eChapters

NEW CELLS ARE PRODUCED BY DIVISION OF PREVIOUSLY EXISTING CELLS

All cells come from previously existing cells

To make a new cell identical to itself a cell must perform 4 tasks:

It must grow and make additional copies of all its organelles, enzymes, etc..

It must duplicate its DNA

It must accurately separate the DNA into 2 units, so that each cell gets a full set

It must divide into 2 cells (cytokinesis)

SEX IS VERY COSTLY

Large amounts of energy required to find a mate and do the mating: specialized structures and behavior required

Intimate contact provides route for infection by parasites (AIDS, syphillis, etc.)

Genetic costs: in sex you pass on only half your genes to your children

Males are an expensive luxury- in most species they contribute little to rearing offspring

But There are Some Advantages

More genetic diversity: more potential for survival of species when environmental conditions change

Shuffling of genes in meiosis (random separation of homologous chromosomes)

Crossing-over in meiosis (see below)

Fertilization (genes from 2 individuals brought together)

A fair number of practical breeding experiments were done in ancient times

People knew there was a connection between sex and reproduction

The idea had developed that “like begets like”

By selecting certain plants and animals and breeding them many domestic varieties of plants and animals had been developed

Example: corn was developed from a wild grass in Mexico and Central America, probably about 5000 years ago

149 of the top 150 plant crops were domesticated by primitive man

1. Introduction
Molecular techniques are laboratory methods used to study and manipulate DNA, RNA, and proteins. These techniques are crucial for analyzing and understanding the molecular basis of biological processes and have applications in various fields like medicine, agriculture, and forensics.
2. Molecular Marker Analysis
Molecular markers can be expressed as a DNA sequence or gene expression product that represents differences in genomic level in relation to a gene or a property. Molecular markers are markers that can be used to monitor differences at the DNA level and for a gene that is being investigated. DNA markers are also DNA regions in which polymorphism in individuals within a species can be determined.
Molecular markers are nontissue-specific DNA regions that are reliable, repeatable, standardizable, capable of identifying multiple regions in the genome, capable of identifying more than one region in the genome, independent of environmental conditions, dominant and codominant.
Molecular markers are classified as dominant and codominant markers. Heterozygous individuals cannot be distinguished from homozygous dominant individuals, since dominant markers are not suitable for identification of heterozygous individuals when related to dominance between alleles is dominated by dominant markers. Thus, three different individuals (AA, AA and AA) can be distinguished for any marker at any point.
The use of molecular marker systems based on this meta-analysis has become more prevalent in genetic studies conducted by the discovery of the polymerase chain reaction (PCR). The rapid development of technology and the accompanying needs, the facilities of the laboratories where the applications will occur, the biological properties of the species and the abundance of markers in the genome have contributed to the development of DNA markers [5]. Restriction fragment length polymorphism (RFLP), randomly amplified polymorphic DNA markers (RAPD), amplified fragment length polymorphism (AFLP), sequence labeled sequences (STS), microsatellites (SSR), cleaved polymorphic sequence (CAPS), single strand such as complementary polymorphism (SSCP), amplicon length polymorphism (ALP), interspecific sequence repeat polymorphism (ISSR),

BACTERIA HAVE SMALL, COMPACT GENOMES

We now know the complete DNA sequences for about a dozen bacteria

Bacteria seem to need about 500 to 5000 genes to conduct their lives

Because they are small, bacterial genomes are highly organized

Most of the time there are only a few bases between the end of one gene and the beginning of the next

Few introns are found in bacteria

Bacteria contain accessory “chromosomes” called plasmids; each has only a few genes

While developing the toolkit for Participatory Curriculum Development participatory approaches like Focus Group Discussions and Field Level Workshops were adopted. The goal is to provide demand-driven services and to do so, extension professionals need to respond for farmers’ requests rather than deliver predetermined packaged solutions. It is also time to enable the farmers to empower and make their voices heard. Equally important is to make the service providers accountable to the farmers, which is possible when the farmers pay for the services they receive.

In Vedas the cow has been regarded as the mother of Rudras, the daughter of Vashu and the sister of Aditayas and also the use of cow ghee in religious ceremonies had been mentioned in Rig Veda and there is mention of the cow as “Kam Dhenu” in ancient writings. In Shiva temples are found the references of sculpture of “Nandi Bulls”. In Hindu mythology, the male buffalo thought to be the vehicle of the God of death “Yama” and also regarded as physical form of the demon Mahishasur, a symbol of inertia-”Tamas”.

Animal husbandry is an integral component of Indian agriculture supporting livelihood of more than two-third of the rural population. The livestock sector plays a significant role in supplementing family incomes and generating gainful employment in the rural sector, besides providing cheap nutritional food to millions of people. Livestock provides milk, egg, meat as nutritious food, draught power for agriculture, wool, fibre, manure and domestic fuel, hides & skin. In 2010-11, this sector contributed 121.84 million tonnes of milk, 63.02 billion eggs, 42.99 million kg wool, and 4.83 million tonnes of meat. Milk is the main output of livestock sector accounting around two third (67%) of the total output by livestock sector. Meat and egg share 17.5% and 3.6% of the value of livestock output. Livestock contributed 4% to the total GDP and 26% to the agricultural GDP in 2010-11. Livestock are the best insurance against the vagaries of nature like drought, famine and other natural calamities.

There are two assumptions necessary involved in the regression of repeatability. These are:
• The variances of the different measurements are equal and have their components in the same proportions, and
• The different measurements reflect genetically the same character. If these assumptions are not valid the repeatability concept becomes vague without precise meaning in relation to the variance components.
The repeatability differs very much depending on the following:
• The nature of the trait.
• The genetic properties of the population.
• Environmental conditions under which the individuals are kept or raised.
Repeatability indicates the proportion of observed differences in performance between animals caused by differences in real producing ability. That is say, repeatability of butterfat yield is 0.40, and if a cow has an age corrected butter fat yield of 30 kilograms above the herd average, her near producing ability will be equal to 30x 0.40 = 12 kg. above the herd average. This can also be explained in a different way, i.e., if two cows differ in one lactation by 30 kg in butter fat yield. They will have difference of 12 kg of butter fat in the next lactation.
Repeatability has a value 0 to 1 and may also be expressed in percentage. Repeatability of a trait is not a constant, and measurements error or generally, varying environmental conditions tend to increase VEt and thus to decrease repeatability, shrode et al (1960) have shown the effect of a change in environmental conditions on repeatability. They obtained repeatabilities of milk yield, butter fat yield and fat percentage as 0.37, 0.32 and 0.7 respectively and after improving the management removed some of the environmental variations that had marked the cows real producing abilities.

I. Definition

Solute transport in plants, translocation, primarily occurs in the phloem, but it can occur in the xylem.

II. Solute Transport in the Xylem

Some solutes are transported in the xylem

Water and dissolved ions are the main substances in vessels/tracheids

These materials are transported via transpiration stream

Xylem sap may also contain organic materials, usually in relatively low concentration (with a notable exception being maple sap in the spring which is comprised of 2% or more sucrose).

Substances move at different rates depending on matrix effects, metabolic needs, etc.

PLANT NUTRITION

Plants use inorganic minerals for nutrition, whether grown in the field or in a container. Complex interactions involving weathering of rock minerals, decaying organic matter, animals, and microbes take place to form inorganic minerals in soil. Roots absorb mineral nutrients as ions in soil water. Many factors influence nutrient uptake for plants. Ions can be readily available to roots or could be “tied up” by other elements or the soil itself. Soil too high in pH (alkaline) or too low (acid) makes minerals unavailable to plants.

India’s livestock sector is one of the largest in the world and dairy farming is the single largest contributor to country’s GDP, apart from being the biggest source of employment. India has 56.7 per cent of world’s buffaloes. Buffalo genetic resource greatly helps the countries to assess their strengths and potential to harness the nature’s gift and India is fortunate in terms of having largest buffalo population, huge buffalo germplasm diversity (13 recognized plus 14 distinct population groups) and the world renowned buffalo breeds: Murrah, Banni, Jaffrabadi and Nili-Ravi.

Q.1.    What is the most fundamental assumption to be followed by random variable for using the standard method of parametric statistics or parametric inference ?

    Answer
    
    The most fundamental assumption required to be followed by random varibale for using the parametric statistics to have statistical inference drawn from certain set of data is that the random variables have normal distribution.

Definition: Heterosis is defined as the percent increase in the performance of outbred animals over the average of their parents.
The mean superiority of hybrids over the average of their parental lines is called heterosis. Heterosis or hybrid vigor is the increased vigor of the offspring over that of the parents when unrelated individuals are mated. Hybrid vigor includes greater viability, faster growth rate, greater milk production and greater wool production in domestic animals. The amount by which the hybrids exceed the mean performance of better parent is called heterobeltiosis or Euheterosis. The term heterosis was coined by G.H. Shull (1914). Heterosis or hybrid vigour is synonym to each other. However, the heterosis is a phenomena exhibited by an individual or a group of individuals due to heterozygosity of genes. Heterosis in quantitative terms can also be defined as the non-additive gene action. While “hybrid vigour” is the resultant of heterosis phenomena expressed phenotypically by an increase in vigour, size, production, reproduction, survival rate, growth, and economic returns etc. the heterosis is a measure of extent magnitude of out breeding.
In livestock, hybrids may be produced by crossing between two species/breeds/ lines/strains. Technically, heterosis may be positive or negative. However, the desirability of a trait is more important than the sign of heterosis. In some cases, the negative heterosis could be a desirable one (e.g. age at first lay, age at first calving, calving interval, back fat thickness etc.). The amount of heterosis obtained usually depends upon the extent of heterozygosity attained by the hybrids, which in turn is based on the diversity of sire and dam lines crossed. It also depends upon the degree of dominance, over dominance and/ or for which the heterosis is exhibited. Thus, the main causes of heterosis are directional dominance, over dominance and epistasis.

Breeds are the result of the hundreds of years of natural selection and evolution. They are adapted to tropical climate and diseases and perform reasonably well even with low quality of feed and fodder. India has agrarian economy, with majority of population dependent on agriculture. India is a mega diversity hub of different livestock breeds. There are 10 buffalo breeds, 30 cattle breeds, 42 sheep breeds, 20 goat breeds, and 18 poultry breeds contributing significantly to GDP of the country. Despite our vast population of different species, there is a need for conservation of breeds. Conservation is the management of human use of the biosphere, so that it may yield the maximum sustainable benefits to the present generation, as well as maintaining its potential to meet the needs and aspirations of future generation.

Agarose gel electrophoresis is the easiest and commonest way of separating, capable of resolving mixtures of DNA fragment that cannot be separated conveniently by other procedures. The purpose of the gel might be to look at the DNA, to quantify it or to isolate a particular band. The DNA is visualised in the gel by addition of ethidium bromide. This binds strongly to DNA by intercalating between the bases and is fluorescent meaning that it absorbs invisible UV light and transmits the energy as visible orange light.

Agarose, which is extracted from seaweed, is a linear polymer whose basic structure is shown in figure.

It is imperative that the country should develop strategic planning so that available resources in different agro ecological zones of the country to exploited judiciously and utilize sustainably for further enhancing the productivity of cattle and buffaloes. Therefore, agroclimatic region and animal production system-based breeding policy strategies with a focus on large scale implementations of improved animal genetics and breeding innovations by development organizations with active participation of farmers/breeders are discussed here. Before developing sustainable breeding strategies for improving the productivity performance of a particular breed/genetic group of animal population in a given agro-climatic region, it is necessary to have a comprehensive details of population size of breed along with analysis of existing activities such as farmer/breeder’s perceptions and socio-economic levels, agriculture and livestock production systems, available feed and fodder resources, animal genetic resources, their production potentials and utilization pattern, breeding organizations, infrastructure and development facilities . The Quinquennial All India Livestock Census contains information on the herd/flock structure, sex, age, etc. and it does not reflect the factual situation about the status of breeds in terms of their population. Hence, the actual population of each breed and their geographical distribution is not clearly known. The correct picture about these breeds would be available only when breed-wise census of the livestock is carried out and status and performance of breeds are surveyed in their natural habitat and the same has been initiated in the recent survey . In the back ground of the collected and collated information on all above aspects, following region specific animal breeding strategies can be planned for conservation and genetic improvement of bovine genetic resources under different animal production systems.
Genetic Improvement of Non-Descript Zebu Cattle by Crossbreeding
The most rapid and effective approach to genetically improve the largest chunk of non-descript zebu cattle population is through crossbreeding with exotic dairy cattle breeds particularly in milk shed areas around peri-urban and industrial towns