Proteinsynthesis, proteins, and gene expression
DNA is the hereditary material of the cell and has the same chemical structure and function in
all organisms. The information about the traits of the cell and the individual is contained in the
DNA, and this information is passed on to new cells and new organisms. All inherited
information encoded in DNA is called the organism's genome.
Structure of DNA: DNA is made up of small units called nucleotides, which consist of three
parts: a sugar molecule (deoxyribose), a phosphate group, and a nitrogen base. The nitrogen
bases in DNA are either adenine, thymine, cytosine, or guanine. DNA consists of two strands
twisted around each other and is named according to the direction they point. One of the
strands runs in the 5’-3’ direction, while the other runs in the 3’-5’ direction. The DNA strand
forms a DNA double helix, and the backbone consists of an alternating pattern of sugar and
phosphate.
The bonds between the bases occur through hydrogen bonds; the bases that bind to one
another are said to be complementary: A is complementary to T and has two hydrogen bonds,
while C is complementary to G and has three hydrogen bonds.
DNA is organized into chromosomes:
From Gene to Protein
Proteins are made according to instructions in the DNA, and the process of making a protein is
called protein synthesis. DNA contains the recipes for all the proteins that can be made in a
cell.
The traits of an organism are determined by proteins, and for each protein produced in a cell,
there is a coding sequence in the DNA. This code is a gene and is a specific segment of DNA. In
addition, there are genes that code for other products than proteins.
A gene is coded through the sequence of nucleotides.
What is a gene:
The traits of an organism are determined by proteins, and for each protein produced, there is a
coding sequence in the DNA. This code is called a gene and is a specific section of DNA. A gene
is a piece of hereditary DNA that is a recipe for a peptide or protein. Genes are not traits, but
genes are a result of DNA. In addition, there are genes that code for other products than
, proteins, and these products often regulate the processes from gene to protein. The gene is
coded via the sequence of nucleotides along each strand. The size of the gene is determined by
how many base pairs it has.
Amino acids are the building blocks of a protein, and their sequence gives the protein a specific
property and structure. Proteins are built from 20 different amino acids, and of these 20 amino
acids, there are nine that humans cannot produce themselves (essential amino acids), and they
must be obtained through food.
Protein Synthesis
Transcription:
The first process in protein synthesis is to create a copy of the gene that contains the recipe
for the protein. The copying process is called transcription, while the copy is called mRNA.
Before all genes, there is a region that indicates the transcription should start, called a
promoter. The start signal for the transcription of a gene is that a series of proteins called
transcription factors bind to the promoter of the gene, making it possible for RNA polymerase
to attach to the promoter and begin transcription. There are many components in RNA
polymerase that have different roles; one binds to the promoter sequence, another unwinds
the double helix, and the third synthesizes the mRNA strand.
Transcription factors in the nucleus bind to a promoter region on the DNA, RNA polymerase
can attach to the promoter, and starts transcription by producing an mRNA strand.
When we create mRNA, the base thymine is replaced with the base uracil, so T becomes U for
mRNA. A binds to U, and T still binds to A.
mRNA is complementary to the strand that runs from 3’-5’, meaning the mRNA strand runs
from 5’-3’ and is similar to the other non-complementary strand, with T replaced by U. The
mRNA strand therefore replaces the strand that runs from 5’-3’. It is the other strand, the one
that runs from 5’-3’, that is not transcribed; this is the coding strand that contains the genetic
code and the strand on which mRNA is based.
The gene also has some parts that do not code for a recipe; those regions are called introns
and exons. The regions with the recipe are called exons, and between these regions are the
introns. The introns are not expressed, but both introns and exons are transcribed.
Each gene also contains a part that signals RNA polymerase to end transcription, which causes
the growing RNA strand to detach completely from the DNA strand, completing transcription.
Proteins attach that cut the mRNA from polymerase and DNA.
DNA is the hereditary material of the cell and has the same chemical structure and function in
all organisms. The information about the traits of the cell and the individual is contained in the
DNA, and this information is passed on to new cells and new organisms. All inherited
information encoded in DNA is called the organism's genome.
Structure of DNA: DNA is made up of small units called nucleotides, which consist of three
parts: a sugar molecule (deoxyribose), a phosphate group, and a nitrogen base. The nitrogen
bases in DNA are either adenine, thymine, cytosine, or guanine. DNA consists of two strands
twisted around each other and is named according to the direction they point. One of the
strands runs in the 5’-3’ direction, while the other runs in the 3’-5’ direction. The DNA strand
forms a DNA double helix, and the backbone consists of an alternating pattern of sugar and
phosphate.
The bonds between the bases occur through hydrogen bonds; the bases that bind to one
another are said to be complementary: A is complementary to T and has two hydrogen bonds,
while C is complementary to G and has three hydrogen bonds.
DNA is organized into chromosomes:
From Gene to Protein
Proteins are made according to instructions in the DNA, and the process of making a protein is
called protein synthesis. DNA contains the recipes for all the proteins that can be made in a
cell.
The traits of an organism are determined by proteins, and for each protein produced in a cell,
there is a coding sequence in the DNA. This code is a gene and is a specific segment of DNA. In
addition, there are genes that code for other products than proteins.
A gene is coded through the sequence of nucleotides.
What is a gene:
The traits of an organism are determined by proteins, and for each protein produced, there is a
coding sequence in the DNA. This code is called a gene and is a specific section of DNA. A gene
is a piece of hereditary DNA that is a recipe for a peptide or protein. Genes are not traits, but
genes are a result of DNA. In addition, there are genes that code for other products than
, proteins, and these products often regulate the processes from gene to protein. The gene is
coded via the sequence of nucleotides along each strand. The size of the gene is determined by
how many base pairs it has.
Amino acids are the building blocks of a protein, and their sequence gives the protein a specific
property and structure. Proteins are built from 20 different amino acids, and of these 20 amino
acids, there are nine that humans cannot produce themselves (essential amino acids), and they
must be obtained through food.
Protein Synthesis
Transcription:
The first process in protein synthesis is to create a copy of the gene that contains the recipe
for the protein. The copying process is called transcription, while the copy is called mRNA.
Before all genes, there is a region that indicates the transcription should start, called a
promoter. The start signal for the transcription of a gene is that a series of proteins called
transcription factors bind to the promoter of the gene, making it possible for RNA polymerase
to attach to the promoter and begin transcription. There are many components in RNA
polymerase that have different roles; one binds to the promoter sequence, another unwinds
the double helix, and the third synthesizes the mRNA strand.
Transcription factors in the nucleus bind to a promoter region on the DNA, RNA polymerase
can attach to the promoter, and starts transcription by producing an mRNA strand.
When we create mRNA, the base thymine is replaced with the base uracil, so T becomes U for
mRNA. A binds to U, and T still binds to A.
mRNA is complementary to the strand that runs from 3’-5’, meaning the mRNA strand runs
from 5’-3’ and is similar to the other non-complementary strand, with T replaced by U. The
mRNA strand therefore replaces the strand that runs from 5’-3’. It is the other strand, the one
that runs from 5’-3’, that is not transcribed; this is the coding strand that contains the genetic
code and the strand on which mRNA is based.
The gene also has some parts that do not code for a recipe; those regions are called introns
and exons. The regions with the recipe are called exons, and between these regions are the
introns. The introns are not expressed, but both introns and exons are transcribed.
Each gene also contains a part that signals RNA polymerase to end transcription, which causes
the growing RNA strand to detach completely from the DNA strand, completing transcription.
Proteins attach that cut the mRNA from polymerase and DNA.
