Modern Genetics
Everything from agriculture and horticulture, to veterinary and human health science, is being impacted increasingly by our rapidly developing understanding of genetics. While the future may not be predictable, there is little doubt that a knowledge of genetics will lay a very good foundation for many business and employment opportunities over the coming decades. Consider the following.
Farm Animal Breeding
Selective breeding in farm animals is centered around identifying the most desirable characteristics and breeding from those animals that display them. Traits essentially fit into five basic categories.
- Â Fitness traits: these are usually linked to reproduction such as litter size, conception rate, gestation length, survival rates of young
- Â Production traits: these include milk yield, growth rate, feed efficiency, number of eggs.
- Â Quality traits: these include carcass composition, level of fat, meat and milk quality.
- Â Type traits: these include physical appearance such as coat colour, udder shape, number of teats in pigs.
- Â Behavioural traits: these include herding ability in sheep dogs, temperament, mothering ability.
Pet breeding
Whereas the main objective of a farm animal breeding program is to improve performance, breeding programs for pedigree cats and dogs and other pet animals has centered on how they look i.e. the phenotype. This has led to the development of over 1700 different dog breeds throughout the world. Pedigree dog breeding is big business and can generate significant amounts of money for the breeder. In recent years it has come under heavy criticism as one of the consequences of breeding for specific traits that effect appearance is that other genes may also be selected that are detrimental to the dogs health and welfare. In particular some breeds e.g. pugs and King Charles Spaniels were being breed with such shortened noses that they were having breathing problems
Plant Breeding
Plant breeding has been practiced for thousands of years, since near the beginning of human civilization. It is essentially the manipulation of plant species in order to create desired genotypes and phenotypes for specific purposes. These days, this manipulation involves either controlled pollination, genetic engineering, or both, followed by artificial selection of progeny. Classical plant breeding uses the planned crossing of closely or distantly related individuals to produce new crop varieties or lines with desirable properties. These may include colour, shape, disease resistance or potential yield in crop producing plants. Plants are cross bred to introduce traits/genes from one variety or line into a new genetic background.
It is now practiced worldwide by government institutions and commercial enterprises as it is believed that breeding new crops is important for ensuring food security through the development of crops suitable for their environment such as drought conditions or warmer climates.
Human Health
Genetics research has lead to an understanding of what causes disease, the diagnosis of diseases and genetic screening to identify populations that are of risk from a specific genetic disorder.
Diagnosis of disease
Genetic testing is used to diagnose many disorders such as Turner’s syndrome, Klinefleter’s syndrome and many heart and blood disorders. The diagnosis of a genetic disorder may indicate that the relatives of the affected person should be screened for the genetic defect or whether they carry the gene.
Genetic Screening
This is the use of a test to identify people who have, are predisposed to or carriers of a certain genetic disease. It can be applied at many stages of life and used for a variety of purposes.
 Requirements for a successful career in Genetics
A career in Genetics is an exciting, energising one.
For a successful career in genetics, you need to build a foundation first, to understand the universal principles, possibilities and complications conducive of DNA-based life.
The genetic revolution is bringing about massive advancements, and will continue to evolve with developments in human genomics. If you are ready to make a commitment in time, energy, and motivation, the rewards are huge.
Career Opportunities
Genetics is a maturing industry and job opportunities in this field will be highly varied in the future so current students need to “think outside the box”. This course may deliver different things to different graduates. The following are just some of the areas where opportunities in Genetics may be found in the future:
- Â Plant Breeding
- Â Animal Breeding
- Â Genomics
- Â Genealogy
- Â Ancestry
- Â Gene therapy
-  Diagnostic genetic testing – paternity; genetic disorders
- Â Clinical trials
- Â Forensic science
- Â Genetic enhancement
- Â Biotech/Medical Sales and Marketing
- Â Research e.g. medical, public health, anthropological
- Â Dietetics/Nutrition
- Â Nursing
- Â Education
- Â Science Outreach
- Â Technician
- Â Patenting
- Â Quality control
- Â Compliance
- Â Scientific/Technical/Medical Writing and Illustrating
- Â Genetic counseling
- Â Bioinformatics
- Â Administration
- Â Physician Assistant
- Â Genetic programming
Extract
PROKARYOTES AND EUKARYOTESÂ
Cells are the units from which all living organisms are built. Some organisms have only one cell e.g. bacteria, while other organisms are multicellular containing hundreds, thousands, millions and even billions of cells e.g. the human body contains around 100,000 billion cells. Whilst the function of cells varies there are similarities between cells. Each cell is self-contained and partially self-sufficient. All cells have a cell membrane and contain cytoplasm and DNA.
Prokaryotes
Prokaryotes or prokaryotic cells do not have a nucleus, or membranes surrounding their organelles. Their DNA is not organised into chromosomes, but is a single molecule, most often circular. Â Bacteria are prokaryote cells which do not have a nucleus or membranes surrounding their organelles. In prokaryotes DNA is not organised into chromosomes but is a single molecule. Prokaryotes reproduce asexually through binary fission, through binary fission a cell replicates its DNA into two complete sets and as the cell grows each set of DNA moves to opposite ends of the cell. Once the cell reaches a certain size it then splits in two creating two daughter cells with identical DNA.
Eukaryotes
Eukaryotes or eukaryotic cells have membranes surrounding the nucleus and organelles. This effectively divides the cell into distinct compartments that perform distinct functions. Their DNA is organised into linear chromosomes. Â Plants and animals have eukaryote cells which store DNA on chromosomes. The number of chromosomes in a cell varies in different plant and animal species but there are typically between 10 and 50 chromosomes in a eukaryote cell e.g. human beings have 46 chromosomes in each cell. Each chromosome is composed of a tightly coiled DNA molecule. Before a cell divides chromosomes make copies of themselves. Once cell division has taken place the new daughter cells have the same number of chromosomes as the parent cells.
CELL STRUCTURE & FUNCTIONÂ
Organelles in PlantsÂ
Cell WallÂ
Considered an extracellular coat of cells which protects the inside of the cell and in some tissues (particularly wood and bark), the cell wall provides particularly rigid and structural support – it is not alive. It is made up of cellulose including pectin which is a complex carbohydrate. Cellulose is the main constituent and can stretch and contract, but is strong.
A secondary wall may develop over time which contains lignin, lignification gives more strength.
Vacuole
Membrane bound regions in the cytoplasm, are generally large and can take up as much as 90% of the intracellular space to maintain cell turgor (pressure). The enlargement of vacuoles is the major cause of increase in cell size. They are important storage sites for various metabolites and are also the site of breakdown for some molecules.
Plastids
Variously shaped small organelle found in the cytoplasm, surrounded by a double layer membrane and system of internal membranes. Can be found in high numbers often, though sometimes only one or few. Contains pigments and/or food reserve – gives rise to chloroplasts, leucoplasts and proplastids.
Organelles in Plants and AnimalsÂ
Plasma membrane
This is the outer layer of the cell which gives the cell its shape and holds the liquid inside the cell. It is semi-permeable which means it allows certain things to pass in and out of the cell. The main structure of all cell membranes is a bilayer of phospholipids. Animal cell membranes also contain glycolipids and cholesterol.
Cytoplasm
This is the water based fluid inside the cell which contains salts and other ions and molecules suspended in solution. Â Within the cytoplasm you will find filaments, proteins, organelles and vesicles.
Endoplasmic reticulum
Membrane organelle which serves a variety of functions, the most important is protein synthesis and folding. Â Some proteins move on to the Golgi for more modification and final packaging.
RibosomesÂ
Ribosomes are tiny, roughly spherical structures attached to the rough endoplasmic reticulum. They are involved in the synthesis of proteins.
Golgi apparatusÂ
This is essentially a large folding membrane. Â It serves as a processing factory within the cell, primarily working on proteins and lipids Here proteins and lipids produced in the endoplasmic reticulum are packaged for export outside the cell or for other areas within the cell.
It is responsible for synthesising carbohydrates, transporting both proteins derived from the endoplasmic reticulum (ER) to the plasma membrane, and lysosomes from where they are expelled from the cell.
It also packages macromolecules for transport to other regions of the cell, or for secretion.
LysosomesÂ
These organelles contain powerful enzymes known as hydrolases that break down food molecules, old or unwanted organelles and even invading pathogens.
Mitochondria
Mitochondria (plural of mitochondrion = mitochondria) are concerned with the respiration of the cell. Respiration produces energy for the cell. These are the cell’s powerhouses.
Cytoskeleton
A network of protein filaments in the cytoplasm that provide a structural framework for the cell, and it is responsible for cell movements.
Centriole
This is concerned with cell division, the reproduction of the cell and the movement of cell chromosomes.
Peroxisomes
These organelles contain peroxides that digest lipids and some other foods.
Fibrils
These are concerned with nervous responses.
GENETIC STRUCTURES AND MATERIALÂ
NucleusÂ
The nucleus is the organelle that contains the cells genetic material. It is bounded by a pair of membranes, called the nuclear envelope, that isolate the nuclear contents from the rest of the cell. The membrane controls the entry and exit of molecules from the nucleus. Nuclei exist in animal and plant cells.
