GENETIC MATERIAL AND GENE EXPRESSION
Genetics is a field of science that learns about inheritance. Property inheritance is a
biological process in which parents or the parent transfers genes to their children or
offspring. Genetics is a branch of biology that focuses on understanding the inheritance
of the properties of organisms and sub-organisms such as viruses and prions. In
summary, genetics are science related to genes and all aspects. In the context of
biology, genetics studied genes, inheritance properties, and diversity of living things.
This science can be applied in various life studies such as bacteria, plants, animals, and
humans.
In the context of genetics, the DNA contained in the chromosome has a crucial role.
DNA is the main genetic material that regulates the properties of the organism, and the
results of his expression is polypeptide, although not all of them are protein (some can
be expressed as RNA with catalytic functions, such as SNRPS).
Francis Crick described the flow of information brought by DNA in the concept of The
Central Dogma, which stated: Information from DNA can be forwarded to cells or other
individuals through replication, can be expressed in the form of an intermediary signal in
the form of RNA, which is then translated into polypeptides, units Form the phenotype
of the organism.
Based on this information, this paper will discuss genetic material, including
chromosomes, genes, nucleic acids (DNA and RNA), as well as how to expression of
genes.
Discussion
Genetic material
Genetic material consists of chromosomes, nucleic acids (DNA and RNA), and genes.
This material is inherited through reproduction. To express the nature of genes, DNA
must produce protein. Without protein, gene expression cannot occur.
Chromosome
W. Waldayer introduces the term chromosome, which comes from the word "chroma"
(color) and "SOMA" (body), so the chromosome means the body that absorbs the color.
Chromosomes are in the cell nucleus and are seen at the metaphase stage during
mitosis or meiosis.
Chromosome
- It looks only when cells divide.
- Has a length between 0.2 - 40 microns.
- In prokaryotic cells, a single chromosome is not in the core, while in eukaryotic cells,
the number of chromosomes varies and is located in the nucleus.
- Consisting of chromatin (60%), protein (35%), and DNA and RNA (5%).
- Protein includes histones and non-histones (neutral or acid).
- Contains enzymes for DNA synthesis and RNA.
Chromosome classification
The body in the body is divided into two types based on its influence on sex and body
properties:
1. Autosom: Also known as body chromosome, does not play a role in determining
gender. In humans, there are 44 autosomes of a total of 46 somatic cell chromosomes.
Autosomes are symbolized by letter a, so that human autosom notation is 44a or 22aa.
2. Gonosom: Also called genital chromosome, play a role in determining gender. There
are 2 gonosomes in human somatic cells, namely X and Y. Generally, chromosomes x
determines females and y determine male. The gonosomal arrangement in women is xx
and in men is xy. So, somatic cell chromosome notation is 44a + XY (male) or 44A + XX
(woman). For gamet cells, the notation is 22A + X or 22A + Y.
Based on its location, chromosomes are divided into two types:
1. Prokaryotic chromosomes: There are prokaryotic organisms, such as tobacco viruses
with single RNA or Bacteria E. coli with circular DNA.
2. Eukaryotic chromosomes: there is a multicellular organism, consisting of two long
and coated DNA ribbons.
Chromosome structure
Centromer (kinetokor) connects the chromonema and functions as a place inherent in
the bobbin thread when the chromosome moves to the cell pole on the chromosome
cleavage phase.
Chromonema is a spiral tape that contains cromoders and chromomers. Chromomers
are thickening of chromonema consisting of nucleoprotein materials and as genes.
Kromiol is a small thickening chromosome. Telomer is located at the end of the
chromosome, prevents the connection between chromosomes. The matrix is
endoplasm which is rather compacting in the chromosome. Gene locus is an area that
stores genetic information. Satellite is an additional part at the end of the chromosome,
not always in every chromosome. The membrane is a thin layer that covers the
chromosome.
Chromosome type
Chromosomes can be distinguished based on the length of the arm to be metascentric,
submetascentric, acrocentric, and telocentry:
- Metascentric: The chromosome arm is almost as long, with the centromair in the
middle.
- Submetascentric: One of the chromosome arms is shorter, causing a slightest
centromer shifting from the center.
- Acrocentric: One of the chromosomes is very short compared to other arms.
- Telocentry: only has one arm, with a centromere located at the end of the
chromosome.
Number of chromosomes
All eukaryotic organisms have a varied number of chromosomes. In body cells or
somatic cells, chromosomes are usually paired in even number, namely two sets of
chromosomes (diploid, 2n) of each parent. While gamet cells, such as eggs and sperm,
have half of the number of body cell chromosomes, namely a set of chromosomes
(haploid, n). For example, humans have 46 chromosomes on body cells and 23
chromosomes on egg cells or sperm. Fertilization returns the number of body cell
chromosomes to 46.
Gene
Sense
According to W. Johansen, the Gene is the smallest unit of living things that store
hereditary material on the locus of genes, consisting of protein and nucleic acid (DNA
and RNA), with a size between 4-8 microns.
Gene properties
Genes have the following qualities:
- Save genetic information.
- Have different tasks and functions.
- Can double yourself during mitotic cleavage and meiosis.
- determined by nitrogen base arrangements.
- Is part of the chromosome.
Gene function
Gene function includes:
- Continue information to the next generation.
- Determine the inherited nature.
- Manage development and metabolism.
Symbols of genes
- The dominant gene: Covering other gene expression, usually stated with uppercase
letters, like A.
- Resessive genes: unbeatable by the dominant gene so it doesn't appear in phenotypes,
usually represented by lowercase letters.
- Heterozygous genes: combination genes of sperm cells and egg cells, for example AA.
- dominant homozygous genes: two dominant genes from both genital cells, for
example AA.
- Gen Homozygot Recessive: Two gene recessive from both genitals, for example AA.
- homologous chromosome: chromosomes from female parent similar to
chromosomes from the male parent.
- Fenotype: the properties of views that are visible, such as high, low, color, and shapes.
- Genotypes: The nature of the descendants that are not visible, for example AA, AA, and
AA.
Nucleic acid, namely DNA and RNA, is a polinucleotide consisting of mononucleotide
units. DNA is a polynucleotide built from dioxiribonucleotides, while RNA is built from
ribonucleotides. Both have similar chemical and physical structures, with fosfodiester
bonds that connect positions 3 'and 5' between mononucleotides (Harpet, 1980).
DNA and RNA are two main types of nucleic acid. DNA, which is found in the cell's
nucleus, stores genetic information and can replicate itself to produce new cells. DNA
controls the synthesis of RNA, especially Messenger RNA (MRNA), which leaves the
cell's nucleus and directs protein synthesis in accordance with the DNA code
(Fessenden, 1990).
DNA structure
DNA, or deoxiribonucleeat acid, is an important molecule that stores genetic
information from generation to generation (Suryo, 2004: 57). DNA has a double helical
structure, consisting of two chains of pillowotide that is twisted. Every nucleotide in
DNA consists of phosphate groups, nitrogen base, and pentose sugar, namely
deoxiribose, which lacks one oxygen atom. Nitrogen base in DNA is divided into purines
(adenin and guanin) and pyrimidine (cytosine and timin).
Nucleotides are connected through nitrogen and pentose sugar bonds. Watson and
Crick describe the following DNA structure:
- DNA consists of two polynucleotide chains that form double helices.
- Every nucleotide is in a flat field and forms a stair-like structure, with phosphate as
"steps."
- The hydrogen bond connects nitrogen base pairs in both chains.
- Purin base pair is always paired with the base of Pirimidin: Adenin (a) with Timin (T),
and Guanin (G) with cytosine (s).
DNA Replication
DNA replication is a process of accurate DNA duplication, with a human genome
consisting of around 3 billion alkallas per cell. During replication, DNA must be doubled
with high accuracy, ensuring that genetic information is inherited correctly from the
stem cells to the child's cells. This process only occurs in phase S before the cell
divides and is completed before phase M. There are three main theories regarding DNA
replication:
1. Conservative theory: DNA the mother remains intact, while the nitrogen base
sequence is copied to form two identical DNA.
2. Dispersive theory: DNA the parent is divided into pieces, which then composes two
new DNA in the same base sequence as the original.
3. Semiconservative theory: separate polynucleotide chains, and free nitrogen bases in
pairs with bases from the parent chain, produce two identical DNA.
DNA function
- Convey genetic information to the next generation through replication.
- Innountry code for all types of amino acids in cells.
- Set metabolism and protein synthesis in cells.
RNA structure
RNA is a shorter polinucleotide than DNA and consists of one chain. RNA uses ribose
as a pentose sugar and is formed by DNA in the cell's nucleus. Nitrogen bases in RNA
include purines (adenin and guanin) and pyrimidine (cytosine and urasil).
RNA types
1. RNA Duta (MRNA): Transporting DNA information from cell core to ribosomes in the
form of a base triplet called a codon. The codon in MRNA is a complementary of the
DNA codogen. The process of forming the MRNA from DNA in the cell core is called
transcription.
- Example: Codogen (DNA) = ASG ATA SST
- Codon (MRNA) = UGS ASU UUA GGA
2. RNA Transfer (TRNA): recognize the codon and translate it into amino acids in
ribosomes through translation. TRNA has anticodon to recognize codons and important
edges to tie amino acids and ribosomes.
Example: If the codon in the Duta RNA has the order of UGS UUU GGA ass, the
appropriate antiCodon in the transfer RNA is ASG UGG AUA SSU.
Riosome RNA (RNAR) functions as a place to form a protein and consists of two
subunits: a small subunit that binds the RNA ambassador and a large subunit that binds
the appropriate transfer RNA.
DNA and RNA roles in protein synthesis
Protein synthesis is a complex process that involves translation of RNA code into
polypeptides, and requires DNA, RNA, Ribosomes, amino acids, and enzymes. This
process takes place at the cell and ribosomes and consists of two main stages:
1. Transcription
- takes place at the cell core.
- Starting with the opening of the DNA ribbon by Polymerase DNA enzyme.
- DNA ribbon that functions as a RNA template is called a codogen band, while the DNA
band that does not print RNA is called the antisense band.
- RNA is formed along the codogen DNA band with a complementary nitrogen base
order. When finished, RNA left the core towards the ribosome in the cytoplasm and
attached to the ribosome.
2. Translation
- Rnad and Rnat in Ribosomes: Antikodon Rnat pairs with Rnad codons. Example: Aug at
RNAD codon pairs with UAC on the anti-rats, binding metionine amino acids.
- Ribosomes move along the rnad, add amino acids to formed proteins.
- The first amino acid (methionine) is released from the rnat and returns to the
cytoplasm, while the new RNAT comes to pair up with the next Rnad codon.
- This process repeats to form a polypeptide with a specific sequence of amino acids.
Genetic code
Genetic code is information that uses letters to represent nitrogen bases (A, T, C, and G)
and translate various types of amino acids in the body. In other words, genetic code is a
nucleotide sequence coding system in DNA or RNA which determines the sequence of
amino acids during protein synthesis. The type of protein depends on the constituent
amino acid and the length of the polypeptide chain.
Protein synthesis begins with aUG codon which encodes methionine amino acids,
known as the initial codon. This process ends with the uaa codon, UAG, or UGA (on
prokaryotic) and UAA (in eukaryotic), which does not encode amino acids and function
as a codon termination or nonsense. Genetic code is universal, meaning the same code
applies to all living things. Only the basis sequence between the initial codons and
termination codons that function as codons.
DNA and RNA differences
Size and shape
RNA is generally shorter than DNA. DNA has a double helix form, while RNA is a single
ribbon. However, on some plants viruses, RNA is in the form of double helix, but not
spiral.
Chemical array
RNA is also a nucleotide polymer, but is different from DNA in terms of:
- The sugar that composes is ribose, not deoxiribosa.
- The pyrimidine base is uracy, not Timin.
Location
- DNA is usually in the chromosome.
- RNA has a different location depending on the type:
- RNA D (RNA Duta): There is in nucleus, synthesized from one of the DNA ribbons in the
nucleus.
- RNA T (RNA Transfer): Being on the cytoplasm.
- RNA R (RNA Ribosome): Found in ribosomes.
The function of
- DNA serves to store genetic information.
- RNA function varies depending on the type:
- RNA D: Receive genetic information from DNA through the transcription process at the
cell core.
- RNA T: recognize the codon and translate it into amino acids in ribosomes.
- RNA R: plays a role in protein formation.
Gene expression
Gene expression is a process where genetic information is converted into amino acid
sequences in protein synthesis. It also includes the way cells regulate the appearance
of the characteristics of organisms based on the genes they have. Gene expression
associated with protein synthesis through transcription and translation, with DNA
encoding genetic information as needed. In prokaryotic, such as bacteria, gene
expression is selective in accordance with the availability of food ingredients in the
environment, with bacteria activating or deactivating genes for digestive enzymes.
Conversely, on eukaryotic, the mechanism of gene expression is more complex.
Gen expression determines the nature of the organism. Fenotype is the result of gene
expression visible, such as feather variations, sizes, and colors in dogs. Even though the
baby dog looks similar, the differences in characteristics are seen as growth, due to
expression of genes that enable or disable certain genes.
Gene expression on prokaryotic and eukaryotic
In prokaryotic and eukaryotic, cell specialization (differentiation) depends on certain
gene expression. The following is an explanation of gene expression on these two cells.
Gene expression on prokaryotic
In Prokaryotics, protein interactions with DNA can enable or disable genes based on
environmental stimuli. Prokaryotic has a system called LAC operon, which consists of
enzyme coding genes for lactose metabolism. Operon is an organized genetic unit that
includes promoters, operators, and enzyme coding genes. The operator functions as a
"switch" that regulates whether RNA polymerase can bind the promoter or just pass the
gene.
For example, E. coli bacteria use three enzymes for lactose metabolism encoded by
LAC OPERON: LACZ (
β
-galactosidase), Lacy (Permeases), and LACA (transacetilage).
When the repressor binds the operator, LAC operons become inactive and cannot
synthesize enzymes for lactose metabolism. In this condition, the LAC operon is off.
When the inducer (lactose) is present, the repressor becomes inactive because it binds
the inducer. This allows RNA Polymerase to access operons and transcribute, produce
enzymes (
β
-galactosidase, permeases, and transacetlage) needed for lactose
metabolism. Lactose is converted into glucose and galactose for energy.
In Lac Tripptophan operons, transcription usually occurs, but the existence of
trhtptophan inhibits enzyme production. Conversely, lactose eliminates the obstacles of
inhibitors, reactivating the enzyme production process. In E. coli culture, which is given
glucose and lactose, the bacteria will first use glucose until it runs out. After a short lag
phase, the bacteria turned to lactose as a carbon source, because glucose metabolic
enzymes were more constitutive than lactose metabolic enzymes.
Gene expression on eukaryotic
In high-level eukariot, different genes are transcribed in different cell types, indicating
the importance of setting in the transcription and processing stage in the cell
differentiation. Eukaryotic mrna is generally monocistronic, carrying information from
one structural gene. Although the primary transcript often resembles a polysistronics,
they are processed to become monocistronic mRNA.
Control of gene expression on eukariot starts from:
- Transcription initiation: Enhancer binds with promoters to increase polymerase RNA
activity.
- Transcription and modification: Intron Disply so that only the exon is left.
Transcription stability
When MRNA from the core of the cell to the cytosol, the Poly-A tail is shortened by the
enzyme associated with 5 'stamp.
Modification of translation
Covalent modifications such as acetylation, methylation, and the formation of disulfide
bridges occur. For example, insulin is produced in the form of inactive polypeptide
which is then cut and activated with the disulfide bridge.
Six Stages of Eukaryotic Gen Expression Control:
1. Transcription control: set genes during transcription.
2. RNA processing control: Set connection and RNA transcription process.
3. Placement control and RNA Transport: Choose complete MRNA to export from
nucleus to cytosol.
4. Translation control: choose mRNA in cytoplasm to be translated by ribosomes.
5. Control degradation MRNA: Selectively stabilize mrna in cytoplasm.
6. Protein activity control: regulate activity, decreases, or protein placement after
synthesis.
Differences in prokaryotic and eukaryotic genes
The difference between prokaryotic and eukaryotic related genes can be concluded as
follows:
Prokaryotic:
- Polycistronik: Transcription involves several genes (due to operons).
- Circular DNA and without histones.
- Haploid (1 N).
- Transcription and translation take place at the cytoplasm.
- There is no transcription modification because there is no intron.
Eukaryotic:
- Monocistronic: Transcription involves one gene.
- DNA shaped linear with chromatin (chromosome) and histony.
- Diploid (2 N).
- Transcription at the core, translation in cytoplasm.
- Transcription modifications to occur because of introns.
Molecular genetics central dogma:
The central dogma states that information in DNA is used to form RNA through
transcription, and RNA information is used for protein synthesis through translation.
Some references include DNA replication, while others focus on gene expression (DNA
→
RNA
→
protein), and some include DNA replication before gene expression.
Conclusion
The chromosome is located in the core of the cell and can be seen during the mitosis or
meiosis metaphase stage. Gen, the smallest unit of genetic material, is located on the
gene locus and consists of protein and nucleic acid (DNA and RNA), with a size of 4-8
microns. Gene function includes information inheritance, determination of properties,
and developmental and metabolic arrangements. Nucleic acid is a polynucleotide
consisting of mononucleotide; If the unit is deoxinucleotide, it is called DNA, while the
RNA consists of ribonucleotides.
In Prokariot, protein interactions with DNA regulate genes through mechanisms such as
LAC operons, which control lactose metabolism. Operon is a group of genes controlled
by one promoter and operator, serves as a "switch" to determine whether RNA
polymerase can bind the promoter. Conversely, on eukariot, the transcription gene
varies vary depending on the type of cell, with monocistronic mRNA carrying
information from just one gene. This process is important for cell differentiation, where
the primary transcript sometimes resembles a polysistronic but is processed into
monocistronic mRNA.
