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Genes are small segments of DNA that code for proteins inside the genome.
- They provide instructions for our unique characteristics, such as eye and hair color.
- Genes are passed from guardians to posterity and contain the data expected to determine characteristics.
- They are orchestrated in a steady progression on structures called chromosomes.
- Each cell in the human body contains around 30000 genes.
- Genes are useful units of heredity as they are made of DNA.
- The chromosome is made of DNA containing numerous genes.
- Each quality includes a specific arrangement of directions for a specific capacity or protein coding.
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Key Terms: Gene, DNA, Chromosomes, Protein, Genome and Genomics, Cell, RNA, Mutation, Central dogma, Cytosol, Adenine, Thymine
Genes
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Genes are the essential physical and useful unit of heredity.
- They are composed of DNA.
- A few genes set about as guidelines to form atoms called proteins.
- In people, genes change in size from two or three hundred DNA bases to multiple million bases.
- Each cell in the human body contains around 30000 genes.
- Only 2% of the genome is made up of DNA found in genes.
- Many studies on the genes have found the location of over 13000 genes on each of the chromosomes.
- In 1905, William Bateson introduced the word genetics.
- Later, in 1909, Wilhelm Johannes was the first person to coin the word GENE.
- He called it Gene to represent heredity.
Genes
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| Chromosome theory of inheritance | Down’s syndrome | Mendelian inheritance |
| Colour blindness | Chromosomes and genes | Principles of Inheritance and Variation |
Chemical Structure of Genes
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In most organisms, genes consist of deoxyribonucleic acid (DNA), except in some viruses that contain genes comprised of ribonucleic acid (RNA).
- A DNA molecule is comprised of two nucleotide chains that wind about each other to form a twisted ladder.
- The sides of the ladder are composed of sugars and phosphates, while the rungs are composed of bound pairs of nitrogenous bases.
- These bases are adenine (A), guanine (G), cytosine (C), and thymine (T).
- An A on one chain links to a T on the other, making an A-T ladder rung.
- Similarly, a C on one chain bonds to a G on the other, forming a C-G ladder rung.
- If the binding between the bases is broken, the two chains unwind, and free nucleotides within the cell attach to the exposed bases of the now-separated chains.
- According to the base-pairing rule, the free nucleotides align along each chain—A bonds to T, and C bonds to G.
- This process creates two identical DNA molecules from a single original and is the method by which hereditary information is transferred from one cell generation to the next.
Characteristics Determined by Genes
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There are 23 pairs of chromosomes in the human cell.
- The trait is one of the properties that one or more genes determine.
- Certain features are also caused by abnormal genes and genes generated as a consequence of new mutations.
- The size of genes varies depending on the code or protein they create.
- Every cell in the human body has the same DNA.
- The difference between cells is caused by the different types of genes that are activated and hence create a range of proteins.
Functions of Genes
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The following are the functions of genes
The Central Dogma
The DNA in our chromosomes contains genes that get interpreted into RNA.
- There are a few distinct kinds of RNA i.e. tRNA, mRNA, rRNA, and so on.
- They are made out of similar structure impedes yet have various capacities, areas, and constructions.
- Courier RNA (mRNA) might be converted into a protein.
- The standard data stream is:
DNA→RNA→Protein
- The arrangement of genes that are 'on' at some random time is basic.
- Various genes should be 'on' on various occasions relying upon the necessities and elements of a specific cell.
Transcription
The goal of transcription is to form an RNA copy of a gene.
The process of transcription is divided into several distinct steps:
- The transcription factor perceives and ties to a quality's beginning site (advertiser).
- An RNA-production catalyst (RNA polymerase) ties to the recording factor.
- The catalyst makes an RNA duplicate of the quality.
- The enzyme falls off and therefore the RNA is released.
- The RNA will either remain within the nucleus or it'll exit into the cytosol.
Translation
The goal of translation is to form a protein using the knowledge encoded in mRNA.
The process of translation is split into several steps:
- mRNA leaves the nucleus and is recognized and bound by ribosomal subunits within the cytosol.
- The ribosome 'reads' the RNA three nucleotides (one codon) at a time.
- The ribosome inserts the amino alkanoic acid like the codon into the growing protein.
- The ribosome encounters a stop codon and terminates protein synthesis.
- The protein enters a highly regulated folding process and obtains a totally folded structure.
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Things to Remember
- Gene is the essential actual unit of legacy.
- Genes are passed from guardians to posterity and contain the data expected to determine characteristics.
- Genes are DNA.
- A piece of DNA genes comprises A (Adenine), T (Thymine), G (Guanine), and C (Cytosine) nucleotides.
- Introns are mediating non-coding groupings eliminated from the last record.
- Exons are coding portions of a quality that are joined in the wake of grafting and developing the last record.
- Administrative components are situated on the outrageous closures of quality.
- The Central Dogma, Transcription, and Translation are the main functions of the Gene.
Sample Questions
Ques. What are Genes? (1 Mark)
Ans. Genes are the essential physical and useful unit of heredity. They are composed of DNA.
Ques. State the significance of acquired characteristics and procured attributes. Which of the two isn't given to the future? Clarify with the help of the model. (3 Marks)
Ans. Inherited genes are the attributes sent from guardians to their posterity. Gained genes are attributes that are created during the lifetime of a person. Procured attributes are not given to the future. For instance, on the off chance that we breed a gathering of mice, all their descendants will have tails. Presently, if the tails of these mice are eliminated by a medical procedure and permitted to rise, the cutting-edge mice will likewise have tails. In the event that these tails are additionally taken out and permitted to raise, the offspring of mice will again have tails. Expulsion of the tail by a medical procedure is a procured quality and doesn't change the genes of microorganism cells and subsequently, isn't given to the future.
Ques. How many genes are in a human? (1 Mark)
Ans. According to the Human Genome Project, humans have an estimated Trusted Source 30,000 genes.
Ques. "An individual can't give to their descendants the encounters of its lifetime." Justify the assertion with the assistance of a model and furthermore give justification behind the equivalent. (2 Marks)
Ans. Experience accomplished during the lifetime of an individual doesn't roll out any improvement in the quality of the person.
For instance, if an individual pursues a book on birds, the information he acquires by perusing the book doesn't show any improvement in the quality, thus, this information won't get consequently sent to his future. Such an attribute is called gained quality.
Ques. What is implied by the term speciation? Rundown four factors that could prompt speciation. (5 Marks)
Ans. Speciation is the advancement of regenerative detachment among once interbreeding populaces.
Variables that can prompt speciation are:
- Hereditary float: Overages, a hereditary float might aggregate which prompts speciation.
- Normal determination: Natural choice might work contrastingly in various areas which might bring about speciation.
- Serious DNA change.
- A variety might happen that doesn't permit sexual demonstrations between two gatherings.
Ques. Give one illustration of every one of the characters that are acquired and the ones that are gained in people. Notice the contrast between the acquired and the gained characters. (3 Marks)
Ans. The eye tone or hair shade of an individual is an illustration of an acquired person though, body-weight is an illustration of the gained character.
The fundamental contrast between acquired and procured character is that an acquired person is given from a parent to posterity and gained characters are obtained by a person during his lifetime relying on his way of life.
Ques. Define a variety comparable to animal varieties. For what reason is variety advantageous to the species? (3 Marks)
Ans. Variety alludes to the distinctions in the characters or genes among the people of animal varieties. Varieties are advantageous to the species in light of the fact that:
- They empower the life forms to adjust to evolving conditions.
- Varieties structure the premise of heredity.
- They structure the crude materials for the advancement and improvement of new species.
Ques. What are genetic tests used for? (3 Marks)
Ans. Genetic tests in this day and age are utilized for the conclusion of specific issues like Polycystic Kidney Disease, Turners Syndrome, Sickle cell Anemia, Cystic Fibrosis, and so on Hereditary tests additionally are useful in anticipating which infection an individual is probably going to create.
The innovation is excessively exceptional to the point that these Gene deformities can be adjusted by Gene treatment and certain illnesses can be kept away from happening in a person. Researchers are exploring a similar method that might permit the specialists to embed a Gene for the amendment of sickness rather than exposing a person to medications and medical procedures. The examination is as yet continuing for something very similar.
Ques. What is genetic inheritance? (2 Marks)
Ans. The hereditary material is given from guardians to posterity as DNA. All living beings go through the course of development and proliferation. The data that is needed for the multiplication and endurance of these organic entities are encoded in the DNA that is given starting with one age and then onto the next. This is the means by which Genetic legacy happens.
Ques. What is the central dogma? (2 Marks)
Ans. Central dogma is considered the process of converting the DNA instructions into proteins. According to the central dogma, the genetic information moves from the DNA to RNA in order to give rise to a functional product called the protein. Transcription is the process through which DNA gets converted into RNA and through translation, RNA turns into proteins. Francis Crick was the first person to discover central dogma in the year 1958.
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