to pass on information to the offspring. This information is used to make a functional
product. Genes are a part of chromosomes and are made of DNA. How is this information
accessed and used? The first step is transcription. Transcription is the process of making a
copy. In genetics this is referred to synthesizing of RNA form a DNA template. After this
process the DNA is still intact and can still be used to store information.
Proteins encoding genes carry the information for the amino acid of a polypeptide. When a
protein encoding gene is transcribed, the first product is an RNA molecule known as mRNA.
mRNA is a temporary copy of a gene that contains information to make a polypeptide. When
the mRNA is formed a process called translation takes place. Translation means the
production of a polypeptide using the information in mRNA. One or more polypeptides then
assemble into a functional protein.
The cohesion of the process from a gene to a functional protein is called the central dogma
of genetics.
