Forest Genetics Terminologies
Forest Genetics Terminologies
The new characters which are adopted by an individual during its lifetime.
The acquired characters are actually the changes or modifications which are adopted by an organism due to changing environments during its developments. Eg we can develop our muscles by exercise.
An allele is a Greek word which means ‘belonging to one another’.
Members of a gene pair which occupy the same position (locus) on two homologous chromosomes are called allele or allelomorph.
The term allele is used for the individual members of a gene pair. Eg in the gene pair Tt, ‘T’ is an allele of ‘t’ and ‘t’ is an allele of ‘T’. Similarly in the gene pair ‘Aa’, both are an allele of one another but neither of these is the allele of either ‘T’ or ‘t’.
The point at which two chromatids join during the fusion and exchange of genetic material crossing over in cell division
Greek khrōma “color” + sōma “body”; because chromosomes readily take up the dye.
A rod-shaped structure, usually found in pairs in a cell nucleus that carries the genes that determine sex and the characteristics an organism inherits from its parents. A human body cell usually contains 46 chromosomes arranged in 23 pairs.
The term clone is derived from κλών, the Greek word for “trunk, branch”, referring to the process whereby a new plant can be created from a twig. “A plant, animal, or other organisms that are genetically identical to its parent, having developed by vegetative reproduction from a bulb, cutting, or other parts, or, in experimental conditions, from a single cell”.
Cloning in biology is the process of producing populations of genetically-identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning), or organisms.
Cloning of any DNA fragment essentially involves four steps
- Fragmentation – breaking apart a strand of DNA
- Ligation – gluing together pieces of DNA in the desired sequence
- Transfection – inserting the newly formed pieces of DNA into cells
- Screening/Selection – selecting out the cells that were successfully transfected with the new
The modern cloning techniques involving nuclear transfer have been successfully performed on several species. Landmark experiments in chronological order:
- Tadpole: (1952) Many scientists questioned whether cloning had actually occurred and unpublished experiments by other labs were not able to reproduce the reported results.
- Carp: (1963) In China, embryologist Tong Dizhou produced the world’s first cloned fish by inserting the DNA from a cell of a male carp into an egg from a female carp. He published the findings in a Chinese science journal.
- Mice: (1986) A mouse was the first successfully cloned mammal. Soviet scientists Chaylakhyan, Veprencev, Sviridova, and Nikitin had the mouse “Masha” cloned. The research was published in the magazine “Biofizika” volume ХХХII, issue 5 of 1987.
- Sheep: (1996) From early embryonic cells by Steen Willadsen. Megan and Morag cloned from differentiated embryonic cells in June 1995 and Dolly the sheep from a somatic cell in 1997.
- Rhesus Monkey: Tetra ( January 2000) from embryo splitting
- Gaur: (2001) was the first endangered species cloned.
- Cattle: Alpha and Beta (males, 2001) and (2005) Brazil
- Cat: CopyCat “CC” (female, late 2001), Little Nicky, 2004, was the first cat cloned for commercial reasons
- Mule: Idaho Gem, a john mule born 4 May 2003, was the first horse-family clone.
- Horse: Prometea, a Haflinger female born 28 May 2003, was the first horse clone.
- Water Buffalo: Samrupa was the first cloned water buffalo. It was born on February 6, 2009, at India‘s Karnal National Dairy Research Institute but died five days later due to the lung infection.
- Camel: (2009) Injaz, is the first cloned camel.
Studies on clone are called the clonal trial.
The character (trait/ alleles) that appears in the offsprings of F1 generation of two parents is known as dominant. While the gene controlling this character is known as the dominant gene.
Or; the trait/ allele which show their complete expression in homozygous and also in heterozygous condition are called Dominants.
Mendel called dominant to those characters (eg tallness) which always appeared in F1. These characters show their complete effect in homozygous as well as in heterozygous condition. In the heterozygous condition, they prevent to express the effect of recessive character or gene. The dominants are always expressed by capital letters like T, Y, R, L, etc. eg the phenotype of a pea plant will be tall if it has TT (homozygous) or Tt (heterozygous) genotype.
A DNA molecule consists of a ladder, formed of sugars and phosphates, and four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G). The genetic code is specified by the order of the nucleotide bases, and each gene possesses a unique sequence of base pairs. Scientists use these base sequences to locate the position of genes on chromosomes and to construct a map of the entire human genome.
Nucleic acids are complex molecules produced by living cells and are essential to all living organisms. These acids govern the body’s development and specific characteristics by providing hereditary information and triggering the production of proteins within the body. This computer-generated model shows two strands of deoxyribonucleic acid (DNA) and the double-helical structure typical of this class of nucleic acids.
The organisms, cell or a nucleus which has two sets of chromosomes is called diploid (2n).
The term diploid is used to describe an organism, cell or nucleus which contains two sets of the chromosome. Diploid nuclei are found in most animal cells except gametes. Diploid nuclei are also found in sporophyte of plants. The diploid nuclei undergo meiosis to form haploid (1n) nuclei. When two haploids (1n) nuclei combine then a diploid number of chromosomes is restored.
Eg the no of chromosomes in man is 46 per nucleus. This number is called the diploid number.
An introduced, non-native tree species (LoF)
Stands for ‘First filial generation’ the offsprings of parental generation at the beginning of a genetic experiment are called F1 generation.
‘F’ stands for ‘filial’ which is a Latin word which means ‘offsprings’ while ‘1’ stands for first. So F1 means first generation offspring.
Eg if a cross is made b/w pure tall and pure dwarf pea plant then their offsprings will be F1 generation.
TT × tt à Tt (F1 generation)
The offsprings which result from the sexual reproduction of F1 generation are called F2 generation.
Gene is a unit of heredity and is responsible for the development of a trait. Or; is a part of the hereditary material (DNA) that controls a specific character of an organism. Genes occur in pairs.
Genes are located on chromosomes. These are made up of DNA. They are always found in pairs. They are responsible for the transmission of characters from one generation to the next generation. Mendel called them factors. Genes are represented by letters or symbols. Capital letters are used for the dominant character while small letters are used for recessive characters. Eg the gene for the tall character (dominant) is represented by ‘T’ while‘t’ represents the gene of dwarf character (recessive).
It is the total collection of genes in a population at any one time. The gene pool is the reservoir from which the members of the next generation of that population derive their genes. It consists of all alleles (alternate form of genes) in all the individuals making lip of population.
Gene therapy may one day be used to treat, cure, or prevent a variety of genetic disorders. In gene therapy, a type of virus known as a retrovirus is used to replace a defective gene in cells with a new, healthy gene. Scientists insert the healthy gene into the ribonucleic acid (RNA) of the retroviruses. These retroviruses are mixed with cells taken from a patient and cultured in a laboratory. The retroviruses insert the healthy gene into the deoxyribonucleic acid (DNA) of the cells. The cells with the new, healthy gene are then injected back into the patient.
The alteration and recombination of genetic material by technological means, resulting in transgenic organisms. Also called Genetic Modification
The genetic composition of a particular trait of an individual is called genotype.
The genotype is the actual genetic makeup of a phenotype. In other words, we can say that genotype is the genetic basis of a particular character. The visible expression of the genotype of a particular trait is called phenotype. The genotype is represented by letter or symbols.
Eg TT, Tt, tt are the genotypes of height. In these examples ‘T’ stands for tall character and ‘t’ for the dwarf character. The genotype may be homozygous (TT, tt) or heterozygous (Tt)
The organism cell or nucleus which has a single set of unpaired chromosomes is called haploid.
The term haploid is used to describe an organism or cell or a nucleus which contains a single set of unpaired chromosomes. The haploid nuclei are found in the names of plants and animals. They are also found in the gametophytes of plants. The haploid nuclei are formed by the process of meiosis in a diploid. The haploid number is half then the diploid number.
Eg there are 46 chromosomes per nucleus in human beings called the diploid number. Due to meiosis, the chromosome number become half in gametes ie gametes are haploid.
It is defined as the passing of characteristics from the parents to the offsprings or from one generation to the next generation.
Heredity is actually a physical and organic relationship b/w parents and offsprings. It is a common observation that offsprings receive many characteristics from their parents. So we can say that heredity is a quality of offsprings to resemble their parents.
Improved traits resulting from crossbreeding: the increased growth, disease resistance, or fertility seen in hybrid species. Also called Hybrid vigor.
For example, mules, the offspring of mares and donkeys, are stronger and longer-lived than the parent animals
(Greek: hetero = different; zygous = pair)
The genotype in which the gene pair is different is called heterozygous genotype.
In the heterozygous genotype, the makeup consists of a pair of contrasting genes. Eg Tt genotype shows heterozygous tall.
(Greek, Homo = same; zygous = pair)
That genotypes in which the gene pair is identical is called homozygous genotype.
In homozygous the genetic makeup consists of a pair of similar genes. Eg TT genotype shows homozygous tall while tt genotype shows homozygous dwarf.
Hybrids are the offspring which are resulted from a cross b/w two genetically unlike individuals.
When a cross is carried out b/w two genetically different parents then their progeny will have the characters of both parents and the progeny is called a hybrid. If a single trait is involved then it is called monohybrid. Eg if a cross is made b/w pure tall and pure short pea plants then offspring will be hybrid.
TT (pure tall) × tt (pure dwarf) à Tt (hybrid)
If two traits are involved then it is called dihybrid. If three traits are involved, then it is called trihybrid and so on.
It is a phenomenon in which the offsprings receive characters or genetic material from parents and ancestors.
Eg a human child receives many characters from parents like blood group, eye color, skin color, color blindness, etc.
The proximity of two or more genes on a chromosome, which tends to cause them to be inherited together, is called Linkage.
The position of a gene on the chromosome is called its locus.
Change in genetic material: a random change in a gene or chromosome resulting in a new trait or characteristic that can be inherited. Mutation can be a source of beneficial genetic variation, or it can be neutral or harmful in effect.
The external appearance of a particular trait is called its phenotype.
The term phenotype is used to show the visible expression of a particular character of an individual. The phenotype is always expressed in words. Eg tall, dwarf, green, brown, etc. all these words have represented the external appearance or phenotype of character.
Having more than twice the basic number of chromosomes
The offspring of an identified parent is called progeny.
When the characteristic of progeny is studied it is called progeny trial.
Pure or True Breeding Variety
A variety which produces offspring identical to parents is called pure or true breeding variety.
If the offspring always have the traits like their parents then the parents are called true breeding or pure breeding. The offspring of true breeding variety will show the same behavior in the next generation.
Eg suppose we collect the seeds from a white-flowered plant and grow them in the soil. If the next generation shows the same white-flowered plants then their parents are called true breeding or pure breeding.
The traits or alleles which show their complete expression only homozygous condition but not in heterozygous condition are called recessives.
Mendel called recessive to those characters (eg dwarfness) which did not appear in F1 generation by reappeared in F2 generation. A recessive character cannot show their effects in the presence of dominants. They show their complete expression when they are present in double dose eg in homozygous condition. The recessive traits or alleles are always expressed by small letters like t, y, r, l, etc.
Eg the phenotype of pea plant will be dwarf if it has ‘tt’ genotype but in case of ‘Tt’ the phenotype will be tall due to the presence of dominant ‘T’.
- RNA (ribonucleic acid) is a polymer of Nucleotide.
- It is single stranded protoplasmic material. It consists of pentose Sugar Ribose and the bases A, C, G, and Uracil.
- It translates genetic information into action.
Types of RNA:
- There are three types of RNA
- Messenger RNA – m – RNA
- It takes a message from DNA to the ribosome in the cytoplasm.
- Transfer RNA – t – RNA
- It carries a specific amino acid from the cytoplasm to the ribosome to be placed in a polypeptide chain. It is made up of 75 – 80 nucleotides and it has a family of 45 – 60 t – RNAs.
- Ribosomal RNA – r – RNA
- Along with proteins, it makes up the ribosomes which make proteins.
- Messenger RNA – m – RNA
It stabilizes the function of m and t – RNA and detaches m – RNA from the DNA in the nucleus
Survival of fittest: the process by which organisms that adapt well to their environment produce offspring, while those that do not adapt die out, resulting in gradual changes in a species. Selection may take place naturally natural selection or as the result of breeding for specific characteristics artificial selection
- The growth of tissue: the growth of tissue outside an organism in a nutrient medium, or the techniques involved in this process
- Tissue culture is the growth of tissues and/or cells separate from the organism. This is typically facilitated via use of a liquid, semi-solid, or solid growth media, such as broth or agar.
- Tissue culture commonly refers to the culture of animal cells and tissues, while the more specific term plant tissue culture is used for plants.
- However, “tissue culture” can also be used to refer to the culturing of tissue pieces, i.e. explant culture or whole organs, i.e. organ culture.
That specific expression in an individual which is developed by genes is called character or trait.
Each individual is recognized due to its characters. These characters of an individual may be similar or different from others. Eg suppose we have two flowers ie one is red and the other is white. The red and white are the color traits of the flowers.
The difference in the same basic character in a group is called Variation.
In a normal population, we can see that no two individuals are similar. Variation is found in every character. Eg there are many colors of eyes in human beings.
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