Variation & Selection Flashcards
Def. Evolution
The gradual change of organisms over millions of years
What are the five stages of natural selection?
- There is an overproduction of offspring
- This contributes to genetic variation in the population
- Selective pressure leads to a struggle for existence
- There is a greater chance of reproduction by ‘fittest’, the individuals that are better adapted to the environment than others
- These individuals pass on their alleles to the next generation by reproduction
How does genetic variation arise?
- Mutation
Also Recombination, but this is not needed to know
How do bacteria reproduce asexually?
Binary fission
Similar to mitosis
Describe natural selection leading to antibiotic resistance
- Overproduction of the bacteria occurs
- Variations such as antibiotic resistance exist in the population due to genetic mutations
- An antibiotic creates a selective pressure
- Some individuals are better-adapted than others and have antibiotic resistance
- The ones with resistance alleles are fitter/better competitors and can survive exposure to antibiotics
- They then survive and reproduce through binary fission passing on the allele for resistance to their offspring
- Over time the allele for no resistance is selected out of the population
- Individuals die and cannot pass on their genes
Def. Adaptive feature
Inherited characteristics of an organism that enables them to survive and reproduce in its environment and increase fitness
Def. Fitness
The probability of an organism surviving and reproducing in a particular environment
What are the 4 main examples of genetic engineering?
- Insertion of human genes into bacteria to produce human insulin, penicillin and mycoprotein
- Insertion of genes into crop plants to confer resistance to herbicides
- Insertion of genes into crop plants to confer resistance to insect pests
- Insertion of genes into crop plants to provide additional vitamins
Why are bacteria useful in biotechnology and genetic engineering?
- Rapid reproduction rate
- Ability to make complex molecules
- Lack of ethical concerns over their manipulation and growth
- Genetic code shared with all other organisms
- Presence of plasmids
Def. Restriction Enzyme
Enzymes produced by certain bacteria that have the property of cleaving DNA molecules at or near a specific sequence of bases.
Def. DNA Ligase
A specific type of enzyme that facilitates the joining of DNA strands together.
Def. Recombinant DNA molecules
DNA molecules formed by laboratory methods of genetic recombination (such as molecular cloning) to bring together genetic material from multiple sources, creating sequences that would not otherwise be found.
Describe the recombination of bacterial DNA to produce insulin
Form of genetic engineering
- Isolation of the DNA making up a human gene using restriction enzymes, forming sticky ends
- Cutting of bacterial plasmid DNA with the same restriction enzymes, forming complementary sticky ends
- Insertion of human DNA into bacterial plasmid DNA using DNA ligase to form a recombinant plasmid
- Insertion of recombinant plasmids into bacteria (specific details are not required)
- Multiplication of bacteria containing recombinant plasmids
- Expression in bacteria of the human gene to make the human protein
What conditions are necessary to be adjusted to create a fermenter in which penicillium thrives and reproduces, creating penicillin?
- Optimum temperature - Created by the mix of substances inserted into the fermenter
- Optimum pH - Created by the mix of substances inserted into the fermenter, such as ammonia
- Oxygenation - Air is pumped
- Water - Water and steam pumped in
-
Nutrients - These are inserted through a tube as well
- Vitamin
- Amino acids - from ammonia
- Minerals
- Glucose
- Agitation (Constant stirring with paddles to maintain these conditions)
- Aseptic precautions - Sterilisation to reduce competition
Waste products produced by the penicillium also need to be removed
Describe the role of the fungus Penicillium in the production of the antibiotic penicillin
Under the right conditions, maintained in a fermenter, the fungus penicillium produces penicillin which can then be removed from a fermenter
