Unifying Themes in Life Science

1. Levels of Organization

It is a highly organized and structure, following a hierarchy that can be examined on a scale from small to large. The level of complexity and functionality increases from the atom to biosphere.

  1. Atom– is the smallest and most fundamental unit of matter
  2. Molecule– can be found in all matter, living and non-living and make up the most basic structures of living beings.
  3. Cell– is the basic unit of life.
  4. Cell Organelle – is the cellular components that include membrane and non – membrane bound organelles.
  5. Tissue– made of cells that work together to perform a certain task.
  6. Organ– is a system of tissues that works together on a larger scale to do certain jobs within a body.
  7. Organ system– is a group of organs that work together to perform specific bodily functions.
  8. Organism- is a distinguishable, self-sufficient individual.
  9. Population– is a group of various organisms of the same species within a specific area.
  10. Community– is consists of all the diverse species within a definite area.
  11. Ecosystem– is made up of all the communities in a certain area, as well as all the non-living, physical components of the environment.
  12. Biosphere– is the entirely ecosystems on Earth altogether.

2. The Flow of Energy (Calorific Flow)

 Energy is necessary for the organisms in order to grow and do work. Through photosynthesis, plants capture the energy from the sunlight and use it to make complex molecule that serve as the source of fuel to animals when they eat the plant. Flow of Energy helps determine how organisms interact within their environment.

3. Evolution

Evolution is the change in living things over time. The theory of evolution helps explains why organisms look the way they do today, how all kinds of organism came into existence, and how the organism from the past is related to the present organisms.

Theory of evolution by natural selection presumes that organism with more favorable traits (adaptations) would be more likely to survive and reproduce in a certain environment.

4. Interacting Systems

All living things interact with one another and their environment. They are interdependent with one another. It is a result of a long process of evolution in which cooperation is favored by the selection. It also includes the social behavior and the community dynamics.

5. Structure and Function

A relationship exists between structure and function at all levels of biological organization.  Structure is always related to function. Many organisms have a body structures that may seem to be carefully designed to carry out their functions.

6.  Ecology

Ecology is the study of the relationships between organisms and their environment.  Organism needs a physical environment (where they can found water, nutrients, and gases) in order to survive. A stable environment depends on the healthy functioning of organisms in an environment.

7.  Science and Society

For many years Science and Society becomes interdependent with one another. They play a big role with one another. The knowledge from different branches of science helps shaping of the society that we have today. In vice versa the society has the key role in the developing and discoveries the wonder of the world that we live in.

Perpetuation of Life

All organisms strive to survive up until today, and in order to do that they rely on their characteristic to survive and to reproduce. It is a vital law in biology that living things can only be produced by another living thing. Every living organism that is present today owes its existence to the reproductive deeds of the organisms that existed in the past and also to the desirable traits that they pass on during the reproduction.

Reproduction is a process that guarantees the existence of the species. During reproduction, living things generate new individual of the same kind to continue its existence. Living organisms pass their traits through genes that they transferred to their offspring through reproduction. These genes are small fragments of deoxyribose nucleic acid (DNA) which carries the genetic code that will determine the characteristics of a living thing.

How Animals Reproduce

Sexual reproduction in animals happens when an offspring is produced by combining the genetic material of more than one parent. Most of the animals reproduce sexually. Where the male produces sperm and female which produce the egg. This egg and sperm unite to form zygote through the process of fertilization. However, some animal undergoes a self-fertilization. Self-fertilization happens for those organisms that finding a mate is not possible like the tapeworm.

Fertilization can happen in an open environment. This is known as the external fertilization. Meeting of gametes (egg and sperm) happens outside the body of an organism. Most of the animals that use this fertilization are aquatic animals or animals that can stay in water.  Wet environment makes it possible for egg and sperm to meet.  In order to have a successful fertilization organism release large number of eggs and sperm. However, there are environmental factor that may hinder the fertilization such as predator, drying of the environment, and sudden change of temperature. In connection, most reptiles and amphibians lay eggs that is surrounded and protected by tough membrane (shell). These eggs are often incubated by the parent until it hatched and release a fully-developed offspring.

In contrast, most mammals give birth to a live and fully-developed offspring. This is what we called the internal fertilization, wherein male deposits the sperm in a female reproductive organ during mating. It is one of the adaptations of land animals which led to successful reproduction of their own kind.

Asexual reproduction in animals mostly happens to animals that are stationary or unable to move. It can be advantageous as animal produce numerous offspring but it can also be disadvantageous because genetic variation does not occur therefore, there is no improvement in the characteristics of the animals. These new characteristics of the animal may use to adapt in a sudden change of their environment.

Methods of Reproduction in some Animals

Text Box: Figure 1 Asexual reproduction of Hydra and Starfish Hydra

Hydra is organism that can be found in fresh water lakes, ponds, and stream. Hydra generally reproduce asexually during warm weather, undergoes budding. Once it is fully form, it detaches is now free to swim on its own until it finds support and starts to reproduce. Sexually reproduction occurs during autumn when the cold climate triggers the development of sperm and eggs.  Sperm cell release on water and reached ovary of the nearby hydra and start fertilization, zygote, embryo until reached as new hydra.

Sponges

Text Box: Figure 2. Sponges are multicellular organism that can reproduce sexually and asexually  The Myth of Precambrian Sponges | Evolution NewsThey are able to reproduce asexually and sexually, asexually by budding and fragmentation. In some sponges, the new individual buds from the parent. In others, parent sponge breaks into many fragments, and each fragment grows into a new sponge. Sexually can reproduce after male sponge release sperm into the water, then reached the female sponges and fertilization take place. Egg develops into larvae then attached to solid surface to grow as new sponges.

Jellyfish

Are organisms that can reproduce sexually in external fertilization, during their life cycle: polyp stage and medusa stage. Medusa stage releases either sperm or egg into the water where fertilizations occur. From zygote to blastula then to planula and it will attach in the ocean floor to become polyp. Then it will undergo strobilation process wherein polyps are grown to medusa stage.

Starfish

This organism undergoes fragmentation, if the body parts break into two or more parts, each of which may grow into a separate individual. This organism can also do sexual reproduction, fertilization occurs in the water with males and females releasing sperm and eggs into the environment.

Flatworm (planaria)

Most living aquatic flatworms are planaria; they can reproduce sexually and asexually. Asexually happen by regeneration if it is cut into two and each part regrows into new planaria. Flatworms are hermaphrodite they can reproduce sexually through mating with other flatworm.

Earthworms

Earthworms are hermaphrodite and they can reproduce sexually, by mating joining head to tail for the exchange of egg and sperm. Fertilization occurs and cocoon is form. Weeks later, baby worm hatches and slips out of the cocoon.

Squids

Squids are cephalopods that undergo sexual reproduction. Male squid uses a specialized tentacle to transfer sperm from its cavity of the female, where fertilization occurs. The female lays a mass of fertilized eggs encased in a gelatinous material.

Parthenogenesis

Parthenogenesis is a type of asexual reproduction in which a female gamete or egg cell develops into an individual without fertilization. The term comes from the Greek words parthenos (meaning virgin) and genesis (meaning creation.) Parthenogenesis occurs in many types of invertebrates including scorpions, nematodes, mites, water fleas, wasps, some bees, and other insects.

Vertebrates Animals in sexual reproduction

Frogs

Frogs undergo external fertilization, as female release egg at first then male frog releases sperm over the eggs to fertilize them. The frogs leave the fertilized eggs to develop on their own.

Some fishes and amphibians

Text Box: Figure 3 egg and sperm are fertilized externally mostly to amphibians and frogs and some fishes.They are reproduced also as external fertilization, in which the sperm fertilizes the egg outside the female’s body. They lay their eggs in water or in very moist areas.

With internal fertilization, the egg and sperm join inside the female body that is commonly among reptiles, birds, mammals and some fishes.  Amniotic egg common among reptiles and birds they lay their egg on land.

Other mammals, such as marsupial and placental mammals, bear their young alive. Examples of marsupials are kangaroo where their young keep on their pouch (marsupium).   Placental mammals give birth to their young alive. After birth, most placental mammals provide their young with a period of care.

Preparing a Genetically Modified Organism (GMOs)

Starting from the reproduction where genetic information is passed on from one generation to another. Organisms produce offsprings, which resemble their parents as a result of recombination of their genetic makeup. DNA (deoxyribonucleic acid) the molecule of life, carries the instructions for assembling a wild variety of proteins, which in turn are responsible for the formation of a variety of structures.

Nucleic Acids – a group of organic compounds which function as a storage of genetic information (DNA) and is transmitted from one generation to the next in all living organisms, also function in protein synthesis as they carry the code needed in the formation of specific proteins.  A single-stranded chromatid will copy itself by producing its sister chromatid through a process called replication. Before the productions of proteins, RNA (ribonucleic acid) is first synthesized by a process called transcription, which uses the DNA as a template. RNA is finally used as a code to produce the desired protein as dictated in the code of DNA found in the nucleus of the cell through the process called translation. RNA bases form triplets called codons.

One codon corresponds to one amino acid, the basic building blocks of proteins.

Modification of Organism

Selective breeding (artificial selection)

This is the process of using plants and animals with specific traits to reproduce offspring with those traits. Or selective breeding involves choosing parents with particular characteristics to breed together and produce offspring with more desirable characteristics.

Types of Selective breeding:

a. Inbreeding – or pure breed, is when the animals bred are very genetically alike

b. cross-breeding – involves breeding two unrelated individuals and is often used to very close relatives such as siblings. Continued inbreeding results in offspring that produce offspring with desirable characteristics from two different individuals. An example is Labradoodle from the cross-breeding of Labrador and Poodle.

Genetic engineering

is a technique that allows genes from one organism to be transferred into the DNA of another organism.

Biotechnology – is a field of life science that uses living organisms and biological systems to create modified or new organisms or useful products. A major component of biotechnology is genetic engineering. The vaccines, soy sauce, cheese, and bread you buy at the grocery store, the plastics in your daily environment, your wrinkle-resistant cotton clothing, the cleanup after news of oil spills, and more are all examples of biotechnology. They all “employ” living microbes to create a product. Even a Lyme disease blood test, a breast cancer chemotherapy treatment, or an insulin injection might be the result of biotechnology.

How does Genetic Engineering work?

To help explain the process of genetic engineering we have taken the example of insulin, a protein that helps regulate the sugar levels in our blood.

  • Normally insulin is produced in the pancreas, but in people with Type 1 Disbetes there is a problem with insulin production.
  • People with diabetes therefore have to inject insulin to control their blood sugar levels.
  • Genetic engineering has been used to produce a type of insulin, very similar to our own, from yeast and bacteria like E. coli.
  • This genetically modified insulin, Humulin, was licensed for huan use in 1982.

The Genetic Engineering Process

  1. A small piece of circular DNA called a plasmid is extracter from bacteria or yeast cell.
  2. A small section is then cut out of the cicular olasmid by restriction enzymes, molecular scissors.
  3. The gene for human insulin is inserted into the gap in the plasmid. This plasmid is now genetically modified.
  4. The genetically modified plasmid is introduced into a new bacteria or yeast cell.
  5. This cell then divides rapidly and starts making insulin.
  6. To create large amount of cells, the genetically modified bacteria or yeast are grown in large fermentation vessels that contain all nutrients they need. The more the cell divide, the more insulin is produced.
  7. When fermentation is complete, the mixture is filtered to release the insulin.
  8. The insulin is then purified and packaged into bottles and insulin pens for distribution to patient with diabetes.

Figure 9.1 show how the genetic modification is used to produce insulin        

Genetically Modified Plants – scientists explored ways of genetic modification and introduction of foreign genes to give desirable characteristics of food crops that are:

  1. Pest resistance – example of which is introducing bacteria in tomato and cotton plants the Bacillus thuringiensis (Bt) a soil bacterium which produces a protein that is toxic when eaten by crop pests or hornworms.
  2. Herbicide resistance – which means plants are genetically modified by inserting gene that has resistant enzyme bacteria against glyphosate .
  3. More Nutritional Values – example of which is the “Golden Rice” which is fortified with vitamin A and Iron.
  4. Productive livestock – using growth hormone example to dairy cow to increase milk production. The gene containing the instruction for producing growth hormone has been introduced into bacteria.
  5. Mass – produced drugs – genes that produce medically – important proteins can be inserted into bacteria. Some proteins produced by genetically – engineered bacteria among drugs dissolve blood clots, helping to prevent heart attack and stroke, high blood pressure, kidney function, discovering and developing vaccines.

Genetically Modified (GM) foods are crop plant created for human or animal consumption using the latest genetic engineering methodologies. Among the GM foods successfully produced include the Flvr Svr tomato to improve taste, the seedless watermelon, tomatoes, and cantaloupes with modified ripening characteristics, protein-enrich potatoes, corn with enriched lysine and tryptophan, and many more.

Text Box: Figure 9.2  Genetically modified Organisms, Bt corn of the PhilippinesCorncobs, also called cob of corn or corn on the cobThe Philippines is the first country in Southeast Asia to approve the commercial cultivation of a genetically modified crop for feed and food. Bangladesh was the first country in South Asia to approve such a crop with its commercialization of pest-resistant Bt brinjal, or eggplant. But corn in the Philippines was designed to be resistant to the Asiatic corn borer (ACB), Ostrinia furnacalis (Guenee), one of the nation’s most destructive corn pests.  The crop also presents a practical and ecologically sustainable solution for poor corn farmers everywhere to increase their yields and decrease pesticide use, thus improving their health and livelihoods, alleviating poverty.

Genetically Modified Animals

Techniques involving the introduction of genes into the eggs of animals have allowed the production of animals with larger sizes, such as fishes, cows, pigs, rabbits, and sheep.

  • Transgenic Animals – gene pharming use of transgenic animals to produce pharmaceutical products for therapeutic and diagnostics purposes. Several diseases are being studied to find a cure for cystic fibrosis, cancer, and blood diseases using this treatment.
  • Cloning Transgenic Animals for Various purposes 
  • Dolly the sheep – first sheep cloned. Researchers have managed to transfer human genes that produce useful proteins into sheep and cows, so that they can produce, for instance, the blood-clotting agent factor IX to treat haemophilia or alpha-1-antitrypsin to treat cystic fibrosis and other lung conditions. Inserting these genes into animals is a difficult and laborious process; cloning allows researchers to only do this once and clone the resulting transgenic animal to build up a breeding stock.
  • SRY DNA Mouse – “knockout mouse” or inactivated used to study gene function in cystic fibrosis to avoid mistakes on human subjects.
  • Xenotransplantation – use of animal organs instead of human organs in transplant patients. By genetically modifying pigs to make their organs less likely to be rejected by humans, we can solve the problems of tissue incompatibility.

Since Genetically Modified Animals give promising results, this issue also brought great impact in terms of Ethical, Legal, and Social Issues.

GM Food Consumption and Its Potential Risks

  1. It can pose potential harm to other organisms – an example of which is from the pollen of the transgenic crops (Bt corn) could be harmful to some insects. These could affect the larvae of some butterflies that may lead to issues of biodiversity loss for some species.
  2. Eliciting resistance –has an impact on some pest that later on has resistance to insecticides.
  3. Disrupting (affecting) gene flow – contributed to the lack of genetic diversity of plants and animals will be reduced in the natural environment.
  4. There are still some concerns with GMOs like environmental hazards, health risks, and the economy.
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