eChapters

ALL LIVING ORGANISMS ARE MADE UP OF UNITS CALLED CELLS

All living creatures are made from 1 or more cells

All cells are produced from previously existing cells (no spontaneous generation)

All cells appear to be descended from the first cell which existed about 4 billion years ago

For a species to exist its reproductive cells must be potentially immortal (no aging)

Our bodies start from a single cell and contain about 100,000,000,000,000 (10^14) cells at maturity

Principle

Cell viability refers to the quantity of healthy cells in a sample, while cell proliferation is a crucial indicator for comprehending the mechanisms and pathways involved in the survival of cells or death following exposure to toxic substances. The methods used to assess viability are typically the same as those used to detect cell proliferation. Cell cytotoxicity and proliferation assays are commonly employed in drug evaluations to determine if the test compounds impact cell proliferation or exhibit direct cytotoxic effects. Cell viability can be determined by calculating the ratio of total live cells to the total number of cells (live and dead). Staining also helps to observe the general cell structure. Cell proliferation assay by MTT. Metabolically active cells reduce the yellow tetrazolium MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) through dehydrogenase enzymes to produce NADH and NADPH. The purple formazan produced inside the cell can be dissolved and measured using spectrophotometry. The MTT Cell Proliferation Assay quantifies cell proliferation rate and detects decreases in cell viability caused by metabolic events leading to apoptosis or necrosis. The MTT Reagent produces minimal absorbance values when no cells are present.

I. WALL COMPONENTS – CHEMISTRY

The main ingredient in cell walls are polysaccharides (or complex carbohydrates or complex sugars) which are built from monosaccharides (or simple sugars). Eleven sugars are common in these polysaccharides including like glucose and galactose. Carbohydrates are good building blocks because they can produce a nearly infinite variety of structures. There are a variety of other components in the wall including protein, and lignin. Let’s look at these wall components in more detail:

A. Cellulose: β1,4-glucan (structure provided in class). Made of as many as 25,000 individual glucose molecules. Every other molecule (called residues) is “upside down”. Cellobiose (glucose-glucose disaccharide) is the basic building block. Cellulose readily forms hydrogen bonds with itself (intra-molecular H-bonds) and with other cellulose chains (inter-molecular H-bonds). A cellulose chain will form hydrogen bonds with about 36 other chains to yield a microfibril. This is somewhat analogous to the formation of a thick rope from thin fibers. Microfibrils are 5-12 nm wide and give the wall strength - they have a tensile strength equivalent to steel. Some regions of the microfibrils are highly crystalline while others are more “amorphous”.

Cells are the Working Units of Life

With the possible exception of viruses, every form of life on Earth either is a cell or composed of cells. All cells come into existence through the activity of other cells.

All Cells are either Prokaryotic or Eukaryotic

All cells can be classified as prokaryotic or eukaryotic. All plants, animals, fungi, and protists are either single eukaryotic cells or are composed of eukaryotic cells. Prokaryotic cells are either bacteria or archaea. Eukaryotic cells have most of their DNA contained in a membrane-lined nucleus, whereas prokaryotic cells do not have a nucleus. Eukaryotic cells also have more specialized structures, called organelles, than do prokaryotic cells. All prokaryotes are single-celled, whereas many eukaryotes are multi-celled.

The Eukaryotic Cell

There are five principal components to the eukaryotic animal cell: the nucleus, other organelles, the cytosol, the cytoskeleton, and the plasma membrane. Organelles are “tiny organs” within the cell that carry out specialized functions, such as energy transfer and material recycling. The cytosol is the fluid in which these organelles are immersed (The cytoplasm is the region of the cell inside the plasma membrane but outside the nucleus.) The cytoskeleton is composed of several groups of proteins that give the cell support and facilitate transportation of cellular elements. The plasma membrane is the chemically active outer boundary of the animal cell. Plant cells have a plasma membrane that has, outside of it, a cell wall.

Introduction

Robert Brown discovered the nucleus in some plant cells in 1831. After analyzing tissues from a range of animals and plants, T. Schwann (1839) declared, “All living organisms are composed of cells.”

The fundamental elements of Prokaryotic and Eukaryotic cells

The simplest cells, called prokaryotic cells, have a straightforward structural arrangement. There is only one membrane system in it. They contain rickettsia, spirochete, mycoplasma, virus, blue-green algae, and bacteriablue-green algae, or cyanobacteria are the largest and most intricate prokaryotes, where higher plant photosynthesis occurs and have changed throughout time.

Prokaryotic cells

Prokaryotic cells range in size from 1 to 10 µm. They take place in a range of formats. A bacterial cell is made up of three basic parts:

I. External layer: It is composed of the inner cell or plasma membrane, middle cell wall and outer slimy capsule.

a. Cell membrane: The thin, flexible membrane of the cell, composed of proteins and lipids, regulates the flow of chemicals throughout the cell. It carries respiratory enzymes for reactions that release energy. Respiratory enzymes are found in mesosomes, which are folded regions of the plasma membrane that are compared to the mitochondria in eukaryotic cells. Similarly, the pigments and enzyme molecules found in photosynthetic cells are linked to the in-folds of the plasma membrane known as photosynthetic lamella, which is responsible for absorbing light and converting it into chemical energy.

b. The cell wall: It is the non-living, semi-rigid layer that encloses the cell membrane, with a thickness that varies from 1.5 to 100 µm. It is chemically made up of peptidoglycans. Certain bacteria, such as mycoplasma, don’t have cell walls.

Introduction
Embryogenesis begins with the fertilization of the oocyte by the sperm, leading to the formation of a zygote. This single cell undergoes a series of highly regulated mitotic divisions known as cleavage, forming a multicellular structure called the blastocyst. As the blastocyst implants in the uterine wall, the cells continue to divide and differentiate into the three primary germ layers: the ectoderm, mesoderm, and endoderm. Each of these layers gives rise to specific tissues and organs, controlled by genetic instructions and cellular signalling mechanisms.One of the most critical aspects of embryogenesis is the intricate interplay of cellular signalling pathways and genetic mechanisms, which regulate the precise growth and differentiation of cells into tissues and organs. Understanding these mechanisms not only helps in comprehending normal embryonic development but also in diagnosing and treating developmental disorders in veterinary practice.
Cellular Signalling in Embryonic Development
Cellular signalling is a fundamental process in embryogenesis that ensures cells communicate with each other to perform specific tasks. The coordination of cell proliferation, differentiation, migration, and apoptosis (programmed cell death) is essential for the proper formation of tissues and organs.
Types of cell signalling
1. Short range signalling: It involves communication within a cell as well as between nearby cells. This includes:
a) Paracrine signalling: where a cell releases signals that affect neighbouring cells.
b) Autocrine signalling: where a cell sends signals to itself, affecting its own behaviour.

Introduction

The smallest, most basic, most primitive organisms are known as prokaryotic (Greek: pro= primitive or prior, and karyon = nucleus). Likely, they originated around 3.5 billion years ago. Bacteria, such as Mycoplasma and Cyanobacteria, are known to contain these cells. A prokaryotic cell is a deeply organized single-enveloped system. Its constituent nuclear parts are encased in a plasma membrane, with the cytoplasmic ground substance encircling the center. Prokaryotic cells’ cytoplasm lacks distinct cytoplasmic organelles, the nuclear envelope, and any other cytoplasmic membrane.

Despite being incredibly thin and delicate structures, in Eukaryotes plasma membranes are essential to many of a cell’s most vital processes. Membranes are lipid-protein assemblages where non-covalent linkages hold the constituents in place in a thin sheet. Both integral protein and phospholipid lateral mobility are significantly impacted by the physical condition of the lipid bilayer. The plasma membrane is a selectively permeable barrier that permits solute passage via assisted diffusion, active transport, and simple diffusion via membrane channels or the lipid bilayer. A system of membrane organelles, such as the endoplasmic reticulum, Golgi complex, and lysosomes, is found in the cytoplasm of eukaryotic cells. These organelles are physically and functionally connected to the plasma membrane and one another. The cytoplasm is separated into a luminal region inside the ER membranes and a cytosolic space outside the membranes by the endoplasmic reticulum (ER), a network of tubules, cisternae, and vesicles. Additionally, the ER is where the majority of a cell’s membrane lipids are generated and transported to different locations. Proteins’ asparagine residues are added with sugars (a process known as glycosylation), which starts in the rough ER and continues in the Golgi complex.

13.1 Challenges in the technology transfer process
Technology transfer (TT) is more complex and involves the complex interrelationships between universities, research institutes, the private sector, the state, and society. Though TT is all about translating research findings into purposeful solutions that can support the economy and society, it is not a linear process. The challenges can be described as legal, institutional, cultural, financial, policy, and human resource. All this is accompanied by bottlenecks that inhibit or decelerate the diffusion of promising technologies.
13.1.1 Legal and intellectual property challenges
The vital component of technology transfer is the proper management of intellectual property (IP), which is often the most challenging aspect.
• Ambiguities in IP ownership: During multi-institutional or shared funder research, ownership is quite controversial. As an example, when a government lab and a university collaborate on the project, there is ambiguity as to who would have the ultimate licensing authority over the technology: the university, the lab, or the funding agency. This kind of fight hinders commercialisation and scares off industry partners.
• Lengthy patent filing and prosecution timelines: In several jurisdictions, the filings, examination, and granting of a patent may take between three and five years or more. Such delay is not compatible with the rapid cycle of invention in other fields such as ICT or biotechnology, where patent claims may become invalid before they are granted.
• High costs of IP protection: International direct patenting, like under the Patent Cooperation Treaty (PCT), is costly and involves legal services, fees, and upkeep costs. These costs are excessively high, which cannot be easily compensated by universities and startups, and where technologies are not secured or limited to local markets.

The state of Uttaranchal was carved out of Uttar Pradesh on 9^th November 2000 as the 27th state of the union of India and renamed as Uttarakhand. The state is located in western Himalayan region and is one of the geographically smallest states of the country. However, the state is enriched with livestock biodiversity represented by cattle, buffaloes, goats, pigs, horses, mules and poultry.  The climate of the state varies from subtropical in the valleys to temperate on higher slopes with a summer monsoon. The temperature ranges from -5.4ºC (Muketshwar, higher hills) to 40.2ºC (Pantnagar, plains) but it drops below freezing point in many parts of high mountainous areas of the region during winter. Preponderance of hilly terrains and forestland restricts the size of the agricultural land/ holding. The average rainfall recorded in the year 2008 was 1605 mm.  Higher rainfall, abundance of natural pastureland and suitable climatic conditions makes the state favorable for livestock development. The human population was 84.89 lacs with a density of 159 people per sq km during the year, 2001.

Carbohydrates are the most abundant class of organic compounds found in living organisms. Carbohydrates are also called sugars and are found in plants and animals. Plants synthesize them through photosynthesis (endothermic) by fixing carbon, hydrogen, and oxygen in the presence of solar energy and chlorophyll pigments.
nCO2 + nH2O + energy → CnH2nOn + nO2
Carbohydrates are stored as starch in plants as a source of energy. They are also stored in animals as glycogen in muscles and the liver. They are also found in skeletal structures of cell walls in plants (cellulose), bacteria (peptidoglycans), insects, and crustaceans. This stored food is consumed by animals and man, and upon their oxidation in the body, energy is released for various metabolic activities (work, growth, and various productive functions). Compositionwise, plants are more prosperous in carbohydrates (30%) than animals (1%), with water at 60% and ash at 4%. Plants are poor in proteins (5%) and lipids (1%) as compared to proteins (20%) and lipids (15%) in animals.
2.1 Introduction to Carbohydrates
Carbohydrates or saccharides (sakcharon=sugar or sweetness) are a chemical term applied to a large group of substances, which are organic compounds containing elements Carbon, Hydrogen, and Oxygen in a ratio of 1:2:1. Hydrogen and Oxygen atoms are in the ratio of two to one as in water molecules. As the ratio of hydrogen to oxygen is like H2O, they are also known as “hydrates of carbon” and are represented as (CH2O)n. But there is an exception to this general formula. Deoxyribose (C5H1OO4) and rhamnose (C6H12O5) do not have the required ratio of 2:1 for hydrogen to oxygen. On the other side, some compounds possess this required ratio but are not carbohydrates, e.g., formaldehyde (CH2O), acetic acid (C2H4O2), and lactic acid (C3H6O3). Further, some carbohydrates have nitrogen(glucosamine), phosphorus, and sulfur but do not satisfy the above general formula. The simplest sugars are called monosugars or monosaccharides. There are two main functional groups in

The Structure of Proteins

Proteins are composed of building blocks called amino acids. A string of amino acids is called a polypeptide chain. Once such a chain has folded into its working three-dimensional shape, it is a protein. Though there are tens of thousands of different proteins, all of them are put together from a starting set of 20 amino acids. It is the order in which the amino acids are linked in a polypeptide chain that determines which protein will be produced.

11.1 Introduction

Chi-square test is a non-parametric test. Such non-parametric tests have assumed great importance in statistical analysis and statistical inference because they are easy to compute and can be used without making assumptions about parameters as they are distribution-free tests.

Since the linking of the abnormal chromosome constitution of 45, XO to the peculiar phenotype of Turner’s syndrome (Ford 1959), an increased interest in the association between abnormal chromosome constitution and some clinical syndromes was perceived worldwide. The advent of “banding” techniques in the late 1960s helped to refine the detection accuracy and provided for more and better information about cytogenetic make-up of cells and contributed significantly to the localisation of certain genes (McKusik 1992). This phenotypic-karyotypic correlation was done on the basis of visual deletions, insertions, and duplications etc. of DNA segments of various lengths. However, many instances are known in which, because of a parent carrying a balanced translocation, two or more offsprings suffer from a deficiency and/or excess of chromosomal material. Some familial chromosomal arrangements are beyond detection by our current cytogenetic methods, although remarkable results have been forthcoming with high resolution banding. Similarly, paracentric inversions in a parent may not be evident except when carefully studied with high resolution banding, but can give rise to a variety of abnormalities in children.

(Chroma - Colour; Some - Body)
A chromosome is a thread-like self-replicating genetic structure containing organized DNA molecule package found in the nucleus of the cell. Clear and detaile decriptions of mitotic chromosomes in plants and animals were published by Strasburger in 1875 and by the German scientist Walter Flemming in 1879- 1882.Heinrich Wilhelm Gottfried Waldeyer coined the term chromosome in 1888.
Normally Chromosomes are of two types
Autosomes - Control characters other than sex characters or carry genes for somatic characters.
Sex chromosomes (S    
Humans and most other mammals have two sex chromosomes X & Y, also called heterosome, odd chromosome, or idiosome. Females have two X chromosomes in diploid cells; males have an X and a Y chromosome. In birds the female (ZW) is hetero-gametic and male (ZZ) is homo-gametic.
Haploid: Haploid cells (N) have only one copy of each chromosome.
Diploid: Diploid cells (2N where N- chromosome number) have two homologous copies of each chromosome. The body cells of animals are diploid.In animals, gametes (sperm and eggs) are haploid.
Homologous Chromosomes
Diploid organisms have two copies of each chromosome (except the sex chromosomes). Both the copies are ordinarily identical in morphology, gene content and gene order and hence known as homologous chromosomes.Each pair of chromosomes made up of two homologs.
Homologous chromosome is inherited from separate parents; one homolog comes from the mother and the other comes from the father.