MODULE 6: Genetic Change Flashcards
Discuss the use of artificial pollination as a reproductive techonology
Dusting of fertile stigmas with pollen from another plant with desirable characteristics.
Advantages: controlled inheritance of favourable traits (Via pure or cross breeding) , higher crop yields and creation of monocultures.
Disadvantages: loss of genetic variation overtime
Discuss the use of artifical insemination as a reproductive technology
Injection of semen into the reproductive tract (E.g via insemination gun)
Advantages: synchronise births, passing of favourable traits to offspring and increased efficacy of livestock industry -> could assist with conservation of a species
Disadvantages: Limited genetic variability overtime, long term variation is reduced making the species susceptible to changing selection pressures
Biotechnology ETHICS
Plant Example: Bt cotton (Transgenic species)
- Bt toxin gene is inserted into cotton crops and reduces the use of insecticides, as toxins are released when insects eat the crops.
- > increase in crop yield, reduced use of insectcides, saves time and money
- > contributes to limited genetic variability and may be toxic to non-target animals
Animal Example: Transgenic Salmon (Bovine Growth Hormone in genome)
- grows faster-> higher yield and profitability for fisheries-> more produce for commerical consumers
- > may be detrimental to natural ecosytems
note: ETHICS-> human wellbeing and environmental sustainability
Compare and the processes and effects of point mutations and chromosomal mutations. Include examples
All mutations are changes to DNA. They occur during DNA replication during
– mitosis (for cell proliferation and growth of the organism)
– meiosis (for the production of gametes).
Point mutations are changes that occur in a single nucleotide. These changes can be substitution with the wrong nucleotide, an extra nucleotide added (addition) or a nucleotide not included (deletion). It is possible to have multiple point mutations along a chromosome. The order of nucleotide bases determines the protein that is produced by the cell.
The point mutation may have no effect on the protein produced as the change may still enable a triplet code for the same amino acid, or the change of one amino acid might not have a significant effect on the resulting protein. The point mutation may mean that the triplet code initiates a stop sequence, in which case the protein will not be produced, or it may mean that a range of proteins is not produced at all or that greater quantities of protein are produced.
A frameshift point mutation is caused by an addition or deletion. Every triplet on the DNA after the point mutation is affected. This can radically change the protein product of the cell.
Chromosomal mutations involve large sections of the chromosome breaking off completely (deletion), or breaking off and reassembling in reverse order (inversion) or breaking off and adhering to another chromosome (translocation).
These breakups of chromosomes move genes to new loci and can break up genes by splitting the chromosome in the middle of the gene sequence. These types of chromosome changes can radically affect cell activity. Chromosomal mutations can also include non-disjunction of homologous chromosomes at anaphase, resulting in cells with too many or too few chromosomes.
These mutations can have radical effects on cell activity and the organism. Both point mutations and chromosomal mutations can cause disease. For example, point mutations: cystic fibrosis, sick
le cell anaemia; chromosomal mutations: Down’s syndrome, Turner’s syndrome. Both kinds of mutations have also generated new alleles which have in some cases been adaptive and contributed to evolution.
‘The application of reproductive technologies in plant and animal breeding limits genetic diversity.’ To what extent is this statement correct?
Artificial pollination is the transfer of pollen from the anther of one plant to the stigma of another. Artificial insemination is the collection of semen and its delivery into the reproductive system of a female, using equipment.
Both technologies can be used to increase the number of offspring with the desired characteristics that can be generated by one parent and therefore can result in decreased genetic diversity in the population.
Other individuals in the population do not contribute to the next generation. For example semen from the same bull can be used to impregnate hundreds of cows, or pollen from one male flower is more likely to be transferred to a female flower.
However, reproductive technologies can overcome geographical barriers and therefore allow genes to be spread more widely across the world. These techniques could increase genetic diversity by allowing interbreeding between geographically separated organisms, and generating new hybrids.
