genetic engineering Flashcards
What is a transformed organism? (1)
An organism that has had its DNA altered by genetic engineering
What is recombinant DNA? (1)
DNA containing sections from two species
What is a transgenic organism? (1)
An organism genetically engineered to include a gene from a different species
Why can organisms produce proteins from DNA of another species? (3)
The genetic code is universal; Transcription and translation mechanisms are similar across species; The recipient organism can use the transferred DNA to produce proteins
How is the desired DNA fragment isolated during genetic engineering? (2)
The DNA fragment containing the desired gene;
is isolated using restriction endonucleases
What are restriction endonucleases and their function? (2)
Enzymes that cut DNA at specific sequences of bases;
Recognition site
What is a palindromic sequence in DNA? (2)
A nucleotide sequence that reads the same from 5’-3’ direction on one strand;
As it does 3’-5’ on the complementary strand
What are sticky ends in DNA? (1)
Overhanging sequences of nucleotides exposed after a restriction enzyme cuts the DNA in an oblique manner
Why do restriction endonucleases cut DNA only at specific places? (2)
The shape of the recognition site is complementary;
To the enzyme’s active site
How can restriction endonucleases be used to produce DNA fragments? (3)
DNA is incubated with a specific restriction endonuclease;
Which cuts the DNA fragment through a hydrolysis reaction;
Leaving sticky ends that can join to other DNA fragments with the same sticky ends
How is the DNA fragment containing the desired gene inserted into a vector? (1)
Using restriction endonucleases and DNA ligase (in vivo cloning)
What is a vector in genetic engineering? (2)
Something used to transfer DNA into a cell;
The most common vectors are plasmids and bacteriophages
How is a DNA fragment inserted into a plasmid? (4)
The plasmid DNA is cut open with the same restriction endonuclease that isolated the DNA fragment;
Leaving complementary sticky ends;
The DNA fragment is mixed with the plasmid DNA and DNA ligase;
Which joins the sticky ends to form recombinant DNA
What is the end result of inserting a DNA fragment into a plasmid? (2)
A recombinant plasmid carrying the gene of interest;
Consisting of vector DNA and the DNA fragment
How is the gene transferred into bacteria using a vector? (1)
The vector with recombinant DNA is used to transfer the gene into bacterial cells
What is electroporation and how is it used to introduce recombinant plasmids into bacterial cells? (2)
Technique where bacterial cells and plasmid vectors are mixed and placed in an electroporator;
Which creates an electrical field that increases the cell membrane’s permeability, allowing plasmids to enter
What are the advantages of PCR over in vivo gene cloning? (5)
PCR is safer (uses DNA/enzymes, not whole cells);
Quicker: takes hours, whereas in vivo cloning takes weeks;
Less equipment: requires only a tube and heat block;
Less labour-intensive;
Can use low-quality DNA (e.g. forensic DNA)
What are the disadvantages of PCR over in vivo gene cloning? (4)
In vivo is less prone to mutation (Taq polymerase in PCR may introduce errors);
In vivo is cheaper (bacterial growth materials vs. expensive PCR chemicals);
In vivo can clone longer DNA pieces, while PCR is limited in size;
In vivo cloning is less technically complex (less critical conditions)
What are the positive and negative ethical issues associated with genetically modifying plants? (3)
Positive: Reduces pesticide use, which is better for the environment and cheaper;
Negative: Encourages monoculture, decreases biodiversity, and increases susceptibility to disease;
Genetically modified genes may spread to wild populations
What are the positive and negative ethical issues associated with genetically modifying animals? (2)
Positive: Can produce large quantities of drugs, making them more accessible;
Negative: Potential harm to animals, reduces animals to commodities, and concerns about animal welfare
What are the positive and negative ethical issues associated with genetically modifying pathogens? (2)
Positive: Large-scale production of human forms of hormones/antibiotics. Research can treat previously untreatable diseases;
Negative: Risk of infection for scientists, reversion of modified pathogens causing outbreaks, and potential use in biological warfare
What are the positives of genetically engineered organisms being owned by big companies? (2)
Owners of the patent receive money from selling the product;
Encouraging faster development of genetically engineered products
What are the negatives of genetically engineered organisms being owned by big companies? (1)
Farmers in poor countries may not be able to afford the patent for genetically modified seeds.
