Introduction to breeding Flashcards
- elaborate on plant breeding
2. …………………in a plant are what determine what type of traits it will have
Pant breeding is the science of altering the traits of the plant in order to result in desired characteristics.
it is also the branch of applied botany to achieve improvement in the agriculture plants .
Plant breeding involves basic methods from simply selection of the desirable plant characteristics for propagation to a level of implementing chromosomes and genetic knowledge , to complex degree of molecular techniques.
plant breeders strive to create a specific outcome of the plants and potentially a new varieties.
2.Genes
- what are the objectives of plant breeding?
The prime objectives of plant breeding is to create and develop superior plants over the existing ones in parallel with their economic value.
some other objectives are
1.Higher productivity- it is one the significant aim of plant breeders which can be accomplished by developing more efficient genotypes having greater physiological efficiency
2.Improved quality-better qualities and features such as grain size, taste, color, fragrance, milling quality in grains etc.
3. disease and Insect resistance - It offers the cheapest and convenience technique of disease and pest management
4.Abiotic resistance- Having resistance over abiotic factors such as drought, salinity, extreme temperature, cold and frost serves as great advantages over plant losses
5.change in maturation duration/earliness- having improved features of these like shorter duration of maturity hold a considerable advantage.
Desirable agronomic characteristics- some of the features such as tillering capacity, plant height, growth habit, branching is also important
Give some examples of achievements of plant breeding
- development of Mexican semi dwarf wheat varities from a gene wheat variety Norin 10 and later introduced in india swaminathan and number of hogh ileding varieties like kalyan sona,Sharbathi sonara were developed
- The miracle rice variety IR 8 was developed from the dwarf gene Dee-geo-woo-gene being the first variety which led to green revolution in Asia.
What is Green Revolution?
Green revolution is the advancement of agriculture system through the adoption of research and technology initiated in 1960s radically improving the production worldwide.
The initiatives resulted in the adoption of new technologies, including high yielding varieties(HYVs) of cereals, especially dwarf wheat and rice, in association with chemical fertilizers andagro-chemicals, irrigation and new methods of cultivation, including mechanization.
- Explain cell Theory
2. elaborate on the features of chromosomes?
The ‘cell theory’ was propounded by Schleiden and Schwann in 1838 and Virchow in 1855 which stated that all organisms are composed of one or more cells and these cells arise only from pre-existing cells
The nucleus contains thread like bodies termed as chromosomes
Chromosomes are the structural unit of inheritance and carry genes on them which are the functional unit of a trait or character
Each species has a specific number of chromosomes ranging from 4 in drosophila fly to 254 in shrimps
In human beings, the number is 46 (23 pairs)
Differentiate between mitosis and meiosis
Mitosis is the process of increasing the cell number without disturbing the genetic constitution of the cell
In Meiosis, the genetic composition is changed through sexual recombination
Haploid (n) and diploid (2n) numbers
Describe the characteristics of DNA?
Deoxyribonucleic acid(DNA) is a moleculethat encodes the geneticinstructions used in the development and functioning of all known living organisms
DNA consists of two long chains of subunits twisted around one another to form a double-stranded helix
The sub-units of each strand are nucleotides, each of which contains any one of four chemical constituents called base
The four bases in DNA are Adenine (A), Thymine (T), Guanine (G) and Cytosine (C)
- Genetic information is like a ……………….
2.In DNA, the alphabet is only. 4 letters (A,T,G and C) long
These letters are used to form the genetic words called……………………
3.These codons combine together to form ………………………called genes
4.All the sentences join together to form a book that contains all genetic information about an organism called ……………………..
- Language
- Codon
- sentences
- genome
- amino acids
Genes and Protein
Proteins are large biological molecules made up of basic building blocks called amino acids
Amino acids are made up of hydrogen, carbon, nitrogen, oxygen and sulphur
There are more than 100 amino acids in nature, however there are about 20 essential amino acids that animals require
Proteins play a variety of roles such as transport, storage, structural framework of cells, antibodies etc that catalyzes biochemical reactions essential for metabolic activities
Examples of proteins include hemoglobin, collagen, thyroid hormone, insulin, and myosin.
- Give a brief description of Protein synthesis.
2. Differentiate between DNA and RNA
1.Proteins are produced by genes coded in the DNA
For example, the base sequence ATG in a DNA strand specifies the amino acid methionine (Met), TTT specifies phenylalanine (Phe), GTG specifies valine (Val)
How the genetic information is transferred from a DNA strand into the amino acid sequence of a protein is known as the central dogma of molecular genetics
The main concept in the central dogma is that DNA does not code for protein directly but acts through an intermediary molecule called ribonucleic acid (RNA)
The structure of RNA is similar, but not identical, to that of DNA as the sugar is ribose rather than deoxyribose
RNA is single-stranded and contains a base, uracil (U), that takes the place of thymine (T) in DNA.
- Genetic Significance of Chromosomes
2. One pair of chromosomes - X and Y - determines sex; the other 22 pairs are called …………………
They form the only link between two generations
A diploid chromosome set consists of two morphologically similar sets, one is derived from the mother and another from the father at fertilization
The genetic material, DNA or RNA is localized in the chromosome and its contents are relatively constant from one generation to the next
The chromosomes maintain and replicate the genetic information contained in their DNA molecule, which is used by RNA molecules to direct the synthesis of proteins
he human genome is the set of genetic information encoded in 46 chromosomes
The chromosomes are organized into 23 pairs – one chromosome of each pair is inherited from the mother and one from the father
2.autosomes
Mendelian Inheritance
Gregor Mendel (1866) proposed the Theory of Quantitative Genetics, which is the basis for plant breeding
Mendel experimented with garden pea, crossing white flower and purple flower pea plants
The offspring (known as the F1generation) was purple-flowered
In F2 generation, he obtained a purple flower to white flower in the ratio of 3:1
The gene for flower color in pea plants exists in two forms, one for purple and the other for white
The alternative versions of a gene are now called alleles
An organism that has two identical alleles for a gene is said to be Homozygous (e.g. BB) for that gene (and is called a homozygote)
An organism that has two different alleles for a gene is said to be Heterozygous(Bb) for that gene
Dominant and Recessive genes
Mendelian Laws
The Law of Segregation
Every individual contains a pair of alleles for each particular trait which segregate or separate during cell division for any particular trait and that each parent passes a randomly selected copy (allele) to its offspring
The Law of Independent Assortment
Aso known as “Inheritance Law”, states that separate genes for separate traits are passed independently of one another from parents to offspring
The Law of Dominance
States that recessive alleles will always be masked by dominant alleles.
Define the following laws
a. Law of segregation
b. law of independent assortment
c, Law of dominance
a. Law of segregation
During gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene
b. law of independent assortment
Genes for different traits can segregate independently during the formation of gametes.
Law of Dominance
Some alleles are dominant while others are recessive; an organism with at least one dominant allele will display the effect of the dominant allele.
Differentiate between Phenotype and Genotype
A phenotype is the appearance or performance of an organism as a result of the interaction of a genotype with that of a given environment
A genotype determines what an individual should be while phenotype reveals what it is
A genotype is constant from birth till death whereas phenotype changes with time, place, age, food, environment etc.
