Understanding Variation and Selection

• Variation and selection are key concepts in biology.

Variation

• Variation refers to the differences between individuals of the same species.
• Continuous variation results in a range of phenotypes between two extremes, like body length and mass.
• Discontinuous variation results in a limited number of phenotypes with no intermediates, such as ABO blood groups, seed shape, and seed color in peas.
• Discontinuous variation is usually caused by genes only.
• Continuous variation is caused by both genes and the environment.
• Mutation is a genetic change that forms new alleles.
• Ionizing radiation and some chemicals can cause mutations.
• Variation exists due to different reasons.

Meiosis

• During meiosis, half of the chromosomes go into one gamete and half into the other gamete.
• Each set of chromosomes carries alleles with particular characteristics, causing variation.

Fertilization

• Fertilization leads to a random combination of alleles.
• One sperm from millions fuses with one ovum, creating varied characteristics.

Mutation

• Mutation is a sudden change in a gene, genes, chromosome, or chromosomes.
• Chemicals like mustard gas, tobacco, and food preservatives can cause mutations by altering DNA structure.
• Radiation, such as X-rays, gamma rays, and cosmic radiation, can cause breaks in DNA.
• Mutagens are factors that cause mutation.
• Mutations can be changes in one or more chromosomes, increase/decrease the number of chromosomes, and even be the snapping/loss of a chromosome part.
• Down's syndrome is an example.
• Sickle cell anemia is caused by a change in an individual's gene.

Continuous Variation

• There are no distinct categories.
• Tends is more quantitative.
• Controlled by many genes
• Strongly is influenced by the environment.

Discontinuous Variation

• Has distinct categories
• Tends to be qualitative
• Controlled by a few genes
• Unaffected by the environment

Factors Affecting Continuous Variation

• Multiple pairs of alleles
• Affected by the environment.

Examples of Continuous Variation

• Height in numbers
• Intelligence
• Weight
• Fingerprints

Selection

• Selection is the process of choosing the best varieties adapted to the environment, allowing them to grow and reproduce.

Artificial Selection

• Artificial selection is carried out by humans to choose and breed the best varieties of domestic animals and plants to improve their strain.
• Artificial selection results in varieties within a species but rarely forms new species.

Natural Selection

• Natural selection is when organisms best adapted to their environment tend to have an increased chance of survival.
• Dark moths in polluted areas survive better by camouflaging against predators.
• Desert plants with long roots have a better chance of survival due to water scarcity.

Natural Selection Elements

• Genetic variation within populations
• Production of many offspring
• Struggle for survival, including competition for resources
• A greater chance of reproduction occurs for individuals better adapted to the environment than others
• These individuals pass on their alleles to the next generation

Selective breeding

• Selection by humans of those who produce the desirable features
• Crossing these individuals to produce the next generation
• Selection of offspring showing the desirable features

Antibiotic Resistance in Bacteria

• Mutation in bacteria results in new strains that are resistant to certain antibiotics.
• Non-resistant bacteria die while resistant bacteria live and reproduce.
• By using antibiotics, the non-resistant bacteria are killed off, leaving only resistant bacteria to survive and multiply, leading to antibiotic resistance.
• Factors increasing the development of antibiotic-resistant bacteria include failure to complete the full course of antibiotics.
• Some antibiotics are no longer used frequently due to bacterial resistance, while others are restricted due to side effects or limited use for specific diseases.

Evolution

• Evolution is the change in adaptive features of a population over time as a result of natural selection; it considers natural selection a mechanism leading to evolution.
• Individuals within a species are slightly different; some differences called variation make it more likely for one to survive better than another.
• Most organisms produce more young than will reach adulthood.
• If climate or food supply changes, those with characteristics to better survive are more likely to live.
• The variety that is best adapted to the new conditions can live longer and reproduce more than the other varieties, so passing on their advantageous characteristic to their offspring.
• The best adapted variety will see an increase in numbers and then replace the other varieties, leading to evolution.
• DNA and organisms that are closely related include a more recent ancestor are base sequences in DNA and are similar than those that only share a distant ancestor.
• Sequences of bases in DNA and of amino acids in proteins are a more accurate means of classification.

Artificial Selection in way of Plants

• Increase crop yield
• Developing plants resistant to pests
• Increase rate of reproduction in plants
• Developing identical plants with food characteristics by cloning
• Developing plants that can grow with less fertilizer
• To avoid self-pollination, remove the stamen before the maturation of the color. Cover with a plastic bag to collect the flowers and apply to another one.
• Using the best rates of mutation will allow them to grow and reproduce.
• Through example using artificial election, cross-pollination between types of rice which are resistant to high pest which can reach high yields and then reproduce these seeds and repeat process untill 100% are produced.

Genetic Modification

• It changes the genetic material by removing, changing, or inserting individual genes as an example in the production of humane insulin.
• Some need humane insulin that is produced through genetic medication but could previously be harvested from animals that were killed for food.

Disadvantages of Insulin production from animals:

• Some people disagree with the use of animals fro insulin
• Animal insulin isn't the exact same as that of humane
• Has limited quantities
• Is Expensive

Using Plasmid as a Vector

• They can be easily extracted from bacteria
• They can easily be put back inside bacteria
• Bacteria is useful in gene medication because they have plasmids that can be isolated and then introduced into the Bacteria
• Bacteria reproduce at great speed leading them to produce genetically identical offspring's
• There is lack of ethical concern when use the have have genetic code shared with organisms

Advantages of Insulin production from genetic engineered bacteria:

• The production rate is very high when obtained
• This insulin is identical which will lead to little rejection
• As the diseases come from animals they will be lead to less production rate

Steps of Production using Genetic Engineering

• Cutting the human cut into short lenghths.
• Identify the type of lenghth of Dna in with insulin
• Isolating certain Dna of insulin is separated by cutting the plasma
• Add the genetically genetic engineered plasts to what is added to bacteria which is added to the culture
• Multiple can add there bacteria

Genetic Engineering

• Insertion of of of into other types of plants
• Some genes and inserted to resist against other types of insects
• Genes are put in place so that it gives additional vaitimes

Other Advantages

• A plant can resist certain vestites and herbs
• Increase Yieldies
• Disease resistant

Disadvantage

• Some herbicide can spread resistance against some herbs

Fermenters

• A steel vessel in which organisms such as bacteria and is placed will be able to produce there offspring in the same condition
• Use of Sterliuzation is that will avoid the presence of microorganisms

Puddles/Stirrers in Fermenter

• Use of stirrers to mix the contents
• Keep temperature even
• Inject Air

Adjusting Temperature using Fermentr

• Keep it the same by detecting the value with the tempuature
• Reduce by cold water
• Use acid resistance due to microorganisms

Using Fementers to produce Enzymes

• Using Yeast, fungi, and bacteria
• The enzymes are steriluzed to produce micorrganisima which can allow them to produce enzymes

Explore concepts of continuous variation, selective breeding, and the introduction of new alleles. Learn about adaptation through antibiotic resistance in bacteria and beak variations in birds. Also includes understanding plant breeding.