Genetic Engineering
Genetic Engineering Uses
DNA Fingerprinting and Uses
What is Gel Electrophoresis?
What is PCR?
What is a Clone? Why Clone?
Ecology and its Factors
Types
Information
Symbiotic Relationships
Population size, density, growth rate, and dispersion
Human Activities
Habitat Destruction
Climate change includes:
Sequence of Speciation
Reproductive Potential
About Variation
Competition
Natural Selection
About Divergence
Isolation
The Fossil Structure
Genetic Engineering Uses
- Curing Diseases, Treat Genetic Disorders, Improve Food Crops
- Found in the immune systems of bacteria
- Over 1500 restriction enzymes identified so far
- Each restriction enzyme cuts DNA at a specific point- Ex: EcoRI cuts DNA at CTTAA-G
- Restriction enzymes cut each strand of DNA molecule, one from left to right, and the other from right to left
- Once finished, they leave sticky ends
- Cloning Vectors- a carrier that is used to clone a gene and transfer it from one organism to another
- Most common cloning vector is plasmid, a ring of DNA from Bacteria
- Plasmid is cut with the same restriction enzyme as donor organism, leaving the same sticky ends
- Donor gene is spliced into the plasmid, making recombinant DNA
- The plasmid is returned to the bacterium, now a transgenic organism, where it is replicated with other DNA, making clones of the donor gene
DNA Fingerprinting and Uses
- DNA Fingerprinting is a pattern of bands made up of specific fragments from an individual’s DNA
- Banding patterns from two individuals can be compared if they are related
- Banding patterns from two species can be compared to see if they are similar
- Technology is used in forensic science and in medical research to:
- Convict criminals from blood samples and tissue samples
- Determining the origin of diseases
- The Method for making a DNA Fingerprint is called (RFLP) Restriction Fragment Length Polymorphism Analysis
- The DNA sample is first cut into many fragments by restriction enzymes
- The DNA fragments are separated according to size by Gel Electrophoresis
- Radioactive probes then bind to DNA fragments that have been selected for comparison
- Photographic film allows visualization of the radioactive probes, producing the DNA Fingerprint
- Every person, except identical twins, has a unique sequence of DNA in their cells
- The sections that vary the most between individuals are the non-coding sectors of DNA
- In non-coding sections of DNA, there meaningless patterns of meaningless code (GGAT)
- There is less than a million in one chance that 2 people have the exact same repeating pattern in 5 specific non-coding portions of DNA
- The FBI uses a comparison of 12 sites. The probability of 2 people having the exact same repeating pattern at 12 sites is 1/60,000,000,000 (60 Billion)
What is Gel Electrophoresis?
- Electrophoresis- A method for separating large molecules by placing them in a gel in the presence of an electric field
- Used to separate DNA, RNA, and Proteins
- Extraction – DNA is removed from white blood cells, hair root cells, or tissue
- Restriction – DNA is cut with restriction enzymes into fragments
- Separation – DNA is negatively charged and is naturally attracted to the positive side of the gel, repelled by the negative ends of the gel. DNA fragments travel through micro-pores in the gel.
- Separation is based on 3 characteristics- Charge, size, and shape.
- Mix agarose, buffer, and water
- Buffer – Controls pH, Conducts electricity
- Microwave for 1 minute, swirl
- Repeat step 2 until solution is clear
- Place flask in water bath to lower temp to 55 degrees Celsius
- Pour solution into molds until level with rubber stoppers
- Holds exactly 40 microliters
- DO NOT TURN UPSIDE DOWN!
- To fill Micropipette – Depress, Hold, Insert, Release, Remove
- To fill Gel – Insert, Depress, Hold, Remove, Release
What is PCR?
- PCR – Polymerase Chain Reaction
- Used to quickly make copies of DNA
- Starting materials – DNA Fragment (to be copied), DNA Polymerase, free nucleotides, primers (single stranded sequences of DNA used to initiate replication)
- Starting materials are placed in a flask and heated to 95 degrees Celsius (Denatures the DNA Strand)
- Flask is cooled to 37 degrees Celsius (bonds primers to DNA)
- Flask is heated back to 72 degrees Celsius (initiates replication)
- Can be done every 5 minutes to double amount of DNA
- RFLP requires large amounts of DNA, so PCR helps scientists take only a little DNA to run RFLP
- Rather than killing an embryo, just a few cells need to be removed
- Ancient Genetic material ca be better studied
What is a Clone? Why Clone?
- A clone is an organism produced by asexual reproduction that is genetically identical to its parent
- Cloning can produce many animals with particularly good traits
- Cloning could provide organs that would not be rejected by people struck by accident or disease
- In 1996 the first successful cloning of a mammal occurred
- The cloning involved differentiated cells from an adult mammal
- The DNA was removed from an unfertilized egg cell of 1 sheep
- An udder cell was removed from a different sheep
- The cells were fused with an electric shock
- The cells were developed in vitro (outside of a womb)
- The cells were implanted into a surrogate mother
- Dolly was born on July 5th, 1996, the one survivor of 277 tries
Ecology and its Factors
- Ecology – The study of the interaction of organisms with other organisms and with their environment
- Abiotic Factors – The non-living factors that affect an organism
- Biotic Factors – The living factors that affect and organism
- Habitat – Where the organism lives and interacts
- The greater the number of different species in a community the greater the biodiversity
- Niche – An organism, its habitat, and its role
- Biosphere – The thin volume of Earth and its atmosphere that supports life
- Ecosystem – All the living organisms and the non-living factors found in one place
- Community – All of the interacting organisms living in an area
- Population – All the members of one species that live in one area
- Organism – An individual living thing
Types
- Producer – Creates energy to make food – Autotrophs
- Consumer – Eats other organisms – Heterotrophs
- Types:
- Producer
- Herbivore – Eats plants
- Carnivore – Eats meat
- Omnivore – Eats both plants and meat
- Detritivore – Eats Dead things – Earthworms, Vultures
- Decomposers – Causes Decay – Bacteria
Information
- Food Chains are paths of energy in a linear trophic relationship
- Producers – Primary Consumers – Secondary Consumers – Tertiary Consumers
- Food Web – More realistic food chain made of interconnecting food chains
- Energy Pyramid – The flow of energy through an ecosystem following the 10% rule
Symbiotic Relationships
- Symbiosis – Any close relationship or association between members of two or more species
- Mutualism – When two organisms benefit from each other
- Commensalism – When one species benefits, and the other species is neither helped nor harmed
- Parasitism – When one species (the parasite) benefits and the host if harmed
Population size, density, growth rate, and dispersion
- Population Size – The number of individuals in a population
- Population Density – The number of individuals that live in an area (Population size/area)
- Growth Rate: Birth Rate – Death rate = Growth Rate
- Dispersion – The ways individuals of a population spread
- Density Dependent Factors – Limited Resources whose rates of depletion depend on the density of the population using them – Food, Water
- Density Independent Factors – Factors unaffected by density that affects the growth of populations – Climate, Geography
- Carrying Capacity (K) – The number of individuals in a population that an environment can hold
- Population Models- Hypothetical populations that attempt to exhibit the key characteristics of a real population
- Exponential Models- “J” shaped curves showing a rapid increase in population size
- Logistic Models- The population in which exponential growth is limited by density dependent factors
- R-strategists – An opportunistic population where the population density fluctuates, usually in open habitats with little competition
- K-strategists – A population in equilibrium; its density hovers near carrying capacity
- R-Strategists: Maturation Time- Short, Lifespan- Short, Death Rate- Often high, Number of Offspring per Episode- Many, Number of Reproductive Episodes per Lifespan- Usually one, Time of First Reproduction- Early in Life, Size of Offspring- Small, Parental Care- None
- K-Strategists: Maturation Time- Long, Lifespan- Long, Death Rate- Usually Low, Number of Offspring per Episode- Few, Number of Reproductive Episodes per Lifespan- Several, Time of First Reproduction- Later in Life, Size of Offspring- Large, Parental Care- Extensive
Human Activities
- As of March 2016, the human population was approximately 7.4 billion
- Humans inhabit all ecosystems of the Earth
- Human activities include
- Agriculture
- Irrigation
- Fishing
- Meat Production
- Mining
- HIPPCO – Impacts of human activities of the environment and biodiversity/ An acronym that explains how and why humans are negatively impacting the environment
- Habitat destruction
- Invasive species
- Population growth
- Pollution
- Climate Change
- Overpopulation
Habitat Destruction
- Scientists say that the greatest threat to wildlife is habitat loss, degradation, and fragmentation
- The greatest eliminators of species are:
- Deforestation in tropical areas
- Clearing wetlands
- Loss of coral reefs
- Invasive species are plants, animals, or pathogens that are alien to the ecosystem
- Threaten native species
- An estimated 7100 species introduced into the US have caused ecological and economic harm
- Human population growth and excessive and wasteful consumption of resources have caused premature extinction of species
- Improved health-care and sanitation have extended human life expectancy
- May not be enough resources to sustain the human population
- Many families in poverty may want more children
- Must consider cultural tradition and religious beliefs
- Pollution is the introduction of contaminants into the natural environment that cause adverse change
- Air, water, nutrient, light, and noise pollution all harm organisms
- Pollution can be natural (Volcanoes), or anthropogenic, or made by humans
- Air pollution can cause respiratory problems
- Water pollution can cause disease
Climate change includes:
- Global Warming
- Frequency and severity of storms
- Changing ocean current patterns
- Loss of ice lands
- Rising sea levels
- Greenhouse Effect
- Natural greenhouse effect warms the Earth
- Greenhouse gasses create a layer around Earth that traps solar radiation
- Results in Earth’s surface getting hotter
- Overfishing and Overhunting
- Commercial extinction – when it is no longer profitable to continue fishing the affected species
- Bycatch – Non-target species caught in fishing – Comprises of 1/3 of all catch
- About 3079 animals and 2655 plants are endangered
- Some species are hunted purely for fur and horns
- Some species have (obviously) become extinct
- The endurance of systems and processes to make natural resources could last indefinitely
- 3 Pillars of Sustainability – Economy, Society, and Environment
Sequence of Speciation
- The process of becoming a new species
- Reproductive Potential – Organisms have the potential to produce more offspring than the environment can support
- Variation – Within every population there are many variations
- Competition – There is competition between the members of every population for the limited resources in their environment
- Natural Selection – Some individuals in every population are selected for and survive, and some are selected against and die
- Divergence – Divergence occurs when there is an accumulation of differences in allele frequencies between reproductively isolated populations in a species
- Isolation – Isolation occurs when diverging populations are kept from reproducing with one another
- New Species – Eventually, a new species forms
Reproductive Potential
- All organisms have the potential to have more offspring than the environment can sustain
About Variation
- Individuals do not evolve; Populations do
- All individuals in a population share certain traits
- 3 kinds of variable traits
- Morphological – External traits
- Physiological – Body functions
- Behavioral – How they act
- Genetic Mutation – Only variation that creates a new species
- Abnormal changes in chromosome structure and/or number
- Crossing over and genetic recombinant during meiosis
- Independent assortment of chromosomes during meiosis
- Fertilization between different gametes
Competition
- In every population there is competition between individuals
- There is competition for different resources
- Those who lose do not pass on genes
- Types of competition
- Intraspecific – Same Species
- Interspecific – Different Species
- Competition exclusion principle – Two similar species competing for the same resource cannot co-exist
Natural Selection
- Natural selection is based off the idea that the environment limits growth of population by increasing the rate of death or decreasing the rate of reproduction, or both
- Organisms that have a greater number of favorable traits tend to have more offspring
- Darwin called the different degrees of successful reproduction natural selection
- Populations of organisms adapt to their environment
- Resulting change in genes make a population go through evolution
- Natural Selection is a passive process
- Selection differs as the environment changes
- Types of Selection
- Stabilizing – Average is preferred
- Directional – One extreme is preferred
- Disruptive – Either extreme is preferred
- Sexual – Females chose – Different kind of selection
About Divergence
- Evolution is when a population’s genetic material begins to change – Which is divergence
- Any violations of the 5 conditions necessary for Hardy-Weinberg equilibrium can result in divergence
- The stability of gene frequency across generations
- Ideal hypothetical population
- Large Population
- Isolated Population
- No Net Changes
- Random Mating
- All Genotypes Equal in Reproductive Success
- Mutations – Mutations occur at a constant low rate
- Mutating can affect genetic equilibrium by producing new alleles
- Migration – Gene Flow – The change in gene frequency due to immigration/emigration of a population
- Genetic Drift – Allele frequency changes at random in small populations
- Mating – Non-random mating brings about divergence
- Mate selection due to geographical proximity/similar characteristics can cause genotypes to change, but not allele frequency
- P+Q=1
- P2+2PQ+Q2=1
- P = Frequency of Dominant Allele
- Q = Frequency of Recessive Allele
- P2 = Frequency of Homozygous Dominant Allele
- 2PQ = Frequency of Heterozygous Allele
- Q2 = Frequency of Homozygous Recessive Allele
Isolation
- When two parts of a formerly interbreeding population stop interbreeding, they have become isolated
- Geographic Isolation – Physical Separation
- Reproductive Isolation – The result of barriers to successful reproduction, often following disruptive selection
- Prezygotic Isolation – Isolation that occurs before fertilization (Wrong mating call)
- Postzygotic Isolation – Isolation that occurs after fertilization (Underdeveloped offspring)
The Fossil Structure
- Fossils are formed when organisms are preserved before they decay
- Fossils are formed in sedimentary rock
- Different kinds of fossils – Imprints, Casts
- Fossils can be dated through Carbon 14
- Fossils can be used to date other artifacts
- Homologous structures are similar and are derived from the same body part
- If structures are similar, it is assumed the animals who possess them are related
- Vestigial Structures are body parts that are reduced in size and appear to have little to no function
- Analogous structures are similar structures that do not indicate evolutionary relationships
- An embryo is an organism in its earliest stage of development
- An organism develops in the same way as its ancestors
- Organisms that are related have the same DNA sequence